Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
  • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
  • A61B5/1116—Determining posture transitions
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
  • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
  • A61B5/0537—Measuring body composition by impedance, e.g. tissue hydration or fat content
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
  • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
  • A61B5/1113—Local tracking of patients, e.g. in a hospital or private home
  • A61B5/1114—Tracking parts of the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/48—Other medical applications
  • A61B5/4842—Monitoring progression or stage of a disease
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/48—Other medical applications
  • A61B5/4848—Monitoring or testing the effects of treatment, e.g. of medication
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
  • A61B5/7271—Specific aspects of physiological measurement analysis
  • A61B5/7275—Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/74—Details of notification to user or communication with user or patient ; user input means
  • A61B5/746—Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B2505/00—Evaluating, monitoring or diagnosing in the context of a particular type of medical care
  • A61B2505/07—Home care

Definitions

• This invention relates to sleep therapy systems, for treating sleep apnea, and including at least a positional therapy function.
• Sleep apnea is a multifactorial disorder. Age, gender, body weight, cardiac insufficiencies, pulmonary diseases, seasonal infections, and life style contribute to, and worsen, the disorder.
• Obstructive sleep apnea is characterized by a narrowing and collapse of the upper airway.
• Anatomical properties and features contribute mainly to the collapse.
• Beside static anatomical features, also dynamic alterations of the upper airway impede the narrowing of the airway.
• the gravitational displacement and swelling of soft tissue in the airway narrow the airway and increase the Apnea Hypopnea index (AHI).
• CSA Central sleep apnea
• the decrease of neural activity leads to a decline in tidal volume, a full cessation of airflow or a periodic breathing (Cheyne-Stokes Breathing).
• the first line therapy in OSA is a positive airway pressure therapy (PAP) and the first line therapy in CSA is an adaptive support ventilation by an Average Volume Assure Pressure Support (AV APS) device.
• PAP positive airway pressure therapy
• AV APS Average Volume Assure Pressure Support
• An alternative, less invasive, treatment approach for sleep apnea is to control the posture of the patient during sleep, in particular to ensure they sleep on their side rather than on their back.
• a traditional method of positional sleep training is known as the “Tennis Ball Technique”. With this technique, a tennis ball is sewn into the back of a shirt worn to bed by the subject so that the subject finds sleeping on his or her back uncomfortable.
• Electronic positional sleep therapy devices are also well known for treating positional sleep apnea.
• Typical positional sleep therapy device use an accelerometer system to detect whether a subject is sleeping on his or her back and provide vibratory feedback to the subject that prompts the subject to change his or her position.
• the known sleep therapy systems are for providing position control based on detection of sleep apnea events. However, they do not provide therapy which addresses other physiological problems, in particular problems relating to fluid accumulation and fluid shift.
• Fluid accumulation and fluid shift are known physiological alterations in sleep.
• the body compartments being effected are the upper airway (nasal, pharyngeal airway), pulmonary airway (bronchi, alveoli) and the heart chambers and vascular structures in the thorax.
• the fluid uptake is one of the causes of sleep disordered breathing SDB.
• the primary cause is the body position in sleep.
• the transition from an upright body position to lying down changes the hydrostatic pressure and gravitational forces.
• CHF heart failure
• COPD pulmonary disease
• the fluid accumulation is more severe and needs a preventing therapy.
• the affected anatomical structures and the amount of fluid shift depend on the type of comorbidity and its severity.
• Rostral fluid shift the change of the hydrostatic pressure difference between upper airway and lower body compartments (legs) is the driving force to shift liquid into the upper airway causing swelling.
• the amount of volume accumulation in different parts of the body depends on the height position of the heart relative to the whole body. In a left lateral body position the heart is in a low position and the hydrostatic pressure is higher than in the right lateral position. This relative height difference, and hence the difference in hydrostatic pressure, causes a higher venous return flow. This is the major cause of the volume overloading, for example in coronary heart failure (CHF) patients. Such volume overloading causes stretching of the heart chamber.
• CHF coronary heart failure
• the baroreceptor and Bainbridge receptors in the central veins and in the right atrium trigger a sympathetic response causing a hemodynamic alteration (which is manifested as a change in heart rate and stroke volume).
