System and method for non-invasively determining an internal component of respiratory effort

Abstract

A non-invasive method and system is provided for determining an internal component of respiratory effort of a subject in a respiratory study. Both a thoracic signal (T) and an abdomen signal (A) are obtained, which are indicators of a thoracic component and an abdominal component of the respiratory effort, respectively. A first parameter of a respiratory model is determined from the obtained thoracic signal (T) and the abdomen signal (A). The first parameter is an estimated parameter of the respiratory model that is not directly measured during the study. The internal component of the respiratory effort is determined based at least on the determined first parameter of the respiratory model. The first model parameter is determined based on the thorax signal (T) and the obtained abdomen signal (A) without an invasive measurement.

What is claimed: 
     
         1 . A non-invasive method for determining an internal component of respiratory effort of a subject in a respiratory study, the method comprising:
 obtaining a thoracic signal (T), the thoracic signal (T) being an indicator of a thoracic component of a respiratory effort of the subject;   obtaining an abdomen signal (A), the abdomen signal (A) being an indicator of an abdominal component of the respiratory effort;   determining at least a first parameter of a respiratory model from the obtained thoracic signal (T) and the abdomen signal (A), the first parameter being an estimated parameter of the respiratory model that is not directly measured during the study; and   determining the internal component of the respiratory effort based at least on the determined first parameter of the respiratory model;   wherein the first model parameter is determined based on the obtained thorax signal (T) and the obtained abdomen signal (A) without an invasive measurement obtained from the subject.   
     
     
         2 . The method according to  claim 1 , wherein the internal component of the respiratory effort includes
 intra-thoracic pressure;   upper airway resistance;   respiratory muscle activation;   respiratory tissue elasticity; or   internal respiratory resistance.   
     
     
         3 . The method according to  claim 1 , wherein the internal component of the respiratory effort includes one or more of the following:
 thoracic contribution (β) to breathing of the subject relative to abdomen contribution;   abdomen contribution (γ) to breathing of the subject relative to thoracic contribution;   respiratory muscle induced airway pressure (Pmus);   respiratory drive (v);   respiratory abdomen tissue compliance (Cab);   respiratory thoracic tissue compliance (Cth);   respiratory compliance ratio;   respiratory exhalation time constant (τex);   respiratory inhalation time constant (τin);   respiratory internal time constant between abdomen and thorax (τabth);   respiratory abdomen exhalation time constant (τabex);   respiratory abdomen inhalation time constant (τabin);   respiratory thoracic exhalation time constant (τthex);   respiratory thoracic inhalation time constant (τthin);   respiratory system eigenvalues (λ);   respiratory system frequency response;   respiratory system impulse response;   respiratory system step response;   respiratory internal resistance (R);   upper airway resistance during inhalation;   upper airway resistance during exhalation;   dynamic response of the upper airway resistance;   pharyngeal anatomy or collapsibility;   loop gain (LG) of a ventilator control system;   upper airway gain (UAG);   esophageal pressure (Pes); and   an arousal threshold.   
     
     
         4 . The method according to  claim 1 , wherein the study is a sleep study. 
     
     
         5 . The method according to  claim 1 , wherein the thoracic signal (T) and the abdomen signal (A) are obtained by a Respiratory Inductive Plethysmograph (RIP) system. 
     
     
         6 . The method according to  claim 5 , further comprising obtaining a flow signal (F) indicating a respiratory flow of the subject, wherein the flow signal (F) is obtained from the thoracic signal (T) and the abdomen signal (A) obtained by a Respiratory Inductive Plethysmograph (RIP) system, and the first model parameter is determined in part based on the obtained flow signal (F). 
     
     
         7 . The method according to  claim 5 , further comprising obtaining a flow signal (F) indicating a respiratory flow of the subject, wherein obtaining the flow signal (F) includes directly measuring the respiratory flow of the subject, and the first model parameter is determined in part based on the obtained flow signal (F). 
     
     
         8 . The method according to  claim 1 , further comprising phenotyping sleep disordered breathing of the subject based at least on the determined first parameter of the respiratory model. 
     
     
         9 . The method according to  claim 1 , wherein the respiratory model is based at least in part on a dissipative resistance (R) of the lung tissue of the subject, respiratory tissue intertia (L) of the subject, or respiratory tissue compliance (C) of the the subject. 
     
     
         10 . The method according to  claim 9 , wherein the respiratory model is further based at least in part on a thoracic contribution (β) to breathing of the subject relative to abdomen contribution. 
     
