NZ755711A - Methods and apparatus for respiratory treatment - Google Patents
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- NZ755711A NZ755711A NZ755711A NZ75571116A NZ755711A NZ 755711 A NZ755711 A NZ 755711A NZ 755711 A NZ755711 A NZ 755711A NZ 75571116 A NZ75571116 A NZ 75571116A NZ 755711 A NZ755711 A NZ 755711A
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- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Abstract
Apparatus and methods provide control for generation of a flow of air to a patient’s airways for different respiratory therapies. The pressure and a flow rate may be simultaneously controlled so as to provide a pressure therapy and a flow therapy. The system may include one or more flow generators, in which the control of the pressure and flow rate may include altering the output of one or more of the flow generators and/or an optional adjustable vent. The pressure and flow rate may each be held at a constant. One or both of the pressure and flow rate may also vary in accordance with a desired therapy. The air may be provided via a patient interface that includes a vent to atmosphere, which may be the adjustable vent. The vent may be actuated by a controller to implement the simultaneous control of pressure and flow rate of the air.
Description
METHODS AND APPARATUS FOR RESPIRATORY TREATMENT
1 CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of United States Provisional Application
No. 62/265,700, filed 10 December 2015, the entire disclosure of which is hereby
incorporated herein by reference.
2 STATEMENT REGARDING FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
Not Applicable
3 SEQUENCE LISTING
Not Applicable
4 BACKGROUND OF THE INVENTION
4.1 FIELD OF THE INVENTION
The present technology relates to one or more of the detection, diagnosis,
treatment, prevention and amelioration of respiratory-related disorders. In particular,
the present technology relates to medical devices or apparatus, and their use and may
include devices for directing treatment gas to a patient's respiratory system.
4.2 DESCRIPTION OF THE RELATED ART
4.2.1 Human Respiratory System and its Disorders
The respiratory system of the body facilitates gas exchange. The nose and
mouth form the entrance to the airways of a patient.
The airways include a series of branching tubes, which become narrower,
shorter and more numerous as they penetrate deeper into the lung. The prime function
of the lung is gas exchange, allowing oxygen to move from the air into the venous blood
and carbon dioxide to move out. The trachea divides into right and left main bronchi,
which further divide eventually into terminal bronchioles. The bronchi make up the
conducting airways, and do not take part in gas exchange. Further divisions of the
airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated
region of the lung is where the gas exchange takes place, and is referred to as the
respiratory zone. See “Respiratory Physiology”, by John B. West, Lippincott Williams
& Wilkins, 9th edition published 2011.
A range of respiratory disorders exist.
Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing
(SDB), is characterized by occlusion or obstruction of the upper air passage during
sleep. It results from a combination of an abnormally small upper airway and the normal
loss of muscle tone in the region of the tongue, soft palate and posterior oropharyngeal
wall during sleep. The condition causes the affected patient to stop breathing for periods
typically of 30 to 120 seconds duration, sometimes 200 to 300 times per night. It often
causes excessive daytime somnolence, and it may cause cardiovascular disease and
brain damage. The syndrome is a common disorder, particularly in middle aged
overweight males, although a person affected may have no awareness of the problem.
See US Patent 4,944,310 (Sullivan).
Cheyne-Stokes Respiration (CSR) is a disorder of a patient's respiratory
controller in which there are rhythmic alternating periods of waxing and waning
ventilation, causing repetitive de-oxygenation and re-oxygenation of the arterial blood.
It is possible that CSR is harmful because of the repetitive hypoxia. In some patients
CSR is associated with repetitive arousal from sleep, which causes severe sleep
disruption, increased sympathetic activity, and increased afterload. See US Patent
6,532,959 (Berthon-Jones).
Obesity Hyperventilation Syndrome (OHS) is defined as the combination
of severe obesity and awake chronic hypercapnia, in the absence of other known causes
for hypoventilation. Symptoms include dyspnea, morning headache and excessive
daytime sleepiness.
Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a
group of lower airway diseases that have certain characteristics in common. These
include increased resistance to air movement, extended expiratory phase of respiration,
and loss of the normal elasticity of the lung. Examples of COPD are emphysema and
chronic bronchitis. COPD is caused by chronic tobacco smoking (primary risk factor),
occupational exposures, air pollution and genetic factors. Symptoms include: dyspnea
on exertion, chronic cough and sputum production.
Neuromuscular Disease (NMD) is a broad term that encompasses many
diseases and ailments that impair the functioning of the muscles either directly via
intrinsic muscle pathology, or indirectly via nerve pathology. Some NMD patients are
characterised by progressive muscular impairment leading to loss of ambulation, being
wheelchair-bound, swallowing difficulties, respiratory muscle weakness and,
eventually, death from respiratory failure. Neuromuscular disorders can be divided into
rapidly progressive and slowly progressive: (i) Rapidly progressive disorders:
Characterised by muscle impairment that worsens over months and results in death
within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular
dystrophy (DMD) in teenagers); (ii) Variable or slowly progressive disorders:
Characterised by muscle impairment that worsens over years and only mildly reduces
life expectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic muscular
dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised
weakness, dysphagia, dyspnea on exertion and at rest, fatigue, sleepiness, morning
headache, and difficulties with concentration and mood changes.
Chest wall disorders are a group of thoracic deformities that result in
inefficient coupling between the respiratory muscles and the thoracic cage. The
disorders are usually characterised by a restrictive defect and share the potential of long
term hypercapnic respiratory failure. Scoliosis and/or kyphoscoliosis may cause severe
respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion,
peripheral oedema, orthopnea, repeated chest infections, morning headaches, fatigue,
poor sleep quality and loss of appetite.
Otherwise healthy individuals may take advantage of systems and devices
to prevent respiratory disorders from arising.
4.2.2 Therapies
Nasal Continuous Positive Airway Pressure (CPAP) therapy has been used
to treat Obstructive Sleep Apnea (OSA). The mechanism of action is that continuous
positive airway pressure acts as a pneumatic splint and may prevent upper airway
occlusion by pushing the soft palate and tongue forward and away from the posterior
oropharyngeal wall.
Non-invasive ventilation (NIV) provides ventilatory support (pressure
support) to a patient through the upper airways to assist the patient in taking a full breath
and/or maintain adequate oxygen levels in the body by doing some or all of the work
of breathing (e.g., mechanical work of breathing). The ventilatory support is provided
via a patient interface. NIV has been used to treat CSR, OHS, COPD, MD and Chest
Wall disorders.
Invasive ventilation (IV) provides ventilatory support to patients that are no
longer able to effectively breathe themselves and may be provided using a tracheostomy
tube.
High Flow therapy (HFT) is the provision of a continuous, heated,
humidified flow of air to an entrance to the airway through an unsealed or open interface
at flow rates similar to, or greater than peak inspiratory flow. HFT has been used to
treat OSA, CSR, COPD and other respiratory disorders. One mechanism of action is
that the high flow rate of air at the airway entrance improves ventilation efficiency by
flushing, or washing out, expired CO2 from the patient’s anatomical deadspace. HFT
is thus sometimes referred to as a deadspace therapy (DST).
Another form of flow therapy is supplemental oxygen therapy, whereby air
with an elevated percentage of oxygen is supplied to an entrance to the airway through
an unsealed interface.
4.2.3 Systems
One known device used for treating sleep disordered breathing is the S9
Sleep Therapy System, manufactured by ResMed. Ventilators such as the ResMed
Stellar™ Series of Adult and Paediatric Ventilators may provide support for invasive
and non-invasive non-dependent ventilation for a range of patients for treating a number
of conditions such as but not limited to NMD, OHS and COPD.
The ResMed Elisée™ 150 ventilator and ResMed VS III™ ventilator may
provide support for invasive and non-invasive dependent ventilation suitable for adult
or paediatric patients for treating a number of conditions. These ventilators provide
volumetric and barometric ventilation modes with a single or double limb circuit.
A treatment system may comprise a Positive Airway Pressure (PAP)
device/ventilator, an air circuit, a humidifier, a patient interface, and data management.
4.2.4 Patient Interface
A patient interface may be used to interface respiratory equipment to its
user, for example by providing a flow of air. The flow of air may be provided via a
mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea
of the user. Depending upon the therapy to be applied, the patient interface may form a
seal, e.g. with a face region of the patient, to facilitate the delivery of gas at a pressure
at sufficient variance with ambient pressure to effect therapy, e.g. a positive pressure of
about 10cmH O. For other forms of therapy, such as HFT, the patient interface may not
include a seal sufficient to facilitate delivery to the airways of a supply of gas at a
positive pressure of about 10cmH2O.
4.2.5 Respiratory Apparatus (PAP device / Ventilator)
Examples of respiratory apparatuses include ResMed’s S9 AutoSet PAP
device and ResMed’s Stellar™ 150 ventilator. Respiratory apparatuses typically
comprise a pressure generator, such as a motor-driven blower or a compressed gas
reservoir, and are configured to supply a flow of air to the airway of a patient, typically
via a patient interface such as those described above. In some cases, the flow of air may
be supplied to the airway of the patient at positive pressure. The outlet of the respiratory
apparatus is connected via an air circuit to a patient interface such as those described
above.
4.2.6 Humidifier
Delivery of a flow of air without humidification may cause drying of
airways. Medical humidifiers are used to increase humidity and/or temperature of the
flow of air in relation to ambient air when required, typically where the patient may be
asleep or resting (e.g. at a hospital). As a result, a medical humidifier is preferably small
for bedside placement, and it is preferably configured to only humidify and/or heat the
flow of air delivered to the patient without humidifying and/or heating the patient’s
surroundings.
BRIEF SUMMARY OF THE TECHNOLOGY
The present technology is directed towards providing medical devices used
in the diagnosis, amelioration, treatment, or prevention of respiratory disorders having
one or more of improved comfort, cost, efficacy, ease of use and manufacturability.
A first aspect of the present technology relates to apparatus used in the
diagnosis, amelioration, treatment or prevention of a respiratory disorder.
Another aspect of the present technology relates to methods used in the
diagnosis, amelioration, treatment or prevention of a respiratory disorder.
Another aspect of the present technology relates to the provision of a dead
space therapy comprising a controlled generation a flow of air towards a patient's
respiratory cavity for flushing expired gas (CO ) from the patient's anatomical
deadspace.
Another aspect of the present technology relates to the provision of a
pressure therapy comprising a controlled generation of pressurized air at a patient's
respiratory system, (e.g., pressure support therapy to mechanically assist with patient
respiration).
Another aspect of the present technology relates to methods of providing
such a pressure therapy and such a dead space therapy simultaneously.
Another aspect of the present technology relates to apparatus configured for
provision of such a pressure therapy and such a dead space therapy simultaneously or
alternatively.
Some versions of the present technology may include a method for
controlling a supply of air to a patient’s airways for a respiratory therapy. The method
may include identifying, by one or more controllers, a predetermined pressure and a
predetermined flow rate of the air to be provided to a patient via a patient interface.
The method may include determining, with a plurality of sensors, a pressure and a flow
rate of the air being provided to the patient via the patient interface. The method may
include controlling, by the one or more controllers, a first flow generator and a second
flow generator, each flow generator being configured to provide a flow of the air to the
patient interface, so as to simultaneously control the pressure and the flow rate of the
air at the patient interface to correspond with the predetermined pressure and the
predetermined flow rate, respectively.
In some method versions, the controlling the first flow generator and the
second flow generator may include adjusting output of at least one of the first flow
generator and the second flow generator. The patient interface may include a projection
portion configured to conduct a flow of the air into a naris of the patient and a mask
portion configured to apply pressure of the air to the patient. The mask portion may be
a nasal mask. The mask portion may include nasal pillows. The method may include
detecting a continuous mouth leak, and reducing the predetermined pressure upon
detecting the continuous mouth leak. The first flow generator may provide the flow of
the air through the projection portion of the patient interface and the second flow
generator may apply pressure of the air to the mask portion of the patient interface. At
least one, or both, of the predetermined pressure and the predetermined flow rate may
vary over a period of time corresponding to a breathing cycle of the patient. The
predetermined flow rate may be constant for at least some predetermined period of time
and/or the predetermined pressure may be constant during the predetermined period of
time. The mask portion of the patient interface further may include a vent.
In some versions, the method may include limiting the predetermined
flow rate to be less than a maximum flow rate. The maximum flow rate may be a vent
flow rate minus a peak expiratory flow rate of the patient. The simultaneously
controlling of the pressure and the flow rate may further include controlling an
adjustment of the vent. The vent may include an active proximal valve. The
simultaneously controlling of the pressure and the flow rate may be performed so as to
provide the patient with a positive airway pressure therapy and a deadspace therapy.
The positive airway pressure therapy may be a ventilation therapy. The method may
include determining, by the one or more controllers, the predetermined pressure and the
predetermined flow rate so as restrict the predetermined pressure and the predetermined
flow rate to a curve of equal efficacy. The method may include calculating, in a
controller of the one or more controllers, a target ventilation based on anatomical
deadspace information and a deadspace therapy reduction value. The method may
include generating, in a controller of the one or more controllers, a cardiac output
estimate by controlling a step change in the predetermined flow rate of the air and
determining a change in a measure of ventilation in relation to the step change. The
method may include initiating, by the controller of the one or more controllers, the
controlling of the step change in the predetermined flow rate of the air in response to a
detection of sleep.
Some versions of the present technology may include a system for
delivery of a flow of air to a patient's airways. The system may include a first flow
generator and a second flow generator, each configured to provide air to a patient via a
patient interface. The system may include one or more controllers. The one or more
controllers may be configured to determine a pressure and a flow rate of the air being
provided to the patient via the patient interface with a plurality of sensors. The one or
more controllers may be configured to control the first flow generator and the second
flow generator so as to simultaneously control the pressure and the flow rate of the air
at the patient interface to correspond with a predetermined pressure and a
predetermined flow rate, respectively.
In some versions, the system may include the patient interface, wherein
the patient interface may include a projection portion configured to conduct a flow of
the air into a naris of the patient and a mask portion configured to apply pressure of the
air to the patient. The mask portion may be a nasal mask. The mask portion may be
nasal pillows. The first flow generator may conduct the flow of the air through the
projection portion and the second flow generator may apply pressure of the air to the
mask portion. The plurality of sensors may include a flow rate sensor and a pressure
sensor. An output of the first flow generator may be measured by the flow rate sensor
and an output of the second flow generator may be measured by the pressure sensor.
The one or more controllers may be configured to maintain at least one of the
predetermined pressure and the predetermined flow rate at a constant value for at least
some period of time. The one or more controllers may be further configured to vary at
least one of the predetermined pressure and the predetermined flow rate over a period
of time corresponding to a breathing cycle of the patient. The mask portion of the
patient interface may include a vent. The one or more controllers may be configured
to limit the predetermined flow rate to be less than a maximum flow rate. The one or
more controllers may be configured to determine the maximum flow rate by subtracting
a peak expiratory flow rate of the patient from a vent flow rate. The vent may be an
adjustable vent and the one or more controllers may be configured to control the
adjustable vent so as to control the pressure and the flow rate. The adjustable vent may
include an active proximal valve. The simultaneous control of the pressure and the
flow rate of the air may provide the patient with a positive airway pressure therapy and
a deadspace therapy. The positive airway pressure therapy may be a ventilation
therapy.