• a positional therapy itself may thus influence the rostral fluid shift.
• Negative inspiratory pressure in an apnea and hypopnea event The negative pressure in the lung increases the transmural pressure in the alveoli and increases the venous return flow into the right atrium. This higher pressure is the cause of liquid accumulation in the lung.
• a secondary cause for an increased fluid shift is the side effect of a sleep apnea therapy.
• the positive pressure by a positive applied pressure (PAP) device to the airway increases the transmural pressure in the upper and pulmonary airway.
• the transmural pressure changes are a driving force for a liquid uptake in the lung and a volume accumulation the heart chambers and blood vessels.
• the extrinsic positive pressure in the lung has a similar physiological effect as the PEEP in COPD patients.
• the intrathoracic pressure also modulates the systemic circulation; the venous return (preload at right atrium) will change and the stroke volume of the left ventricle will change.
• the intrathoracic pressure thus has implications on the cardiac preload and afterload.
• the cardiac system responds by a change in heart rate and stroke volume, in particular an increased heart rate and an increased systemic arterial pressure.
• the pressure is the cause of an increased vascular resistance, which leads, in particular in heart failure patients, to a cardiac volume overload.
• the therapy target is to eliminate the stress caused by the apnea event.
• the secondary cause explained above, namely the therapy device related stress, can generally be neglected in this patient cohort.
• a positional sleep therapy system to adapt in response to fluid accumulation and fluid shifts, for example which may be caused by a sleep apnea therapy which is being used in combination with the positional sleep therapy system.
• US 2010/0234716 discloses the monitoring of fluid content within body tissues, for example using an ultrasound patch. If a patient sleeps on their right side, fluid accumulation in the lung can be detected by placing the sensor at the bottom of the lung when in this sleep position.
• US 2013/267791 discloses a system for locating clinicians, and for generating an alert to a most suitable subset of clinicians when a patient monitoring system detects a need for a clinician.
• the patient monitoring system for example may detect a possible future clinical event of fluid build-up on the lungs.
• EP 1 731 088 discloses an implantable cardiac diagnostic system.
• a sleep therapy system comprising: a sensor arrangement for detecting physiological parameters of a subject; a detection system for detecting a sleeping position of the subject; an alert system for instructing a change in sleep position of the subject; a feedback system for inducing a change in sleep position; and a controller, wherein the controller is adapted to: identify, from the physiological parameters, fluid accumulation in a region of the body of the subject; and control the alert system to instruct the feedback system to induce a change in sleep position of the subject intended to remedy the fluid accumulation.
• the change in sleep position is induced by a feedback system until the patient moves to the desired posture.
• Multiple feedback units e.g. vibration units
• This sleep therapy system uses position therapy to address fluid accumulation in a region of the body (such as the lungs, heart or airway). Physiologically, any change of a transmural pressure in the vascular structures contributes to a fluid shift. This can for example arise when performing other sleep therapy approaches, such as positive airway pressure therapies in conjunction with the position therapy.
• the position therapy may thus be one part of an overall therapy solution including other types of therapy, such as a PAP therapy (such as CPAP) or AV APS therapy.
• the type of fluid accumulation (shift, tissue swelling or volume overloading) which will be experienced by a patient depends on the type(s) of comorbidity and the type of fluid shift is specific for the comorbidity.
• the choice of therapy and the therapy solution can thus be based on the known patient records and a diagnostic examination. By sensing these fluid accumulation conditions, the invention enables a dynamic adaptation of sleep therapy during sleep.
• the system may be designed to detect and address any of these types of fluid shift.
• the system comprises a sensor arrangement for detecting parameters which are indicative of the type of fluid shift being detected.
• the sensor arrangement comprises one or multiple sensors which sense the type of fluid shift and the severity.
• the positional therapy implemented by the system may be one of various possible therapies which may be used in various combinations.
• the system is able to balance the treatment of the sleep apnea itself with addressing issues arising from fluid accumulation, which may for example be side effects which result from those other sleep apnea therapies.
• the sensor arrangement may comprise: a bioimpedance sensor for mounting against the chest thereby to enable identification of fluid accumulation in the lungs.
