Systems and methods for respiratory event detection

A method for recognizing respiratory events in a monitored subject comprising:

• deriving a signal (Vt) indicative of lung volume from a plurality of respiratory signals received from the monitored subject,
• deriving from the Vt signal one or more temporal sequences of respiratory parameters including one of more of the inspiratory/expiratory (IE) ratio, the fractional inspiratory time, the inspiratory flow rate, and the expiration time;
• and
• recognizing speech events, wherein one or more breaths are recognized as comprising speech in dependence on the derived temporal sequences of one or more of the parameters inspiratory/expiratory (IE) ratio, the fractional inspiratory time, the inspiratory flow rate, or the expiratory time.

A method for recognizing respiratory events in a monitored subject comprising:

• deriving a signal (Vt) indicative of lung volume from a plurality of respiratory signals received from the monitored subject,
• deriving from the Vt signal one or more temporal sequences of respiratory parameters, including minute ventilation volume and peak expiratory flow (PEF) parameters;
• and
• recognizing dyspnea events, wherein dyspnea is recognized in dependence on a ratio of these derived parameters.

A method for recognizing respiratory events in a monitored subject comprising:

• deriving a signal (Vt) indicative of lung volume from a plurality of respiratory signals received from the monitored subject,
• deriving one or more temporal sequences of respiratory parameters including the time to reach peak expiratory flow, the expiratory time, the peak expiratory flow, and the mean expiratory flow;
• and
• recognizing changes in the ratio of forced expiratory volume in one second to vital capacity in dependence on a ratio of the derived temporal sequences of the time to reach peak expiratory flow and the expiratory time paarameters, or on a ratio of the derived temporal sequences of the peak expiratory flow and the mean expiratory flow parameters.

A method for recognizing respiratory events in a monitored subject comprising:

• deriving a signal (Vt) indicative of lung volume from a plurality of respiratory signals received from the monitored subject,
• deriving from the Vt signal and a signal reflective of rib cage size one or more temporal sequences of respiratory parameters including a temporal sequence of the rib cage contribution to the tidal volume;
• and
• recognizing changes in the ratio of forced expiratory volume in one second to vital capacity in dependence on this derived parameter.

A method for recognizing a cough in a monitored subject comprising:

• recognizing a candidate sound event when an input level of a microphone signal exceeds a sound-event threshold, wherein the microphone is responsive to the subject's vocalizations,
• filtering a lung volume signal (Vt) in dependence on characteristics of the candidate sound event,
• recognizing a candidate respiratory event if the selected filtered tidal volume signal exhibits an expiration and a following inspiration having amplitudes greater than a amplitude threshold,
• determining the occurrence of a cough if the candidate sound event coincides temporally with the candidate respiratory event.

A method for recognizing a cough in a monitored subject comprising:

• recognizing a candidate sound event when an input level of a microphone signal exceeds a sound-event threshold, wherein the microphone is responsive to the subject's vocalizations,
• filtering a lung volume signal (Vt) in dependence on characteristics of the candidate sound event into a lower frequency band (LFB) if the candidate sound event has a duration longer than a duration threshold, and into a higher frequency band (HFB) if the candidate sound event has a duration shorter than the duration threshold,
• recognizing a candidate respiratory event if the selected filtered tidal volume signal exhibits an expiration and a following inspiration having amplitudes greater than a amplitude threshold, and
• determining the occurrence of a cough if the candidate sound event coincides temporally with the candidate respiratory event.

A method for recognizing a cough in a monitored subject comprising:

• recognizing a candidate sound event when an input level of a microphone signal exceeds a sound-event threshold, wherein the microphone is responsive to the subject's vocalizations.
• filtering a lung volume signal (Vt) in dependence on characteristics of the candidate sound event,
• recognizing a candidate respiratory event if the selected filtered tidal volume signal exhibits an expiration and a following inspiration having amplitudes greater than a amplitude threshold,
• determining the occurrence of a cough if the candidate sound event coincides temporally with the candidate respiratory event and if the candidate sound event has a pitch characteristic below a cough-pitch threshold.