NZ765241A - Conduit for use in a respiratory apparatus - Google Patents
Conduit for use in a respiratory apparatusInfo
- Publication number
- NZ765241A NZ765241A NZ765241A NZ76524107A NZ765241A NZ 765241 A NZ765241 A NZ 765241A NZ 765241 A NZ765241 A NZ 765241A NZ 76524107 A NZ76524107 A NZ 76524107A NZ 765241 A NZ765241 A NZ 765241A
- Authority
- NZ
- New Zealand
- Prior art keywords
- conduit
- cuff
- passage
- heater
- patient
- Prior art date
Links
Landscapes
- Electrotherapy Devices (AREA)
Abstract
A conduit arrangement for use in delivering pressurized breathable gas to a patient. The conduit arrangement includes a first cuff configured to be attached to a respiratory therapy treatment system, the first cuff comprising a tubular air inlet portion and an electrical connector portion including three electrical terminals configured to engage an electrical connector of the respiratory therapy treatment system; a second cuff (56) comprising a tubular air outlet configured to pass the pressurized breathable gas towards an inlet of a patient interface (5); a structure (air delivery hose 4) forming a passage for the pressurized breathable gas from the tubular air inlet of the first cuff towards the tubular air outlet of the second cuff; and a helical rib (4b) on an outer surface of the structure forming the passage. The rib contains a pair of heating wires (4d, 4e) and a signal wire (4c), which extend at least the length of the structure forming the passage. The helical rib is in contact with the outer surface of the structure forming the passage. The heating wires are configured to heat the pressurized breathable gas flowing through the passage. The signal wire is configured to convey a signal indicative of a condition within the passage. A sensing device is positioned within the second cuff, the sensing device being configured to output the signal indicative of a condition inside the conduit arrangement. Each of the heating wires and the signal wire is connected to a corresponding one of the three electrical contacts of the electrical connector. The pair of heating wires and the signal wire are positioned in a side-by-side arrangement within the helical rib so that the pair of heating wires and the signal wire form a row in which one of the wires is between the other two wires. The three electrical terminals are positioned in a side-by-side arrangement that forms a row in which one of the electrical terminals is between the other two electrical terminals. The first cuff and the second cuff have different shapes.
Description
HUMIDIFIER FOR RESPIRATORY APPARATUS
CROSS REFERENCE TO RELATED ATIONS
This application claims priority to US. Application 60/955,222, filed August 10,
2007, and to Australian Provisional Application 2006906224, filed er 8, 2006, the
entire contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The t invention relates to humidification and heater ements used to
control the humidity of able gases used in all forms of respiratory apparatus ventilation
systems including invasive and non-invasive ventilation, Continuous Positive Airway Pressure
(CPAP), Bi-Level therapy and treatment for sleep disordered ing (SDB) ions such
as Obstructive Sleep Apnea (OSA), and for various other respiratory disorders and diseases.
2 Description of Related Art
Respiratory apparatus commonly have the ability to alter the humidity of the
breathable gas in order to reduce drying of the patient's airway and consequent patient
discomfort and associated complications. The use of a humidifier placed between the flow
generator and the patient mask, produces humidified gas that zes drying of the nasal
mucosa and increases t airway comfort. In addition in cooler climates, warm air applied
generally to the face area in and about the mask, as may occur inadvertently by a leak, is more
comfortable than cold air.
Many humidifier types are available, although the most convenient form is one
that is either integrated with or configured to be coupled to the relevant respiratory apparatus.
While passive humidifiers can provide some relief, generally a heated humidifier is required to
provide sufficient humidity and temperature to the air so that patient will be comfortable.
fiers typically comprise a water tub having a capacity of l hundred milliliters, a
heating element for heating the water in the tub, a control to enable the level of humidification
to be varied, a gas inlet to receive gas from the flow generator, and a gas outlet adapted to be
connected to a patient conduit that rs the humidified pressurized gas to the patient’s
mask.
Typically, the g element is orated in a heater plate which sits under,
and is in thermal t with, the water tub.
The humidified air may cool on its path along the conduit from the humidifier to
the patient, leading to the phenomenon of “rain-out”, or condensation, forming on the inside of
the conduit. To counter this, it is known to additionally heat the gas being supplied to the
t by means of a heated wire t inserted into the patient conduit which supplies the
humidified gas from the humidifier to the patient’s mask. Such a system is illustrated in
Mosby’s Respiratory Care ent (7th edition) at page 97.
Such a heating method for the patient conduit may only provide poor heat
er due to the wire locating itself along the conduit wall rather than in the main gas stream.
A wire will also only give poor turbulent mixing due to its low profile. As a result heat er
may be poor and the mixing of water vapor and gas may also be poor.
atively the heating wire circuit may be located in the wall of the patient
conduit. Such a system is described in US. Patent 6,918,389.
US. Patent 6,918,389 describes a number of humidifier arrangements for
supplying low relative humidity, high temperature humidified gas to the patient. Some of these
arrangements include pre- or post-heating of the gas to reduce the relative humidity.
None of these prior art devices provides an entirely satisfactory solution to the
provision of comfortable fied breathable gas to the patient, nor to ease of construction
and hygiene requirements and to energy and patient t requirements at startup.
SUMMARY OF THE INVENTION
Examples of the present invention aim to provide an alternative humidifier
arrangement which overcomes or ameliorates the disadvantages of the prior art, or at least
provides a usefiil choice.
In one sample embodiment of the invention, a humidifier and/or temperature or
other sensing or control apparatus for use with respiratory apparatus comprises a heating
t in thermal contact with the gas and/or water, wherein the filament is in the form of an
elongate tape. The tape may be flexible, and may, in a sample embodiment, be passed along
the bore of the patient gas conduit, or incorporated into the conduit wall.
In another sample embodiment, a humidifier for use with atory apparatus
comprises a heater in contact with water in the humidifier tub, and which floats or otherwise
rises and falls with s in the water level in the fier tub.
In a further form, the invention provides a humidifier ement for
respiratory apparatus, including an elongate filament heater in contact with the air path in the
regions before and after the humidification chamber. The filament heater may be further in
t with a body of water in the humidification chamber.
g of the filament may be divided into two or more separately controllable
zones.
A r sample embodiment of the invention provides a method of sing
patient t during start-up of humidification, the method comprising providing a heating
element to thermally contact breathable gas being provided to the patient along a gas flow path
and to thermally contact water in a humidifier apparatus; and configuring the heating element
to heat the gas in the gas flow path and to heat the water in the humidifier apparatus, such the
patient is initially provided with heated gas while the temperature of the water in the humidifier
apparatus is being increased to its operating temperature.
The heating of the gas in the gas flow path may include heating of a part of the
gas flow path am of a humidification chamber such that passage of the heated gas
through the humidifier apparatus provides an initial degree of humidification.
According to a sample embodiment of the invention, a conduit for use in a
respiratory apparatus for delivering breathable gas to a patient comprises a tube; a helical rib on
an outer e of the tube; and a plurality of wires supported by the helical rib in t with
the outer surface of the tube.
According to another sample embodiment of the invention, the conduit may
further comprise a connector block connected to an end of the conduit, wherein the connector
block is configured to be connected to a flow generator or a patient interface of the respiratory
apparatus.
According to a fiirther sample embodiment of the invention, a respiratory
apparatus for delivering breathable gas to a patient, comprises a flow generator to generate a
supply of pressurised gas to be delivered to the t; a humidifier to vaporize water and to
r water vapor to humidify the gas; a first gas flow path leading from the flow generator to
the humidifier; and a second gas flow path leading from the humidifier to a patient interface,
wherein the first gas flow path comprises a first conduit having a first connector block
configured to be ted to the flow generator and the second gas flow path comprises a
second t having a second connector block configured to be connected to the patient
interface.
According to still another sample embodiment of the invention, a method of
delivering breathable gas to a patient comprises ring a humidified flow of breathable gas
to a patient interface via a conduit; heating the conduit by supplying a DC current at a
predetermined duty cycle to a plurality of wires supported by the conduit; g a
temperature in the conduit during an OFF cycle of the predetermined duty cycle; and
controlling the DC current to maintain the temperature in the conduit at a selected temperature.