• a first type of fluid accumulation is fluid accumulation in the lungs. This may be detected at least in part using bioimpedance sensing.
• the sensor arrangement may additionally comprise a blood oxygen saturation sensor for detecting a ventilation perfusion mismatch.
• the sensor arrangement may further comprise a breathing sensor for monitoring a respiratory flow pattern.
• the breathing sensor may be used to enable identification of atrial fluid accumulation.
• a second type of fluid accumulation is fluid accumulation or volume overloading in the heart chambers and pulmonary/ systemic veins. This may be detected at least in part using analysis of breathing flow patterns and the analysis of the pulsatility and flow patterns in a PPG signal.
• the sleep therapy system may then further comprise an adaptive support ventilation system, and wherein the breathing sensor (i.e. respiratory flow sensor) is part of the adaptive support ventilation system, wherein the controller is adapted to trigger the detection of body position or the position of part of the body (such as the head or chinbone) based on the respiratory flow pattern.
• An adaptive support system may then be used to elevate the head and/or tilt the bed or mattress.
• a system may also be used to advance the mandible.
• the system makes use of a respiratory flow sensor, for instance of a ventilation support system or a nasal or oral flow sensor or an abdominal and chest belt. Based on monitoring the sleeping posture or head position, the patient can then be triggered to change posture if an alternative posture is better, or a system may be used to change automatically the posture of the patient.
• a respiratory flow sensor for instance of a ventilation support system or a nasal or oral flow sensor or an abdominal and chest belt.
• the sensor arrangement may comprise a hemodynamic sensor (ECG and/or PPG sensor) thereby to enable detection of cardiac stress.
• ECG hemodynamic sensor
• PPG PPG sensor
• Cardiac stress is caused by cardiac volume overloading (result from a change of venous return flow, increased vascular resistance, or a decline of ejection fraction and stroke volume), and thus consequently the change of the pulmonary intravascular pressure relates to fluid movement and fluid accumulation in the lung.
• This cardiac stress may be manifested as a decline in stroke volume (SV) and ejection fraction (EF). These conditions may for example be determined based on measurements of heart rate, heart rate variability and blood pressure.
• SV stroke volume
• EF ejection fraction
• the controller may in this case be adapted to instruct a change in sleep position to a right side. This reduces cardiac volume overload.
• the heart is at the left side in the chest, so that in a right lateral body position the heart is at an elevated position. This change of the hydrostatic pressure impedes the venous return flow (filling of right atrium) and the stroke volume.
• the sensor arrangement may further comprise a breathing sensor for monitoring a respiratory flow pattern to enable detection of breathlessness.
• the breathing sensor is for example adapted to detect Cheyne-Stokes respiration or hypoventilation.
• This respiration can be detected based on respiratory movements such as chest movements and respiratory flow pattern. It is a typical compensatory effect in chronic heart failure patients.
• the controller may be adapted to instruct a change in sleep position to the opposite side when Cheyne-Stokes respiration is detected. If the venous return flow declines, the system may for example trigger a positional change to the left lateral position. In case of an increased venous return flow the system may trigger a positional change to the right lateral position.
• the sensor arrangement may comprise: an ECG sensor for detecting volume overload; a heart rate sensor; an oxygen saturation sensor; a bioimpedance sensor for identifying rostral fluid shift.
• the heart rate sensor could be a PPG sensor, for measuring pulse rate and oxygen saturation SpO2.
• the sleep therapy system may further comprise a breathing ventilation system, and wherein the controller is further adapted to control the breathing ventilation system in response to the identified fluid accumulation in a region of the body of the subject.
• the position therapy system is one part of a combination of therapies.
• the fluid accumulation may indeed be an unintended side effect of the breathing ventilation therapy particularly in comorbid patients.
• the breathing ventilation system may be an AV APS system or a CPAP system.
• the controller is for example adapted to control the breathing ventilation system provide increased ventilation of the lung compartments, to improve/rebalance the mismatch in ventilation/circulation.
• the invention also provides a method of controlling a sleep therapy system, comprising: receiving detected physiological parameters of a subject; identifying, from the physiological parameters, fluid accumulation in a region of the body of the subject; receiving a detected sleeping position of the subject; and control an alert system to instruct a feedback system to induce a change in sleep position of the subject intended to remedy the fluid accumulation.
