Apnea detection system
A method and apparatus are described for utilizing a source of vascular pulse waveform data from a patient for the purpose of measuring pulsus paradoxus. The arterial pulse waveform data source described is a pulse oximeter plethysmograph but can be any similar waveform data source, including an intra-arterial transducer, external blood pressure transducer, or plethysmograph. Through incorporation of measurements of values, such as an area under a pulse waveform curve, that are time-domain functions of a change in amplitude of the pulse waveform over a duration of the waveform, embodiments of the present invention represent a significant improvement upon previously described methods of measuring pulsus paradoxus.
1. A method, for detecting apnea in a mammal, comprising:
obtaining data indicative of pulsatile cardiovascular behavior from the mammal, the data comprising at least a first and a second pulse waveform;
determining, by a processor, a first value of a function of a change in amplitude of the first pulse waveform, with respect to time, over at least a partial duration of the first pulse waveform;
determining a second value of a function of a change in amplitude of the second pulse waveform, with respect to time, over at least a partial duration of the second pulse waveform; and
determining at least one of a probability of apnea, a presence of apnea, and an absence of apnea based on a comparison of the first value and the second value;
wherein said first pulse waveform is generated during one of either a respiratory inspiration and a respiratory expiration of said mammal, and said second pulse waveform is generated during the other of the inspiration and the expiration of said mammal.
2. The method of claim 1 , further comprising measuring pulsus paradoxus from a comparison of said first value and said second value.
3. The method of claim 1 , wherein the function of a change in amplitude of the first pulse waveform comprises a slope.
4. The method of claim 1 , wherein the function of a change in amplitude of the first pulse waveform comprises an integral.
5. The method of claim 1 , wherein the function of a change in amplitude of the first pulse waveform comprises an AUC.
6. The method of claim 1 , wherein the comparing comprises correlating a magnitude of the difference between the first value and second value with at least one of a predetermined magnitude and range of pulsus paradoxus.
7. The method of claim 6 , wherein the magnitude of pulsus paradoxus is used to determine the presence of apnea.
8. The method of claim 1 , wherein the comparison of the first and second values is used to determine the presence of central apnea.
9. The method of claim 1 , wherein the comparison of the first and second values is used to determine the presence of obstructive apnea.
10. The method of claim 1 , wherein the comparison of the first and second values is used to determine the presence of mixed apnea.
11. The method of claim 1 , wherein the comparison of the first and second values is used to monitor an infant.
12. The method of claim 1 , further comprising providing an alarm to indicate that the presence of apnea is detected.
13. The method of claim 1 , further comprising alerting a healthcare professional when the presence of apnea is detected.
14. A method for measuring pulsus paradoxus in a mammal, the method comprising:
obtaining data indicative of pulsatile cardiovascular behavior from the mammal, the data comprising a first plethysmographic or pressure amplitude obtained at a first time interval after an onset of a first pulse, and a second plethysmographic or pressure amplitude obtained at a second time interval after the onset of the first pulse;
determining, by a processor, a first value of a function of a difference between the first and second plethysmographic or pressure amplitudes;
obtaining a third plethysmographic or pressure amplitude obtained at the first time interval after an onset of a second pulse, and a fourth plethysmographic or pressure amplitude obtained at the second time interval after the onset of the second pulse;
determining a second value of a function of a difference between the third and fourth plethysmographic or pressure amplitudes;
comparing the first value and the second value to determine a value of pulsus paradoxus;
and comparing the pulsus paradoxus value with at least one of a predetermined value and range so as to determine at least one of a probability of apnea, a presence of apnea, and an absence of apnea.
15. The method of claim 14 , wherein the comparison of the measured pulsus paradoxus indicates the presence of central apnea.
16. The method of claim 14 , wherein the comparison of the measured pulsus paradoxus indicates the presence of obstructive apnea.
17. The method of claim 14 , wherein the comparison of the measured pulsus paradoxus indicates the presence of mixed apnea.
18. A system for measuring pulsus paradoxus in a mammal, the system comprising:
means for obtaining data indicative of pulsatile cardiovascular behavior from the mammal, the data comprising at least components of a first and a second pulse waveform; and
means for comparing a first value of a time-domain function of a change in amplitude of the first pulse waveform over at least a partial duration of the first pulse waveform, with a second value of a time-domain function of a change in amplitude of the second pulse waveform over at least a partial duration of the second pulse waveform, so as to determine at least one of a probability of apnea, a presence of apnea, and an absence of apnea;
wherein the means for comparing comprises a microprocessor configured to compare pulsus paradoxus measured from the comparison of the first value with the second value with at least one of a predetermined pulsus paradoxus value and range to determine the presence of central apnea, obstructive apnea or mixed apnea.
19. A system for measuring pulsus paradoxus in a mammal, the system comprising:
a detector module that obtains data indicative of pulsatile cardiovascular behavior from the mammal, the data comprising at least components of a first and a second pulse waveform;
a comparing module that compares a first AUC from at least one component of the first pulse waveform, and a second AUC from at least one component of the second pulse waveform, so as to determine at least one of a probability of apnea, a presence of apnea, and an absence of apnea.
20. The system of claim 19 , wherein the comparing module comprises a microprocessor.
21. A system for measuring pulsus paradoxus in a mammal, the system comprising:
a detector module that obtains data indicative of pulsatile cardiovascular behavior from the mammal, the data comprising at least components of a first and a second pulse waveform;
a comparing module that compares a value of a function of a change in amplitude of the first pulse waveform over at least a partial duration of the first pulse waveform, with a value of a function of a change in amplitude of the second pulse waveform over at least a partial duration of the second pulse waveform, so as to determine at least one of a probability of apnea, a presence of apnea, and an absence of apnea;
wherein the function of a change in height of the first pulse waveform comprises a slope, an integral or an AUC.
22. The system of claim 21 , further comprising an indicator module coupled to the comparing module, said indicator module being configured to indicate the presence of the apnea.