BRIEF PTION OF THE DRAWINGS
Embodiments of the invention will now be described with reference to the
accompanying drawings, in which:
Fig. l—A is a tic side sectional View of the patient conduit with a flexible
tape heater in an embodiment of the present invention;
Fig. l-B is an alternative embodiment of Fig. l-A where the flexible tape heater
is in a helical configuration;
Fig. 1-C: is an alternative embodiment of Fig. l-A where the flexible tape heater
is twisted about its longitudinal axis;
Fig. 2 is a schematic ctive View of another embodiment of the flexible
tape heater;
Fig. 3 is a schematic side sectional view of the humidification chamber with an
embodiment of the floating heater;
Figs. 4-A-D schematically illustrate a number of embodiments that the g
heater may have within the fication chamber;
Fig. 4-A is a side perspective View of an embodiment of the floating heater, a
circular floating plate heater which is secured under a floating plastic support grid;
Fig. 4-B is a side perspective View of another embodiment of a floating heater;
Fig. 4-C is a perspective side view of another embodiment of a floating, helical
flexible tape heater;
Fig. 4-D is a plan view of r embodiment of a e tape heater wound
in a horizontal spiral;
Fig. 5 schematically illustrates a flcation heater arrangement comprising
multiple zones;
Fig. 6-A is a transverse cross—sectional view of the patient conduit showing the
flexible tape heater ted to the conduit wall;
Fig. 6-B is another view of the connector embodiment of Fig. 6—A where the
connector is disengaged;
Fig. 7 illustrates the floating heater plate located in a shallow bath that also
floats at the water surface of the body of water;
Fig. 8 rates a power supply/controller connected to an inlet conduit by a
connector according to a sample embodiment of the invention;
Fig. 9 illustrates the inlet conduit of Fig. 8 connected to a flow generator;
Fig. 10 illustrates a patient conduit or hose according to a sample embodiment of
the invention connected to a patient interface;
Fig. 11 illustrates an inlet conduit, including a flow generator connector cuff,
connected to a connector ing to a sample embodiment of the invention;
Fig. 12 illustrates the inlet conduit of Fig. 11 disconnected from the connector;
Fig. 13 illustrates a cross section of the inlet conduit and connector of Fig. 11;
Fig. 14 is a rear perspective View of the inlet conduit and portions of the flow
generator connector cuff with the terminal clip connected thereto;
Fig. 15 is a front ctive view of the inlet conduit, flow generator connector
cuff portions, and terminal clip of Fig. 14;
Fig. 16 is a top perspective View of the inlet conduit and flow generator
connector cuff ns without the terminal clip;
Fig. 17 is a perspective view of the terminal clip according to a sample
embodiment of the present invention;
Fig. 18 is a perspective view of the connector block of the flow generator
connector cuff according to a sample embodiment of the invention;
Fig. 19 is a perspective view of the connector according to a sample of the
invention;
Fig. 20 is a perspective View of the contacts of the connector of Fig. 19;
Fig. 21 is a cross section of the ts and the connector of Fig. 20;
Fig. 22 is a perspective View of the patient conduit or hose and portions of the
mask cuff or connector according to a sample embodiment of the invention;
Fig. 23 is a cross section of the patient conduit and mask cuff of Fig. 22 with
portions of the cuff removed;
Fig. 24 is a cross section of the patient conduit and mask cuff of Fig. 10;
Fig. 25 is a top perspective view of the connector block of the mask cuff
ing to a sample ment of the ion;
Fig. 26 is a bottom perspective View of the connector block of Fig. 25;
Fig. 27 is a top perspective View of the connector block of the mask cuff in
connection with the patient conduit and including a printed circuit board of the mask cuff
according to a sample embodiment of the invention;
Fig. 28 is a side perspective view of the connector block of Fig. 27 disconnected
from the patient t;
Fig. 29 is a cross section of the patient conduit and connector block of Fig. 27;
Fig. 30 is a perspective view of the t conduit and the connector block of
the mask cuff according to a sample embodiment of the invention;
Fig. 31 is a perspective View of the patient conduit and mask cuff according to a
sample embodiment of the invention;
Fig. 32 is a cross section of the patient t and mask cuff of Fig. 31;
Fig. 33 is a schematic illustration of the temperature sensor and thermal fuse of
the circuit of the mask cuff according to a sample embodiment of the invention;
Fig. 34 schematically illustrates the circuit of the mask cuff provided on the
connector block of the mask cuff;
Fig. 35 schematically illustrates power supply/controller according to a sample
embodiment of the present invention;
Fig. 36 schematically illustrates a three wire heated tube according to a sample
embodiment of the invention;
Fig. 37a tically illustrates a sample embodiment of the ts of the
power supply/controller;
Figs. 37b—1 — 37B-4 schematically illustrate a sample embodiment of the circuit
of Fig. 37a;
Figs. 38-40 are perspective views of overmolded grip portions for the flow
generator cuff and/or mask cuff;
Fig. 41 illustrates a t according to a sample embodiment of the invention;
Fig. 42 illustrates a conduit ing to a sample embodiment of the invention;
Fig. 43 illustrates a patient conduit and mask cuff according to a sample
embodiment of the ion.
DETAILED DESCRIPTION
Flexible Tape Heater
Figs. l-A to 1-C illustrate the use of a flexible tape heater 3 within the patient
t 4 of a respiratory apparatus. The patient conduit 4 is located between the
fication chamber 1 and the patient interface, e. g. mask 5. The patient conduit 4 conveys
the flow of gas from the humidification chamber 1 to the patient mask 5 in respiratory
apparatus. The humidification chamber 1 in turn receives pressurized gas from a flow
generator 20 (Fig. 5) or blower.
The flexible tape heater 3 in the patient t 4 is used to heat the flow of gas
in the patient conduit 4. Heating of the gas enables the gas t features of temperature and
humidity to be attained and maintained for the gas delivered by the respiratory apparatus.
The flexible tape heater 3 is electrically coupled to a heater controller 21 (Fig. 5)
by a patient t connector end 2. The heater controller 21 may be orated in the
humidifier or the flow generator 20 or the base unit 22, or be a separate unit 21, for example
supplying a DC voltage of, for example, 0.1-24V.
The patient conduit connector end 2 may connect to the heater controller 21 via
another flexible tape heater (partially shown on the left side in Fig. 1) or to the conduit wall 25,
of the patient conduit 4, via a connector 23, 24 shown in Figs. 6-A and 6-B. The connector
may include a male connector element 23 and a female connector element 24 which may make
an electrical, communications and/or mechanical connection between the flexible tape heater 3
and the conduit wall 25. The male connector element 23 and the female connector element 24
may be interchangeable in position. The connector 23, 24 locks the flexible tape heater 3 in
position on the conduit wall 25, but may also be disengaged. The connector 23, 24 may be used
at any location along or around the conduit wall 25.
The patient conduit 4 may be insulated or a heated conduit as in the prior art in
order to reduce heat loss and minimize consequent water condensation or “rain-out” within the
t conduit 4. The insulation could be an outer sleeve or wrapping about the patient
conduit 4. The outer sleeve or wrapping could be foam, fabric or an air space in the case of a
double walled conduit.
In another embodiment the flexible tape heater 3 may be combined with the wall
of the t conduit 4 in order to provide heating to the wall to prevent condensation, while
optionally an additional flexible tape heater 3 within the patient conduit 4 provides the g
to the gas flow.
In a further embodiment the patient conduit 4 is formed by making a helix of the
flexible tape heater 3 and joining the edges the flexible tape heater 3 to form the patient t
The flexible tape heater 3 should be sufficiently flexible so that in use flexing of
the patient t 4 is not restricted. The flexibility of the flexible tape heater 3 also should be
sufficient to enable insertion and removal of the flexible tape heater 3 within the patient conduit
4, while being ently stiff so that the flexible tape heater 3 can be inserted into the patient
conduit 4 and will support itself in a desired position and not collapse against a wall or to one
end of the patient conduit 4. Additionally the stiffness should be sufficient so that the e
tape heater 3 will not flutter in the gas stream to produce an ed e noise.
The thin, flat and extended nature of the flexible tape heater 3 enhances heat
transfer with the gas flow while also providing low impedance to the gas flow. The flexible
tape heater 3 can be placed in the patient t 4 such that it has a helical configuration (Fig.
l-B) and/or the flexible tape heater 3 can be twisted or bent about one or more of the flexible
tape heater 3 axes. The longitudinal axis twist configuration is illustrated in Fig l-C.
Alternative profiles or geometric structures for the flexible g tape may
include:
The transverse cross-section of the flexible tape heater may be rectangular,
elliptical or arbitrary;
The surface of the flexible tape heater 3 may be rough or smooth or dimpled;
and/or
One or more surfaces of the e tape heater 3 may be rippled.
The dimensions of the thickness and width may vary along the length of the
e tape heater. For example a r section of the flexible tape heater 3 in the patient
conduit 4 may be provided to give a i effect of increasing the gas flow rate so that flow
detection may be possible by pressure sensors along the length of the flexible tape heater 3.
The use of these d, helical or other configurations described above
increases the length of the flexible tape heater 3 in the patient conduit 4 and thus the available
surface area for heat transfer between the gas flow and the surface of the flexible tape heater 3.
Additionally these configurations can be used to enhance the turbulent mixing of the water
vapor produced in humidification chamber 1 with the gas flow.
The various configurations may also be used to provide zones of differing flow,
acoustic, ty or temperature properties along the patient conduit 4 or the apparatus as a
whole, as show in Fig. 5 for example.