• the invention also provides a computer program comprising computer program code which is adapted, when said program is run on a computer, to implement the method defined above.
• Figure 1 shows a first example of a sleep therapy system
• Figure 2 shows a second example of a sleep therapy system
• Figure 3 shows a third example of a sleep therapy system.
• the invention provides a sleep therapy system, comprising a sensor arrangement for detecting physiological parameters of a subject, a detection system for detecting a sleeping position of the subject and an alert system for instructing a change in sleep position of the subject. From the monitored physiological parameters, fluid accumulation is identified in a region of the body of the subject. The alert system is controlled to instruct a change in sleep position thereby to address e.g. reverse the fluid accumulation.
• the position therapy may reduce the fluid accumulation or it may improve the patient condition in other ways. For example, pneumonia is a possible cause of edema. Pneumonia is caused by an infection which causes a local edema. Position therapy cannot get rid of the edema, but other compartments may be better ventilated and/or better perfused.
• the invention is based on the recognition that for an optimized sleep apnea therapy, both the physiological stress during a sleep apnea event and the physiological stress caused by the therapy itself should both be considered in order to achieve the best therapy for the patient.
• the invention is based on the use of positional therapy to address these stress conditions.
• the invention involves sensing physiological stress by detecting the consequent fluid shift (e.g. volume accumulation). A therapy goal is then to avoid and mitigate the therapy-related stress condition. If a fluid shift is detected, the aim is for example to counteract and rebalance the fluid shift.
• PAP e.g. CPAP
• AV APS therapy e.g. AV APS therapy
• PEEP Positive end expiratory pressure
• Hydrostatic pressure changes such as a fluid shift from the lower body compartments (legs) to upper body compartments (airway, neck) when going to bed, resulting from the positional change from upright to laying down.
• a single therapy or a combination of different therapies may need to be provided.
• the positional therapy which is the subject of this invention may be one of various possible therapies which may be used in various combinations.
• the position therapy may involve:
• Control of body position or posture for example to provide an elevated position of the head in order to lower a fluid shift from a lower body compartment;
• Control of body position or posture for example to control a position of the thorax in order to improve ventilation of all compartments of the lung.
• Additional therapies which may be used in combination with the positional therapy include:
• Positive pressure therapy in which the therapy pressure may be adapted in dependence on the detected fluid accumulation;
• Mandibular advancement to reduce the airway flow resistance in the pharyngeal and oropharyngeal airway.
• the system for example has respective subsystems to sense and monitor the fluid shift at a specific anatomical structures or in a compartment within one structure.
• the three anatomical structures of interest are:
• the upper airway The upper airway.
• fluid shift may be used to detect these different types of fluid accumulation, i.e. fluid shift from one part of the body to another, either directly or by surrogate means.
• the analysis and post processing of the sensor data may be used to determine whether the fluid shift is above a threshold.
• the fluid shift may then be considered to be the result of physiological stress which needs to be addressed.
• the three types of fluid accumulation will now be discussed in turn.
• Figure 1 shows an example of a system which adapts a position therapy in order to detect and react to fluid accumulation in the lungs.
• the system comprises a sensor arrangement 10 for detecting physiological parameters of a subject, a detection system 12 for detecting a sleeping position of the subject (e.g. the body and thorax position) and an alert system 14 for instructing a change in sleep position of the subject.
• the detection system is for example an accelerometer or optionally a camera.
• a controller 16 identifies, from the physiological parameters, fluid accumulation in the lungs and controls the alert system 14 to instruct a change in sleep position thereby to remedy the fluid accumulation.
• the controller 16 optionally may also control the settings applied by one or more other therapy systems 20 such as CPAP system or an AV APS system.
• the alert system triggers a position change based on the location/compartment of the liquid accumulation (derived from the bio-impedance sensors) and the severity of liquid accumulation (derived from flow data).
• the positional change is performed in a way to elevate the compartment to a higher position to decrease the hydrostatic transmural pressure.
• the change in position triggered by the system may be to a lateral position such that a fluid shift occurs into the inferior body side (after positioning) due to the change in hydrostatic pressure.
