PULSE DETECTION APPARATUS, SOFTWARE, AND METHODS USING PATIENT PHYSIOLOGICAL SIGNALS

• US 20120022339A1
• Filed: 09/29/2011
• Published: 01/26/2012
• Est. Priority Date: 09/30/1999
• Status: Abandoned Application

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Physio-Control Incorporated (Stryker Corporation)
• Inventors: Joo, Tae H., Stickney, Ronald E., Jayne, Cynthia P., Lank, Paula, O'Hearn, Patricia, Hampton, David R., Taylor, James W., Crone, William E., Yerkovich, Daniel
• Application Number:
  US13/249,081
• Publication Number:
  US 20120022339A1
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/39044 in combination with cardiopulmonary resuscitation [CPR] therapy
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

The presence of a cardiac pulse in a patient is determined by evaluating physiological signals in the patient. In one embodiment, a medical device evaluates two or more different physiological signals, such as phonocardiogram (PCG) signals, electrocardiogram (ECG) signals, patient impedance signals, piezoelectric signals, and accelerometer signals for features indicative of the presence of a cardiac pulse. Using these features, the medical device determines whether a cardiac pulse is present in the patient. The medical device may also be configured to report whether the patient is in a VF, VT, asystole, or PEA condition, in addition to being in a pulseless condition, and prompt different therapies, such as chest compressions, rescue breathing, defibrillation, and PEA-specific electrotherapy, depending on the analysis of the physiological signals. Auto-capture of a cardiac pulse using pacing stimuli is further provided.

Claims

1. A medical device for detecting the presence of a cardiac pulse, comprising:

(a) a sensor system configured to sense two or more different physiological signals in a patient and produce physiological signal data in response thereto; and

(b) processing circuitry configured to evaluate the physiological signal data from the different physiological signals for features indicative of the presence of a cardiac pulse, the processing circuitry using the features to determine whether a cardiac pulse is present in the patient.

2. The medical device of claim 1, in which one of the physiological signals is a phonocardiogram (PCG) signal sensed in the patient, and in which the physiological signal data includes PCG data.

3. The medical device of claim 2, in which the feature from the PCG data is determined based on an evaluation of temporal energy in the PCG data.

4. The medical device of claim 3, in which the processing circuitry is configured to evaluate temporal energy in the PCG data by estimating instantaneous and background energies in the PCG data and comparing the instantaneous energy with the background energy.

5. The medical device of claim 2, in which the feature from the PCG data is determined based on an evaluation of spectral energy in the PCG data.

6. The medical device of claim 5, in which the processing circuitry is configured to evaluate spectral energy in the PCG data by calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the peak energy value with a threshold energy value.

7. The medical device of claim 5, in which the processing circuitry is configured to evaluate spectral energy in the PCG data by calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the frequency of the peak energy value with a threshold frequency.

8. The medical device of claim 1, in which one of the physiological signals is an impedance signal that reflects an impedance of the patient, and in which the physiological signal data includes impedance signal data.

9. The medical device of claim 8, in which the feature from the impedance signal data is determined based on an evaluation of energy in the impedance signal data.

10. The medical device of claim 9, in which the processing circuitry is configured to evaluate the impedance signal data by calculating energy in the impedance signal data and comparing the energy in the impedance signal data with a threshold energy.

11. The medical device of claim 1, further comprising a defibrillation pulse generator in communication with the processing circuitry that is configured to automatically prepare a defibrillation pulse for delivery to the patient if the processing circuitry determines that a cardiac pulse is not present in the patient.

12. The medical device of claim 1, further comprising a display, in which the processing circuitry is configured to provide a message on the display prompting application, of defibrillation electrodes to the patient if a cardiac pulse is determined not present in the patient.

13. The medical device of claim 1, in which the processing circuitry is further configured to provide a graph on the display showing a representation of at least one of the two or more physiological signals in the patient.

14. The medical device of claim 13, in which the graph includes a representation of a phonocardiogram (PCG) signal sensed in the patient.

15. The medical device of claim 1, further comprising a display, in which the processing circuitry is configured to provide a message on the display prompting delivery of chest compressions or cardiopulmonary resuscitation to the patient if a cardiac pulse is determined not present in the patient.

16. The medical device of claim 1, in which one of the physiological signals is an electrocardiogram (ECG) signal sensed in the patient, and in which the physiological signal data includes ECG data.

17. The medical device of claim 16, in which the feature from the ECG data is determined based on the presence of a ventricular complex in the ECG data.

18. The medical device of claim 17, in which the processing circuitry is configured to evaluate the ECG data, determine the presence of a ventricular complex, and evaluate physiological signal data from one or more of the other physiological signals using the physiological signal data that corresponds in time proximity to the ventricular complex.