It may be desirable to modify the acoustic impedance properties of the patient
conduit 4 using the e tape heater 3. For example:
The generation or ion in white noise (broad frequency spectrum noise);
The damping or filtering of a particular acoustic noise frequency component/s,
e. g. structure-borne or air-borne flow generator tonal noise; and/or
Enhancement of the propagation of patient respiratory acoustic signals h
the patient conduit 4 and to the base unit 22 (Fig. 5) for monitoring and diagnosis.
The alteration of acoustic impedance ties using the flexible tape heater 3
may be achieved by the choice of the materials making up the flexible tape heater 3 and the
configurations described above of the flexible tape heater 3 in the patient conduit 4, and
additionally as shown in Figs. l-A to l-C.
Fig. 2 illustrates one embodiment of the flexible tape heater 3, in which the
heating is by a g element 6.
In one embodiment, the g element 6 is formed by d circuit
techniques applied to a surface of a flexible substrate such as KAPTON®, silicone , all-
polyimide, PTFE. ed in the printed circuit techniques which may be used are etched foil,
printing and vacuum deposition techniques.
Another sheet of the substrate al is then laid upon the bottom substrate
with the g element and the two sheets of substrate material adhered or fused together to
encapsulate the heating element. The ThermofoilTM range of the type of flexible heaters by
Minco of polis USA, described at www.minco.com, are examples of commercially
available strip heaters which may be modified for use in the present invention.
An alternative embodiment to produce a flexible tape heater 3 is to use a
laminator, such as a twin silicon roller laminator, to encapsulate a heating element 6, that is in
the form of wire or ribbon, within two tapes of polycarbonate film. The resulting tape may for
example have dimensions ranging from 1 to 10 mm wide and 0.1 to 1 mm thick. Dimensions
of from about 0.2 to 0.5 mm in thickness and about 5 mm wide are usable in the t conduit
The heating element 6 wire or ribbon may have any suitable transverse cross—
section, for example ar, elongate or rectangular. The heating element 6 may for example
consist of a resistive conductor.
The arrangement of the heating element 6 between the laminating films may be
of the flexible tape heater
any ordered or disordered arrangement that increases the heat transfer
3 to the surrounding media, be it gas or liquid. The heating element 6 may also have a positive
thermal coefficient (PTC) for resistance such that heating decreases as the temperature
increases towards a d temperature.
Alternatively the heating element 6 may have a negative thermal coefficient
(NTC) to allow g of the temperature of the heating element 6 or surrounding media.
In other embodiment there may be multiple heating element ts within the
flexible tape heater 3. The multiple heating elements may be connected in series or parallel.
The use of these multiple heating circuits within a flexible tape heater 3 s additional
heating to be applied as required in the operation of the respiratory apparatus.
In other embodiments the laminating films may be ter, polypropylene or
any suitable and ed substance for respiratory medicine use. Alternatively, multiple
laminating films may be used to create a composite strip having the desired ties while
retaining the desired compatibility of the outer film for respiratory medicine use. Other
conductors may also be t n each of these multiple layers, for example so as to
form multiple heating circuits, such as to allow multiple g zones along the length of the
tape heater.
In another embodiment, a sensor 7 for air temperature, such as a thermocouple,
um ance thermometer or thermistor with its attendant signal wires 9, may be
included between the two sheets of polycarbonate film. The sensor tip may be flat with a
thickness of less than about 2mm, and may be less than 1 mm. Other circuit components such
as surface mount circuit components may be incorporated onto the ate film for sensing
and/or lling and hence into the flexible tape. Also, the heating element 6 and other
circuit components can exist in multiple layers separated by substrate films as described above.
For the flexible tape heater 3 the other circuit components all have the common
physical feature that they are of a small enough dimension to enable them to be accommodated
in the overall profile of the flexible tape heater 3 and collocated with the heating element 6.
In an alternative embodiment the flexible tape may not have a heater t 6,
but instead incorporate one or more other circuit components for sensing and controlling. Thus
a atory tus may contain two or more flexible tapes, one or more undertaking a
heating function and one or more undertaking a sensing and/or controlling function.
The range of other circuit components that may be used is shown by way of
example in the following:
] Relative and absolute humidity sensors 7a;
Temperature sensors 7a with a positive temperature coefficient (PTC) or
negative temperature coefficient (NTC) in the form of a thermistor or alternatively the PTC
property may be intrinsic to the heating element 6 so that the flexible tape heater 3 is self
limiting;
Thermocouples, platinum resistance thermometers and the like may be used to
produce an actual temperature value signal for control and monitoring;
Directional flow sensing of the gas may realized by using at least two
independently lled heating sections spaced along the flexible tape heater each comprising
a temperature sensor (e.g. thermistor). The two or more heating sections are controlled and the
temperatures sensed to detect the direction of gas flow;
Hot wire anemometry for gas flow sensing 7a;
Ambient pressure sensing 7a, e. g. inspiratory versus expiratory pressures;
Controller 7b that makes use of the output from a sensor 7a, such as for
temperature, to control, for example, a transistor which regulates the current applied to a
heating t 6 used for the heating element(s);
Identification-Communication-Memory chips 8 which enable identification and
ication of the operating parameters of the flexible tape heater 3 to the base unit 22,
other heaters and components in the respiratory apparatus. For example, the flexible tape
heater 3 may icate regarding itself as well as detect and report regarding other
ents that are attached to the respiratory apparatus such as the patient mask 5 type or the
patient conduit 4 type or an active vent system. The information thus gathered by the flexible
tape heater 3 may then be sent to the base unit 22. The identification-communication-memory
system may consist of in part a radio frequency identification chip (RFID) to store the heater 6
and sensor 7a identification and operating parameters. The base unit 22 may have a lity
to communicate with the RFID chip and adjust its operation accordingly. Such a system has
been described in the Australian Patent Application No. 2005907200, titled “Identification
System and Method for Mask and ator Components,” the entire contents of which are
incorporated herein by nce. The communication may also be used to control an active
vent ;
Electromagnetic communication protocols via ure aerials and receivers,
e. g. “Bluetooth.”. s for transmitting and receiving information may be located for
example in the flexible tape heater 3, the wall of the patient conduit 4, or an active vent system,
or within the other components of the respiratory apparatus as illustrated in Fig. 5. In another
embodiment the aerials could be of a dimension as allowed by the length of the flexible tape
heater 3 or the patient conduit 4;
Power supply to the flexible tape heaters may be in a similar manner to the
electromagnetic communication described above. In this embodiment the aerials or inductive
coils would be adapted for power transmission.
These components can be located anywhere along the flexible tape heater 3 as
appropriate to their function. For example, a thermocouple may be located on the flexible tape
heater 3 at the end adjacent the patient mask 5 to enable closed loop temperature control based
on gas temperature red to the patient mask 5.
In an alternative embodiment the temperature sensor may be located in or in the
vicinity of the patient mask 5 but separated from the flexible tape heater 3. However the
ature sensor may communicate with the flexible tape heater 3 in the one of the manners
described above to enable closed loop l of the temperature of the gas delivered to the
patient.
The flexible tape heater 3 may also comprise microtubes 26 (Fig. 2) to allow
remote sensing away from the flow generator and/or humidification chamber 1. The
microtubes may, for example, provide pressure, snore and/or cardiological signal sensing.
For example, the microtubes may be attached to the side of the flexible tape heater 3 and
connected back to the flow tor 20 in one of the s described above. The use of
microtubes 26 es the benefit of avoiding flow noise within the patient conduit 4 and
other areas in the respiratory apparatus.
The sensing and control methods described above allow closed loop control to
be used for improving gas delivery to the patient mask 5 so that it is at the desired temperature
and humidity. Alternatively, a simple open loop system may be used where driving es or
currents for the heating element may be, for example, from 0.1 to 24 V direct current or the
power equivalent for alternating current, that may for example be from 0.1 to 50 W. The
sensing and control may also control the level of intentional gas leak from an active vent
system, depending on the amount of pressure being supplied. For example, as the ventilator
pressure increases the active vent system may be controlled to reduce the level of its intentional
leak to an acceptable level.
Additionally, the sensors 7a can be used for ance or statistical data
gathering.
Furthermore, the different components of the heater and/or sensing/control
system bed herein may be used as stand alone components in a respiratory tus not
employing a humidifier, and such arrangements are within the scope of the invention.
A flexible tape heater 3 as thus described would be easily removable from the
patient conduit 4 to enable cleaning, maintenance or replacement. The flexible tape heater 3
also offers efficient heating with sensing and control ents 7 being easily incorporated
into the flexible tape heater 3.
Floating Heater
In Fig. 3 a humidifier arrangement utilizing a floating heater 12 is illustrated.
The floating heater 12 floats in the body of water 13 in the humidifier chamber tub I such that a
substantial portion of the floating heater 12 is immersed but is still adjacent to the water surface
14 so as to heat that part of the water near the surface 14.