In some versions, the one or more controllers may be configured to
determine the predetermined pressure and the predetermined flow rate so as to restrict
the predetermined pressure and the predetermined flow rate to a curve of equal efficacy.
The one or more controllers may include one controller configured to control the first
flow generator and the second flow generator. The one or more controllers may include
a first controller configured to control the first flow generator and a second controller
configured to control the second flow generator. The first controller may be configured
to obtain the flow rate of the air being provided by the second flow generator. The
second controller may be configured to obtain the pressure of the air being provided by
the first flow generator. In some cases, a controller of the one or more controllers may
be configured to compute a target ventilation based on anatomical deadspace
information and a deadspace therapy reduction value. A controller of the one or more
controllers may be configured to generate a cardiac output estimate by controlling a
step change in the predetermined flow rate of the air and determining a change in a
measure of ventilation in relation to the step change. The controller of the one or more
controllers may be configured to initiate control of the step change in the predetermined
flow rate of the air in response to a detection of sleep.
Some versions of the present technology may include a system for
delivery of a flow of air to a patient's airways. The system may include a flow generator
configured to provide air to a patient via an air circuit and a patient interface. The
system may include an adjustable vent. The system may include one or more
controllers. The one or more controllers may be configured to determine a pressure and
a flow rate of the air being provided to the patient via the patient interface with a
plurality of sensors. The one or more controllers may be configured to control the flow
generator and the adjustable vent so as to simultaneously control the pressure and the
flow rate of the air at the patient interface to correspond with a predetermined pressure
and a predetermined flow rate, respectively.
In some versions, the system may include the patient interface. The
patient interface may include a projection portion configured to conduct a flow of the
air into a naris of a patient and a mask portion configured to apply pressure of the air to
the patient. The adjustable vent may be part of the mask portion of the patient interface.
The plurality of sensors may include a pressure sensor for determining a measured
pressure of the air. The plurality of sensors may include a flow rate sensor for
determining a measured flow rate of the air through the projection portion of the patient
interface. In some cases, at least one of the pressure sensor and the flow rate sensor
may be located at an output of the flow generator. In some cases, at least one of the
pressure sensor and the flow rate sensor may be located at the patient interface. The
one or more controllers may be configured to maintain at least one, or both, of the
predetermined pressure and the predetermined flow rate at a constant value for a period
of time. The one or more controllers may be further configured to vary the
predetermined pressure in accordance with a breathing cycle of the patient. The
simultaneous control of the pressure and the flow rate of the air may provide the patient
with a positive airway pressure therapy and a deadspace therapy. The positive airway
pressure therapy may be a ventilation therapy. The one or more controllers may be
configured to determine the predetermined pressure and the predetermined flow rate to
restrict the predetermined pressure and the predetermined flow rate to a curve of equal
efficacy.
In some versions, the system may further include a variable resistance
in the air circuit, wherein the one or more controllers may be configured to control one
or more of the pressure and the flow rate of the air by adjusting the resistance of the
variable resistance. In some cases, a controller of the one or more controllers may be
configured to compute a target ventilation based on anatomical deadspace information
and a deadspace therapy reduction value. A controller of the one or more controllers
may be configured to generate a cardiac output estimate by controlling a step change in
the predetermined flow rate of the air and determining a change in a measure of
ventilation in relation to the step change. The controller of the one or more controllers
may be configured to initiate control of the step change in the predetermined flow rate
of the air in response to a detection of sleep.
Some versions of the present technology may include a method for
controlling a supply of air to a patient’s airways for a respiratory therapy. The method
may include identifying, by one or more controllers, a predetermined pressure and a
predetermined flow rate of the air to be provided to a patient via an air circuit and a
patient interface. The method may include determining, with a plurality of sensors, a
pressure and a flow rate of the air being provided to the patient via the patient interface.
The method may include controlling, by the one or more controllers, a flow generator
configured to provide the air to the patient interface, and an adjustable vent so as to
simultaneously control the pressure and the flow rate of the air at the patient interface
to correspond with the predetermined pressure and the predetermined flow rate,
respectively. The patient interface may include a projection portion configured to
conduct a flow of the air into a naris of the patient and a mask portion configured to
apply pressure of the air to the patient. The flow generator may provide the flow of the
air through the projection portion of the patient interface thereby applying pressure of
the air to the mask portion of the patient interface. The method may include
maintaining, by the one or more controllers, at least one of the predetermined pressure
and the predetermined flow rate at a constant value for a period of time. The method
may include varying, by the one or more controllers, the predetermined pressure in
accordance with a breathing cycle of the patient. The simultaneous control of the
pressure and the flow rate of the air may include control of a positive airway pressure
therapy and a deadspace therapy. The positive airway pressure therapy may be a
ventilation therapy.
In some versions, the method may include determining, by the one or
more controllers, the predetermined pressure and the predetermined flow rate so as to
restrict the predetermined pressure and the predetermined flow rate to a curve of equal
efficacy. The controlling of the adjustable vent comprises adjusting, by the one or more
controllers, a venting characteristic of the adjustable vent in synchrony with the
patient’s breathing cycle so as to maintain the pressure of the air at the patient interface
to correspond with the predetermined pressure. The method may include adjusting, by
the one or more controllers, a resistance of a variable resistance in the air circuit so as
to control one or more of the pressure and the flow rate of the air. The method may
include calculating, in the one or more controllers, a target ventilation based on
anatomical deadspace information and a deadspace therapy reduction value. The
method may include generating, in the one or more controllers, a cardiac output
estimate by controlling a step change in the predetermined flow rate of the air and
determining a change in a measure of ventilation in relation to the step change. The
method may include initiating, by the one or more controllers, the controlling of the
step change in the predetermined flow rate of the air in response to a detection of sleep.
In yet another aspect of the present technology, a supply of air to a patient’s
airways may be controlled in connection with a respiratory therapy. The respiratory
therapy may include identifying, by one or more controllers, a predetermined pressure
and a predetermined flow rate of air to be provided to a patient via a patient interface;
determining, by one or more sensors, a pressure and a flow rate of the air being provided
to a patient via a patient interface; and controlling, by the one or more controllers, a
first flow generator and a second flow generator, so as to simultaneously control the
pressure and the flow rate of the air to correspond with the predetermined pressure and
the predetermined flow rate, respectively. Controlling the first flow generator and the
second flow generator may include adjusting an output of at least one of the first flow
generator and the second flow generator. In addition, the patient interface may include
a projection portion configured to conduct a flow of the air into a naris of the patient
and a mask portion configured to apply pressure of the air to the patient. The first flow
generator may conduct the flow of the air through a projection portion of the patient
interface and the second flow generator may apply pressure from the air to a mask
portion of the patient interface.
In still another aspect, at least one of the predetermined pressure and the
predetermined flow rate may vary over a period of time corresponding to a breathing
cycle of the patient. The predetermined flow rate may also be constant for at least some
predetermined period of time and the predetermined pressure may be constant during
the predetermined period of time.
In another aspect, the patient interface may include a vent, and
simultaneously controlling the pressure and the flow rate may include controlling an
adjustment of the vent. The vent may include an adjustable proximal valve.
In still another aspect, simultaneously controlling the pressure and the flow
rate may be performed so as to provide the patient with a pressure therapy and a
deadspace therapy.
In another aspect, a system for delivery of a flow of air to a patient's airways
may include a first flow generator and a second flow generator for providing air to a
patient respiratory interface and one or more controllers configured to: determine a
pressure and a flow rate of the air with a plurality of sensors, and control the first flow
generator and the second flow generator so as to simultaneously control the pressure
and the flow rate of the air at the patient interface. The patient interface may include a
projection portion configured to conduct a flow of the air into a naris of the patient and
a mask portion configured to apply pressure of the air to the patient. In addition, the
first flow generator may conduct the flow of the air through the projection portion and
the second flow generator may apply air pressure to the mask portion. The plurality of
sensors may include a flow sensor and a pressure sensor, and an output of the first flow
generator may be measured by the flow sensor and an output of the first flow generator
may be measured by the pressure sensor. The controllers may be configured to maintain
at least one of the pressure and the flow rate at a constant for at least some period of
time. The controllers may also be configured so that at least one of the pressure and
the flow rate is variable over a period of time. The patient interface may include an
adjustable vent and the one or more controllers may be further configured to control the
adjustable vent.
In still another aspect, a system for delivery of a flow of air to a patient's
airways may include a flow generator for providing air to a patient via a patient
interface, an adjustable vent, and one or more controllers. The one or more controllers
may be configured to determine a pressure and a flow rate of the air with one or more
sensors and control at least one of the flow generator and the adjustable vent so as to
simultaneously control and vary the pressure and the flow rate of the air over a breathing
cycle of the patient. The patient interface may include a projection portion configured
to conduct a flow of the air into a naris of a patient and a mask portion configured to
apply pressure of the air to the patient. The adjustable vent may be a part of the mask
portion of the patient interface. The system may also include a pressure sensor for
determining a measured pressure of the air corresponding to the pressure of the air at
the mask portion of the patient interface and a flow sensor for determining a measured
flow rate of the air through the projection portion of the patient interface. At least one
of the pressure sensor and the flow sensor may be located at an output of the flow
generator or at the patient interface. In addition, the controllers may be configured to
vary the pressure in accordance with a detected breathing cycle. The flow generator
may also include a first flow generator and a second flow generator.
Of course, portions of the aspects may form sub-aspects of the present
technology. Also, various ones of the sub-aspects and/or aspects may be combined in
various manners and also constitute additional aspects or sub-aspects of the present
technology.
Other features of the technology will be apparent from consideration of the
information contained in the following detailed description, abstract, drawings and
claims.
6 BRIEF DESCRIPTION OF THE DRAWINGS
The present technology is illustrated by way of example, and not by way of
limitation, in the figures of the accompanying drawings, in which like reference
numerals refer to similar elements including:
6.1 TREATMENT SYSTEMS
Fig. 1A shows a system including a patient 1000 wearing a patient interface
3000, in the form of a nasal pillows, receives a supply of air at positive pressure from
a Combination Therapy (CT) device 4000. Air from the CT device is humidified in a
humidifier 5000, and passes along an air circuit 4170 to the patient 1000. A bed partner
1100 is also shown.
Fig. 1B shows a system including a patient 1000 wearing a patient interface
3000, in the form of a nasal mask, receives a supply of air at positive pressure from a
CT device 4000. Air from the CT device is humidified in a humidifier 5000, and passes
along an air circuit 4170 to the patient 1000.
Fig. 1C shows a system including a patient 1000 wearing a patient interface
3000, in the form of a full-face mask, receives a supply of air at positive pressure from
a CT device 4000. Air from the CT device is humidified in a humidifier 5000, and
passes along an air circuit 4170 to the patient 1000.
6.2 THERAPY
6.2.1 Respiratory system
Fig. 2 shows an overview of a human respiratory system including the nasal
and oral cavities, the larynx, vocal folds, oesophagus, trachea, bronchus, lung, alveolar
sacs, heart and diaphragm.
Fig. 3 shows a patient interface in the form of a nasal mask in accordance
with one form of the present technology.
6.3 COMBINATION THERAPY (CT) DEVICE
Fig. 4A shows example components of a CT device in accordance with one
form of the present technology.
Fig. 4B shows a schematic diagram of either a pressure control or flow
control pneumatic circuit of a CT device in accordance with one form of the present
technology. The directions of upstream and downstream are indicated.
Fig. 4C shows a schematic diagram of the electrical components of a CT
device in accordance with one aspect of the present technology.
6.4 HUMIDIFIER
Fig. 5 shows an isometric view of a humidifier suitable for use with a
respiratory apparatus.
6.5 PATIENT INTERFACE
Fig. 6 shows a conventional nasal cannula;
Fig. 7 shows the nasal cannula of Fig. 6 in use with a mask;
Fig. 8 is an illustration of a nasal cannula with a coupler extension;
Figs. 9A, 9B, 9C and 9D illustrate various cross sectional profiles for
coupler extensions of the present technology taken along line A—A of Fig. 8;
Fig. 10A is an illustration of a nasal cannula with a coupler extension in use
with a mask;
Fig. 10B is an illustration of a nasal cannula with a coupler extension in use
with a mask showing a seat portion;
Fig. 11 is another illustration of a nasal cannula with a coupler extension
having a seat ridge, the figure also includes a cross sectional view of the coupler
extension taken along line A--A;
Fig. 12 is another illustration of a nasal cannula with a coupler extension
Fig. 11 in use with a mask;
Fig. 13 is an illustration of another version of a nasal cannula with a coupler
extension in use with a mask;
Fig. 14A is a plan view and a front elevation view of another example
coupler extension for a nasal cannula of the present technology;
Fig. 14B is a front elevation view of another coupler extension for a nasal
cannula;
Fig. 14C is a front elevation view of another coupler extension for a nasal
cannula;
Fig. 15A is an illustration nasal interface of the present technology with
nasal projections;
Fig. 15B is an illustration of another nasal interface with nasal projections;
Fig. 16 shows the nasal interface of Fig. 15A in use by a patient;
Fig. 17A and 17B show elevation and cross sectional views respectively of
a further example nasal interface;
Fig. 18 is an illustration of a further nasal interface with a pillow vent;
Fig. 19A and 19B are illustrations of a further nasal interface with pillow
vents in showing inspiratory flow and expiratory flow respectively;
Fig. 20A and 20B are illustrations of a further nasal interface with vents
showing expiratory and inspiratory operations respectively;
Fig. 20C and 20D are illustrations of a further nasal interface with vents
showing expiratory and inspiratory operations respectively;
Fig. 20E and 20F are illustrations of a further nasal interface with vents
showing expiratory and inspiratory operations respectively;
Fig. 21 is an illustration of a nasal pillow with a further example nasal
projection;
Fig. 22 is an illustration of a valve membrane of the example nasal
projection of Fig. 21;
Figs. 23A and 23B show expiratory and inspiratory operations respectively
of the valve membrane of the example nasal projection of Fig. 21;
Fig. 24 illustrates an external side view of a mask frame with interface ports
for coupling with supply conduits;
Fig. 25A shows a plenum chamber or patient side of a mask frame for some
versions of the present technology;
Fig. 25B shows another plenum chamber or patient side of a mask frame of
another version of the present technology;
6.6 COMBINATION THERAPY SYSTEM
Fig. 26 is an example schematic diagram of a combination therapy system
in accordance with some versions of the present technology;
Fig. 27 shows an electrical circuit model representing the flow of air in a
combination therapy system in accordance with some versions of the present
technology;
Fig. 28 is another example schematic diagram of a combination therapy
system in accordance with some versions of the present technology;
Fig. 29 is an example control methodology diagram for a combination
therapy in accordance with some versions of the present technology;
Fig. 30 is a graph illustrating the relationship between interface pressure
and vent flow in one implementation of the present technology;
Fig. 31 is a graph illustrating the relationship between interface pressure
and vent flow in one implementation of the present technology;
Fig. 32 is a graph illustrating the additive or complementary nature of
combination therapy according to the present technology; and
Fig. 33 shows an electrical circuit model representing the flow of air in a
combination therapy system in accordance with another implementation of the present
technology.
