Non-invasive method and device to monitor cardiac parameters

• US 20060064026A1
• Filed: 11/03/2005
• Published: 03/23/2006
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: Robert Hirsh
• Original Assignee: Robert Hirsh
• Inventors: Hirsh, Robert
• Granted Patent: US 7,657,306 B2
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00

Abstract

A method of and a device for non-invasively measuring the hemodynamic state of a subject or a human patient involve steps and units of non-invasively measuring cardiac cycle period, electrical-mechanical interval, mean arterial pressure, and ejection interval and converting the measured electrical-mechanical interval, mean arterial pressure and ejection interval into the cardiac parameters such as Preload, Afterload and Contractility, which are the common cardiac parameters used by an anesthesiologist. The converted hemodynamic state of a patient is displayed on a screen as a three-dimensional vector with each of its three coordinates respectively representing Preload, Afterload and Contractility. Therefore, a medical practitioner looks at the screen and quickly obtains the important and necessary information.

Claims

1-55. -55. (canceled)

56. A system for retrofitting existing non-invasive cardiac parameter measuring devices to generate invasive cardiac analogues, comprising:

an interface unit for receiving predetermined non-invasive cardiac parameters of a subject from the existing non-invasive cardio monitoring devices; and

a conversion unit connected to said interface unit for converting the non-invasive cardiac parameters into a plurality of the invasive cardiac analogues based upon a set of predetermined conversion equations.

57. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 wherein the existing non-invasive cardiac parameter measuring devices measure the predetermined non-invasive cardiac parameters from a human.

58. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 wherein the existing non-invasive cardiac parameter measuring devices measure the predetermined non-invasive cardiac parameters from an animal.

59. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 wherein the existing non-invasive cardiac parameter measuring unit further comprises a heart rate monitor for measuring heart rate as denoted by HR, a vibration sensing device for measuring an ejection interval as denoted by EI and a mechanical event M of an electrical-mechanical interval as denoted by E-M, a blood pressure measuring device for measuring mean arterial pressure as denoted by MAP and an electrocardiogram measuring device for measuring an electrical event E of the electrical-mechanical interval.

60. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 wherein the existing non-invasive cardiac parameter measuring unit further comprises a heart rate monitor for measuring heart rate as denoted by HR, a vibration sensing device for measuring an ejection interval as denoted by EI, a plethysmographic device for measuring a mechanical event M of an electrical-mechanical interval as denoted by E-M, a blood pressure measuring device for measuring mean arterial pressure as denoted by MAP and an electrocardiogram measuring device for measuring an electrical event E of the electrical-mechanical interval.

61. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 59 wherein said vibration sensing device comprises at least one of a Doppler ultrasound device and a fiber optic device.

62. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 59 wherein said conversion unit outputs the predetermined invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C.

63. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 62 wherein said conversion unit determines the P, the A and the C based upon the predetermined conversion equations including

P=k1(EI*MAP*E-M)+c1,
A=k2(MAP*E-M)+c2, and
ln(C)=k3(1 /E-M)+c3

where k1, k2, k3, c1, c2 and c3 are empirical proportionality constants.

64. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 62 wherein said conversion unit determines the P, the A and the C based upon the predetermined conversion equations including

P=k1′

((T−

EI)*MAP*E-M)+c1′

,
A=k2′

(MAP*E-M)+c2′

, and
ln(C)=k3′

(1/E-M)+c3′

where k1′

, k2′

, k3′

, c1′

, c2′ and

c3′

are empirical proportionality constants for a particular one of the subjects and T is a time period of the cardiac cycle for the particular one of the subjects.

65. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 62 wherein said conversion unit determines the P, the A and the C based upon the predetermined conversion equations including

P=k1′

(DI*MAP*E-M)+c1′

,
A=k2′

(MAP*E-M)+c2′

, and
ln(C)=k3′

(1/E-M)+c3′

where k1′

, k2′

, k3′

, c1′

, c2′ and

c3′

are empirical proportionality constants for a particular one of the subjects and T is a time period of the cardiac cycle for the particular one of the subjects.

66. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 64 wherein the M in the E-M is defined as a time when a second derivative with respect to time, M″

(t), reaches a maximum value.

67. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 66 wherein said non-invasive cardiac parameter measuring unit measures an electrical event in determining the E-M, the electrical event being selected from the group consisting of a Q-wave as denoted by Q, a R-wave as denoted by R, a S-wave as denoted by S and an artificial ventricular pacemaker spike.

68. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 66 wherein said non-invasive cardiac parameter measuring unit measures an electrical event in determining the E-M interval by double differentiating an EKG voltage curve which corresponds to ventricular depolarization, V(t), with respect to time and defining the electrical event as a time when V″

(t) reaches a maximum positive value.

69. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 66 wherein said non-invasive cardiac parameter measuring unit measures the mechanical event in determining the E-M, the mechanical event selected from the group consisting of a time of an arterial blood pressure upstroke as denoted by TA and a time of a flow velocity upstroke as denoted by TF.

70. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 62 wherein said conversion unit determines the P, the A and the C based upon the predetermined conversion equations including

P=k1′

((T−

EI)*MAP*E-M)+c1′

,
A=k2′

*MAP/[K+exp(1/E-M)]+c2′

, and
ln(C)=k3′

(1/E-M)+c3′

where k1′

, k2′

, k3′

, c1′

, c2′

, c3′

, and K are empirical proportionality constants for a particular one of the subjects and T is a time period of the cardiac cycle for the particular one of the subjects.

71. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 further comprising a display unit connected to said conversion unit for displaying the invasive cardiac analogues in three dimensional coordinate space that is defined by a first axis indicative of the P, a second axis indicative of the A and a third axis indicative of the C.

72. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 71 wherein said display unit additionally displays a three dimensional object defining a safe zone indicative of a safe hemodynamic state.

73. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 72 wherein said display unit displays the first axis, the second axis, the third axis and the safe zone respectively in a predetermined color.

74. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 72 wherein said display unit additionally displays a vector cross product indicative an amount of physiologic stress.

75. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 further comprising a determination unit connected to said conversion unit for determining a fitness level of the subject based upon the invasive cardiac analogues.

76. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 further comprising a determination unit connected to said conversion unit for determining management of an anesthetic-related procedure of the subject based upon the invasive cardiac analogues.

77. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 further comprising a determination unit connected to said conversion unit for determining an abnormal cardiac condition of the subject based upon the invasive cardiac analogues.

78. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 further comprising a data communication unit connected to the existing non-invasive cardiac parameter measuring devices at one location for transferring the non-invasive cardiac parameters to said interface unit at another location before converting the non-invasive cardiac parameters into the invasive cardiac analogues.

79. The system retrofitting existing non-invasive cardio monitoring devices according to claim 78 wherein said data communication unit transfers the non-invasive cardiac parameters to said interface unit via the Internet.

80. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 78 wherein said data communication unit transfers the non-invasive cardiac parameters to said interface unit via telecommunication.

81. The system for retrofitting existing non-invasive cardio monitoring devices according to claim 56 wherein the existing non-invasive cardio monitoring devices are all portable.

82. A method of determining a patient'"'"'s cardiac contractility, comprising the steps of:

non-invasively measuring the patient'"'"'s electrocardiograph having a predetermined electrical wave;

determining a first point within a predetermined cardiac cycle based upon the predetermined electrical wave;

non-invasively measuring the patient'"'"'s arterial pressure with respect to time;

determining a second point in the predetermined cardiac cycle when a second derivative of a predetermined physiological function with respect to time reaches maximum; and

obtaining the cardiac contractility based upon the first point and the second point.

83. The method of determining a patient'"'"'s cardiac contractility according to claim 82 wherein said predetermined electrical wave is selected from the group consisting of a Q-wave as denoted by Q, a R-wave as denoted by R, a S-wave as denoted by S and an artificial ventricular pacemaker spike.

84. The method of determining a patient'"'"'s cardiac contractility according to claim 82 wherein the electrical event in determining the E-M interval is determined by double differentiating an EKG voltage curve which corresponds to ventricular depolarization, V(t), with respect to time and defining the electrical event as a time when V″

(t) reaches a maximum positive value.

85. The method of determining a patient'"'"'s cardiac contractility according to claim 82 wherein an improved cardiac contractility measure is further defined as proportional to an exponential function of a reciprocal of a time interval defined between the first point and the second point.

86. A system for determining a patient'"'"'s cardiac contractility, comprising:

an electrocardiogram unit for non-invasively measuring the patient'"'"'s electrocardiograph having a predetermined electrical wave;

an arterial pressure measuring unit for non-invasively measuring the patient'"'"'s arterial pressure with respect to time; and

a determination unit connected to said electrocardiogram unit and said arterial pressure measuring unit for determining a first point having a minimum within a predetermined cardiac cycle based upon the predetermined electrical wave and for determining a second point in the predetermined cardiac cycle when a second derivative of a predetermined physiological function with respect to time reaches maximum based upon the patient'"'"'s arterial pressure, said determination unit obtaining the cardiac contractility based upon the first point and the second point.

87. The system for determining a patient'"'"'s cardiac contractility according to claim 86 wherein said predetermined electrical wave is selected from the group consisting of a Q-wave as denoted by Q, a R-wave as denoted by R, a S-wave as denoted by S and an artificial ventricular pacemaker spike.