The floating heater 12 may se a length of flexible tape heater of similar
uction to that discussed above with reference to Figs l-A to l—C and 2. The end of the
heater located in the inlet conduit 10 leading from the flow generator 20 may be provided with
a connector 11 which enables the g heater 12 to connect with a flexible tape heater,
where that flexible tape heater is connected to the base unit 22 (Fig. 5) of the respiratory
apparatus. The floating heater 12 receives its electrical supply via the upstream end connector
11. Any sensing or controlling signals to or from the floating heater 12 are also received via
the upstream end tor 11.
The downstream end 2 of the g heater, located in the patient conduit 4
leading to the patient interface, may have a further connector for supplying power and any
ication with a further portion of flexible tape heater located in the patient t 4
(see Figs. l—A, l-B, l-C and 2).
The heater 12 may be adapted to float either by the natural buoyancy of the
heater itself, by surface tension effects, or may be supported in a manner which keeps the
heater near the water e less of changes in the water level.
Figs 4-A-E illustrate a number of embodiments that the g heater 3, 12, 16,
17 may have within the humidification chamber 1. The floating heater 3, l2, l6, 17 in each
embodiment is formed either from a flexible tape heater of the type previously described or a
plate form of the flexible tape heater 3, the floating plate heater 16.
The construction and use of a g flexible tape heater 3 and the floating
plate heater 16 is the same as described for the flexible tape heater 3 above, except that it is
applied to water. This has the significant advantage that the heater for both applications is
robust to gas or water immersion, since a floating flexible tape heater 3 or a floating plate
heater 16 could be partially immersed in water during the respiratory apparatus’ operation,
either unintentionally as the body of water increases or decreases in volume or by tilting of the
device, or intentionally to in the temperature of the water vapor in the gas of the
humidification chamber 1.
Fig 4-A illustrates a ar floating plate heater 16 which is secured under a
g t grid or plate 15, for example of a buoyant plastics material. The support grid
provides a floating oning mechanism for the floating plate heater 16 spacing the heater
element just below the water surface 14 so that there is sufficient contact with the water to
cause vaporization. In an ative embodiment shown in Fig. 7, the floating heater plate is
located in a shallow bath that also floats at the water surface 14 of the body of water 13. In this
embodiment the floating plate heater comprises at least one aperture to allow water to fill the
bath to cover the heater plate 16. The small volume of water in the bath is rapidly heated to
produce vapor.
Fig. 4—B shows another embodiment where the plate form is rippled or dimpled
in a regular or irregular fashion. The ng and/or dimpling provides valleys which allow
pockets of water to accumulate on the upper surface of the floating plate heater 16. In this
ment, the floating plate heater 16 is lly t, so it can float without the need
for a support grid or other buoyancy device.
Fig. 4—C illustrates a flexible tape heater 3 which has been wound into a helix.
In this embodiment the floating, helical flexible tape heater 17 can intrinsically float such that a
sufficient portion of the floating, helical flexible tape heater 17 is immersed in the body of
water 13. In another embodiment the flexible tape heater 3 could be wound in a horizontal
spiral, Fig. 4-D. For both the Figs. 4-C and 4-D embodiments a t grid 15 as used in Fig.
4-A may be used to position the flexible tape heaters 3, 12, 17.
The preceding embodiments for the floating heater 3, 12, l6, 17 ent a
number of defined configurations whereas in use the floating heater may assume a combination
of the defined or undefined configurations. For example a long helix which continues as a
spiral, combining Figs. 4-C and 4-D.
In the above embodiments of the floating heater 3, 12, 16, 17 the heater provides
effective heat transfer to the water surrounding the heater. In addition, the water adjacent to the
water surface is heated for vaporization rather than heating the whole body of water from the
bottom up as in the case of a heater being located at the bottom of the body of water 13.
Additionally, the flexible tape heater formation may be spiraled or otherwise
formed so as to be partly immersed in the body of water 13 so that it heats both the water near
the air and the air near the water to produce a stratified zone of heat to improve water uptake
for humidification. Thus, the floating heater 3, 12, 16, 17 may be more power efficient in
generating water vapor, and more effective in quickly achieving the d water surface
temperature for fication at start—up of the apparatus.
Multiple Zone Heating
Fig. 5 illustrates a respiratory apparatus which makes use of three heaters that
are of the same general construction and use as described for the flexible tape heater 3 and the
floating plate heater 12, 16, 17 bed above.
The heaters may comprise multiple heating circuits, so that each of the three
heater zones may be operated ndently.
A flow generator 20 or blower supplies gas supplied from an ambient
temperature supply which may be the air in the room or augmented or replaced by a specific
gas supply such as oxygen. A pre—heater 18 is located in the blower coupling 10 leading to the
humidifier 1. The blower coupling may be rigid, flexible or a conduit as required for the
operation of the blower coupling 10 or the ion of the pre-heater 18 located within the
blower coupling 10. The ater 18 is connected to the controller/power supply 21, of the
base unit 22, which supplies power and communication with any sensing or controlling
ents 7 of the pre-heater 18, as per the flexible tape heater 3 embodiment. The pre-heater
18 is connected to the floating heater 12, 16, 17 of the fication chamber 1 at the blower
t connector end 11. The floating heater 12, 16, 17 receives the controller/power supply
21 power supply and any communication, with the sensing or lling components 7 of the
floating heater 12, 16, 17, via the pre-heater 18.
Alternatively the floating heater l2, l6, 17 may also connect with the
controller/power supply 21 via the wall of the blower coupling 10 in the manner described
above in on to Figs. 6-A and 6-B discussing the patient conduit 4.
The post heater 19 is located in the patient conduit 4. The patient conduit
connector end 2 es the controller/power supply 21 power supply and communication for
the sensing and lling components 7 of the post heater 19. The patient conduit connector
end 2 may connect to the controller/power supply 21 via floating heater 12, 16, 17 as shown in
fig 5 or via the conduit wall 25, as shown in Figs. 6-A and 6—B, and then Via the humidification
chamber 1 to the controller/power supply 21 in the base unit 22.
In an alternative embodiment one or more of the heaters may not be of the type
described above but another suitable heating element. For example, the pre-heater 18 may be
formed as a simple wire heater or other tional heater type rather than as a e tape
heater of the type described herein.
The use of such arrangements may give the advantages of:
A single inter-connected heater system which is internal to the blower ng
, humidification chamber 1 and patient conduit 4;
The complete heater, sensor and l system can be removed simply for
cleaning, nance or replacement;
] The interconnection facilitates a high degree of closed loop control for
temperature and humidity of the gas delivered to the patient;
The ability to sense temperature and humidity at different sections of the patient
conduit 4 in order to control the condensation at various sections in the patient t 4;
The different components of the heater and/or sensing/control system may be
used in combination or separately within a conventional humidifier. For example the flexible
heating tape 3 may also be used to heat the patient conduit 4 er with a conventional
humidifier with a heating base plate. Alternatively the floating heater 12, 16, 17 or flexible
tape heater 3 may be used to heat the body of water 13 in the humidification r 1
together with a heated or insulated wall t conduit 4, as described above; and/0r
The ability to install multiple heaters in parallel and series at any on of the
respiratory apparatus. This may allow, for example, “super heating” during the beginning
operation of the respiratory apparatus when the body of water 13 requires time to reach the
desired temperature. The temporary extra heating of the air with multiple heater circuits would
increase the capacity of the air to take up the cooler water. This may be controlled or profiled
in response to the temperature of the water in the body of water 14 to provide the appropriate
level of humidity.
For the respiratory apparatus the ent of the three s, and the timing
and sequence of their use allows the gas comfort features of temperature and humidity to be
managed by allowing the separate, staggered tion of:
] Heating of an ambient gas that has a low absolute humidity;
] Water vaporization; and/or
Heating of the gas that has an increased absolute humidity (after the
humidification chamber 1).
The following example of use illustrates an advantage in the operation of the
sample embodiments described herein.
Patient respiratory gas es attention to the t features of temperature
and humidity, in particular in winter and colder climates. In the embodiments, the aim of the
system from a cold start-up is to rapidly deliver warm gas initially and then increase humidity
over time as the fier warms up. This approach allows the patient to receive comfortable
warm air closely followed by an increasing relative humidity, before there is an onset of any
adverse symptoms of low humidity respiratory assistance.
For a cold start in a winter climate the three heater system may thus operate in
the following . Firstly, the cool ambient temperature gas from the flow generator 20 is
warmed by using the pre-heater 18 in the blower coupling 10 with perhaps assistance from the
post-heater 19 in the patient conduit 4. This initially provides warm, dry air to the patient.
As the warmed gas flow begins to absorb appreciable water vapor from the
unheated water in the humidification chamber 1, the post-heater 19 in the t conduit 4
would begin or increase its heating in order to prevent “rain-ou ” condensation in the patient
conduit 4. The initial warming of the air with the pre—heater 18 has the advantage of
ately commencing a degree of humidification, as a simple “pass-over” operation, while
the floating heater 12, l6, 17 is still warmng up the water. The heat for vaporization in the
simple “pass-over” operation being provided by the heated air.