7 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY
Before the present technology is described in further detail, it is to be
understood that the technology is not limited to the particular examples described
herein, which may vary. It is also to be understood that the terminology used in this
disclosure is for the purpose of describing only the particular examples discussed
herein, and is not intended to be limiting.
7.1 THERAPY
In one form, the present technology comprises a control method for treating
a respiratory disorder comprising controlling positive pressure to the entrance of the
airways of a patient 1000 so as to provide pressure therapy as well as controlling the
flow rate of air to the patient, so as to provide deadspace therapy, so as to allow for
anatomical and/or apparatus deadspace flushing.
7.2 TREATMENT SYSTEMS
In one form, the present technology comprises an apparatus for treating a
respiratory disorder. The apparatus may comprise a CT device 4000 for supplying
pressurised air to the patient 1000 via an air circuit 4170 to a patient interface 3000.
7.3 PATIENT INTERFACE
A non-invasive patient interface 3000 in accordance with one aspect of the
present technology comprises the following functional aspects: a seal-forming structure
3100, a plenum chamber 3200, a positioning and stabilising structure 3300, a vent 3400,
a decoupling structure 3500, a connection port 3600 for connection to air circuit 4170,
and a forehead support 3700. In some forms a functional aspect may be provided by
one or more physical components. In some forms, one physical component may provide
one or more functional aspects. In use the seal-forming structure 3100 is arranged to
surround an entrance to the airways of the patient so as to facilitate the supply of air at
positive pressure to the airways.
An alternative non-invasive patient interface is an oro-nasal interface (full-
face mask) that seals around both the nose and the mouth of the patient 1000.
7.4 COMBINATION THERAPY (CT) DEVICE
An example CT device 4000 in accordance with one aspect of the present
technology may comprise mechanical and pneumatic components 4100, electrical
components 4200 and may be programmed to execute one or more therapy algorithms.
The CT device preferably has an external housing 4010, preferably formed in two parts,
an upper portion 4012 and a lower portion 4014. Furthermore, the external housing
4010 may include one or more panel(s) 4015. Preferably the CT device 4000 comprises
a chassis 4016 that supports one or more internal components of the CT device 4000.
In one form one, or a plurality of, pneumatic block(s) 4020 (e.g., two) is supported by,
or formed as part of the chassis 4016. The CT device 4000 may include a handle 4018.
The CT device 4000 may have one or more pneumatic paths depending on
the types of patient interface coupled with the device. A pneumatic path of the CT
device 4000 may comprise an inlet air filter 4112, an inlet muffler 4122, a pressure
device 4140 capable of supplying air at positive pressure (such as a blower 4142) and
a flow device 4141 capable of supplying air at a desired or target flow rate (e.g., a
blower or oxygen supply line etc.), one or more pneumatic blocks 4020 and an outlet
muffler 4124. One or more transducers 4270, such as pressure sensors or pressure
transducers 4274 and flow rate sensors or flow transducers 4272 may be included in the
pneumatic path(s). Each pneumatic block 4020 may comprise a portion of the
pneumatic path that is located within the external housing 4010 and may house either
pressure device 4140 or flow device 4141.
The CT device 4000 may have an electrical power supply 4210, one or more
input devices 4220, a central controller 4230, a therapy device controller 4240, a
pressure device 4140, flow device 4141, one or more protection circuits 4250, memory
4260, transducers 4270, data communication interface 4280 and one or more output
devices 4290. Electrical components 4200 may be mounted on a single Printed Circuit
Board Assembly (PCBA) 4202. In an alternative form, the CT device 4000 may include
more than one PCBA 4202.
The CT device 4000 may be configured to control provision of any of the
pressure and/or flow therapies described throughout this specification.
7.4.1 CT device mechanical & pneumatic components 4100
7.4.1.1 Air filter(s) 4110
A CT device in accordance with one form of the present technology may
include an air filter 4110, or a plurality of air filters 4110 for each pneumatic path.
In one form, an inlet air filter 4112 is located at the beginning of the
pneumatic path upstream of a pressure device 4140. See Fig. 4B.
In one form, an outlet air filter 4114, for example an antibacterial filter, is
located between an outlet of the pneumatic block 4020 and a patient interface 3000. See
Fig. 4B.
7.4.1.2 Muffler(s) 4120
In one form of the present technology, an inlet muffler 4122 is located in
the pneumatic path upstream of a pressure device 4140. See Fig. 4B.
In one form of the present technology, an outlet muffler 4124 is located in
the pneumatic path between the pressure device 4140 and a patient interface 3000. See
Fig. 4B.
7.4.1.3 Pressure device 4140 and flow device 4141
In one form of the present technology, CT device 4000 may contain two
flow generators, such as a pressure device 4140 and a flow device 4141 (see Fig. 4C).
Pressure device 4140 may provide a supply of air at positive pressure to a first portion
of the patient interface 3000, and flow device 4141 may provide a flow of air to a second
portion of patient interface 3000. Each flow generator may include a controllable
blower 4142. For example the blower 4142 may include a brushless DC motor 4144
with one or more impellers housed in a volute. The blower may be preferably capable
of delivering a supply of air, for example at a rate of up to about 120 litres/minute, at a
positive pressure in a range from about 4 cmH O to about 20 cmH O, or in other forms
up to about 30 cmH O. The blower may include a blower as described in any one of the
following patents or patent applications the contents of which are incorporated herein
in their entirety: U.S. patent number 7,866,944; U.S. patent number 8,638,014; U.S.
Patent number 8,636,479; and PCT patent application publication number WO
2013/020167.
The pressure device 4140 and flow device 4141 may operate under the
control of the therapy device controller 4240. Alternatively, the pressure device 4140
and the flow device 4141 may operate under the control of separate controllers.
In other forms, a pressure device 4140 or flow device 4141 may be a piston-
driven pump, a pressure regulator connected to a high pressure source (e.g. compressed
air reservoir) or bellows.
7.4.1.4 Transducer(s) 4270
Transducers may be internal of the device, or external of the CT device.
External transducers may be located for example on or form part of the air circuit, e.g.
the patient interface. External transducers may be in the form of non-contact sensors
such as a Doppler radar movement sensor that transmit or transfer data to the CT device.
In one form of the present technology, one or more transducers 4270 are
located upstream and/or downstream of the pressure device 4140. The one or more
transducers 4270 may be constructed and arranged to measure properties such as a flow
rate, a pressure or a temperature at that point in the pneumatic path.
In one form of the present technology, one or more transducers 4270 may
be located proximate to the patient interface 3000.
In one form, a signal from a transducer 4270 may be filtered, such as by
low-pass, high-pass or band-pass filtering.
7.4.1.4.1 Flow transducer 4272
A flow transducer 4272 in accordance with the present technology may be
based on a differential pressure transducer, for example, an SDP600 Series differential
pressure transducer from SENSIRION.
In use, a signal representing a flow rate from the flow transducer 4272 is
received by the central controller 4230.
7.4.1.4.2 Pressure transducer 4274
A pressure transducer 4274 in accordance with the present technology is
located in fluid communication with the pneumatic circuit. An example of a suitable
pressure transducer is a sensor from the HONEYWELL ASDX series. An alternative
suitable pressure transducer is a sensor from the NPA Series from GENERAL
ELECTRIC.
In use, a signal from the pressure transducer 4274, is received by the central
controller 4230.
7.4.1.4.3 Motor speed transducer 4276
In one form of the present technology a motor speed transducer 4276 is
used to determine a rotational velocity of the motor 4144 and/or the blower 4142. A
motor speed signal from the motor speed transducer 4276 is preferably provided to the
therapy device controller 4240. The motor speed transducer 4276 may, for example,
be a speed sensor, such as a Hall effect sensor.
7.4.1.5 Anti-spill back valve 4160
In one form of the present technology, an anti-spill back valve is located
between the humidifier 5000 and the pneumatic block 4020. The anti-spill back valve
is constructed and arranged to reduce the risk that water will flow upstream from the
humidifier 5000, for example to the motor 4144.
7.4.1.6 Air circuit 4170
An air circuit 4170 in accordance with an aspect of the present technology
is a conduit or a tube constructed and arranged in use to allow a flow of air to travel
between two components such as the pneumatic block 4020 and the patient interface
3000.
In particular, the air circuit may be in fluid connection with the outlet of the
pneumatic block and the patient interface. The air circuit may be referred to as air
delivery tube. In some cases there may be separate limbs of the circuit for inhalation
and exhalation and/or for multiple patient interfaces. In other cases a single limb is
used.
7.4.1.7 Oxygen delivery 4180
In one form of the present technology, supplemental oxygen 4180 is
delivered to one or more points in the pneumatic path, such as upstream of the
pneumatic block 4020, to the air circuit 4170 and/or to the patient interface 3000, such
as via the nasal projections or prongs of a cannula.
7.4.2 CT device electrical components 4200
7.4.2.1 Power supply 4210
A power supply 4210 may be located internal or external of the external
housing 4010 of the CT device 4000.
In one form of the present technology power supply 4210 provides
electrical power to the CT device 4000 only. In another form of the present technology,
power supply 4210 provides electrical power to both CT device 4000 and humidifier
5000.
7.4.2.2 Input devices 4220
In one form of the present technology, a CT device 4000 includes one or
more input devices 4220 in the form of buttons, switches or dials to allow a person to
interact with the device. The buttons, switches or dials may be physical devices, or
software devices accessible via a touch screen. The buttons, switches or dials may, in
one form, be physically connected to the external housing 4010, or may, in another
form, be in wireless communication with a receiver that is in electrical connection to
the central controller 4230.
In one form the input device 4220 may be constructed and arranged to allow
a person to select a value and/or a menu option.
7.4.2.3 Central controller 4230
In one form of the present technology, the central controller 4230 is one or
a plurality of processors suitable to control a CT device 4000.
Suitable processors may include an x86 INTEL processor, a processor
based on ARM Cortex-M processor from ARM Holdings such as an STM32 series
microcontroller from ST MICROELECTRONIC. In certain alternative forms of the
present technology, a 32-bit RISC CPU, such as an STR9 series microcontroller from
ST MICROELECTRONICS or a 16-bit RISC CPU such as a processor from the
MSP430 family of microcontrollers, manufactured by TEXAS INSTRUMENTS may
also be suitable.
In one form of the present technology, the central controller 4230 is a
dedicated electronic circuit.
In one form, the central controller 4230 is an application-specific integrated
circuit. In another form, the central controller 4230 comprises discrete electronic
components.
The central controller 4230 may be configured to receive input signal(s)
from one or more transducers 4270, and one or more input devices 4220.
The central controller 4230 may be configured to provide output signal(s)
to one or more of an output device 4290, a therapy device controller 4240, a data
communication interface 4280 and humidifier controller 5250.
In some forms of the present technology, the central controller 4230is
configured to implement the one or more methodologies described herein such as the
one or more algorithms. In some cases, the central controller 4230 may be integrated
with a CT device 4000. However, in some forms of the present technology the central
controller 4230 may be implemented discretely from the flow generation components
of the CT device 4000, such as for purpose of performing any of the methodologies
described herein without directly controlling delivery of a respiratory treatment. For
example, the central controller 4230 may perform any of the methodologies described
herein for purposes of determining control settings for a ventilator or other respiratory
related events by analysis of stored data such as from any of the sensors described
herein.
7.4.2.4 Clock 4232
Preferably CT device 4000 includes a clock 4232 that is connected to the
central controller 4230.
7.4.2.5 Therapy device controller 4240
In one form of the present technology, therapy device controller 4240 is a
pressure control module 4330 that forms part of the algorithms executed by the central
controller 4230. The therapy device controller 4240 may be a flow control module that
forms part of the algorithms executed by the central controller 4230. In some examples
it may be both a pressure control and flow control module.
In one form of the present technology, therapy device controller 4240 may
be one or more dedicated motor control integrated circuits. For example, in one form a
MC33035 brushless DC motor controller, manufactured by ONSEMI is used.
7.4.2.6 Protection circuits 4250
Preferably a CT device 4000 in accordance with the present technology
comprises one or more protection circuits 4250.
The one or more protection circuits 4250 in accordance with the present
technology may comprise an electrical protection circuit, a temperature and/or pressure
safety circuit.
7.4.2.7 Memory 4260
In accordance with one form of the present technology the CT device 4000
includes memory 4260, preferably non-volatile memory. In some forms, memory 4260
may include battery powered static RAM. In some forms, memory 4260 may include
volatile RAM.
Preferably memory 4260 is located on the PCBA 4202. Memory 4260
may be in the form of EEPROM, or NAND flash.
Additionally or alternatively, CT device 4000 includes removable form of
memory 4260, for example a memory card made in accordance with the Secure Digital
(SD) standard.
In one form of the present technology, the memory 4260 acts as a non-
transitory computer readable storage medium on which is stored computer program
instructions expressing the one or more methodologies described herein, such as the
one or more algorithms.
7.4.2.8 Data communication systems 4280
In one preferred form of the present technology, a data communication
interface 4280 is provided, and is connected to the central controller 4230. Data
communication interface 4280 is preferably connectable to remote external
communication network 4282 and/or a local external communication network 4284.
Preferably remote external communication network 4282 is connectable to remote
external device 4286. Preferably local external communication network 4284 is
connectable to local external device 4288.
In one form, data communication interface 4280 is part of the central
controller 4230. In another form, data communication interface 4280 is separate from
the central controller 4230, and may comprise an integrated circuit or a processor.
In one form, remote external communication network 4282 is the Internet.
The data communication interface 4280 may use wired communication (e.g. via
Ethernet, or optical fibre) or a wireless protocol (e.g. CDMA, GSM, LTE) to connect
to the Internet.
In one form, local external communication network 4284 utilises one or
more communication standards, such as Bluetooth, or a consumer infrared protocol.
In one form, remote external device 4286 is one or more computers, for
example a cluster of networked computers. In one form, remote external device 4286
may be virtual computers, rather than physical computers. In either case, such remote
external device 4286 may be accessible to an appropriately authorised person such as a
clinician.
Preferably local external device 4288 is a personal computer, mobile phone,
tablet or remote control.
7.4.2.9 Output devices including optional display, alarms
An output device 4290 in accordance with the present technology may take
the form of one or more of a visual, audio and haptic unit. A visual display may be a
Liquid Crystal Display (LCD) or Light Emitting Diode (LED) display.