19. The medical device of claim 16, further comprising a display, in which the processing circuitry is configured to prompt a message via the display reporting whether the patient is in a state of pulseless electrical activity (PEA).

20. The medical device of claim 19, in which the processing circuitry determines the patient to be in a state of PEA if a ventricular complex is found in the ECG data and the patient is determined to be pulseless.

21. The medical device of claim 19, in which the processing circuitry is further configured to analyze the patient'"'"'s ECG data for at least ventricular fibrillation (VF), ventricular tachycardia (VT), and asystole, and if the patient is determined to be pulseless and not in a VF, VT, or asystole condition, the processing circuitry then prompting the message reporting that the patient is in a state of PEA.

22. The medical device of claim 1, further comprising a display, in which the processing circuitry is further configured to report via the display whether a cardiac pulse is present in the patient.

23. The medical device of claim 1, in which one of the physiological signals is obtained from photodetection, and in which the physiological signal data includes photodetection signal data.

24. The medical device of claim 23, in which the photodetection signal is a pulse oximetry signal.

25. The medical device of claim 23, in which the processing circuitry is configured to evaluate a temporal parameter in the photodetection signal data.

26. The medical device of claim 23, in which the processing circuitry is configured to evaluate a spectral parameter in the photodetection signal data.

27. The medical device of claim 1, in which one of the physiological signals is a CO₂ waveform signal from a capnography system applied to the patient, and in which the physiological signal data includes capnography signal data.

28. The medical device of claim 27, in which the processing circuitry is configured to evaluate a temporal parameter in the capnography signal data.

29. The medical device of claim 28, in which the temporal parameter reflects cardiogenic oscillations in the capnography signal data.

30. The medical device of claim 27, in which the processing circuitry is configured to evaluate a spectral parameter in the capnography signal data.

31. The medical device of claim 1, in which one of the physiological signals is a Doppler probe signal, and in which the physiological signal data includes Doppler signal data.

32. The medical device of claim 31, in which the processing circuitry is configured to evaluate a temporal parameter in the Doppler signal data.

33. The medical device of claim 33, in which the processing circuitry is configured to evaluate a spectral parameter in the Doppler signal data.

34. An electrotherapy device, comprising:

(a) a sensor configured to sense a phonocardiogram (PCG) signal in a patient;

(b) an electrotherapy generator for delivering electrotherapy to the patient; and

(c) processing circuitry configured to analyze the PCG signal for a feature indicative of the presence of a cardiac pulse in the patient and determine the presence of a cardiac pulse based on said feature.

35. The electrotherapy device of claim 34, further comprising an electrode adapted to sense electrocardiogram (ECG) signals in the patient, the processing circuitry being further configured to analyze the patient'"'"'s ECG signal for ventricular tachycardia and prompt the delivery of defibrillation therapy to the patient if the patient is determined to be pulseless and experiencing ventricular tachycardia.

36. The electrotherapy device of claim 35, in which the processing circuitry is further configured to prompt the delivery of defibrillation therapy if the patient is determined to be pulseless and experiencing ventricular tachycardia with a rate exceeding 100 beats per minute.

37. The electrotherapy device of claim 34, further comprising an electrode adapted to sense electrocardiogram (ECG) signals in the patient, the processing circuitry being configured to analyze the patient'"'"'s ECG signal for at least ventricular fibrillation (VF), ventricular tachycardia (VT), and asystole, and if the patient is determined to be pulseless and not in a VF, VT, or asystole condition, the processing circuitry being further configured to prompt delivery of electrotherapy to the patient designed specifically for pulseless electrical activity (PEA).

38. The electrotherapy device of claim 34, the processing circuitry being further configured to report the return of spontaneous circulation in the patient if a cardiac pulse is determined present in the patient after delivery of defibrillation therapy to the patient.

39. The electrotherapy device of claim 34, further comprising an electrode adapted to sense electrocardiogram (ECG) signals in the patient, the processing circuitry being configured to analyze the patient'"'"'s ECG signal for one or more of ventricular fibrillation (VF), ventricular tachycardia (VT), asystole, and pulseless electrical activity (PEA), the processing circuitry being further configured to prompt a report of VF, VT, asystole, or PEA, if detected and if the patient is determined to be pulseless.

40. The electrotherapy device of claim 34, in which the sensor adapted to sense a PCG signal is a first sensor, the electrotherapy device further comprising a second sensor adapted to receive an impedance-sensing signal that has been communicated through a patient, in which the processing circuitry is configured to analyze each of the PCG and impedance-sensing signals for features indicative of the presence of a cardiac pulse in the patient and determine the presence of a cardiac pulse based on said features.