As the floating heater 12, 16, 17 begins to warm the water surface and rapidly
increase the absolute humidity in the gas passing through the humidification chamber to
achieve the desired level of humidification, the post-heater 19 in the t conduit 4 would
adjust its heating to maintain the absolute humidity by preventing condensation in the patient
conduit 4. The eater 19 may also serve to maintain the desired gas temperature in the
t t 4. The pre-heater 18 may have a heating profile based on the level of heating of
the body of water 13 in the humidification r 1, the heating profile being the rate of
heating of the gas flow in a period of time that can be provided by changing the power to the
pre-heater 18 or the structural configuration of the pre-heater 18. It is believed that there may
be more effective and control of the humidity by controlling the air temperature as opposed to
heating the water.
An onal advantage of this sample embodiment is that it allows reduced
be able to
power consumption at humidification start up so that the respiratory apparatus may
be operated by direct t power supply or a portable power supply. Also, satisfactory
operation can still be obtained when two or more heaters are multiplexed, one heater is
operated at a time but there is cycling in operation between two or more s.
Inlet Conduit Connection
Referring to Fig. 8, the power /controller 21 may be connected to the inlet
conduit/blower ng 10 by a connector 52. The connector 52 has a first connector 52a
connected to the power supply/controller 21 and a second connector end 52b connected to the
inlet conduit 10. The inlet conduit 10 has a flow generator cuff or connector 54. The flow
generator cuff 54 has an end 54a which is red for connection with the flow generator
. The flow generator cuff 54 also has an overmolded grip or cuff 54b which defines a
terminal clip 54c.
As shown in Fig. 9, the inlet conduit 10 is connected to the flow generator 20 by
the flow generator cuff 54. The connector 52 is connected to the flow generator cuff 54 at the
terminal clip 54c. Although not shown in Fig. 9, it should be appreciated that the first end 52a
of the connector 52 is ted to the power supply/controller 21. The power
supply/controller 21 provides electrical current and signals to the flow generator cuff 54
through the connector 52.
t Conduit Connection
The patient conduit/air delivery hose 4 is connected to the patient interface 5 by
a mask connector or cuff 56, as shown in Fig. 10. The patient conduit 4 includes a tube 4a, for
example of thermoplastic elastomer, and a helical rib 4b of very low density polyethylene.
Wires 4c, 4d, 4e are supported in the helical rib 4b so as to be in contact with the outer surface
of the tube 4a. The wires 40, 4d, 4e may be used to heat the tube 4a and to carry signals to and
from the power supply/controller 21. It should be appreciated that the inlet conduit 10 may
have a construction similar to the patient conduit 4, including a tube 10a, a helical riblOb, and
wires 100-10e supported by the helical rib on the tube.
Inlet Conduit and Flow Generator tor Cuff
Referring to Fig. 11, the flow generator cuff 54 includes a connector block 54a.
A grip or cuff 54b is overmolded on the connector block 54a to connect the connector block
54a to the inlet conduit 10. The overmolded grip or cuff 54b includes grip features 54d, such as
recesses for a user’s fingers, in the outer surface of the overmolded grip or cuff 54b to provide
a better grip on the connector cuff 54.
As shown in Figs. 8, 12 and 13, the flow generator cuff 54 includes a terminal
clip 540 that receives the second tor end 52b of the connector 52. As shown in Fig. 13,
the terminal clip 540 includes a rib 54n that is received in a lead-in 52e of the connector 52.
The rib 54n s the lead-in 52e to secure the connector 52 to the terminal clip 54c.
] The terminal clip 540 also includes a tooth 54e that locates the wires 100, 10d,
10e of the inlet conduit 10. The wires 100, 10d, We are placed on the outer surface of the
plastic elastomer tube 10a and held in place on the outer surface by the helical rib 10b.
A channel 54j is provided in the connector block 54a to allow the overmolded
al 54b to flow and bond to the inside of the tube 10a to establish the connection between
the connector block 54a and the inlet conduit 10. The connector block 54, the tube 10a and the
overmolded material 54b may be formed of als that will ally bond.
Referring to Fig. 14, the terminal clip 54c includes terminal clip pins 54h that
are received in hinged slots 54g of a al clip hinge 54f. The terminal clip hinge 54f is
provided on the connector block 54a. The terminal Clip 540 is snap-fit into the terminal clip
hinge 54f to ensure connection of the tooth 546 with the wires 100, 10d, We of the inlet conduit
. As shown in Fig. 15, the terminal Clip 540 may be attached to the connector block 54a prior
to attachment of the inlet conduit 10 to the connector block 54a. The al clip pins 54h are
attached in the hinge slots 54g and the terminal clip 54c is tilted or rotated forward. The inlet
conduit 10 is then attached to the connector block 54a and the terminal clip 540 is then rotated
or pivoted back so that the tooth 54e contacts the wires 100, 10d, We of the inlet conduit 10.
As shown in Figs. 16 and 17, the connector block 543 includes a guide away 54p for the helical
rib 10b of the inlet conduit 10 to position the wires 10c, 10d and 10e for contacting by the tooth
Referring to Fig. 17 the al clip 54c includes an arched portion 54k that
defines a l with the guide way 54p (Fig. 16) when the terminal clip 54c is inserted into
the terminal clip hinge 54f. A groove 54i (Fig. 18) is provided in the connector block 54a to
receive the helical rib 10b and the wires lOc, 10d, 10e of the inlet conduit 10. The groove 54i
has a smooth surface and wide contact area to prevent or minimize damage to the wires 10c,
10d, 10e. As also shown in Fig. 18, a void 54m is provided adjacent to the channel 54j to allow
for the passage of any air during the overmolding of the grip or cuff 54b to the connector block
Referring to Figs. 19-21, the second tor end 52b has a grip feature 52c to
permit easier ng of the second tor end 52b. Strain relief features 52d are also
formed in the second connector end 52b to increase flexibility. The grip and strain relief
features may also be ed to the first connector end 52a of the connector 52.
Contacts 52f, 52g, 52h are provided for sending and receiving signals from the
wires 100, 10d, 10e of the inlet conduit 10. Although the inlet conduit 10 is shown as including
three wires and a terminal Clip 540 is shown as having three terminals for receipt of the three
contacts of the second connector end 52a, it should be appreciated that any number of wires,
terminals and contacts may be used for the delivery and receipt of signals from the power
supply/controller 21 to the inlet conduit 10.
Patient Conduit and Mask Connector Cuff
Referring to Figs. 22-1, a mask connector or cuff 56 is provided for the
connection of the patient conduit/air delivery hose 4 to the patient interface 5. The mask
connector or cuff 56 includes a tor block 56a that is ted to the patient conduit 4
by an overmolded grip or cuff 56b. The connector block 56a, the tube 4a and the overmolded
cuff 56b may be formed of materials that will chemically bond.
] As shown in Fig. 24, the connector block 56a is connected to an inlet 5a of the
patient interface 5. The inlet 5a may be, for example, the swivel elbow of a mask.
] A printed circuit board (PCB) 56c is provided around the outer surface of the
connector block 56a. The wires 4c, 4d, 4e of the patient conduit 4 are attached to the PCB 560.
As shown in Figs. 25, 27 and 28, the connector block 56a includes snaps or pins 56i that
around an outer
engage holes or apertures 56u in the PCB 560. The PCB 560 is thus wrapped
surface of the connector block 56a and held in place. A thermal fuse 56d and a temperature
sensor 56e, for example a thermistor, are provided on the PCB 560. As shown in Figs. 23 and
26, one or more windows 56j are provided in the outer surface of the tor block 56a
where the thermal fuse 56d and the temperature sensor 56e are provided. The windows 56j are
covered by the PCB 560, as shown in Fig. 24. As discussed in more detail below, the PCB 56c
includes a heater track that is cooled by exposure of the PCB 560 to the airflow along the
window 56j.
] A helical rib 56f is provided on the outer surface of the connector block 56a to
locate the patient conduit 4, as shown in Figs. 22-26. As shown in Fig. 25, the outer surface of
the connector block 56a includes a stepped recess 56h to allow the overmold al to flow
and bond to the underside of the flexible PCB 560. As shown in Fig. 29, the connector block
56a also includes a channel 56t to allow the overmold material to bond with the inside of the
tube 4a of the t conduit 4. Referring back to Fig. 25, a void 56g is provided adjacent the
l 56t to allow for the escape of air during overmolding. As also shown in Figs. 28 and
29, the end of the connector block 56a includes a profile 56n that minimizes the capacity for
debris to collect and to be cleaned if debris does collect. The end of profile 56n also minimizes
flow impedance of the overmolded material.