7.4.2.9.1 Display driver 4292
A display driver 4292 receives as an input the characters, symbols, or
images intended for display on the display 4294, and converts them to commands that
cause the display 4294 to display those characters, symbols, or images.
7.4.2.9.2 Display 4294
A display 4294 is configured to visually display characters, symbols, or
images in response to commands received from the display driver 4292. For example,
the display 4294 may be an eight-segment display, in which case the display driver
4292 converts each character or symbol, such as the figure “0”, to eight logical signals
indicating whether the eight respective segments are to be activated to display a
particular character or symbol.
7.5 HUMIDIFIER
In one form of the present technology there is provided a humidifier 5000
as shown in Fig. 5 to change the absolute humidity of air for delivery to a patient relative
to ambient air. Typically, the humidifier 5000 is used to increase the absolute humidity
and increase the temperature of the flow of air relative to ambient air before delivery to
the patient’s airways.
7.6 COMBINATION THERAPY APPLICATIONS
As previously described, the patient interface 3000 and CT device 4000
permit an application of various positive airway pressure (PAP) therapies, such as
CPAP or bi-level PAP therapy or ventilation, or any other pressure therapy mentioned
in this specification. In addition, the disclosed system may provide flow therapies,
including deadspace therapies, such as high flow therapy (“HFT”). In HFT, air may be
delivered to the nasal passages at a high flow rate, such as in the range of about 10 to
about 35 litres/minute. A combination of these therapies may be provided to the patient
using the disclosed technology, such as through providing a patient with a combination
of pressure therapy (e.g., CPAP) and deadspace therapy (e.g., HFT). The combined
flow and pressure therapies may be supplied by a common apparatus, such as CT device
4000, or by separate apparatuses. In addition, changes in a patient’s therapy may be
applied with no or minimal changes to the configuration of patient interface on the
patient.
For example, the CT device 4000 previously described may be coupled via
a delivery conduit (air circuit 4170) to the full-face mask 8008 (see e.g., Fig. 7) or via
a delivery conduit (air circuit 4170) to the base portion 16016 of the patient interface
16002 (see Fig. 15A), so as to control pressure delivered to the mask or the chamber of
each naris pillow. In this way, a pressure therapy can be controlled by a pressure control
loop of a controller 4230 of the CT device 4000 so as to control a measure of interface
pressure to meet a predetermined target pressure. The measure of interface pressure
may be determined for example by a pressure sensor. Such target pressures may be
modified over time, such as in synchrony with detected patient's respiration (e.g., Bi-
level therapy or Pressure Support) or expected patient respiration (timed backup
breath). The seal of the mask or the naris pillows will permit the pressure to be
controlled at the entrance to the patient's respiratory system.
In addition to the delivery of a controlled pressure to patient interface 3000,
a controlled flow of air may also be provided to the patient via patient interface 3000.
For example, supplemental oxygen may be supplied by the one or more prongs 7004a,
7004b of the nasal cannula of Figs. 6 and 7, or one or more of the nasal projections
16100 of Fig. 15 or 17. By way of further example, HFT may be supplied to the one
or more prongs 9004a, 9004b of the nasal cannula of, for example, Figs. 6, 7 or 8, or
the nasal projections 16100 of the patient interface of Figs. 15 or 17 such as by a flow
generator configured to provide HFT. In such a case, an additional flow generator or
oxygen flow source may be coupled by a projection conduit 17170 to the nasal
projection or may be coupled by one or more lumens 9012 to the prongs 9004.
Optionally, the flow of gas to the prongs or nasal projections may be controlled by a
flow control loop of a controller. For example, the flow can be controlled by a flow
control loop of a controller of the flow generator or supplemental gas source so as to
control a measure of flow rate of air to meet a predetermined target flow rate. The
measure of flow rate may be determined for example by a flow rate sensor. The prongs
of the cannula and/or nasal projections can permit a supply of air, such as at high flow
rates, within the patient's nasal passages.
In an alternative implementation, the controlled flow of air may be
delivered to the mouth via an oral interface such as that described in PCT Publication
no. , the entire contents of which are herein incorporated by reference.
The oral interface may be positioned within a full-face mask such as the mask 8008, or
beneath a nasal mask such as the mask 3000.
Fig. 26 illustrates a block diagram of an example CT device 4000 by which
a controlled pressure and flow rate of air may be provided to a patient via patient
interface 3000. As described above in connection with Fig. 4C, pressure device 4140
may be controlled by therapy device controller 4240. The pressurized air from pressure
device 4140 may be transmitted to patient interface 3000 via one or more pneumatic
paths, such as air circuit 4170, which connects with patient interface 3000 at connection
port 3600. A pressure sensor 4274 may be configured to measure the pressure of the
air associated with the air circuit 4170. A flow rate sensor (not shown) may be
configured to measure the flow rate of the air through air circuit 4170. In addition to
pressure device 4140, flow device 4141 may provide a flow of air to patient interface
3000 via one or more pneumatic paths, such as projection conduit 17170. Projection
conduit 17170 may connect to patient interface 3000 at one or more secondary ports
19100. A flow rate sensor 4272 may be configured to measure the flow rate of the air
through projection conduit 17170. As set forth above, flow device 4141 may also be
controlled by therapy device controller 4240. Patient interface 3000 may also include
a vent 3400 to allow air to flow out of patient interface 3000 to atmosphere.
The flow rate of air that is provided to the patient at patient interface 3000
will depend on the characteristics of vent 3400, which may be adjustable, as well as the
pressure at patient interface 3000. For example, the flow rate of air out of vent 3400
may correspond with the pressure at patient interface 3000. This correspondence may
be quadratic in nature, in which the square of the flow rate out of vent 3400 may
approximately correspond to the air pressure in patient interface 3000. Accordingly,
the flow rate measured at flow rate sensor 4272 will correspond to both the flow of air
into the patient’s airways as well as the flow of air through vent 3400. In addition, the
flow rate may also vary based on the configuration of other components, such as the
configuration of projection conduit 17170. Accordingly, in order to provide the patient
with a desired flow rate, therapy device controller 4240 may calculate what the flow
rate to the patient will be based on the parameters of the system’s various components.
For example, therapy device controller 4240 may access data from pressure sensor 4274
so as to calculate the flow rate out of vent 3400. Therapy device controller 4240 may
then compensate the flow rate measured at flow rate sensor 4272 by the calculated flow
rate out of vent 3400, so as to determine the effective flow rate of air being provided to
the patient. In addition, by controlling both the pressure and the flow rate of air into
patient interface 3000, CT device 4000 may control the deadspace flushing flow rate
out of vent 3400.
In controlling the output of pressure device 4140 and flow device 4141,
therapy device controller 4240 may simultaneously control the pressure and the flow
rate of the air being provided to the patient via patient interface 3000. In this way, the
disclosed system may provide the patient with a combination of respiratory therapies.
For example, therapy device controller 4240 may control pressure device 4140 and flow
device 4141 so that a patient is provided with CPAP therapy by having a constant
pressure at patient interface 3000, while also providing HFT at a constant flow rate via
projection conduit 17170. Therapy device controller 4240 may be configured so that
the pressure and flow rate of air are considered to be constant if the measured pressure
and the measured flow rate each remain within some predetermined threshold range.
In addition, therapy device controller 4240 may vary the pressure and/or
the flow rate of the air in accordance with a predetermined therapy. For example, the
pressure device 4140 and flow device 4141 may be controlled so as to provide a bi-
level pressure therapy or a CPAP therapy with expiratory pressure relief in which the
pressure of the air at patient interface 3000 increases during a first period of time
corresponding to the patient’s inspiration and decreases during a second period of time
corresponding to the patient’s expiration. During these periods of time the flow rate of
the air may also be controlled so that the flow rate varies by some predetermined
amount in correspondence with the patient’s inspiration and expiration. In another
example, the flow rate of the air may be held constant while the pressure at patient
interface 3000 is varied.
Alternatively, the pressure may be held constant (e.g., CPAP), while the
flow rate is varied. Pressure device 4140 and flow device 4141 may also be
simultaneously controlled so that the pressure and flow rate of the air are both
continuously varying over some period of time in accordance with a therapy that calls
for some predetermined, but varying, pressure and flow rate.
In another example, pressure device 4140 and flow device 4141 may also
be simultaneously controlled so as to provide for auto-titrating CPAP therapy (e.g.,
APAP) along with HFT. For example, a treatment pressure may be increased upon
detection of one or more Sleep Disordered Breathing events. The flow rate of the HFT
may be maintained relatively constant or similarly adjusted based on such detections.
Accordingly, a deadspace therapy that would be otherwise compromised by OSA can
be made more effective through a pressure therapy, such as APAP, that opens the
patient’s upper airways.
In yet another example, pressure device 4140 and flow device 4141 may be
controlled in a manner that allows for the patient to reach some target amount of
ventilation, such as by controlling pressure to provide pressure support therapy. For
example, the pressure device 4140 of the disclosed CT system may implement adaptive
servo-ventilation (ASV) therapy in combination with the high flow therapies described
herein. Thus, the pressure may oscillate synchronously with patient's breathing cycle
or with timed machine generated breaths to enforce a target ventilation. Similarly, the
flow rate may be controlled to remain constant or it may be controlled to vary such as
as a function of the patient's detected breathing cycle or as a function of the target
ventilation.
By combining pressure and flow therapies, the disclosed system may
provide the patient with a more effective overall therapy. For example, the
effectiveness of an HFT therapy is diminished if the upper airway of the patient is
closed. The patient’s airway may be opened through the use of various pressure
therapies, such as a PAP treatment pressure (e.g., APAP or CPAP). Therefore, HFT
therapy may be made to be more effective by being combined with a pressure therapy.
Pressure support or ventilation therapy reduces the work required from the
patient for breathing by providing mechanical pressure support and may allow for
greater recovery of alveolar deadspace, as airways to the lungs are opened by the
pressure support. Flow therapy, such as HFT, also reduces the work of breathing and
allows for greater recovery of anatomical deadspace by flushing carbon dioxide rich
areas of the patient’s airways with air. A combination of pressure therapy and flow
therapy may also assist a patient in achieving sufficient positive end-expiratory pressure
(PEEP). In this way, a combination of a flow therapy and a pressure therapy may allow
a patient who experiences insufficient minute ventilation or alveolar ventilation to
receive a greater volume of gas exchange within the patient’s lungs through the removal
of anatomical and alveolar deadspace and the increase in tidal volume that is being
provided to the patient’s lungs. In addition, simultaneous HFT may also allow pressure
support therapy to be administered at a lower level of pressure support, thereby
improving the acceptability of the pressure support therapy. For example, excessive
levels of pressure support can induce lung injury. As another example, using pressure
support to force air through bronchitis lung produces high flow velocity in the bronchial
flow paths, which can cause discomfort and even further inflammation. As another
example, pressure support therapy results in a cyclic acoustic noise pattern whose
volume increases with the level of pressure support.
Accordingly, a combination of one or more pressure therapies with one or
more flow therapies, as described herein, may be additive or complementary. For
example, Fig. 32 contains a graph 32000 illustrating the possible effects of combination
therapy on a hypercapnic patient (one with elevated PCO ). The horizontal axis
represents the flushing flow rate of the combination therapy and the vertical axis
represents a pressure support of a combination therapy in which the pressure therapy is
a bi-level therapy. The point 32010 represents a therapy in which the pressure support
is zero but the flushing flow rate is high, e.g. 100 litres per minute. In such a case, the
therapy can be considered as essentially just a deadspace therapy. The point 32020
represents a therapy in which the pressure support is high, e.g. 20 cmH O, but the
flushing flow rate is zero. In such a case, the therapy can be considered as essentially
just a pressure support therapy. The points 32010 and 32020 represent forms of therapy
which are equally effective by some measure, e.g. reducing the PCO by 15%. Both
however are “extreme” forms, i.e. involve high flushing flow rate and zero pressure
support, or high pressure support and zero flushing flow rate respectively. All points
along the curve 32030 may represent combination therapies that are as effective as the
extreme therapies represented by the points 32010 and 32020, but are more moderate
in both pressure support and flushing flow rate than either of those extreme therapies.
The present technology allows any point on the curve 32030, e.g. the point 32040,
representing a combination therapy with moderate pressure support and flushing flow
rate, to be chosen for a patient depending on the preferences and characteristics of the
patient, without altering the effectiveness of the combination therapy. The curve 32030
may be referred to as a curve of equal efficacy. In essence, the combination therapy
may have a synergistic effect depending on settings that can provide treatment as
effective as either one of the individual therapies but at reduced levels so as to
unexpectedly reduce the potential for negative consequences that may be associated
with higher levels of each individual therapy.
Accordingly, in some versions, controller(s) of apparatus for generating
such combination therapy may be configured with such a curve (e.g., data values or a
programmed function in a memory representing such a curve) to regulate a synergistic
control of the therapies. For example, if a condition is detected by the controller, a
change in the combination therapy may be made by automatically varying the setting
of each control parameter (e.g., target pressure and target flow rate) so that they are
restricted to the curve. By way of further example, if a change is made to the setting
of a control parameter for one therapy (either automatically or manually), the control
parameter for the other therapy may be set or recommended by the controller according
to such a curve to complement the change to the first control parameter. Thus, the
controller(s) may be configured to vary a target pressure and/or a target flow rate so as
to restrict them to a predetermined curve of equal efficacy.
In accordance with the presently disclosed technology, the combination of
a pressure therapy and a flow therapy may take a number of different forms. For
example, a constant pressure (e.g., CPAP) may be used in combination with either a
variable or a constant flow rate. In another example, the pressure therapy may provide
a semi-fixed pressure that is adjusted in accordance with a patient’s detected breathing
events (e.g., obstructive apnea, hypopnea, etc.). In particular, the pressure therapy (e.g.
APAP) may be provided in accordance with an AutoSet pressure that is automatically
set by the pressure controller to a minimum pressure needed to keep the patient’s
airways open. In yet another example, a variable pressure therapy (e.g., Expiratory
Pressure Relief (EPR) or bi-level pressure, or servo-ventilation bi-level (pressure
support) modes such as ASV, ASV Auto or iVAPS) may be used in combination with
a fixed or a variable flow rate. A variable pressure and variable flow rate may vary
based on characteristics of the patient’s breathing, thereby facilitating the breathing
process.
The control of the flow of air between CT device 4000 and the patient may
be modelled as an electrical circuit 2700, as shown in Fig. 27. The positive airway
pressure (PAP) device shown may be pressure device 4140 described above, while the
deadspace therapy (DST) device may be flow device 4141. The PAP device and the
DST device may be incorporated into a single housing such as the housing 4010 of a
CT device 4000, or may exist as separate units.