41. The electrotherapy device of claim 40, in which the processing circuitry is further configured to analyze the impedance-sensing signal to determine the presence of respiration in the patient, the processing circuitry prompting the delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient.

42. The electrotherapy device of claim 40, in which the processing circuitry is further configured to prompt the delivery of chest compressions or cardiopulmonary resuscitation to the patient if the patient is determined to be pulseless.

43. The electrotherapy device of claim 34, in which the electrotherapy generator and the processing circuitry are implemented in an automated external defibrillator.

44. A method for delivering electrotherapy to a patient in which the electrotherapy is comprised of pacing stimuli and seeks capture of a cardiac pulse in the patient, the method comprising:

(a) delivering a pacing stimulus to the patient;

(b) from the surface of the patient'"'"'s body, sensing a physiological signal in the patient; and

(c) analyzing the physiological signal to determine whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.

45. The method of claim 44, further comprising increasing the current of further pacing stimuli to be delivered to the patient if a cardiac pulse did not occur in the patient after delivery of the pacing stimulus.

46. The method of claim 44, in which the physiological signal is a phonocardiogram (PCG) signal, the method comprising analyzing the PCG signal for a feature indicative of a cardiac pulse and determining whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.

47. The method of claim 44, further comprising repeating steps (a)-(c) and increasing the current of further pacing stimuli to be delivered to the patient until a cardiac pulse occurs after delivery of the each pacing stimulus.

48. The method of claim 44, in which pacing stimuli is delivered to the patient two or more times and the physiological signal is analyzed to determine whether a cardiac pulse occurred after the delivery of each pacing stimulus, in which the current of further pacing stimuli to be delivered to the patient is increased if a cardiac pulse does not consistently occur in the patient after the delivery of each pacing stimulus.

49. The method of claim 48, further comprising repeating the delivery of pacing stimuli and increasing the current of the pacing stimuli until a cardiac pulse consistently occurs in the patient after the delivery of each pacing stimulus.

50. The method of claim 44, further comprising prompting a user to increase the current of the pacing stimuli if a cardiac pulse did not occur in the patient after delivery of the pacing stimulus.

51. An electrotherapy device, comprising:

(a) a sensor configured to sense a physiological signal in a patient;

(b) an electrotherapy generator for delivering pacing stimuli to the patient; and

(c) processing circuitry configured to analyze the physiological signal and determine whether a cardiac pulse occurred in the patient following the delivery of a pacing stimulus to the patient, the processing circuitry increasing the current of further pacing stimuli to be delivered to the patient if a cardiac pulse did not occur in the patient following the delivery of the pacing stimulus.

52. The electrotherapy device of claim 51, in which the physiological signal is a phonocardiogram (PCG) signal and the processing circuitry is configured to analyze the PCG signal for a feature indicative of a cardiac pulse and determine whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.

53. The electrotherapy device of claim 51, in which the electrotherapy device is configured to deliver pacing stimuli to the patient two or more times and the processing circuitry is configured to analyze the physiological signal to determine whether a cardiac pulse occurred after the delivery of each pacing stimulus, the current of further pacing stimuli to be delivered to the patient being increased if a cardiac pulse does not consistently occur in the patient after the delivery of each pacing stimulus.

54. The electrotherapy device of claim 51, in which prior to the current of the pacing stimuli being increased, the processing circuitry is configured to prompt a user of the device to increase the pacing stimuli current.

55. A method for detecting the presence of a cardiac pulse, comprising:

(a) sensing two or more different physiological signals in a patient;

(b) evaluating physiological signal data from each of the two or more physiological signals for a feature indicative of the presence of a cardiac pulse; and

(c) determining whether a cardiac pulse is present in the patient based on the features in the physiological signal data.

56. The method of claim 55, in which one of the physiological signals is a phonocardiogram (PCG) signal sensed in the patient, and in which the physiological signal data includes PCG data.

57. The method of claim 56, in which the feature from the PCG data is determined by evaluating a temporal parameter in the PCG data.

58. The method of claim 57, in which the temporal parameter is energy and evaluating temporal energy in the PCG data includes estimating instantaneous and background energies in the PCG data and comparing the instantaneous energy with the background energy.

59. The method of claim 56, in which the feature from the PCG data is determined by evaluating a spectral parameter in the PCG data.

60. The method of claim 59, in which the spectral parameter is energy and evaluating spectral energy in the PCG data includes calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the peak energy value with a threshold energy value.

61. The method of claim 59, in which the spectral parameter is energy and evaluating spectral energy in the PCG data includes calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the frequency of the peak energy value with a threshold frequency.