As shown in Figs. 25 and 27, an access channel 56m is provided between the
helical rib 56f and the end channel 56t to allow the overmold material to bond the tube 4a to the
connector block 56a. As shown in Fig. 30, the tube 4a is twisted on to the connector block 56a
and the wires 4c, 4d, 4e of the patient conduit 4 are soldered to the flexible PCB 56c as shown
at 56p.
Referring to Fig. 31, the overmolded grip or cuff 56b may include a molded grip
e 56q, such as recesses to accommodate a user’s fingers, to improve the gripping ability
of the mask cuff or connector 56. The connector block 56a may be formed of a rigid polymer
and the overmolded grip or cuff 56 may be formed of a plastic elastomer. As shown in
Fig. 32, the connector block 56a may have a rd 22 mm ISO taper for connection to the
patient interface. As also shown in Fig. 32, the overmolded al may be blanked off at 565
in the region of the thermal fuse 56d.
Referring to Figs. 33 and 1, the circuit on the flexible PCB 56c includes the
thermal fuse or switch 56d and the thermal sensor 56e. One of the wires, e. g. 4c ,may be used
as a temperature sensing wire for sending a temperature signal to the power /controller
21. The other wires, e.g. 4d, 4e, may be used as heater wires to heat the tube 4a of the patient
conduit 4. If the temperature exceeds a certain value, the thermal fuse 56d is configured to cut
off current to the heater wires 4d, 4e.
The flexible PCB 56c and temperature sensor 56e and thermal fuse 56d should
be provided on the tor block 56a as close to the inlet 5a of the patient interface 5 and the
air path through the patient conduit 4 as possible. The mask connector or cuff 56 should also
be formed as small as possible to permit its use with ng breathing apparatus. The use of
the overmolded grip or cuff 56b is also useful for securing the patient conduit 4 to the
connector block 56a and to secure the e PCB 560, including the temperature sensor 56e
and the thermal fuse 56d in place. The use of the overmolded material also helps to reduce or
eliminate any locations where bacteria could grow.
The mask connector or cuff 56 as described herein is formed of biocompatible
materials. The connector block 56a also es an end 56r (Fig. 32) that includes a standard
22 mm female ISO taper for use with existing patient interfaces. The use of the overmolded
material also eases manufacture and improves reliability of the mask connector or cuff.
] Power Supply/Controller
] ing to Fig. 35, the power supply/controller 21 comprises a switch mode
power supply 21a switch 21b, a control unit 210, and a plurality of LED’s 21d. The power
supply/controller 21 has an AC power input 21e, a DC power output 21f, and a bypass AC
power lead 21 g to the flow generator 20. The AC power input 21e may be, for example, 110-
240V AC universal inputs. The switch 21b may be a MOSFET switch in series with the heater
element controlled by the control unit 210. The DC power output 21f may be, for e, a
500mA regulated 5V DC, or a 1.3A, 24V DC output. At 24V the power output is 30W.
The power input 2le is connected to the switch mode power supply 21a and the
bypass 21 g is connected to an AC power socket of the flow generator 20. The power
supply/controller 21 is configured to e power to the inlet conduit 10, regulate preset
temperature levels at the patient interface 5, and act as an ON/OFF control.
The control unit 21c is a closed loop temperature control system. The
temperature sensor 56e located in the mask cuff 56 provides the feedback signal through the
wire 40 of the patient conduit 4 back to the control unit 210. It should be iated, however,
that the control may not rely on a feedback of a temperature signal. The control unit 21c may
instead be configured to provide a predetermined amount of power to the output 21f t
reliance, or ence, on a temperature sensor signal.
The DC power output 21f supplies power to the inlet conduit 10 and the switch
21b is ed in series with the power output 21f and is controlled by the control unit 21c.
The power regulation is based on an ON/OFF control technique. The power regulation has
fixed duty cycles at a rate of about 95 — 99%. The OFF cycle, at a rate of about, for example 1
— 5%, is used for temperature sensing.
The LEDs 21d may include a green LED to indicate that power is on and being
ed to the inlet conduit 10. An amber LED may be provided to te that the power
output 21f is ON, but not provided to the inlet conduit 10. A red LED may be provided to
indicate a fault. Further LEDs may also be provided for indicating and/or controlling the
temperature. Manually operable buttons (not shown) may be provided to the power
supply/controller to allow control of the temperature by a patient or clinician in response to an
indication of temperature by the LED’s.
The control unit 21c is configured to produce a fixed power switching frequency
and duty cycles for the power output 21f to heat the inlet conduit 10. The control unit 21c is
also configured to sense the temperature via the signal sent by the temperature sensor 56c
through wire 4c. Based on the sensed temperature, the l unit 21c is configured to
regulate the temperature to a preset temperature when t temperature changes. The
control unit 210 is further configured to record the preset temperature when the power
control/supply 21 is turned off.
The control unit 21c may also latch a fault state when a fault is ed, and
clear the fault by recycling power. If a fault occurs a fault ion circuit locks into a fault
condition to send a fault signal to a driver block (Fig. 37a) the fault will continue until the
detect faults,
power is turned OFF and ON again. The control unit 21c may be configured to
including any discontinuities in the wires 4c-4e and 10c-10e, any arcing and/or bad connections
in the flow generator cuff 54 and/or the mask cuff 56. The control unit 21c may also detect low
voltage.
The power output 21f is maintained in the OFF state by the control unit 21c
when a fault is detected and is maintained in the OFF state until the power is recycled and the
fault state is cleared.
The status of the power supply/controller 21 may be indicated through the LEDS
As shown, for example in Figs. 5 and 8, the power supply/controller 21 may be
separate from the flow generator 20 and the humidifier. There is no information exchange
between the flow generator 20 and the humidifier and the closed loop control does not include
control based on airflow rate, humidity level, and humidifier outlet temperature, for example.
It should be appreciated, however, that information may be exchanged, for e through the
sensing wire 40. The control described above prevents “rain out” in the patient conduit 4 and
delivers the humidified air to the t ace 5.
It should be appreciated that the power supply/controller 21 may be integrated
with the flow generator 20 or the humidifier control system. Information may be provided to
the ated power supply/controller regarding the ion of the flow generator, the
humidifier, and ambient air. By integrating the power /controller with the flow generator
or the fier, the system will be more able to l the temperature at the patient
interface 5, the humidity levels and “rain out” at a wider range of ambient temperature and
humidities.
Referring to Fig. 36, a three wire heated tube or conduit according to a sample
embodiment of the invention is illustrated. The wires 4d, 4e may be formed for example,
from a 25m long wire having a diameter of 0.23mm, and be formed, for example, of copper.
The sensing wire 40 may be connected to the heating wires 4d, 4e at a connection point 4f that
is approximately the middle of the wire g the wires 4d, 4e and divides the wire into two
resistances Ra, Rb. The total resistance Ra + Rb may be equal to about 15 - 219, for example
about 180, at 20° - 26°C, for example about 23°C. The total resistance Ra + Rb is about 189, ,
and about 2lQ,w hen the wire resistors are heated up to about 33°C using a 24V DC supply at a
J 1 and
power of about 30W. As discussed above, the DC voltage V+ may be supplied across
J3 at a duty cycle of, for example, about 95 - 99%. The ances Ra, Rb generate heat during
the flow of current through the wires 4d, 4e to heat the conduit 4. The sensing voltage Vsen
may be determined during the 1 - 5% OFF cycle. During the OFF cycle, the switch 21b is
activated by the control unit 21c to switch the system into a sensing state and sensing current
from J1 passes resistance Ra and resistance RTl of the temperatures sensor 56e back to J2.
The ance RTl of temperature sensor 566 may be about l-50 k9 and resistance Rb may be
about half of Ra + Rb, or about 5 — 159, for example about 109, so Rb is omitted.
Although the sensing wire 40 is disclosed as being connected to the temperature
sensor 56e, it should be iated that the sensing wire may be connected to a different
control is not a feedback
sensor, such as a pressure sensor, for example in the event that the
control based on the detected ature.
] The fuse F2 of the thermal circuit 56d is lly coupled to the heater track of
the PCB 56c. The PCB 56c may be, for example, about 0.05 - .15 mm thick, for example about
0.1 mm thick, have a resistance of about 0.05 - .159, for example about 0.19, and a power
output of about 0.12 — 0.24 W, for example about 0.18W. As discussed above, one side of
PCB 560 faces the open window 56j so the PCB 560 contacts the air in the patient conduit 4.
The air flowing in the conduit therefore cools the PCB 56C to just above the temperature of the
air in the conduit. If the flow generator stops, or the air flow through the conduit is blocked,
the temperature of the PCB 560 will rise and trip the fuse F2 to protect the patient conduit 4
from damage. The temperature sensor 56e and the fuse F2 of the thermal circuit 56d thus
provide over air temperature protection, tube over heating protection, and low airflow
protection. The l circuit 56d may e a stat, for example a bi-metal strip,
instead of the fuse, and an increase in impedance of the thermostat would act to suppress, or
stop, an increase in the current.