As shown in Fig. 27, air flows from the output of the PAP device at a flow
rate Q1, and air flows from the output of the DST device at a flow rate Q2. The
resistance R1 represents the resistance of air flow that may exist in the pneumatic path
from the output of the PAP device to the plenum chamber 3200 of the patient interface
3000. For example, R1 may include the resistance of air flow along air circuit 4170.
The resistance R2 represents the resistance of air flow that may exist in the pneumatic
path from the output of the DST device to the end of the prongs or projections. For
example, R2 may include the resistance of air flow along projection conduit 17170. The
resistance Rnose represents the resistance of air flow from the end of the prongs or
projections within the patient’s nose back out the nares to the plenum chamber 3200 of
the patient interface 3000. The flow whose flow rate is represented by Q2 is a flushing
flow for both anatomical and mechanical deadspace (i.e. deadspace due to the patient
interface), so Q2 is referred to as the flushing flow rate.
The pressure of the air at the output of the PAP device is represented as Pd.
The pressure of the air at the end of the prongs or projections within the patient’s nose
is represented as Pnose. The pressure Pm represents the air pressure within the plenum
chamber 3200 of the patient interface 3000. Air may flow out of the patient interface
3000 through a fixed or adjustable vent, such as vent 3400. The flow rate through the
vent is represented as Qvent. The vent flow rate Qvent may correspond to the interface
pressure Pm. Accordingly, Qvent may be represented as a function of Pm through the
notation Qvent(Pm). The flow rate of air to the patient (the respiratory flow rate) is
represented by Qr, with the resistance of air flow through the patient’s airways being
represented by Rairway. Air will flow in and out of the patient’s lungs serving as an
alternating pressure source during the patient’s breathing cycle. Plungs is therefore
shown as an alternating pressure source, with Clungs representing the elastic response
of the patient’s lungs to the air flow being provided at the patient interface.
From the topology of the model 2700, it may be shown that the sum of the
PAP and DST flow rates Q1 and Q2 is equal to the sum of the respiratory flow rate Qr
and the vent flow rate Qvent:
Q1 + Q2 = Qvent(Pm) + Qr
Because the average respiratory flow rate Qr over many breathing cycles
is zero, the average or DC component of the vent flow rate Qvent, which may be
referred to as the “bias flow rate”, is the sum of the average or DC components of Q1
and Q2.
The PAP and DST devices of the model 2700 may be controlled so as to
manage both the pressure and flow rate of air in the system, which may be achieved by
control changes of the flow generators of the PAP and/or DST devices, and optionally
in conjunction with controlling mechanical variations of the opening size of the vent.
In general, the interface pressure Pm and the deadspace flushing flow rate Q2 may be
controlled independently by respective control of the PAP and DST devices. In
particular, the PAP device may maintain a given interface pressure Pm by setting its
own output pressure Pd to compensate for the known pressure drop through the
resistance R1 at any given flow rate Q1. However, in order to maintain this control it
is beneficial to maintain a positive flow rate Q1 from the PAP device, to ensure the
device pressure Pd is greater than the interface pressure Pm. To keep Q1 positive, the
flushing flow rate Q2 may be controlled so that throughout the patient’s breathing cycle
the following is true:
Q2 < Qvent(Pm) + Qr
During expiration, the respiratory flow rate Qr is negative, so by
controlling Q2 to be less than Qvent minus the peak expiratory flow rate Qe(peak),
Q1 may be kept positive throughout the breathing cycle. In other words, the
maximum flushing flow rate Q2(max) is Qvent(Pm)-Qe(peak). Since in general a
lower pressure Pm means a lower vent flow rate Qvent, a lower pressure Pm means a
lower ceiling on the flushing flow rate Q2. As long as the flushing flow rate is less
than Q2(max), the positive flow Q1 from the PAP device makes up the difference
between Q2 and Qvent+Qr. Q1 therefore oscillates around a steady state value of
Qvent–Q2 in synchrony with the breathing cycle, rising during inspiration and falling
during expiration.
In this way, the desired flushing of deadspace, such as the flushing of
carbon dioxide from the patient’s anatomical deadspace, may be accomplished through
control of the vent pressure / flow characteristic. For example, for a given interface
pressure Pm, an adjustment to the vent to allow a higher vent flow rate Qvent(Pm)
allows a higher deadspace flushing flow rate Q2.
The vent flow rate, Qvent, may approximate a quadratic relationship with
the patient interface pressure Pm, such that:
Pm = (A * Qvent ) + (B * Qvent)
The terms “A” and “B” are values that may be based on one or more
parameters of the vent. These parameters may be adjusted so as to alter the
relationship between Qvent and Pm such as when the opening size of an active
proximal valve (APV) serving as the vent 3400 is controlled to change. An example
APV is disclosed in PCT Publication no. , the entire disclosure of
which is incorporated herein by reference.
For example, in some cases, changing treatment may require changing of
venting characteristics associated with the patient interface. Thus, in some cases, such
as when a pressure therapy is being provided with the naris pillows and a CT device, it
may thereafter become desirable to initiate a flow therapy with the nasal projections,
such as providing a flow of supplemental oxygen or high flow therapy. This change in
treatment, which may be processor activated in the case of a common apparatus or
manually initiated such as in the case of multiple supply devices, may require an
adjustment to a venting characteristic of the patient interface. For example, a manual
vent may be opened or opened more so as to compensate for the increased flow of gas
to the patient's nares. Alternatively, in the case of an adjustable vent, a processor may
control opening of the vent or opening it more upon activation of the additional flow to
the nasal projections. Similar vent control may be initiated upon application of a mask
over a cannula such as in the illustration of Figs 7, 10, 12 and 13. In the case of
termination of such an additional therapy, the venting characteristics may be changed
again, such as by manually closing or reducing a vent size or by controlling with a
controller a closing or reduction in the vent size of an automatic/electro-mechanical
vent (e.g., an active proximal valve).
The therapy device controller 4240 may control the device pressure Pd of
the pressure device 4140 to deliver a desired or target interface pressure Pm such as for
controlling a generally constant (with respect to breathing cycle) pressure therapy,
without needing to know the flushing flow rate Q2 being delivered by the flow device
4141. In such a case, the therapy device controller 4240 may use conventional methods
of leak estimation and compensation. Under such an approach, the therapy device
controller 4240 may effectively treat the flushing flow as a large, constant, negative
leak flow that may be estimated and compensated for such as when estimating patient
flow and/or adjusting pressure to counter undesired pressure swings induced by patient
respiration. Similarly, to deliver a bi-level pressure therapy, the therapy device
controller 4240 may control the device pressure Pd of the pressure device 4140 to
synchronise the mask pressure Pm with the patient’s breathing cycle without needing
to know the flushing flow rate Q2. Under such an approach, the therapy device
controller 4240 may use conventional leak estimation and compensation methods to
estimate the respiratory flow rate Qr, effectively treating the flushing flow as a large,
constant, negative leak flow. The therapy device controller may then apply
conventional triggering and cycling processing to the respiratory flow rate Qr to
determine when to switch the desired interface pressure Pm from inspiration to
expiration and back.
However, it may be advantageous for the therapy device controller 4240 to
account explicitly for the flushing flow rate Q2 for either or both of controlling the
interface pressure Pm and estimating the respiratory flow rate Qr for triggering and
cycling purposes.
Likewise, it may be advantageous for the therapy device controller 4240 to
use the sensed device pressure Pd from the pressure sensor 4274 in order to compute
the interface pressure Pm and hence the maximum flushing flow rate Q2(max), namely
Qvent(Pm)-Qe(peak), to ensure the flushing flow rate does not exceed this upper limit.
In implementations in which the pressure device 4140 and the flow device
4141 are under the control of a common therapy device controller 4240, as in Fig. 26,
the controller 4240 is aware of all the system variables such as the device pressure Pd
and the flushing flow rate Q2 (such as with sensed values for the variables), and can
therefore control the pressure device 4140, the flow device 4141, and optionally an
adjustable vent 3400 to deliver a desired interface pressure Pm and flushing flow rate
Q2 in accordance with the above description.
However, in implementations in which the pressure device 4140 and the
flow device 4141 are under the control of separate controllers, the pressure device
controller may obtain the flushing flow rate Q2, either by direct communication with
the flow rate transducer 4272, or through communication with the flow device
controller. Likewise, the flow device controller may obtain the device pressure Pd
either by direct communication with the pressure transducer 4274, or through
communication with the pressure device controller.
7.6.1 Single flow generator examples
In some implementations, a single flow generator may be used to supply
both the flushing flow rate of gas through one or more of the nasal projections or prongs
and the air pressure within the patient interface 3000. In one such implementation, the
air circuit 4170 is not used, the connection port 3600 is blocked, and projection conduit
17170 may be connected to the output of a single blower 4142, as shown in Fig. 28. In
such an implementation, which may be modelled by the circuit model 2700 without the
PAP device or the resistance R1, the flow rate Q1 is identically zero, so for any given
venting characteristic Qvent(Pm), the vent flow rate Qvent will oscillate in synchrony
with the breathing cycle around the flushing flow rate Q2, rising to Q2+Qe at peak
expiration, and falling to Q2-Qi at peak inspiration, as illustrated in Fig. 30. The
interface pressure Pm will also oscillate along the venting characteristic around a steady
state pressure Pm0 such that Qvent(Pm0) equals the flushing flow rate Q2, falling
during inspiration to a trough pressure Pmi and rising during expiration to a peak
pressure Pme. Such oscillation in interface pressure may not be desirable and may be
minimised by adjusting the venting characteristic in synchrony with the patient’s
breathing cycle. For example, as illustrated in Fig. 31, to maintain a constant interface
pressure Pm0 at a given flushing flow rate Q2, the parameters of the venting
characteristic may be continually adjusted in synchrony with the patient’s breathing
cycle so that the venting characteristic follows the curve VC-E during expiration,
causing Qvent(Pm0) to rise to Q2+Qe and follows the curve VC-I during inspiration,
causing Qvent(Pm0) to fall to Q2-Qi.
Similar continuous adjustments to the venting characteristic may also be
made to maintain a constant interface pressure Pm throughout the breathing cycle in an
implementation with no DST device, so that Q2 is identically zero. In such an
implementation, for any given PAP device pressure Pd, resistance R1, venting
characteristic Qvent(Pm), and respiratory flow rate Qr, the interface pressure Pm
satisfies the equation
Pd − Pm
=+ Qvent Pm Qr
Continual adjustments to the venting characteristic, or to the device
pressure Pd, in synchrony with the breathing cycle allow Pm to be maintained at its
steady state value (i.e. its value when Qr is zero) as Qr varies over the breathing cycle.
Accordingly, in such single-flow-generator implementations, the interface
pressure Pm and flushing flow rate Q2 may be simultaneously and independently
controlled by varying one or more parameters of the vent 3400 so that a predetermined
pressure and predetermined flushing flow rate are maintained at patient interface 3000
throughout the breathing cycle. Further, this configuration allows for control of both
Pm and Q2 to arbitrary patterns with respect to time and the patient’s respiration. For
example, a bi-level pressure waveform for Pm where the inspiratory pressure is higher
than the expiratory pressure while Q2 is also controlled to vary based on aspects of the
patient’s breathing. Other examples include Pm of pressure therapy modes of CPAP,
APAP, APAP with EPR, ASV, ST, and iVAPS combined with a Q2 of flow therapy
modes such as fixed flow rate, flow rate varying on the patient’s state of inspiration or
expiration, or other ventilation parameters such as relative hyperventilation or
hypoventilation with respect to the ventilation mean.
In another single flow generator implementation in which there is no
separate DST device, the output of the PAP device is connected to both the air circuit
4170 and the projection conduit 17170. Such an implementation may be modelled by
the electrical circuit model 2700a illustrated in Fig. 33. Independent control of the
interface pressure Pm and the flushing flow rate Q2 to their respective target values
throughout the breathing cycle may be enabled by adjusting the vent characteristic in
synchrony with the breathing cycle as described above. Alternatively, or additionally,
independent control of the interface pressure Pm and the flushing flow rate Q2 to their
respective target values throughout the breathing cycle may be enabled by adjusting the
device pressure Pd in synchrony with the breathing cycle. Alternatively, or
additionally, the resistance of the air circuit 4170 may be made variable, e.g. by adding
a variable resistance (e.g., a proportional valve) in the air circuit 4170. Independent
control of the interface pressure Pm and the flushing flow rate Q2 to their respective
target values throughout the breathing cycle may be enabled by adjusting the resistance
of the variable resistance in the air circuit 4170 in synchrony with the breathing cycle.
7.6.2 Nasal Interface Examples
Various flow path strategies may be implemented to wash out exhaled
carbon dioxide given such different therapies and the different configurations of the
nasal interface when controlled in conjunction with any of the aforementioned pressure
control regimes. These may be considered with reference to the flow arrows F of the
figures. In the example of Fig. 15A, either an inspiratory flow (i.e., cyclical supply
activation) or a continuous flow may be supplied toward the patient nasal cavity via
both of the nasal projections 16100 that may be inhaled by the patient during
inspiration. The distal ends (DE) of the nasal projections may be coupled with further
supply conduits such as that illustrated in Fig. 16. Expiratory gases may be exhausted
from the patient nasal cavities into the passage of the naris pillows and out through any
one or more of the optional base vent 16220 and/or pillow vent(s) 18220. The control
of a continuous exhaust flow via such vents during both inspiration and expiration can
assist in ensuring washout of expiratory gases from the nasal cavities.
In the example of Fig. 15B, either an inspiratory flow (i.e., cyclical supply
activation) or a continuous flow is supplied toward the patient nasal cavity via one of
the nasal projections 16100 that may be inhaled by the patient during inspiration. In
this example, although not shown in Fig. 15B, the distal end (DE) of the nasal projection
on the left of the drawing may be coupled to a further supply conduit and a gas source.
This flow supply nasal projection is shown on the left side of Fig. 15B but may
alternatively be on the right. Expiratory gases may then be exhausted from the patient
nasal cavities via the other nasal projection 16100 (e.g., shown on the right of the
figure). In this case, the distal end of one nasal projection may omit a further conduit
and serve as a pillow vent at the proximity of the naris pillow 16010. The control of a
continuous exhaust flow via such a vent during both inspiration and expiration can
assist in ensuring washout of expiratory gases from the nasal cavities.
In the example of Figs. 17A and 17B, the presence of dual nasal projections
permits venting and supply via the nasal projections in each naris. Thus, either an
inspiratory flow (i.e., cyclical supply activation) or a continuous flow is supplied toward
the patient nasal cavity via one of the nasal projections 16100-2 of each naris pillow
that may be inhaled by the patient during inspiration. In this example, although not
shown in Fig. 17B, the distal end DE of one nasal projection of each naris pillow may
be coupled to a further supply conduit and a gas source. Expiratory gases may then be
exhausted from the patient nasal cavities via the other nasal projection 16100-1 of each
naris. In this case, the distal end of one nasal projection of each naris may omit a further
conduit and serve as a pillow vent 18220 at the proximity of the naris pillow 16010.
The control of a continuous exhaust flow via such vents during both inspiration and
expiration can assist in improving washout of expiratory gases (such as carbon dioxide)
from the nasal cavities.