62. The method of claim 55, in which one of the physiological signals is an impedance signal that reflects an impedance of the patient, and in which the physiological signal data includes impedance signal data.

63. The method of claim 62, in which the feature from the impedance signal data is determined by evaluating energy in the impedance signal data.

64. The method of claim 63, in which evaluating the impedance signal data is comprised of calculating energy in the impedance signal data and comparing the energy in the impedance signal data with a threshold energy.

65. The method of claim 55, further comprising automatically preparing a defibrillation pulse for delivery to the patient if a cardiac pulse is determined not present in the patient.

66. The method of claim 55, further comprising providing a display showing a representation of at least one of the two or more physiological signals in the patient.

67. The method of claim 55, further comprising prompting delivery of chest compressions or cardiopulmonary resuscitation to the patient if a cardiac pulse is determined not present in the patient.

68. The method of claim 55, in which one of the physiological signals is an electrocardiogram (ECG) signal sensed in the patient, and in which the physiological signal data includes ECG data.

69. The method of claim 68, in which the feature from the ECG data is determined by evaluating the ECG data for the presence of a ventricular complex.

70. The method of claim 69, further comprising evaluating physiological signal data from one or more of the other physiological signals using the physiological signal data that corresponds in time proximity to the ventricular complex.

71. The method of claim 68, further comprising analyzing the ECG data for ventricular tachycardia and prompting delivery of defibrillation therapy to the patient if the patient is determined to be pulseless and experiencing ventricular tachycardia.

72. The method of claim 71, further comprising prompting the delivery of defibrillation therapy if the patient is determined to be pulseless and experiencing ventricular tachycardia with a rate exceeding 100 beats per minute.

73. The method of claim 68, further comprising analyzing the ECG data for at least ventricular fibrillation (VF), ventricular tachycardia (VT), and asystole, and if the patient is determined to be pulseless and not in a VF, VT, or asystole condition, then prompting delivery of electrotherapy to the patient designed specifically for pulseless electrical activity (PEA).

74. The method of claim 68, further, comprising analyzing the ECG data for one or more of ventricular fibrillation (VF), ventricular tachycardia (VT), asystole, and pulseless electrical activity (PEA), the processing circuitry prompting a report of VF, VT, asystole, or PEA, if detected and if the patient is determined to be pulseless.

75. The method of claim 55, further comprising reporting the return of spontaneous circulation in the patient if a cardiac pulse is determined present in the patient after delivery of defibrillation therapy to the patient.

76. The method of claim 55, in which one of the physiological signals is an impedance-sensing signal that has been communicated through the patient, and in which the physiological signal data includes impedance signal data.

77. The method of claim 76, further comprising analyzing the impedance-sensing signal to determine the presence of respiration in the patient and prompting delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient.

78. The method of claim 76, further comprising prompting the delivery of chest compressions or cardiopulmonary resuscitation to the patient if the patient is determined to be pulseless.

79. An article comprising a storage medium having device-executable instructions stored thereon, in which when the instructions are executed by at least one device, they result in:

(a) delivering a pacing stimulus to the patient;

(b) from the surface of the patient'"'"'s body, sensing a physiological signal in the patient; and

(c) analyzing the physiological signal to determine whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.

80. The article of claim 79, in which the instructions when executed further result in increasing the current of further pacing stimuli to be delivered to the patient if a cardiac pulse did not occur in the patient after delivery of the pacing stimulus.

81. The article of claim 79, in which the physiological signal is a phonocardiogram (PCG) signal, the instructions when executed further resulting in analyzing the PCG signal for a feature indicative of a cardiac pulse and determining whether a cardiac pulse occurred in the patient after delivery of the pacing stimulus.

82. The article of claim 79, in which the instructions when executed further result in repeating steps (a)-(c) and increasing the current of further pacing stimuli to be delivered to the patient until a cardiac pulse occurs after delivery of the pacing stimulus.

83. The article of claim 79, in which pacing stimuli is delivered to the patient two or more times and the physiological signal is analyzed to determine whether a cardiac pulse occurred after the delivery of each pacing stimulus, the instructions when executed further resulting in increasing the current of further pacing stimuli to be delivered to the patient if a cardiac pulse does not consistently occur in the patient after the delivery of each pacing stimulus.

84. The article of claim 83, in which the instructions when executed further result in repeating the delivery of pacing stimuli and increasing the current of the pacing stimuli until a cardiac pulse consistently occurs in the patient after the delivery of each pacing stimulus.

