Method of monitoring patient respiration and predicting apnea therefrom

Claim 1

A method of monitoring waveforms indicative of patient respiration and activating an alarm upon occurrence of predetermined respiration conditions indicative of apnea, comprising the steps of (a) monitoring a respiration waveform and forming a value representative of the instantaneous magnitude of said waveform at regular and continuous time intervals; (b) continuously forming the difference between each such value and at least the second previous such value, and developing therefrom a value representative of the instaneous slope of said waveform; (c) collecting such slope values for a first predetermined time which is at least as long in time as one respiration cycle and selecting from the collected slope values the maximum collected slope value; (d) continuously repeating step (c) for a second predetermined time which is longer than said first predetermined time, and forming the average of all maximum collected slope values; (e) forming a threshold value by selecting a predetermined fraction of said average of step (d); (f) comparing subsequent slope valves as found in step (b) with said threshold value of step (e) and activating said alarm when said subsequent slope values are less than the threshold value of step (e) for longer than a third predetermined time.

Claim 2

A method of monitoring waveforms indicative of patient respiration and activating an alarm upon occurrence of predetermined respiration conditions indicative of apnea, comprising the steps of (a) monitoring a respiration waveform and forming a value representative of the instantaneous magnitude of said waveform at regular and continuous time intervals; (b) continuously forming the difference between each such value and at least the second previous such value, and developing therefrom a value representative of the instaneous slope of said waveform; (c) collecting such slope values for a first predetermined time which is at least as long in time as one respiration cycle and selecting from the collected slope values the maximum collected slope value; (d) continuously repeating step (c) for a second predetermined time which is longer than said first predetermined time, and forming the average of all maximum collected slope values; (e) forming a threshold value by selecting a predetermined fraction of said average of step (d); (f) comparing subsequent slope valves as found in step (b) with said threshold value of step (e) and activating said alarm when said subsequent slope values are less than the threshold value of step (e) for longer than a third predetermined time.

Claim 13

A method of monitoring patient respiration waveforms and activating an audible alarm upon occurrence of predetermined respiration conditions indication of apnea, comprising (a) sampling a respiration waveform at a predetermined sampling rate and recording instantaneous waveform magnitude values obtained from such sampling; (b) subtracting recorded instantaeous magnitude values from previously recorded instantaneous magnitude values and developing therefrom values representative of instantaneous rate of change of respiration; (c) selecting the maximum rate of change value occurring over a first predetermined time period which is at least as long as one respiration cycle; (d) continuously repeating step (c) for a second predetermined time period which is longer than said first time period and accumulating the selected maximum rate of change values over said first and second predetermined time periods; (e) averaging the accumulated maximum rate of change values and forming a threshold value by developing a value which is a predetermined fraction of said averaged values, said fraction being less than one; (f) comparing said threshold value against subsequent values representative of instantaneous rate of change of respiration as developed in step (b); and (g) activating an alarm whenever said threshold value exceeds said values representative of instantaneous rate of change of respiration for a third predetermined time interval.

Claim 14

A method of monitoring patient respiration waveforms and activating an audible alarm upon occurrence of predetermined respiration conditions indication of apnea, comprising (a) sampling a respiration waveform at a predetermined sampling rate and recording instantaneous waveform magnitude values obtained from such sampling; (b) subtracting recorded instantaeous magnitude values from previously recorded instantaneous magnitude values and developing therefrom values representative of instantaneous rate of change of respiration; (c) selecting the maximum rate of change value occurring over a first predetermined time period which is at least as long as one respiration cycle; (d) continuously repeating step (c) for a second predetermined time period which is longer than said first time period and accumulating the selected maximum rate of change values over said first and second predetermined time periods; (e) averaging the accumulated maximum rate of change values and forming a threshold value by developing a value which is a predetermined fraction of said averaged values, said fraction being less than one; (f) comparing said threshold value against subsequent values representative of instantaneous rate of change of respiration as developed in step (b); and (g) activating an alarm whenever said threshold value exceeds said values representative of instantaneous rate of change of respiration for a third predetermined time interval.