In some cases, the washout flow path may be implemented with a unitary
nasal projection in each naris pillow. Such an example may be considered in relation
to Fig. 18. In this example, a gas supply nasal projection is omitted. The unitary nasal
projection 16100 in each naris pillow may then serve as a nasal projection vent, such
as by venting as a pillow vent. Thus, either an inspiratory flow (i.e., cyclical supply
activation) or a continuous flow is supplied toward the patient nasal cavity via each
naris pillow so that it may be inhaled by the patient during inspiration. In this example,
the distal end of the unitary nasal projection 16100 may omit a further conduit and serve
as a pillow vent 18220 at the proximity of the naris pillow 16010. The control of a
continuous exhaust flow via such vents during both inspiration and expiration can assist
in ensuring washout of expiratory gases from the nasal cavities.
In some cases, the washout flow path may be implemented without nasal
projections. Such an example may be considered in relation to the nasal pillows of
Figs. 19A and 19B. In this example, each naris pillow may have a pillow vent for
venting expiratory gases during expiration (See Fig. 19B). The pillow vent may be
open during inspiration and expiration or only open during expiration. Either an
inspiratory flow (i.e., cyclical supply activation) or a continuous flow is supplied toward
the patient nasal cavity via each naris pillow 16010 so that it may be inhaled by the
patient during inspiration (See Fig. 19A). The control of a continuous exhaust flow via
such vents during both inspiration and expiration can assist in ensuring washout of
expiratory gases from the nasal cavities. However, in the absence of the nasal
projection there is a marginal increase in the deadspace.
In the example of Figs. 20A and 20B, vents at the neck or base of each naris
pillow may be activated by an optional vent valve 21410. These naris pillows may
optionally include any of the nasal projections previously described. In this version,
the vent valve may be activated by rising pressure associated with the patient's
expiratory cycle so as to permit cyclical venting at the patient's naris pillow. Thus, as
illustrated in Fig. 20A, during expiration, expiratory gases open the vent valve to expel
expiratory air to atmosphere. At this time, the flow path from the air circuit 4170 to the
naris pillow may be blocked. As illustrated in Fig. 20B, during inspiration, supply gas
from the flow generator or CT device may close the vent valve. At this time, the flow
path from the air circuit 4170 to the naris pillow may be open.
In another example of Figs. 20C and 20D, such valves 21410 may be
configured so that only some of the pillow vents 18220 are closed at any one time. In
this arrangement, the valves 21410 may be configured so that one pillow vent is opened,
while the other is closed. Referring now to Fig. 20C, the pillow vent to the left of the
figure is open, while the pillow vent to the right is closed, and thus expiratory flow from
the patient exits through the open pillow vent. During inhalation, as shown in Fig. 20D,
the flow generator or CT device delivers a flow of supply gas, which is delivered to the
patient while the pillow vent to the left remains open, thereby continuously washing
out gases which has the effect of reducing dead space. An alternative arrangement is
shown in Figs. 20E and 20F, wherein the pillow vent to the left is closed and the pillow
vent to the right is open. In one form, the valves 21410 may be arranged so that they
are switchable from a first arrangement, for example shown in Figs. 20C and 20D to a
second arrangement for example shown in Figs. 20E and 20F. For example, in the case
of an electromagnetic operation of the valves, they may be set to the desired operation
by a controller. For example, they may be alternated on a predetermined or pre-set time
cycle. Optionally, the valves may be manually operated and may be manually switched
at a desired time.
One advantage of switching from the first to the second arrangement and
thus alternating between the left and right nasal passages as described above may be
that it may improve the patient’s comfort level. For instance, the patient using the
patient interface as shown in Figs. 20C-20D may experience discomfort from drying
out of the patient’s right (left on the figure) nasal passage, which may be alleviated by
changing the configuration of the patient interface to that shown in Figs. 20E-20F.
Optionally, such a valve may be extended into a nasal projection (e.g.
shown in Fig. 21) such that the nasal projection may serve as both supply and exhaust
conduit. In such a case, the nasal projection may include a valve membrane 22500 that
divides the conduit. The valve membrane 22550 may be flexible and extend along the
nasal projection 16100 from or near the proximal end toward a vent portion 22510 of
the nasal projection. The vent portion may be proximate to or serve as a pillow vent
18220. The valve membrane 22550 of the nasal projection may be responsive to
inspiratory and expiratory flow such that it may move (See Arrow M of Fig. 22)
dynamically across the channel of the nasal projection as illustrated in Figs. 22, 23A
and 23B. The valve membrane may then dynamically reconfigure the nasal projection
as an inspiratory conduit and expiratory conduit on either side of the membrane. For
example, as shown in Fig. 23A, responsive to patient expiration, movement of the valve
membrane 22550 across the proximal end of the nasal projection enlarges an expiratory
channel portion ECP of the projection that leads to the vent portion 22510. This
movement thereby reduces an inspiratory channel portion ICP of the nasal projection
that leads to a supply gas source or flow generator. Similarly, as shown in Fig. 23B,
responsive to patient inspiration, return movement of the valve membrane 22550 across
the proximal end of the nasal projection reduces an expiratory channel portion ECP of
the projection that leads to the vent portion 22510. This movement thereby expands an
inspiratory channel portion ICP of the nasal projection that leads to a supply gas source
or flow generator.
Nasal interfaces such as the nasal mask 3000 or the pillows interface 16002
have an advantage over oro-nasal interfaces in that they more easily permit the patient
to speak and eat while receiving combination therapy. In addition, when the patient
opens his or her mouth incidentally, for example during sleep, the open mouth acts as
an aperture through which leak may occur. Whether mouth opening is incidental or
purposeful to speak or eat, it would be helpful for the control of combination therapy
to detect such an occurrence. Mouth leak may be continuous or “valve-like”, occurring
intermittently when mouth pressure rises during exhalation. Both kinds of mouth leak
may be detected by estimating and analysing the respiratory flow rate Qr, for example
using the methods described in PCT Patent Publication no. , the entire
contents of which are herein incorporated by cross-reference. If a continuous mouth
leak is detected by the controller, the target interface pressure Pm may be reduced by
the controller, e.g. to zero, for the duration of the mouth opening, to reduce what is
often the unpleasant sensation of air rushing out the mouth and to enable the patient to
eat or speak more comfortably. However, the controller may optionally continue to
control delivery of the deadspace therapy throughout any of the detected mouth leak
events.
In a further implementation, an intentional flow of air out the mouth may
be enabled and controlled by a specially designed oral appliance to be worn by the
patient during therapy, e.g. during sleep. Such a mouth flow may act as an alternative
or supplementary path to ambient for the flushing flow entering the nasal cavity. The
effect of the oral appliance may be modelled in the electrical circuit model 2700 of Fig.
27 by a further resistive element between the nose and ambient, i.e. in parallel with the
airway path on the far right of the model 2700. The presence of this element, and the
mouth flow rate Qmouth through it, effectively adds Qmouth to the ceiling Q2(max) on
the flushing flow rate Q2 for any given interface pressure Pm.
7.6.3 Oro-Nasal Interface examples
In another form, an oro-nasal (full-face) mask may comprise one more flow
directors configured to deliver a flow of gas towards the nares of the user. The flow
directors may be connected to, and receive the flow of gas from a supplemental gas
source such as an oxygen source or a flow generator suitable for HFT. For example, the
patient interface may comprise one or more secondary ports 19100 as shown in Fig. 24
connectable to the supplemental gas source such as via a supply conduit.
One example of the flow directors may be one or more tubes 19200 coupled
to one or more secondary ports 19100 and located outside of a naris of a patient to direct
the flow of gas as shown in Fig. 25A. The one or more tubes 19200 may be a separable
component which can be engaged with the frame of the patient interface (e.g. mask) as
shown in Fig. 25A, where the tubes 19200 are engaged within the plenum chamber
3200. In some forms, the one or more tubes 19200 may be integrally formed with
another portion of the patient interface such as the plenum chamber 3200. The one or
more tubes 19200 may be movably configured relative to the rest of the patient
interface, such as pivotably coupled to the mask as shown in Fig. 25A, to be able to
adjust the direction of the flow of gas.
A flow director may further comprise a locating feature to allow the flow
director to remain in place once it has been adjusted, for example by frictional
engagement with the plenum chamber 3200. Although the arrangement shown in Fig.
25A shows two such tubes that are fluidly connected to each other, as well as to the
secondary ports 19100, it will be understood that any number of ports and tubes may
be used, as well as any combination of connections therebetween, analogously with the
above descriptions of nasal projections. In another example, each tube 19200 may be
independently connected to the plenum chamber 3200 using hollow spherical joints
(not shown) which allow a flow of gas therethrough, while also allowing movements
of the tube relative to the rest of the patient interface. Such a connection may thereby
allow a flow of gas to travel between a secondary port 19100 and the tube 19200.
In some cases, a flow director may be in a form of a flow directing surface
19300 coupled to a secondary port 19100. For instance, each flow directing surface
shown in Fig. 25B may comprise a curved surface shaped to direct the flow of gas from
the supplemental gas source using the Coanda effect, whereby the flow "attaches" or
conforms to the curved surface and follows its profile. In some forms, the flow directing
surface 19300 may be movably configured, for example by being rotatably coupled to
the plenum chamber 3200.
According to another aspect, a flow director or a nasal projection may
comprise a flow element, such as a honeycomb grid (not shown), to reduce turbulence
of the flow, whereby the flow director produces a more laminar flow than otherwise.
Such an arrangement may be particularly advantageous when used in conjunction with
a flow director, as a laminar flow may be more focussed in comparison to a turbulent
flow as it exits out of an orifice. Accordingly, use of a flow element may assist in
delivering a greater proportion of the flow of gas to the naris of the patient, whereas
without a flow element, more of the flow of gas may be lost to the interior of the mask
and possibly washed out through a vent.
7.6.4 Example Flow/Pressure Control Methodology
Fig. 29 shows a flow diagram 2900 in accordance with an aspect of the
disclosed systems and methods. Each block of flow diagram 2900 may be performed
by one or more controllers of a single device, such as CT device 4000, or by controllers
of multiple devices. Various blocks may be performed simultaneously or in a different
order than shown. In addition, operations or blocks may be added or removed from the
flow diagram and still be in accordance with aspects of the disclosed technology.
In block 2902, a controller may identify a predetermined pressure and a
predetermined flow rate of the air to be provided to a patient interface. As described
above, the predetermined pressure and/or the predetermined flow rate may be constant
or variable for a given period of time, and may be selected based on a desired therapy
or combination of therapies to be provided to the patient. For example, a bi-level
pressure therapy may be selected for which the predetermined pressure of the air is to
be adjusted based on the patient’s inspiration and expiration, while the predetermined
flow rate may be maintained at a constant level in accordance with a selected form of
HFT. In block 2904, a controller may receive a measurement of the current pressure
and the current flow rate, as measured by a pressure sensor and a flow rate sensor,
respectively. A controller may compare the measured pressure and flow rate with the
predetermined pressure and the predetermined flow rate, respectively (block 2906).
The comparison may include determining whether the measured pressure and flow rate
are at or within an acceptable range with respect to the predetermined pressure and the
predetermined flow rate. If the measured pressure and flow rate correspond to the
predetermined pressure and flow rate, the controller may return to block 2904.
If the measured pressure or flow rate does not correspond to the
predetermined pressure or flow rate, the controller may adjust the output of one or more
flow generators and/or may adjust one or more parameters of an adjustable vent in a
manner described above (block 2908). For example, the system may include two flow
generators, such as pressure device 4140 and a flow device 4141 described above. If
the measured pressure does not correspond to the predetermined pressure, the controller
may adjust the output of either one or both of the flow generators, so as to bring the
measured pressure into correspondence with the predetermined pressure. The
adjustment to the output of one or both of the flow generators may be performed so that
the measured flow rate continues to correspond with the predetermined flow rate. In
this way, the pressure and flow rate are simultaneously controlled. The controller may
return to block 2904 until the selected therapy session is terminated or the device is no
longer in use (block 2910).
7.6.5 Titration of combination therapy
The optimal parameters (e.g., pressure and flow rate) of combination
therapy, in particular the balance between the two therapies, i.e. the position on the
curve 32030, in combination therapy will vary from patient to patient. The process of
choosing the therapy parameters for a patient is known as titration. In general the
parameters may be chosen or varied based on the patient’s condition as well as
respiratory parameters such as minute ventilation, respiratory rate, expiratory flow
shape, lung mechanics, deadspace, and expired CO . For example, patients with
severe NMD need a predominance of pressure support to assist in the work of
breathing, whereas emphysemic patients may benefit proportionally more from
deadspace therapy. Patients with large lung volume with low pressure support may
indicate high deadspace and therefore proportionally more benefit from deadspace
therapy. Conversely, high respiratory rate indicating significant respiratory effort
may benefit more from pressure support.
One form of pressure support therapy known as iVAPS is based on servo-
control of alveolar ventilation by varying pressure support. In iVAPs, the target level
of ventilation is an alveolar ventilation computed by subtracting anatomical deadspace
ventilation from minute ventilation. The amount of anatomical deadspace for a given
patient is a setting that may be provided to the servo-controller or estimated from the
patient’s height. In combination with deadspace therapy, a controller controlling this
form of pressure support therapy may apply a lower value of anatomical deadspace
than would be expected for the patient without the deadspace therapy such as by
implementing a reduction value applied to the entered or computed anatomical
deadspace information so that the controller can compute a target ventilation setting
for alveolar ventilation that accounts for the DST. A lower value of deadspace
ventilation will result in an alveolar ventilation that is closer to the minute ventilation.
Hence the controller with such a calculated ventilation target will control generally
lower levels of pressure support.
7.6.6 Cardiac output estimation
The Fick technique estimates cardiac output by estimating the response in
expired CO to a deadspace manoeuvre (typically a step change in deadspace). The
flushing flow rate in deadspace therapy can be used to effectively manipulate
deadspace, and a measure of ventilation (e.g., minute ventilation or tidal volume) can
be used as a proxy for CO response, particularly during sleep. Therefore, the Fick
technique can be performed in combination therapy by measuring the change in
ventilation (e.g., minute ventilation or tidal volume) resulting from a step change in
flushing flow rate. For example, a controller may be implemented to calculate or
generate a cardiac output estimate by controlling a step change in the flushing flow
rate and determining change in a measure of ventilation (e.g., minute ventilation or
tidal volume) in relation to the step change in accordance with the Fick technique.
Such a process may be automatically initiated (or periodically) by the controller such
as during a sleep session, such as when sleep has been detected by the controller. The
controller may detect sleep by any known method, such as by any of the automated
methods described in International Patent Application no.
(WO/2011/006199) entitled “Detection of Sleep Condition”, the entire disclosure of
which is incorporated herein by reference.