As the patient conduit 4 delivers the fied air to the patient interface 5, the
and the patient conduit 4
power supply/controller 21, the mask cuff 56 and its components,
should comply with safety standards for temperature regulation, for e, ISO 8185. Under
normal operating conditions, the patient or clinician should be able to set the temperature of the
air delivered to the patient interface 5 from ambient to about 30°C. If no alarm system or
indicator is provided to the system, in accordance with ISO 8185, sections 51 .61-51 .8, under
normal and single fault ions, the temperature of the air delivered to the patient interface 5
should not exceed about 40°- 42°C, for example about 41°C. This maximum temperature (e.g.
41°C) is under the maximum energy level of 43°C at 100% RH. The fuse F2 of the thermal
circuit 56d may be chosen to trip off at the maximum temperature.
] Referring again to Fig. 36, the three wire (4c—4e) electrical circuit of the patient
conduit 4 includes the heating elements Ra, Rb in series with the heater track and fuse F2 of the
PCB 560, the wire 4c for supplying the sensing voltage Vsen, and the thermal sensor 56e
including the l resistor TRl attached to the middle 4f of the of the heater wires 4d, 4e.
The electrical circuit has two states: ON and OFF. In the ON state, also referred to as the
heating state, the wire 4d is connected at J1 to the voltage V+, for example the 24V DC from
the power output 21f. The heating current flows through J3, wires 4d, 4e, J4 and the switch
21b and into ground GND. In the ON state, the g voltage Vsen at J2 will not sense the
air temperature, but will sense about half of voltage V+, e. g. about 12V.
In the OFF state, the switch 21b is switched off and the heater wires 4d, 4e will
be pulled up by V+, e. g. about 24V, and the sensing current passes through J 1, Ra, RT1 and
back to J2.
The power supply/controller 21 may e circuits for performing numerous
functions. These circuits may include: 1) a power switching control circuit; 2) a tube interface
and gate drive circuit (driver block); 3) a fault detection and latching circuit (fault detection
latch); 4) a temperature preset/control circuit; and 5) a start up and tion circuit.
Power Supply/Controller Circuits
A sample ment of the circuits of the power /controller 21 is shown
in Fig. 37a. The circuit includes a temperature control t configured to control the
temperature of the heated conduit(s), a fault ion latch, a sensing circuit and a driver block.
The driver block is connected to the switch 21b, which may be a MOSFET.
Referring to Figs. 37b—l — 37b-4, a sample embodiment of the t of Fig. 37a
may be based on, for example, an UC2843 control IC, available from Texas Instruments.
should be appreciated that other control circuits may be used. The power switching control
circuit has chip over-current and over-voltage protections which can be used for error handling.
The power switching control t may also have an RC clock and under—voltage lockup and a
push-pull output driver. By setting the ating RC clock such that R12 = 22,0009 and C5 =
330 nF, the switch frequency may be set at 138 Hz. The time period for such a frequency is
determined by T = R12 x C15 (22,000 x .00000033) = 7.26mS. By ratio ofR12 and C5, the
is thus
power switching control circuit provides a 100uS OFF period, and the duty cycle
100uS/7.26mS = 1.38%.
At normal heating conditions, the power switching control circuit of Figs. 37b—1
— 37b-4 drives the transistor gate of the switch 21b at about 98.62% duty cycles. The ON state
of the circuit cannot be interrupted by Vfb signals. At the Vfb critical point, the gate signal can
be shown as 50% 69 Hz outputs.
The power switching control circuit has enable input h the Vfb pin. When
of the switch 210. The
any of the signals through D3 and D4 to low, it will disable the output
sensing current Isen is not used for this application as R10 and R20 set the sensing e
Vsen below 1V.
Referring again to Figs. 37a and 37b—1 — 37b—4, the sensing voltage Vsen has
two functions: 1) when the heater power is ON, the sensing voltage Vsen detects the heater
wires continuity, or any arcing or bad connections by sensing middle voltage V+; and 2) when
the heater power is OFF, the sensing voltage Vsen senses the air temperature via the RTI and
R13 divider voltages. The Q2, Q3 network provides right logic for sensing operations and
MOSFET Q3 provides low impedance (Rdson) for ature sensing. Q4 MOSFET gate
drives network R23, R25 limiting the maximum gate e; R24 and D5 together with R23
control the Q4 switch off speed.
The fault detection circuit operates when heater power is ON. The Vsen signal
is fed into a window comparator, for example an ultra-power quad ator, such as the
LP339AM, available from National nductor. U6B, U6D; R31, R36 and R43 divider
provide a +/- 2V window voltage at 12 Volt; the output of window comparator s will feed
into second stage of the comparator U6C.
The second stage of ator samples the Q4 gate signal as a base line and
detecting the error signal from window comparator output. When system has no fault detected,
window comparator outputs as high impedance, R34 and R40 divider has higher e out
then inverting comparator input R33 and R42 divider network, U6C will output high.
] When the system has a fault detected, window comparator outputs low, R34 and
R40//R35 divider has lower voltage then inverting comparator input R33 and R42 divider
network, U6C will output low to U2A latch CLR pin.
When latch CLR pin 1 receives a low signal the Q pin 5 will output a latched
fault signal, it will kill the U3 output switching signals. The latch may be, for example, a
74HCT74D U2A from Fairchild Semiconductor.
The temperature sensing operation is only performed during the power OFF
period. The air ature sensor RTl and divider base resistor R13 provides the temperature
ation Vsen, it directly feed into the comparator U6A inverting input, a potentiometer and
it’s network does the temperature preset function. The output of this comparator drives D4 and
controls the U3 switch output.
The start up circuit provides a 140mS delay when system start up and it will
reset the latch. After reset, the system will at ON state. The start up circuit may be, for
example, an IC U4 , available from TelCom Semiconductor, Inc.
The accuracy of temperature measurement is based on two parts: 1) sensing
accuracy; and 2) accuracy of reference. Sensing accuracy depends on NTC thermistor RTl and
series resistor R13. For example, a good NTC sensor RTl may have up to a l — 5%, for
example about 3%, accuracy tolerance; the series resistor R13 may have up to a 0.5 — 1.5%
tolerance, for example about a 1% nce. The cy of the temperature preset circuit is
determined when the port is at highest setting (30°C). The port resistor is 09 and the accuracy
is dependent on the 1% or network. However, when the port is set to the lowest setting,
% of the port or tolerance will be added in.
The conduits 4 and 10 will overheat when there is no gas flow in the tubes. The
heat can be accumulated in the tube, if the tube is covered, for e under a quilt, and the
heater element temperature can rise to 120-150°C. The heat can accrue when the thermal
switch is exposed in cold air, but part of the tube was covered, for example under the quilt. For
this reason, a no flow or low flow signal from the flow generator should able to trip off the
heated tube power supply.
] A three way tor is provided between thermistor sensor RTl and the
control unit 210. Any bad connection on the contactor will cause increasing nce on the
sensing circuit; for NTC thermistor RTl it will lower the temperature readings, and it can cause
air temperature rise and may trip the thermal switch 21b at the tube.
There are two ways to solve fault states in the temperature sensing. A first way
is to change the voltage divider logics, as contact resistance is high the air temperature goes
low. The other way to protect the sensing contactor is to off-set the g wire by changing
R6 and R31 to 8.2 kg This offset refrence voltage can detect the high impedance connectors.
] Cuff Configurations
As shown in Figs. 38-40, the configuration of the inlet conduit connector cuff
and/or the patient conduit and mask connector cuff may take various forms. Each of the mask
connector or cuff configurations shown and described herein may include grip features, and
sufficient strain relief es to improve the flexibility of the connector or cuff.
Tube Configurations
Referring to Fig. 41, the inlet conduit 10 and/or the patient conduit 4 may
include an inner tube 4a, 10a, a helical rib 4b, 10b, and an outer tube 4f, 10f. The outer tube 4f,
10f may be formed of the same material as the inner tube 4a, 10a. The outer tube 4f, 10f may
also be provided with a fleece or flocked material to improve the feel and/or grip of the conduit,
and/or to improve the thermal tion properties of the tube and/or the visual . If the
outer tube 4f, 10f is not provided, the outer surfaces of the inner tube 4a, 10a and the helical rib
4b, 10b may be provided with a fleece or flocked material for similar reasons.
Referring to Fig. 42, the inlet t 10 and/or the patient conduit 4 may
include an inner tube 4a, 10a and an outer tube 4f, 10f spaced by corrugations 4g, 10g. The
corrugations 4g, 10g may extend axially along the conduit 4, 10, or may extend helically along
the conduit 4, 10. Wires may be provided within the corrugations 4g, 10g, between the inner
tube 4a, 10a and the outer tube 4f, 10f. The corrugations may also be used to provide a
supplemental gas flow along the conduit 4, 10, or to provide a flow of liquid, for example
water, to regulate the temperature of the gas flow in the conduit 4, 10. The corrugations may
also be used to exhaust gas, for example from the patient’s exhalation, from the patient
interface. The outer tube 4f, 10f may also be covered in fleece or flocked material.