• a further positional change may then be triggered to the opposite lateral side.
• the sensor arrangement 10 comprises: An array of bioimpedance sensors 10a integrated in belts or superficial patches worn at the chest. They sense a decrease in impedance that is specific for a liquid accumulation. The data from the array of sensors is used to localize the effected lung compartment and quantifies the liquid uptake.
• the bioimpedance sensors enable analysis of the fluid uptake by analyzing the relative change of the impedance.
• the blood oxygen saturation (SpO2) can be additionally measured by a PPG sensor to detect a ventilation perfusion mismatch.
• the mismatch is predominantly caused by an insufficient ventilation and it is the primary target in the therapy.
• the insufficient circulation contributes further to the desaturation and thus has to be addressed by an advanced therapy approach.
• An air flow sensor 10b measures changes in lung compliance which is specific for liquid/fluid accumulation. This may be a nasal/oral flow sensor to sense the inspiration and expiration flow pattern.
• the data of the sensor is used as follows:
• the array of bio-impedance sensors localize the compartment with increased fluid accumulation.
• the sensors can localize the fluid uptake but cannot quantify the accumulated liquid.
• the airflow sensor measures the change in lung compliance.
• the change in lung compliance allows a quantified analysis of the volume of accumulated liquid.
• These sensors are preferably complemented by an ECG and PPG sensor to measure the mismatch in ventilation and circulation.
• the therapeutic pressure in a CPAP therapy may be reduced during expiration.
• a lowering of the expiratory pressure decreases the pneumatic stenting. It enables a better recoiling of the chest and it increases the pulmonary compliance and mitigates a further liquid accumulation.
• the pulmonary vascular resistance then decreases. As a cardiac response to this reduced vascular resistance, the pulmonary blood pressure and the heart rate will decrease. These can be measured by hemodynamic sensors as feedback indicative of therapy success.
• a ventilation pattern with increased chest breathing may be triggered to improve the ventilation of the upper compartments of the lung with a better blood perfusion.
• nocturnal desaturation is the result of a ventilation-perfusion mismatch in the lung. This is caused either by an insufficient uptake of air (reduced minute air volume) or an insufficient pulmonary blood flow (reduced cardiac output).
• air reduced minute air volume
• pulmonary blood flow reduced cardiac output
• the body can desaturate. This happens when only those compartments of the lung are ventilated which are not sufficiently perfused. This can happen when these compartments of the lung are obstructed by a pulmonary edema, namely a swelling of the tiny bronchi and alveoli.
• the bronchi and alveoli are flexible, highly compliant structures. A liquid accumulation will change the compliance, and hence the capacitive behavior of the lung. The liquid accumulation also has some, but less, impact on the resistive behavior.
• Respiration in rest requests a muscular activity during inspiration.
• the expiration is a passive outflow of the air forced by the chest recoiling.
• the flow pattern is patient specific and depends on the body position.
• the patient specific flow pattern can be measured in advance in a sleep study. These measurements are a baseline for the detection of relative changes in the inspiratory and expiratory airflow.
• a lung edema starts in the lower compartment of the lung. This compartment is then less perfused. When people lay down and fall asleep the breathing becomes more shallow. It becomes predominantly a diaphragm breathing which ventilates better the lower compartment of the lung, which on the other hand is also the compartment where the edema builds up during the day in upright position.
• a relative change in the flow pattern is an indication for a change in the pulmonary airway, and in particular in the alveoli.
• the capacitive behavior can be measured by determining a decline of the residual volume and based on the dynamics of the recoiling chest.
• the first derivative of the expiratory flow and the frequency spectrum is specific for a change in the capacitive behavior.
• the area with an increased fluid uptake should be identified, and a fluid reabsorption or a fluid shift into other compartments should be triggered by a position therapy system.
• a first measure which may be obtained by a processing unit is a measure of change in the capacitive behavior. If the change is above a predefined index, a change in position is triggered to mitigate a further accumulation of liquid in the lung. This results in a change in the hydrostatic conditions and can thus trigger a fluid shift. This pulmonary accumulation also increases the pulmonary vascular resistance. The cardiac system compensates for this by increasing the pulmonary blood pressure and the heart rate. The changes in the pulmonary circulation and ventilation are both specific and complement each other in the therapy decision.