7.7 ADDITIONAL PATIENT INTERFACES FOR OPTIONAL
THERAPIES
Some patients have a need for multiple therapies. For example, some
patients may require supplemental gas therapy. For example, supplemental oxygen
therapy may be delivered to the patient by use of a nasal cannula where prongs of the
cannula supply the oxygen at the patient's nares. Unlike nasal CPAP, such a therapy
does not typically supply the air at therapeutic pressure(s) so as to treat events of sleep
disordered breathing such as obstructive apnea or obstructive hypopneas.
Supplemental oxygen therapy may be considered with reference to the illustration of
Fig. 6. The traditional nasal cannula 7002 includes nasal prongs 7004A, 7004B which
can supply oxygen at the nares of the patient. Such nasal prongs do not generally form
a seal with the inner or outer skin surface of the nares. The gas to the nasal prongs
may typically be supplied by one or more gas supply lumens 7006a, 7006b that are
coupled with the nasal cannula 7002. Such tubes may lead to an oxygen source.
Alternatively, in some cases, such a nasal cannula 7002 may provide a high flow
therapy to the nares. Such a high flow therapy (HFT) may be that described in U.S.
Patent Application Publication No. 2011-0253136 filed as International Application
PCT/AU09/00671 on May 28, 2009, the entire disclosure of which is incorporated
herein by cross reference. In such a case, the lumen from the nasal cannula leads to a
flow generator that generates the air flow for high flow therapy.
During delivery of such supplemental gas therapies with a traditional nasal
cannula, it may be desirable to periodically provide a further therapy, such as a
pressurized gas therapy or positive airway pressure (PAP) therapy that requires a patient
interface to form a pressure seal with the patient's respiratory system. For example,
during oxygen therapy with a traditional nasal cannula, it may be desirable to provide
a patient with a traditional CPAP therapy when a patient goes to sleep, or traditional
pressure support therapy. These additional therapies may require a mask such as a nasal
mask or oro-nasal (mouth and nose) mask that may optionally include an adjustable
vent. Such an example may be considered with reference to Fig. 7. When the mask
8008 is applied to the patient over the traditional nasal cannula, one or more of the
components of the nasal cannula may interfere with the mask's seal forming structure
(e.g., cushion 8010) so as to prevent a good seal with the patient. For example, as
shown in Fig. 7, the lumens 7006a, 7006b may interfere with a cushion 8010 of the
mask. This may result in a substantial cannula induced leak (CIL) at or near the lumen
which may prevent the desired therapy pressure levels from being achieved in the mask.
Apparatus and therapies described herein may be implemented to address such issues
so as to permit simultaneous pressure and flow control.
7.7.1 Modified Nasal Cannula Embodiments
In some implementations of the present technologies, a modified nasal
cannula may be implemented to permit its use with changing therapy needs. For
example, as illustrated in Fig. 8, the nasal cannula 9002 includes a set of projections
(e.g., one or more prongs 9004a, 9004b). Each projection or prong may extend into a
naris of a user. The projection serves as a conduit to deliver a flow of gas into the naris
of the user. The nasal cannula 9002 will also typically include one or more coupler
extensions 9020a, 9020b. The coupler extension may serve as a conduit to conduct a
flow of gas from a gas supply line, such as lumen 9012a, 9012b. The coupler extension
may be removably coupleable with a base portion 9022 of the nasal cannula 9002 and/or
the supply line(s) of the cannula. Alternatively, the coupler extension may be integrated
with either or both.
Typically, each coupler extension(s) may be configured with a seat portion
9024a, 9024b. The seat portion may include a contact surface for another patient
interface. For example, the seat portion can serve as a contact surface for a typical seal
forming structure (e.g., a typical face contact cushion) of a mask so as to permit a seal
there between. Thus, the contact surface of the seat portion may form a seal with a
cushion of a mask. The coupler extension will also typically include a contact surface
for skin/facial contact with a patient to form a seal there between. The seat portion can
include a surface adapted to minimize or eliminate a cannula induced leak CIL. In some
such cases, it may include a surface with a sealing bevel 9090. The sealing bevel 9090
may promote sealing between the cushion of the mask and a facial contact surface. In
this way, it may fill a gap that would otherwise be induced by a traditional nasal cannula
structure.
The sealing bevel of the seat portion may be formed with various cross
sectional profiles to promote sealing. For example, as illustrated in Fig. 9A, the seat
portion 9024 of the coupler extension may have a generally triangular cross sectional
profile. It may be a triangle, for example an isosceles triangle, with the mask sealing
surface on the sides opposite the base. Thus, the sides opposite the base may be equal
or of different lengths. The base 9026 may typically be configured as the patient sealing
surface. Other cross sectional profiles may also be implemented. For example, Figs.
9B, 9C and 9D show a lentil cross sectional profile. Thus, as illustrated, the profile
may be larger centrally and the top and bottom surfaces may gradually converge by
similar slopes toward the opposing ends of the profile.
In some cases, the coupler extension(s) may serve as a conduit for
conducting air between the prongs of the nasal cannula and lumen. For example, as
illustrated in Figs. 9A, 9B, 9C and 9D, the seat portion may include one or more channel
conduits 10030. The channel conduits may be employed for directing gas in different
gas flow directions with respect to the nasal cannula, to provide gas to different prongs
and/or to provide different gases etc. For example, one channel conduit may lead to
one prong of the nasal cannula and another channel conduit, if included, may lead to
the other prong of the nasal cannula. As shown in Fig. 9A and 9C, a single channel
conduit is provided. The single channel conduit is round and may couple with a tube
shaped lumen. However, it may be other shapes, e.g., rectangular. This channel conduit
may lead to both prongs or one prong when coupled with the nasal cannula. As shown
in Fig. 9B and 9D, a double channel conduit is provided. Each channel of the double
channel conduit may have a round, oval or other similar profile and may couple with a
tube shaped lumen. Each channel double conduit shown in Fig. 9b is rectangular and
may be divided by a rib divider structure 10032 centrally located within the coupler
extension. Each channel may lead to both prongs or each channel may lead to a
different prong when coupled with the nasal cannula. Additional channel conduits may
also be provided for example, by providing additional rib dividers.
As shown in Fig. 10A and 10B, when a mask is placed over the nasal
cannula, such that the nasal cannula will be contained within the plenum chamber, the
mask rests not only on the patient's facial contact areas but also on the seat portion of
the nasal cannula. As further illustrated in Fig. 10B, the profile of the seat portion
permits a seal between the seal forming structure of the mask so as to reduce gaps.
Thus, the seat portion will typically have a length L and width W (see, e.g., Fig. 8 or
Fig. 14A) adapted to receive typical mask cushions. The length may be longer than a
typical cushion width. The length may be chosen to ensure seal during lateral
displacement of the mask. A measurement from 0.5 to 3.0 inches may be a suitable
length range. For example, an approximately two inch length may be suitable. The
width may vary depending on the height of the channel conduits and typical flexibility
characteristics of mask cushion materials so as to ensure a gradual sealing bevel that
will avoid gaps.
The coupler extension may be formed by moulding, such as with a flexible
material. For example, it may be formed of silicone. Optionally, the outer or end
portions may be more rigid than the central section such as by having a solid cross
section. The greater rigidity at the ends of the cross section may help with limiting their
deformation so as to maintain their shape and avoid creation of gaps between the mask
cushion and facial contact areas during use. In some versions of the coupler extension
additional materials may be applied such as for improving compliance. For example, a
skin contact surface may include a foam layer or soft material for improved comfort.
Although the version of the modified nasal cannula of Fig. 10A includes a
single supply line on each side of the cannula (e.g., left side and right side supply lines),
additional supply lines may be implemented. For example, as illustrated in Fig. 11 and
12, two lumens are applied or protrude from each coupler extension. In some such
cases, each lumen may be coupled with a different channel conduit of the coupler
extension. In such arrangements, the lumens may be split above and/or below an ear
to provide a more secure fitment for the patient.
Optionally, the seat portion of any of the cannula described herein may
include a mask fitment structure, such as a seat ridge. The ridge can serve as a locating
feature to indicate, or control, a relative position of the mask with respect to the seat
portion. Such a seat ridge 12040 feature is illustrated in Figs. 11 and 12. The seat ridge
may rise from the surface of the seat portion such as on an outer area or edge of the seat
portion (in a direction normal to the sagital plane).
Fig. 13 illustrates another version of the coupler extension of the present
technology. In this version, the width of the seat portion includes an expansion area
EA that expands the seat portion centrally along its length. Such a variation in the
contact surface of the seat portion may assist in improving the seal between the seat
portion and a mask cushion and/or the comfort of the seal between the coupler extension
and the patient's facial contact area.
In some versions of the present technology a coupler extension 15020 may
be formed as an add-on component for a traditional nasal cannula. Such an add-on
coupler extension may be considered with reference to Figs. 14A-14C. The add-on
coupler extension 15020 may include one or more groove(s) 15052 for insertion of a
supply line such as a lumen of a cannula. Thus, the coupler extension with its seat
portion and sealing bevel may be easily applied to or under a lumen of a nasal cannula
to reduce gaps when a mask is applied over the lumen of the traditional cannula. The
coupler extension 15020 may also include any of the features of the coupler extensions
previously described. For example, as shown in Figs. 14A, 14B, and 14C it may have
various cross sectional profiles such as triangular profile and lentil profiles. In the
version of Fig. 14C, two grooves 15052 are provided for insertion of two lumens, such
as in the case that the traditional cannula includes two lumens extending out from one
or both sides of the cannula. Although the figures have illustrated nasal cannula with
two prongs, it will be understood that a nasal cannula of the present technology may be
implemented with one or more nasal prongs (e.g., two).
7.7.2 Modified Nasal Pillow Embodiments
In some versions of the present technology, a common patient interface may
provide a unitary structure for permitting application of various therapies. Thus, unlike
the prior embodiments, the use and periodic application of an additional patient
interface for varying therapy may not be necessary. Moreover, features of such a
patient interface may be designed to minimize dead space.
One such patient interface example that can be implemented for periodic
application of various therapies, for example an oxygen therapy and a PAP therapy,
may be considered with reference to Figs. 15A and 15B. The patient interface 16002
may serve as a nasal interface. Thus, it may include a set of naris pillows (e.g., one or
more naris pillow(s) 16010). Each naris pillow may be flexible and may be configured
to form a seal with the naris of a patient when worn. The naris pillow may have an
outer conical surface 16012 that may engage at a skin periphery of a patient's naris
either internal and/or externally of the nostril. Optionally, the naris pillow may also
have an inner conical portion 16014 in a nested relationship with the outer conical
portion (best seen in Fig. 17B). A gap may exist between the inner conical portion
16014 and the outer conical surface 16012. Each naris pillow may couple by a neck
16015 portion to a common base portion 16016. A passage through the central area of
the outer conical portion (and/or inner conical portion), neck and base portion may
serve as a flow path to and/or from a flow generator of CT device 4000 via an air circuit
4170. The air circuit 4170 may be coupled to the base portion 16016 of the patient
interface at a flange 16018 (best seen in Fig. 17B). Optional base extensions 16020-1,
16020-2 may include connectors 16022-1, 16022-2 for connection of the patient
interface with a stabilizing and positioning structure (e.g., straps or other headgear.)
One or both of the naris pillows may also include one or more nasal
projections. Each nasal projection 16100 may be a conduit to conduct a flow of gas
through the nasal projection. The nasal projection will typically project from the nasal
pillow. As illustrated in Fig. 15A and 15B, the nasal projection may be configured to
extend beyond the seal of the naris pillow (e.g., beyond the edge of the outer conical
portion) so that it may project into or extend into the nasal cavity of a patient when used
further than the naris pillow at a proximal end PE. The nasal projection 16100 may
emanate from within the flow passage of the naris pillow (e.g., extend out of a conical
portion). The nasal projection may optionally adhere to an inside wall of the naris
pillow or other internal passage of the patient interface. In some cases, the nasal
projection may be integrated with or formed with an inside wall of the naris pillow or
other internal passage of the patient interface. Nevertheless, flow passage of the nasal
projection will be discrete from the flow passage of the naris pillow. Typically, the
length of the extension into a nasal cavity by the nasal projection may be in a range of
about 5 mm to 15 mm.
Optionally, as shown in the version of Figs. 15A and 15B, each nasal
projection may extend through a passage of the naris pillow and a passage of the base
portion. At a distal end DE of the nasal projection, the nasal projection may be
removeably coupled to (or integrated with) a further conduit to a gas supply, such as a
flow generator or supplemental gas source (e.g., an oxygen source). Alternatively, at a
distal end DE of the nasal projection, the nasal projection may be open to atmosphere,
such as to serve as a vent. In some cases, the distal end DE of the nasal projection may
have a removable cap so as to close the distal end and thereby prevent flow through the
nasal projection. For example, as illustrated in Fig. 16, a projection conduit 17170-1,
17170-2 may optionally be coupled to each of the nasal projections. Optionally, the
projection conduits 17170 extend along and are external of the air circuit 4170.
However, these projection conduits may extend along and are internal of the air circuit
4170 such as when they extend from the base portion 16016 and through the flange
16018 as illustrated in Fig. 17B.
In some versions of the patient interface 16002, one or more vents may be
formed at or from a surface of the patient interface. In other versions, another
component (e.g. an adapter or an air circuit 4170) including one or more vents may be
fluidly coupled to the patient interface. The vent may serve as a flow passage to vent
expired air from the apparatus. Optionally, such a base vent 16220 may be formed on
the base portion 16016 as illustrated in Fig. 15A so as to vent from the chamber inside
the base portion. In some cases, one or more vents may be formed on the naris pillow,
such as on the neck 16015. In some cases, one or more vents may be formed on a part
of the outer conical surface 16012 such as to vent from the chamber within the naris
pillow portion of the patient interface. In some cases, such a vent may be a fixed
opening with a known impedance. In some such cases, the vent may provide a known
leak. Optionally, such a vent may be adjustable, such as by a manual manipulation, so
as to increase or decrease an opening size of the vent. For example, the vent may be
adjusted from fully open, partially open and closed positions, etc. In some cases, the
vent may be an electro-mechanical vent that may be controlled by the flow generator
so as increase or decrease the size of the vent between various opening and closed
positions. Example vents and control thereof may be considered in reference to
International Patent Application No. filed on September 13, 2012
and PCT Patent Application No. filed on March 14, 2014, the
entire disclosures of which are incorporated herein by reference.
By way of example, in the patient interface 16002 of Figs. 17A and 17B,
the nasal interface includes multiple nasal projections 16100 extending from each naris
pillow. At least one such nasal projection may serve as a pillow vent 18220 for
example, at a bottom portion of the outer conical surface of the naris pillow. In the
example, the nasal projections 16100-1 each form a conduit that lead to atmosphere
through the naris pillow from the nasal cavity of a patient. With such a nasal projection
extending into the nasal cavity, a patient's deadspace can be reduced through a
shortened pathway for expired air (carbon dioxide) to be removed from the patient's
airways. In some such examples, the additional nasal projections 16100-2 may be
coupled with a supplemental gas source such as an oxygen source or a controlled flow
of air as discussed in more detail herein. Optionally, such nasal projections of each
naris pillow may be formed with a deviating projection (shown in Fig. 17A at arrows
DB). Such a deviation such that they are further apart at the proximal end when
compared to lower portions can assist with holding the extensions within the nasal
cavity during use. Thus, they may gently ply within a nasal cavity on opposing sides
of the nasal cavity.