Patient Conduit, Mask Connector Cuff, and Flexible Circuit
Referring to Fig. 43, a patient conduit 400, mask connector cuff 560 and flexible
circuit 570 according to another sample embodiment are rated. The t conduit 400 is
connected to the mask cuff 560 by an overmold material 580 that encompasses the flexible
circuit 570. The overmold material 580 is overmolded onto the patient conduit 400 and the
mask cuff 560. The flexible circuit 570 may include the tube wires, s, fuses and other
ents bed above in relation to the other sample embodiments.
The mask cuff 560 may be formed as a separate part that is connected to the
patient conduit 400 through the overmold material 580. Alternatively, the mask cuff 560 may
be formed as a single piece with the overmold al. 580.
Although the invention has been herein shown and described in what is
conceived to be the most practical and preferred embodiments, it is ized that departures
can be made within the scope of the invention, which is not to be limited to the details
described herein but is to embrace any and all equivalent assemblies, devices and apparatus.
For example, the heating wires may be PTC elements with a e regulation to limit the
temperature of the wires ad/or the air in the conduit(s). As another example, one or more PTC
or NTC wires may be used in conjuction with a resistor to limit the temperature of the wires
and the air. As a further example, NTC Wires may be used with a current regulator, or a
measure resistance, to limit the temperature of the heating wires. The temperature sensing and
g may also be med using only two wires.
In this specification, the word “comprising” is to be understood in its “open”
sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the
sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding
words “comprise,” ised” and “comprises” Where they appear.
It will further be understood that any reference herein to known prior art does
not, unless the contrary indication appears, constitute an ion that such prior art is
commonly known by those skilled in the art to which the invention relates.
JAWS Ref: 504664DIVF
NV Ref: 4403-4051
ResMed Ref: P411NZ8
Claims (22)
1. A conduit arrangement for use in delivering pressurized breathable gas to a patient, the t arrangement comprising: a first cuff configured to be attached to a respiratory therapy treatment system, the first cuff comprising a tubular air inlet portion that is configured to receive the pressurized breathable gas and an electrical connector portion that is adjacent to the tubular air inlet portion and comprises three electrical terminals, the three electrical terminals being configured to engage an electrical tor of the respiratory y treatment system; a second cuff comprising a tubular air outlet configured to pass the rized breathable gas towards an inlet of a patient interface; a structure forming a passage for the pressurized able gas from the tubular air inlet of the first cuff towards the tubular air outlet of the second cuff; a l rib on an outer e of the structure g the e, the rib containing a pair of heating wires and a signal wire, which extend at least the length of the structure forming the passage, wherein the helical rib is in contact with the outer surface of the structure forming the passage, the heating wires being configured to heat the pressurized breathable gas flowing through the passage, the signal wire being configured to convey a signal indicative of a condition within the passage; and a sensing device positioned within the second cuff, the sensing device being configured to output the signal indicative of a condition inside the conduit arrangement, wherein each of the heating wires and the signal wire is ted to a corresponding one of the three electrical contacts of the ical connector, wherein the pair of heating wires and the signal wire are positioned in a side-by-side arrangement within the helical rib so that the pair of heating wires and the signal wire form a row in which one of the wires is between the other two wires, wherein the three electrical terminals are positioned in a side-by-side arrangement that forms a row in which one of the electrical terminals is between the other two electrical als, and wherein the first cuff and the second cuff have different shapes. JAWS Ref: 504664DIVF NV Ref: 4403-4051 ResMed Ref: P411NZ8
2. The conduit arrangement of claim 1, n the first cuff comprises a rim configured to act as a stop and abut an end of an air outlet of the respiratory therapy treatment system.
3. The conduit arrangement of any one of claims 1 to 2, wherein the second cuff comprises an internal ridge configured to act as a stop and abut an end of the inlet of the patient interface.
4. The conduit arrangement of any one of claims 1 to 3, wherein the first cuff comprises finger grips.
5. The conduit arrangement of any one of claims 1 to 4, wherein the first cuff is attached to the structure forming the passage at or towards a first end of the structure forming the passage.
6. The conduit ement of claim 5, wherein the first cuff is overmolded onto the first end of the structure g the passage.
7. The conduit arrangement of any one of claims 1 to 6, n the second cuff is attached to the structure forming the passage at or towards a second end of the structure forming the passage.
8. The conduit arrangement of claim 6, wherein the second cuff is lded onto the second end of the structure forming the passage.
9. The t arrangement of any one of claims 1 to 8, wherein the structure forming the e comprises a first conduit portion and a second conduit portion which together form at least a portion of the passage.
10. The conduit arrangement of claim 9, wherein the first conduit portion has a first end and a second end, and wherein the first end of the first conduit portion provides the first end of the structure forming the passage. JAWS Ref: 504664DIVF NV Ref: 051 ResMed Ref: P411NZ8
11. The conduit arrangement of claim 10, wherein the second end of the first conduit portion is configured to attach to a humidifier unit forming part of the respiratory therapy treatment system.
12. The conduit arrangement of any one of claims 9 to 11, wherein the second t portion includes a first end and a second end, and wherein the second end of the second conduit portion provides the second end of the structure forming the passage.
13. The t arrangement of claim 12, wherein the first end of the second conduit portion is configured to attach to a / the humidifier unit g part of the respiratory therapy treatment system.
14. The conduit ement of any one of claims 1 to 13, wherein the sensing device comprises a temperature sensor, and the signal wire is configured to convey a temperature
15. The conduit arrangement of claim 14, wherein the temperature sensor is a thermistor.
16. The conduit arrangement of claim 15, wherein the pair of heating wires are connected to one end of the thermistor and the signal wire is connected to the other end of the thermistor.
17. The conduit arrangement of any one of claims 1 to 16, wherein the pair of heating wires and the signal wire extend to the second cuff.
18. A respiratory apparatus configured to generate and deliver pressurized breathable gas to a t’s airways, the respiratory apparatus comprising: a respiratory therapy treatment system configured to pressurize the breathable gas; the conduit ement of any one of claims 1 to 17, the first cuff of the conduit arrangement being configured to connect to an air outlet of the respiratory therapy treatment system; and a d t board (PCB) with a control circuit configured to control the conduit arrangement. JAWS Ref: 504664DIVF NV Ref: 4403-4051 ResMed Ref: P411NZ8
19. The respiratory apparatus of claim 18, wherein the atory y treatment system is a flow tor or a combined flow generator and humidifier.
20. The respiratory apparatus of either one of claims 18 or 19, further comprising a thermal fuse configured to terminate a t supplied to the pair of heating wires when a temperature in the passage exceeds a threshold temperature.
21. The respiratory apparatus of any one of claims 18 to 20, further comprising a patient interface with an air inlet configured to receive the pressurized flow of breathable gas from the conduit arrangement, the t interface being configured to sealingly engage a patient’s face.
22. The respiratory apparatus of any one of claims 18 to 21, wherein the air inlet of the patient interface is an elbow.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NZ782870A NZ782870A (en) | 2006-11-08 | 2007-11-08 | Conduit for use in a respiratory apparatus |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2006906224A AU2006906224A0 (en) | 2006-11-08 | Humidifier for Respiratory Apparatus | |
US95522207P | 2007-08-10 | 2007-08-10 | |
NZ74925407 | 2007-11-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
NZ765241A true NZ765241A (en) | 2022-02-25 |
Family
ID=80679542
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NZ765241A NZ765241A (en) | 2006-11-08 | 2007-11-08 | Conduit for use in a respiratory apparatus |
Country Status (1)
Country | Link |
---|---|
NZ (1) | NZ765241A (en) |
-
2007
- 2007-11-08 NZ NZ765241A patent/NZ765241A/en unknown
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US11338104B2 (en) | Humidifier for respiratory apparatus | |
NZ575837A (en) | Conduit for heating a breathable gas in a respiratory apparatus | |
US11707587B2 (en) | Wire heated tube with temperature control system, tube type detection, and active over temperature protection for humidifier for respiratory apparatus | |
CN109550128B (en) | Medical tube and method for manufacturing same | |
US9327093B2 (en) | Heating element, humidifier for respiratory apparatus including heating element, and respiratory apparatus | |
US8303173B2 (en) | Dual potting temperature probe | |
AU2013257505B2 (en) | Conduit for Use in a Respiratory Apparatus | |
NZ765241A (en) | Conduit for use in a respiratory apparatus |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PSEA | Patent sealed | ||
RENW | Renewal (renewal fees accepted) |
Free format text: PATENT RENEWED FOR 16 YEARS UNTIL 08 NOV 2027 BY JAMES + WELLS Effective date: 20220923 |