88. The system for determining a patient'"'"'s cardiac contractility according to claim 86 wherein the electrical event in determining the E-M interval is determined by double differentiating an EKG voltage curve which corresponds to ventricular depolarization, V(t), with respect to time and defining the electrical event as a time when V″

(t) reaches a maximum positive value.

89. The system for determining a patient'"'"'s cardiac contractility according to claim 87 wherein an improved cardiac contractility measure is further defined as proportional to an exponential function of a reciprocal of a time interval defined between the first point and the second point.

90. A method of monitoring an ischemic event, comprising the steps of:

non-invasively measuring a plurality of predetermined non-invasive cardiac parameters from a subject; and

converting the non-invasive cardiac parameters into a single invasive cardiac analogue indicative of the ischemic event based upon a predetermined conversion equation.

91. The method of monitoring an ischemic event according to claim 90 wherein the subject is a human.

92. The method of monitoring an ischemic event according to claim 90 wherein the subject is an animal.

93. The method of monitoring an ischemic event according to claim 90 wherein the predetermined non-invasive cardiac parameters include heart rate as denoted by HR, ejection interval as denoted by EI, mean arterial pressure as denoted by MAP and electrical-mechanical interval as denoted by E-M, which is an interval between an electrical event E and a mechanical event M.

94. The method of monitoring an ischemic event according to claim 93 wherein the predetermined conversion equation includes CP=A3*[EI/(T−

EI)]*[exp(1/E-M)/(MAP*E-M)]+A4, where T is cardiac period, which is obtained from the heartrate HR, A3 and A4 are empirical proportionality constants and wherein the M in the E-M is further defined as a time when, a second derivative of the M with respect to time, M″

(t), reaches a maximum value.

95. The method of monitoring an ischemic event according to claim 94 wherein an electrical event in determining the E-M is selected from the group consisting of a Q-wave as denoted by Q, a R-wave as denoted by R, a S-wave as denoted by S and an artificial ventricular pacemaker spike.

96. The method of monitoring an ischemic event according to claim 94 wherein the electrical event in determining the E-M interval is determined by double differentiating an EKG voltage curve which corresponds to ventricular depolarization, V(t), with respect to time and defining the electrical event as a time when V″

(t) reaches a maximum positive value.

97. The method of monitoring an ischemic event according to claim 94 wherein the mechanical event selected from the group consisting of a time of an arterial blood pressure upstroke as denoted by TA, a time of a flow velocity upstroke as denoted by TF, and a time of plethysmographic upstroke as denoted by TOP.

98. A system for monitoring an ischemic event, comprising:

a measuring unit for non-invasively measuring a plurality of predetermined non-invasive cardiac parameters from a subject; and

a converting unit connected to said measuring unit for converting the non-invasive cardiac parameters into a single invasive cardiac analogue indicative of the ischemic event based upon a predetermined conversion equation.

99. The system for monitoring an ischemic event according to claim 98 wherein the subject is a human.

100. The system for monitoring an ischemic event according to claim 98 wherein the subject is an animal.

101. The system for monitoring an ischemic event according to claim 98 wherein said measuring unit measures the predetermined non-invasive cardiac parameters including heart rate as denoted by HR, ejection interval as denoted by EI, mean arterial pressure as denoted by MAP and electrical-mechanical interval as denoted by E-M.

102. The system of monitoring an ischemic event according to claim 101 wherein the predetermined conversion equation includes CP=A3*[EI/(T−

EI)]*[exp(1/E-M)/(MAP*E-M)]+A4, where T is cardiac period, which is obtained from the heartrate HR, A3 and A4 are empirical proportionality constants and wherein the M in the E-M is further defined as a time when, a second derivative of the M with respect to time, M″

(t), reaches a maximum value.

103. The system of monitoring an ischemic event according to claim 102 wherein an electrical event in determining the E-M is selected from the group consisting of a Q-wave as denoted by Q, a R-wave as denoted by R, a S-wave as denoted by S and an artificial ventricular pacemaker spike.

104. The system of monitoring an ischemic event according to claim 102 wherein the electrical event in determining the E-M interval is determined by double differentiating an EKG voltage curve which corresponds to ventricular depolarization, V(t), with respect to time and defining the electrical event as a time when V″

(t) reaches a maximum positive value.

105. The system of monitoring an ischemic event according to claim 103 wherein the second mechanical event selected from the group consisting of a time of an arterial blood pressure upstroke as denoted by TA, a time of a flow velocity upstroke as denoted by TF, and a time of plethysmographic upstroke as denoted by TOP.