7.8 GLOSSARY
For the purposes of the present technology disclosure, in certain forms of
the present technology, one or more of the following definitions may apply. In other
forms of the present technology, alternative definitions may apply.
7.8.1 General
Air: In certain forms of the present technology, air may refer to atmospheric
air as well as other breathable gases. For instance, air supplied to a patient may be
atmospheric air or oxygen, and in other forms of the present technology, air may
comprise atmospheric air supplemented with oxygen.
Ambient: In certain forms of the present technology, the term ambient will
be taken to mean (i) external of the treatment system or patient, and (ii) immediately
surrounding the treatment system or patient.
7.8.2 Anatomy of the respiratory system
Diaphragm: A sheet of muscle that extends across the bottom of the rib
cage. The diaphragm separates the thoracic cavity, containing the heart, lungs and ribs,
from the abdominal cavity. As the diaphragm contracts the volume of the thoracic
cavity increases and air is drawn into the lungs.
Larynx: The larynx, or voice box houses the vocal folds and connects the
inferior part of the pharynx (hypopharynx) with the trachea.
Lungs: The organs of respiration in humans. The conducting zone of the
lungs contains the trachea, the bronchi, the bronchioles, and the terminal bronchioles.
The respiratory zone contains the respiratory bronchioles, the alveolar ducts, and the
alveoli.
Nasal cavity: The nasal cavity (or nasal fossa) is a large air filled space
above and behind the nose in the middle of the face. The nasal cavity is divided in two
by a vertical fin called the nasal septum. On the sides of the nasal cavity are three
horizontal outgrowths called nasal conchae (singular "concha") or turbinates. To the
front of the nasal cavity is the nose, while the back blends, via the choanae, into the
nasopharynx.
Pharynx: The part of the throat situated immediately inferior to (below) the
nasal cavity, and superior to the oesophagus and larynx. The pharynx is conventionally
divided into three sections: the nasopharynx (epipharynx) (the nasal part of the
pharynx), the oropharynx (mesopharynx) (the oral part of the pharynx), and the
laryngopharynx (hypopharynx).
7.8.3 Aspects of PAP devices
APAP: Automatic Positive Airway Pressure. Positive airway pressure that
is continually adjustable between minimum and maximum limits, depending on the
presence or absence of indications of SDB events.
Controller: A device, or portion of a device that adjusts an output based on
an input. For example one form of controller has a variable that is under control- the
control variable- that constitutes the input to the device. The output of the device is a
function of the current value of the control variable, and a set point for the variable. A
servo-ventilator may include a controller to provide a ventilation therapy. Such a
ventilation therapy has ventilation as an input, a target ventilation as the set point, and
level of pressure support as an output. Other forms of input may be one or more of
oxygen saturation (SaO ), partial pressure of carbon dioxide (PCO ), movement, a
signal from a photoplethysmogram, and peak flow. The set point of the controller may
be one or more of fixed, variable or learned. For example, the set point in a ventilator
may be a long term average of the measured ventilation of a patient. Another ventilator
may have a ventilation set point that changes with time. A pressure controller may be
configured to control a blower or pump to deliver air at a particular pressure. A flow
controller may be configured to control a blower or other gas source to deliver air at a
particular flow rate.
Therapy: Therapy in the present context may be one or more of positive
pressure therapy, oxygen therapy, carbon dioxide therapy, deadspace therapy, and the
administration of a drug.
7.8.4 Terms for ventilators
Adaptive Servo-Ventilator: A ventilator that has a changeable, rather than
fixed target ventilation. The changeable target ventilation may be learned from some
characteristic of the patient, for example, a respiratory characteristic of the patient.
Backup rate: A parameter of a ventilator that establishes the minimum
respiration rate (typically in number of breaths per minute) that the ventilator will
deliver to the patient, if not otherwise triggered.
Cycled: The termination of a ventilator's inspiratory phase. When a
ventilator delivers a breath to a spontaneously breathing patient, at the end of the
inspiratory portion of the breathing cycle, the ventilator is said to be cycled to stop
delivering the breath.
Pressure support: A number for a ventilation therapy that is indicative of
the increase in pressure during ventilator inspiration over that during ventilator
expiration, and generally means the difference in pressure between the maximum value
during inspiration and the minimum value during expiration (e.g., PS = IPAP – EPAP).
In some contexts pressure support means the difference which the ventilator aims to
achieve, rather than what it actually achieves.
Servo-ventilator: A ventilator that provides a ventilation therapy for which
the device measures patient ventilation, has a target ventilation, and which adjusts the
level of pressure support to bring the patient ventilation towards the target ventilation.
Spontaneous/Timed (S/T) – A mode of a ventilator or other device that
attempts to detect the initiation of a breath of a spontaneously breathing patient. If
however, the device is unable to detect a breath within a predetermined period of time,
the device will automatically initiate delivery of the breath.
Triggered: When a ventilator delivers a breath of air to a spontaneously
breathing patient, it is said to be triggered to do so at the initiation of the respiratory
portion of the breathing cycle by the patient's efforts.
Ventilation: A volumetric measure of gas being exchanged by the patient’s
respiratory system, such as a tidal volume. Measures of ventilation may include one or
both of inspiratory and expiratory flow, per unit time. When expressed as a volume per
minute, this quantity is often referred to as “minute ventilation”. Minute ventilation is
sometimes given simply as a volume, understood to be the volume per minute. A
ventilation therapy can provide a volume of gas for patient respiration so as to perform
some of the work of breathing.
Ventilator: A mechanical device that provides pressure support to a patient
to perform some or all of the work of breathing.
7.9 OTHER REMARKS
A portion of the disclosure of this patent document contains material which
is subject to copyright protection. The copyright owner has no objection to the facsimile
reproduction by anyone of the patent document or the patent disclosure, as it appears in
the Patent and Trademark Office patent file or records, but otherwise reserves all
copyright rights whatsoever.
Unless the context clearly dictates otherwise and where a range of values is
provided, it is understood that each intervening value, to the tenth of the unit of the
lower limit, between the upper and lower limit of that range, and any other stated or
intervening value in that stated range is encompassed within the technology. The upper
and lower limits of these intervening ranges, which may be independently included in
the intervening ranges, are also encompassed within the technology, subject to any
specifically excluded limit in the stated range. Where the stated range includes one or
both of the limits, ranges excluding either or both of those included limits are also
included in the technology.
Furthermore, where a value or values are stated herein as being
implemented as part of the technology, it is understood that such values may be
approximated, unless otherwise stated, and such values may be utilized to any suitable
significant digit to the extent that a practical technical implementation may permit or
require it.
Unless defined otherwise, all technical and scientific terms used herein
have the same meaning as commonly understood by one of ordinary skill in the art to
which this technology belongs. Although any methods and materials similar or
equivalent to those described herein can also be used in the practice or testing of the
present technology, a limited number of the exemplary methods and materials are
described herein.
When a particular material is identified as being preferably used to
construct a component, obvious alternative materials with similar properties may be
used as a substitute. Furthermore, unless specified to the contrary, any and all
components herein described are understood to be capable of being manufactured and,
as such, may be manufactured together or separately.
It must be noted that as used herein and in the appended claims, the singular
forms "a", "an", and "the" include their plural equivalents, unless the context clearly
dictates otherwise.
All publications mentioned herein are incorporated by reference to disclose
and describe the methods and/or materials which are the subject of those publications.
The publications discussed herein are provided solely for their disclosure prior to the
filing date of the present application. Nothing herein is to be construed as an admission
that the present technology is not entitled to antedate such publication by virtue of prior
invention. Further, the dates of publication provided may be different from the actual
publication dates, which may need to be independently confirmed.
Moreover, in interpreting the disclosure, all terms should be interpreted in
the broadest reasonable manner consistent with the context. In particular, the terms
"comprises" and "comprising" should be interpreted as referring to elements,
components, or steps in a non-exclusive manner, indicating that the referenced
elements, components, or steps may be present, or utilized, or combined with other
elements, components, or steps that are not expressly referenced.
The subject headings used in the detailed description are included only for
the ease of reference of the reader and should not be used to limit the subject matter
found throughout the disclosure or the claims. The subject headings should not be used
in construing the scope of the claims or the claim limitations.
Although the technology herein may have been described with reference to
particular embodiments, it is to be understood that these embodiments are merely
illustrative of the principles and applications of the technology. In some instances, the
terminology and symbols may imply specific details that are not required to practice
the technology. For example, although the terms "first" and "second" may be used,
unless otherwise specified, they are not intended to indicate any order but may be
utilised to distinguish between distinct elements. Furthermore, although process steps
in the methodologies may be described or illustrated in an order, such an ordering is
not required. Those skilled in the art will recognize that such ordering may be modified
and/or aspects thereof may be conducted concurrently or even synchronously.
It is therefore to be understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised without departing
from the spirit and scope of the technology.
Claims (28)
1. A system for delivery of a flow of air to a patient ’s airways comprising: a flow generator configured to provide air to a patient via an air circuit and a patient interface; an adjustable vent; and one or more controllers configured to: determine a pressure and a flow rate of the air being provided to the patient via the patient interface with a plurality of sensors; and control the flow generator and the adjustable vent so as to simultaneously control the pressure and the flow rate of the air at the patient interface to correspond with a predetermined pressure and a predetermined flow rate, respectively.
2. The system of claim 1, further comprising the patient interface, wherein the patient interface comprises a projection portion configured to conduct a flow of the air into a naris of the patient and a mask portion configured to apply pressure of the air to the patient.
3. The system of claim 2, wherein the adjustable vent is part of the mask portion of the patient interface.
4. The system of any one of claims 2 to 3, wherein the plurality of sensors comprise: a pressure sensor for determining a measured pressure of the air; and a flow rate sensor for determining a measured flow rate of the air through the projection portion of the patient interface.
5. The system of claim 4, wherein at least one of the pressure sensor and the flow rate sensor is located at an output of the flow generator.
6. The system of claim 4, wherein at least one of the pressure sensor and the flow rate sensor is located at the patient interface.
7. The system of any one of claims 1 to 6, wherein the one or more controllers are further configured to maintain at least one of the predetermined pressure and the predetermined flow rate at a constant value for a period of time.
8. The system of any one of claims 1 to 6, wherein the one or more controllers are further configured to vary the predetermined pressure in accordance with a breathing cycle of the patient.
9. The system of any one of claims 1 to 8, wherein the simultaneous control of the pressure and the flow rate of the air provides the patient with a positive airway pressure therapy and a deadspace therapy.
10. The system of claim 9, wherein the positive airway pressure therapy is a ventilation therapy.
11. The system of any one of claims 1 to 10, wherein the one or more controllers are configured to determine the predetermined pressure and the predetermined flow rate to restrict the predetermined pressure and the predetermined flow rate to a curve of equal efficacy.
12. The system of any one of claims 1 to 11, further comprising a variable resistance in the air circuit, wherein the one or more controllers are configured to control one or more of the pressure and the flow rate of the air by adjusting the resistance of the variable resistance.
13. The system of any one of claims 1 to 12 wherein a controller of the one or more controllers is configured to compute a target ventilation based on anatomical deadspace information and a deadspace therapy reduction value.
14. The system of any one of claims 1 to 13 wherein a controller of the one or more controllers is configured to generate a cardiac output estimate by controlling a step change in the predetermined flow rate of the air and determining a change in a measure of ventilation in relation to the step change.
15. The system of claim 14 wherein the controller of the one or more controllers is configured to initiate control of the step change in the predetermined flow rate of the air in response to a detection of sleep.
16. A processor-readable medium having instructions stored thereon that, when executed by one or more processors, cause the one or more processors to ’: identify a predetermined pressure and a predetermined flow rate of air to be provided to a patient via an air circuit and a patient interface; determine, with a plurality of sensors, a pressure and a flow rate of the air being provided to the patient via the patient interface; and control a flow generator configured to provide the air to the patient interface, and an adjustable vent so as to simultaneously control the pressure and the flow rate of the air at the patient interface to correspond with the predetermined pressure and the predetermined flow rate, respectively.
17. The processor-readable medium of claim 16, wherein the patient interface comprises a projection portion configured to conduct a flow of the air into a naris of the patient and a mask portion configured to apply pressure of the air to the patient.
18. The processor-readable medium of claim 17, wherein the flow generator provides the flow of the air through the projection portion of the patient interface thereby applying pressure of the air to the mask portion of the patient interface.
19. The processor-readable medium of any one of claims 16 to 18, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to maintain at least one of the predetermined pressure and the predetermined flow rate at a constant value for a period of time.
20. The processor-readable medium of any one of claims 16 to 18, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to vary the predetermined pressure in accordance with a breathing cycle of the patient.
21. The processor-readable medium of any one of claims 16 to 20, wherein the simultaneous control of the pressure and the flow rate of the air comprises control of a positive airway pressure therapy and a deadspace therapy.
22. The processor-readable medium of claim 21, wherein the positive airway pressure therapy is a ventilation therapy.
23. The processor-readable medium of any one of claims 16 to 22, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to determine the predetermined pressure and the predetermined flow rate so as to restrict the predetermined pressure and the predetermined flow rate to a curve of equal efficacy.
24. The processor-readable medium of any one of claims 16 to 23, wherein controlling the adjustable vent comprises adjusting a venting characteristic of the adjustable vent in synchrony with the patient ’s breathing cycle so as to maintain the pressure of the air at the patient interface to correspond with the predetermined pressure.
25. The processor-readable medium of any one of claims 16 to 23, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to adjust a resistance of a variable resistance in the air circuit so as to control one or more of the pressure and the flow rate of the air.
26. The processor-readable medium of any one of claims 16 to 25, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to calculate a target ventilation based on anatomical deadspace information and a deadspace therapy reduction value.
27. The processor-readable medium of any one of claims 16 to 26, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to generate a cardiac output estimate by controlling a step change in the predetermined flow rate of the air and determining a change in a measure of ventilation in relation to the step change.
28. The processor-readable medium of claim 27, wherein the instructions, when executed by the one or more processors, further cause the one or more processors to initiate the controlling of the step change in the predetermined flow rate of the air in response to a detection of sleep.
Applications Claiming Priority (3)
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US201562265700P | 2015-12-10 | 2015-12-10 | |
US62/265,700 | 2015-12-10 | ||
NZ743113A NZ743113B2 (en) | 2015-12-10 | 2016-12-09 | Methods and apparatus for respiratory treatment |
Publications (2)
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NZ755711A true NZ755711A (en) | 2021-03-26 |
NZ755711B2 NZ755711B2 (en) | 2021-06-29 |
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