     
         11 . A system for determining an internal component of respiratory effort of a subject in a respiratory study, the system comprising:
 a first sensor device configured to obtain a thoracic signal (T), the thoracic signal (T) being an indicator of a thoracic component of a respiratory effort of the subject;   a second sensor device configured to obtain an abdomen signal (A), the abdomen signal (A) being an indicator of an abdominal component of the respiratory effort;   a processor configured to receive the thoracic signal (T) and the abdomen signal (A);   wherein the processor is further configured to determine at least a first parameter of a respiratory model from the obtained thoracic signal (T) and the abdomen signal (A), the first parameter being an estimated parameter of the respiratory model that is not directly measured during the study; and   the processor is configured to determine the internal component of the respiratory effort based at least on the determined first parameter of the respiratory model;   wherein the first model parameter is determined based on the obtained thorax signal (T) and the obtained abdomen signal (A) without an invasive measurement obtained from the subject.   
     
     
         12 . The system according to  claim 11 , wherein the internal component of the respiratory effort that the processor is configured to determine includes
 intra-thoracic pressure;   upper airway resistance;   respiratory muscle activation;   respiratory tissue elasticity; or   internal respiratory resistance.   
     
     
         13 . The system according to  claim 11 , wherein the internal component of the respiratory effort that the processor is configured to determine one or more of the following:
 thoracic contribution (β) to breathing of the subject relative to abdomen contribution;   abdomen contribution (γ) to breathing of the subject relative to thoracic contribution;   respiratory muscle induced airway pressure (Pmus);   respiratory drive (v);   respiratory abdomen tissue compliance (Cab);   respiratory thoracic tissue compliance (Cth);   respiratory compliance ratio;   respiratory exhalation time constant (τex);   respiratory inhalation time constant (τin);   respiratory internal time constant between abdomen and thorax (τabth);   respiratory abdomen exhalation time constant (τabex);   respiratory abdomen inhalation time constant (τabin);   respiratory thoracic exhalation time constant (τthex);   respiratory thoracic inhalation time constant (τthin);   respiratory system eigenvalues (λ);   respiratory system frequency response;   respiratory system impulse response;   respiratory system step response;   respiratory internal resistance (R);   upper airway resistance during inhalation;   upper airway resistance during exhalation;   dynamic response of the upper airway resistance;   pharyngeal anatomy or collapsibility;   loop gain (LG) of a ventilator control system;   upper airway gain (UAG);   esophageal pressure (Pes); and   an arousal threshold.   
     
     
         14 . The system according to  claim 11 , wherein the study is a sleep study. 
     
     
         15 . The system according to  claim 11 , wherein the first sensor device is a thoracic belt of a Respiratory Inductive Plethysmograph (RIP) system, and the second sensor device is a abdomen belt of the Respiratory Inductive Plethysmograph (RIP) system. 
     
     
         16 . The system according to  claim 11 , wherein the processor is further configured to determine a flow signal (F) from the thoracic signal (T) and the abdomen signal (A) obtained by a Respiratory Inductive Plethysmograph (RIP) system, and the processor is configured to determine the first model parameter in part based on the obtained flow signal (F). 
     
     
         17 . The system according to  claim 11 , wherein the system further includes a sensor configured to obtain a flow signal (F) by directly measuring the respiratory flow of the subject, and the processor is configured to determine the first model parameter in part based on the obtained flow signal (F). 
     
     
         18 . The system according to  claim 11 , wherein the processor is further configured to phenotype sleep disordered breathing of the subject based at least on the determined first parameter of the respiratory model. 
     
     
         19 . The system according to  claim 17 , wherein the respiratory model is based at least in part on a dissipative resistance (R) of the lung tissue of the subject, respiratory tissue intertia (L) of the subject, respiratory tissue compliance (C) of the subject, or a thoracic contribution (β) to breathing of the subject relative to abdomen contribution. 
     
     
         20 . A hardware storage device having stored thereon computer executable instructions which, when executed by one or more processors, implement a non-invasive method for determining an internal component of respiratory effort of a subject in a respiratory study, the method comprising:
 obtaining a thoracic signal (T), the thoracic signal (T) being an indicator of a thoracic component of a respiratory effort of the subject;   obtaining an abdomen signal (A), the abdomen signal (A) being an indicator of an abdominal component of the respiratory effort;   determining at least a first parameter of a respiratory model from the obtained thoracic signal (T) and the abdomen signal (A), the first parameter being an estimated parameter of the respiratory model that is not directly measured during the study; and   determining the internal component of the respiratory effort based at least on the determined first parameter of the respiratory model;   wherein the first model parameter is determined based on the obtained thorax signal (T) and the obtained abdomen signal (A) without an invasive measurement obtained from the subject.