• a liquid uptake in the pulmonary airway is caused primarily by an increased transmural pressure in the lung.
• transmural pressures There are two transmural pressures to be considered: the air pressure in the alveoli and the blood pressure in the pulmonary capillaries.
• the liquid accumulation contributes to a pulmonary edema.
• Figure 2 shows an example of a system which adapts a position therapy in order to detect change in venous return flow and atrial loading.
• the sensor arrangement 10 comprises:
• An ECG sensor lOd to measure the change of heart rate, heart rate variability; which is specific for a change of the stroke volume and the modulation of the stroke volume by the respiration cycle;
• Air flow sensor lOe Air flow sensor lOe
• a chest belt lOf to sense respiration drive A chest belt lOf to sense respiration drive.
• the data of the sensor is used as follows:
• the analysis of the PPG signal in the time domain provides specific data to quantify the change in the stroke volume.
• the variability of the heart rate is specific for the modulation of ejection fraction and stroke volume. It is a surrogate means to analyze the baroreceptor activation by the atrial (over)loading.
• the airflow sensor complements the measurement.
• the Cheyne-Stokes Respiration (CSR) flow pattern is specific for an atrial overloading.
• the detection system 12 is in particular to sense the position of the thorax. As described above, a change in the atrial loading is sensed by baroreceptors in the atrium. These Bainbridge sensors sense the stretching (dilating) of the atrium which corresponds to the loading/venous return flow. The sympathetic activity as a response to the Bainbridge receptors is twofold: an increase of the heart rate and the heart rate variability and an increase of respiration drive (change of tidal volume).
• the air flow sensor detects a CSR pattern
• the ECG sensor detects a change in HR and HRV
• the PPG sensor detect a variability in stroke volume and oxygen desaturation a processing unit will quantify the data. These quantified data are correlated with prerecorded data stored in a personalized data base. If the changes are above predefined threshold, a body position therapy will be triggered and the CPAP pressure settings are adapted accordantly.
• the controller for example triggers a positional change from a left lateral position to a right lateral position to decrease the hydrostatic pressure.
• the hydrostatic pressure correlates with the filling pressure of the right atrium which is a surrogate measure for the venous return flow.
• Typical in heart failure patients is a blood volume accumulation, resulting in a decline in stroke volume (SV) and ejection fraction (EF).
• SV stroke volume
• EF ejection fraction
• It can be caused by: a change in the cardiac preload or afterload, or an atrial overloading and dilated atrium, or a decline in contractibility, or a cardiac infarction or other coronary diseases.
• the cardiac system tends to compensate by an increased heart rate and blood pressure.
• the pressure becomes strongly negative in the obstructed airway. This negative pressure impedes preload/afterload and the atrial filling. This has a strong impact on SV and EF.
• a change in SV and EF can be measured indirectly (surrogately) based on heart rate, heart rate variability and blood pressure and photoplethysmography (PPG).
• the positional therapy can be adapted in a similar manner as explained above.
• the body position has an impact on the cardiac preload (atrial filling pressure is lower in the right lateral position). This changes the atrial fluid accumulation and the pulmonary circulation.
• the positional therapy can be used to decrease the apnea-hypopnea index (AHI) and oxygen saturation index (OSI). Furthermore, by lowering the needed mean PAP pressure, it can improve the venous return flow and the pulmonary flow thereby decrease CSA events for example by lowering the Adaptive support ventilation AV APS pressure settings.
• AHI apnea-hypopnea index
• OSI oxygen saturation index
• AV APS is the preferred ventilation support therapy for CSA patients.
• a high peak pressure is uncomfortable and a major reason for low therapy compliance, and pressure related claustrophobia is typical in breathless persons.
• a high pressure is a hemodynamic burden, impeding the venous return, the atrial filling, increasing the pulmonary arterial pressure, contributing to lung edema, decreasing the stroke volume and cardiac output.
• device settings in a CPAP device or an AV APS device can also be modified to reduce the pressure related implications on preload/afterload.
• the therapy outcome will rebalance SV and EF, which are again surrogately measured using the heart rate and blood pressure and PPG.