85. The article of claim 79, in which the instructions when executed further result in prompting a user to increase the current of the pacing stimuli if a cardiac pulse did not occur in the patient after delivery of the pacing stimulus.

86. An article comprising a storage medium having device-executable instructions stored thereon, in which when the instructions are executed by at least one device, the result in:

(a) sensing two or more different physiological signals in a patient;

(b) evaluating physiological signal data from each of the two or more physiological signals for a feature indicative of the presence of a cardiac pulse; and

(c) determining whether a cardiac pulse, is present in the patient based on the features in the physiological signal data.

87. The article of claim 86, in which one of the physiological signals is a phonocardiogram (PCG) signal sensed in the patient, and in which the physiological signal data includes PCG data.

88. The article of claim 87, in which the feature from the PCG data is determined by evaluating a temporal parameter in the PCG data.

89. The article of claim 88, in which the temporal parameter is energy and evaluating temporal energy in the PCG data includes estimating instantaneous and background energies in the PCG data and comparing the instantaneous energy with the background energy.

90. The article of claim 87, in which the feature from the PCG data is determined by evaluating a spectral parameter in the PCG data.

91. The article of claim 90, in which the spectral parameter is energy and evaluating spectral energy in the PCG data includes calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the peak energy value with a threshold energy value.

92. The article of claim 90, in which the spectral parameter is energy and evaluating spectral energy in the PCG data includes calculating an energy spectrum of the PCG data, locating a peak energy value in the spectrum, and comparing the frequency of the peak energy value with a threshold frequency.

93. The article of claim 86, in which one of the physiological signals is an impedance signal that reflects an impedance of the patient, and in which the physiological signal data includes impedance signal data.

94. The article of claim 93, in which the feature from the impedance signal data is determined by evaluating energy in the impedance signal data.

95. The article of claim 94, in which evaluating the impedance signal data is comprised of calculating energy in the impedance signal data and comparing the energy in the impedance signal data with a threshold energy.

96. The article of claim 86, in which the instructions when executed further result in automatically preparing a defibrillation pulse for delivery to the patient if a cardiac pulse is determined not present in the patient.

97. The article of claim 86, in which the instructions when executed further result in providing a display showing a representation of at least one of the two or more physiological signals in the patient.

98. The article of claim 86, in which the instructions when executed further result in prompting delivery of chest compressions or cardiopulmonary resuscitation to the patient if a cardiac pulse is determined not present in the patient.

99. The article of claim 86, in which one of the physiological signals is an electrocardiogram (ECG) signal sensed in the patient, and in which the physiological signal data includes ECG data.

100. The article of claim 99, in which the feature from the ECG data is determined by evaluating the ECG data for the presence of a ventricular complex.

101. The article of claim 100, in which the instructions when executed further result in evaluating physiological signal data from one or more of the other physiological signals using the physiological signal data that corresponds in time proximity to the ventricular complex.

102. The article of claim 99, in which the instructions when executed further result in analyzing the ECG data for ventricular tachycardia and prompting delivery of defibrillation therapy to the patient if the patient is determined to be pulseless and experiencing ventricular tachycardia.

103. The article of claim 102, in which the instructions when executed further result in prompting the delivery of defibrillation therapy if the patient is determined to be pulseless and experiencing ventricular tachycardia with a rate exceeding 100 beats per minute.

104. The article of claim 99, in which the instructions when executed further result in analyzing the ECG data for at least ventricular fibrillation (VF), ventricular tachycardia (VT), and asystole, and if the patient is determined to be pulseless and not in a VF, VT, or asystole condition, then prompting delivery of electrotherapy to the patient designed specifically for pulseless electrical activity (PEA).

105. The article of claim 99, in which the instructions when executed further result in analyzing the ECG data for one or more of ventricular fibrillation (VF), ventricular tachycardia (VT), asystole, and pulseless electrical activity (PEA), the processing circuitry prompting a report of VF, VT, asystole, or PEA, if detected and if the patient is determined to be pulseless.

106. The article of claim 86, in which the instructions when executed further result in reporting the return of spontaneous circulation in the patient if a cardiac pulse is determined present in the patient after delivery of defibrillation therapy to the patient.

107. The article of claim 86, in which one of the physiological signals is an impedance-sensing signal that has been communicated through the patient, and in which the physiological signal data includes impedance signal data.

108. The article of claim 107, in which the instructions when executed further result in analyzing the impedance-sensing signal to determine the presence of respiration in the patient and prompting delivery of rescue breathing therapy to the patient if respiration is determined not present in the patient.

109. The article of claim 108, in which the instructions when executed further result in prompting the delivery of chest compressions or cardiopulmonary resuscitation to the patient if the patient is determined to be pulseless.