Method, apparatus, and system for measuring respiratory effort

A method of measuring respiratory effort of a subject, the method comprising:

• obtaining a thorax effort signal (T), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort,
• the thorax effort signal (T) including a volume-contributing thoracic component (VST) and a thoracic paradox component (PT), the thoracic paradox component (PT) representing a non-volume-contributing thoracic component of the respiratory effort, and the volume-contributing thoracic component (VST) representing a volume-contributing component of the respiratory effort;
• obtaining an abdomen effort signal (A), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort,
• the abdomen effort signal (A) including a volume-contributing abdominal component (VSA) and an abdomen paradox component (PA), the abdomen paradox component (PA) representing a non-volume-contributing abdominal component of the respiratory effort, and the volume-contributing abdominal component (VSA) representing a volume-contributing component of the respiratory effort, wherein the abdominal paradox component (PA) is negatively proportional to the thoracic paradox component (PT);
• performing a calibration of the thorax effort signal (T) and the abdomen effort signal (A) based on the obtained thorax effort signal (T) and the abdomen effort signal (A) by
• weighting the thorax effort signal (T) by a first weight factor (kT) and weighting the abdomen effort signal (A) by a second weight factor (kA) to obtain a volume-proportional signal (VSw), the volume-proportional signal (VSw) being proportional to the actual respiratory volume of the respiratory effort;
• and
• optimizing the first and second weight factors (kT and kA) by determining values for the first and second weight factors (kT and kA) that maximize the power of lower frequencies in the volume proportional signal (VSw) compared to the power of higher frequencies in the volume proportional signal (VSw) over a period of time.

A method of measuring respiratory effort of a subject, the method comprising:

• obtaining a thorax effort signal (T), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort,
• the thorax effort signal (T) including a volume-contributing thoracic component (VST) and a thoracic paradox component (PT), the thoracic paradox component (PT) representing a non-volume-contributing thoracic component of the respiratory effort, and the volume-contributing thoracic component (VST) representing a volume-contributing component of the respiratory effort;
• obtaining an abdomen effort signal (A), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort,
• the abdomen effort signal (A) including a volume-contributing abdominal component (VSA) and an abdomen paradox component (PA), the abdomen paradox component (PA) representing a non-volume-contributing abdominal component of the respiratory effort, and the volume-contributing abdominal component (VSA) representing a volume-contributing component of the respiratory effort, wherein the abdominal paradox component (PA) is negatively proportional to the thoracic paradox component (PT);
• performing a calibration of the thorax effort signal (T) and the abdomen effort signal (A) based on the obtained thorax effort signal (T) and the abdomen effort signal (A) by
• weighting the thorax effort signal (T) by a first weight factor (kT) and weighting the abdomen effort signal (A) by a second weight factor (kA) to obtain a volume-proportional signal (VSw), the volume-proportional signal (VSw) being proportional to the actual respiratory volume of the respiratory effort;
• and
• deriving
• the thoracic paradox component (PT) of the thorax effort signal (T) or the abdomen paradox component (PA) of the abdomen effort signal (A), or
• a derivative of the thoracic paradox component (PT) of the thorax effort signal (T) or the abdomen paradox component (PA) of the abdomen effort signal (A)
• by determining values for the first and second weight factors (kT and kA) that minimize an amplitude or power of the volume proportional signal (VSw) compared to the sum of the powers of the thoracic effort signal weighted by the first weight factor (kT) and the abdomen effort signal (A) weighted by the second weight factor (kA) over a period of time.

A hardware storage device having stored thereon computer executable instructions which, when executed by one or more processors, implement a method of measuring respiratory effort of a subject comprising:

• obtaining a thorax effort signal (T), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort,
• the thorax effort signal (T) including a volume-contributing thoracic component (VST) and a thoracic paradox component (PT), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort, the thoracic paradox component (PT) representing a non-volume-contributing thoracic component of the respiratory effort, and the volume-contributing thoracic component (VST) representing a volume-contributing component of the respiratory effort;
• obtaining an abdomen effort signal (A), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort
• the abdomen effort signal (A) including a volume-contributing abdominal component (VSA) and an abdomen paradox component (PA), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort, the abdomen paradox component (PA) representing a non-volume-contributing abdominal component of the respiratory effort, and the volume-contributing abdominal component (VSA) representing a volume-contributing component of the respiratory effort, wherein the abdominal paradox component (PA) is negatively proportional to the thoracic paradox component (PT);
• and
• performing a calibration of the thorax effort signal (T) and the abdomen effort signal (A) based on the obtained thorax effort signal (T) and the abdomen effort signal (A) by
• weighting the thorax effort signal (T) by a first weight factor (kT) and weighting the abdomen effort signal (A) by a second weight factor (kA) to obtain a volume-proportional signal (VSw), the volume-proportional signal (VSw) being proportional to the actual respiratory volume of the respiratory effort;
• calculating a ratio between an amplitude or power, or a transformation function of the amplitude or power of the volume-proportional signal (VSw) and a sum of the amplitudes, power, or a transformation function of the thorax effort signal (T) weighted by the first weight factor (kT) and the abdomen effort signal (A) weighted by the second weight factor (kA);
• and
• selecting the first and second weight factors (kT and kA) that minimize said calculated ratio.

A respiratory effort measuring system comprising:

• a first sensor device configured to obtain a thorax effort signal (T), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort,
• the thorax effort signal (T) including a volume-contributing thoracic component (VST) and a thoracic paradox component (PT), the thoracic paradox component (PT) representing a non-volume-contributing thoracic component of the respiratory effort, and the volume-contributing thoracic component (VST) representing a volume-contributing component of the respiratory effort;
• a second sensor device configured to obtain an abdomen effort signal (A), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort,
• the abdomen effort signal (A) including a volume-contributing abdominal component (VSA) and an abdomen paradox component (PA), the abdomen paradox component (PA) representing a non-volume-contributing abdominal component of the respiratory effort, and the volume-contributing abdominal component (VSA) representing a volume-contributing component of the respiratory effort, wherein the abdominal paradox component (PA) is negatively proportional to the thoracic paradox component (PT);
• and
• a processor configured to receive the thorax effort signal (T) and the abdomen effort signal (A);
• wherein the processor performs a calibration of the thorax effort signal (T) and the abdomen effort signal (A) based on the obtained thorax effort signal (T) and the abdomen effort signal (A) by
• weighting the thorax effort signal (T) by a first weight factor (kT) and weights the abdomen effort signal (A) by a second weight factor (kA) to obtain a volume-proportional signal (VSw), the volume-proportional signal (VSw) being proportional to the actual respiratory volume of the respiratory effort;
• calculating a ratio between an amplitude or power, or a transformation function of the amplitude or power of the volume-proportional signal (VSw) and a sum of the amplitudes, power, or a transformation function of the thorax effort signal (T) weighted by the first weight factor (kT) and the abdomen effort signal (A) weighted by the second weight factor (kA);
• and
• selecting the first and second weight factors (kT and kA) that minimize said calculated ratio.

A method of measuring respiratory effort of a subject, comprising:

• obtaining a thorax effort signal (T), the thorax effort signal (T) being an indicator of a thoracic component of the respiratory effort,
• the thorax effort signal (T) including a volume-contributing thoracic component (VST) and a thoracic paradox component (PT), the thoracic paradox component (PT) representing a non-volume-contributing thoracic component of the respiratory effort, and the volume-contributing thoracic component (VST) representing a volume-contributing component of the respiratory effort;
• obtaining an abdomen effort signal (A), the abdomen effort signal (A) being an indicator of an abdominal component of the respiratory effort,
• the abdomen effort signal (A) including a volume-contributing abdominal component (VSA) and an abdomen paradox component (PA), the abdomen paradox component (PA) representing a non-volume-contributing abdominal component of the respiratory effort, and the volume-contributing abdominal component (VSA) representing a volume-contributing component of the respiratory effort, wherein the abdominal paradox component (PA) is negatively proportional to the thoracic paradox component (PT);
• performing a calibration of the thorax effort signal (T) and the abdomen effort signal (A) based on the obtained thorax effort signal (T) and the abdomen effort signal (A) by
• weighting the thorax effort signal (T) by a first weight factor (kT) and weighting the abdomen effort signal (A) by a second weight factor (kA) to obtain a volume-proportional signal (VSw), the volume-proportional signal (VSw) being proportional to the actual respiratory volume of the respiratory effort;
• and
• calculating a ratio between a transformation function of the volume-proportional signal (VSw) and a sum of a transformation function of the thorax effort signal (T) weighted by the first weight factor (kT) and the abdomen effort signal (A) weighted by the second weight factor (kA);
• and
• selecting the first and second weight factors (kT and kA) that minimize said calculated ratio.