• An AV APS device may be used to monitor the respiratory flow pattern, and if the pressure and the flow pattern are beyond predefined thresholds, the body position will be sensed. The system then creates an alarm if the respiratory pressure/flow patterns are above predefined values and the body is detected by the position therapy system to be in a supine and/or left lateral position. The position therapy system can then trigger movement to the right lateral side.
• the position therapy system can then trigger movement to the right lateral side.
• the Central Venous Pressure CVP is about 5 mmHg in healthy persons.
• the change in position may be triggered by the position therapy system (Philips Night Balance for instance) or it may use features of another therapy system such as a vibrating element embedded in the mask of the AV APS device or a high frequency modulation of the pressure provided by the AV APS device.
• the positional therapy system may comprise hemodynamic sensors integrated into a chest belt.
• An ECG sensor may be used to detect volume overloading by heart rate changes, or a PPG sensor may be used to detect stroke volume changes.
• a PPG sensor can also detect desaturation during sleep.
• a bioimpedance sensor may also be used to measure a rostral fluid shift
• a breathing sensor may be used to detect changes in breathing pattern which are specific for persons who feel breathless. For example, it is debated in the medical community that Cheyne - Stokes Respiration, CSR, is a compensatory effect in congestive heart failure patients (CHF). Respiratory movements may for example be measured by sensors integrated as part of the belt (e.g. using respiratory inductance plethysmography).
• a surrogate measure may be obtained from am accelerometer used for body position detection.
• a position change may be triggered based on detection of specific breathing patterns such as CSR.
• the position therapy may favor repositioning to left side.
• Figure 3 shows an example of a system which adapts a position therapy in order to detect and react to airway tissue welling.
• the sensor arrangement 10 comprises:
• An air flow sensor 10g (a nasal/oral flow sensor) to sense airway occlusion and hypoventilation.
• the change of the expiratory flow pattern is specific for the increase of the flow resistance.
• the increased flow resistance correlates to the decrease of cross-section of the upper airway;
• the quantified decrease in tissue impedance correlates to the narrowing of the airway.
• a database may be used to compare with bioimpedance values with recent values during a preceding time period;
• the data of the sensor is used as follows:
• the analysis of the bio-impedance sensors are specific for the liquid accumulation and the narrowing of the airway.
• the analysis of the flow sensor in the expiration cycle is specific for an increased flow resistance of the upper airway.
• the chest and abdominal belts measure the respiration drive/work of breathing.
• the increased respiration drive is a surrogate for increased sympathetic activity.
• the increased sympathetic activity impedes the sleep quality.
• the PPG complements the measurement.
• a desaturation is specific for this disorder resulting from a decreased airflow caused by an airway occlusion (short term alterations of flow pattern) or by tissue swelling (long term alteration of flow pattern).
• the change in position triggered by the system is for example that the patient will be either alerted to reposition the body as defined in a protocol, or a motorized system will elevate the head, tilt the bed and change the bending of the neck.
• intracellular liquid is accumulated in the lower comportment of the body when the person is in an upright position.
• the accumulated liquid from the lower body compartments will be redistributed due to a change in the position related hydrostatic pressure.
• a liquid uptake in the upper airway is caused primarily by the rostral fluid shift from the lower body compartment to upper compartments.
• the liquid uptake in the nasal airway, tonsils and pharyngeal airway decreases the cross-section of the upper airway.
• Some of the intracellular liquid can contribute to a swelling of the soft tissue in the airway (nose, palate, pharynx). This will narrow the upper airway and can be measured by an increased flow resistance during inspiration and expiration.
• a flow pattern processing unit may be used to analyze these flow patterns to distinguish between an airway narrowing by an OSA event in inspiration and an airway narrowing by tissue swelling.
• the rostral fluid shift is a slow process that may take an hour. The narrowing of the airway in an OSA event will happen within one or several breath cycles.
• a processing unit records the flow changes. Based on the timely behavior it distinguish between fluid shift and OSA related airway narrowing.
• the change in position therapy for example involves instructing the patient to from supine to a lateral side in the case of an obstructive airway collapse.
• the instruction may be to elevate the head and chest in the case of tissue swelling in order to lower the hydrostatic pressure, which is a cause for the liquid accumulation in the airway.
• CPAP/BiPAP therapy in addition to controlling the position therapy, other therapy systems may be controlled.
• the inspiratory CPAP pressure is increased to treat an obstructive event.
• the CPAP pressure will instead be decreased during expiration in case of a soft tissue swelling.
• Bioimpedance sensors for example located at the neck, lower extremities, and/or chest;
• An airflow pattern analyzer for example for determining: the inspiration/expiration ratio; dynamics in inspiration and expiration; the airflow resistance in the upper airway (nasal and pharyngeal airway narrowing); and/or the airflow resistance in the lower airway, such as constriction of bronchi (i.e. asthma) and collapse of alveoli (COPD) and swelling of alveoli (pulmonary edema);
• An ECG sensor and/or PPG sensor to sense heart rate, heart rate variability and SpO2;
• a blood pressure sensor A blood pressure sensor
• An EMG sensor A sensor for measuring the venous pulsation, to sense changes in venous return at the jugular vein.
• the venous return flow and its alterations can be measured surrogately.
• the increased venous return activates baroreceptors (Bainbridge receptors) which will increase the heart rate.
• the change of the volume (per heart cycle) - the stroke volume changes - can be surrogately measured by a PPG signal.
• the sympathetic response to cardiac volume accumulation may for example be derived from analysis of heart rate, heart rate variability changes, blood pressure and pulse transit time.
• the baroreceptor response in cardiac volume overloading may be derived from analysis of the heart rate and blood pressure.
• Persistent feedback may be provided until the patient moves to the desired posture.
• Multiple feedback units e.g. vibration units
• the system is preferably able to detect each of the three types of fluid shift discussed in detail above.
• the fluid shift in the three anatomical structures (upper airway, pulmonary airway and cardiac chambers) are thus all diagnosed and quantified by the sensors and processing units described above.
• a decision support unit may then prioritize a positional change corresponding to the most severe fluid shift/liquid accumulation.
• the decision support unit may provide a timing protocol to trigger different positional changes in a sequential manner.
• the patient cohort is for example already diagnosed in a sleep study and is a candidate for an OSA/CSA therapy.
• OSA/CSA therapy In a regular sleep study, the severity of OSA is known and quantified by the AHI value.
• the effectiveness of the CPAP therapy is validated and CPAP is prescribed as the first line therapy.
• the progression in pulmonary edema and pneumonia worsens the health condition and may cause a hospital readmission.
• the overall target of the therapy is to stop or slow down the fluid accumulation in the lung.
• Positional therapy is one element in the therapy adaptation, and other therapies may also be adapted.
• the patient stratification will determine which is the primary therapy and which other therapies complement the primary one.
• a sleep study in OSA patients with comorbidities becomes a multifactorial study.
• the therapy goal is to rebalance the ventilation.
• it will study the side effect of the selected therapy with respect to fluid shift and its implication on the comorbidity.
• a positional therapy alone or in combination with other therapies e.g. CPAP may be proposed to optimize the treatment at home.
• the settings of the therapy devices will be adapted, in particular, this invention relates to an approach by which a change of the body position will be triggered.
• the adaptions of the therapy settings are recorded and caregivers will be alerted in case the sensed fluid shift is beyond predefined thresholds.
• the aim of the improvement of the sleep therapy provided by the invention is to keep the physiological burden as low as possible to avoid a disease exacerbation during treatment.
• this is particularly relevant for congestive heart failure (CHF) and COPD patients after release from hospital.
• CHF congestive heart failure
• COPD COPD patients after release from hospital.
• it is important to avoid a hospital readmission in the first 30 days after release from the clinical ward.
• the invention is of particular interest for patients with both pulmonary and cardiac diseases.
• the pulmonary diseases for example may include COPD, asthma and/or pulmonary hypertension.
• the cardiac diseases (and insufficiencies) may include right heart insufficiencies, left heart insufficiencies, systemic hypertension and/or cardiac arrhythmias.
• an adapted therapy system comprising at least positional therapy, but typical comprising a suitable combination of positional therapy, positive airway pressure therapy and repositioning of anatomical structures.
• a computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

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