Non-invasive method and device to monitor cardiac parameters without use of electrical-mechanical interval

• US 7,761,141 B2
• Filed: 03/22/2007
• Issued: 07/20/2010
• Est. Priority Date: 10/31/2001
• Status: Expired due to Fees

• Current Assignee: Robert Hirsh
• Original Assignee: Robert Hirsh
• Inventors: Hirsh, Robert
• Primary Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US11/689,934
• Publication Number:
  US 20070191724A1
• Time in Patent Office: 1,216 Days
• Field of Search: None
• US Class Current: 600/513
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• 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 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• 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
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00

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 or minimally invasively measuring cardiac cycle period, mean arterial pressure, stroke volume, diastolic interval and ejection interval and converting the measured mean arterial pressure, stroke volume, diastolic interval and ejection interval into the cardiac parameters such as Preload, Afterload and Contractility, which are the common cardiac parameters used by an anesthesiologist. In the current invention, the use of electrical-mechanical interval has been eliminated for various advantageous reasons. 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. A method of monitoring cardiac parameters, comprising the steps of:

calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner;

non-invasively measuring from a subject a plurality of predetermined non-invasive cardiac parameters including the MAP, the SV, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C in a monotonically increasing one-to-one and onto manner; and

displaying a vector indicating a hemodynamic state.

2. The method of monitoring cardiac parameters according to claim 1 wherein the subject is a human.

3. The method of monitoring cardiac parameters according to claim 1 wherein the subject is an animal.

4. The method of monitoring cardiac parameters according to claim 1 wherein said converting step is performed based upon predetermined conversion equations including

P=k1*[(DI)(MAP)/ln(SV/EI)]+c1,

A=k2*[MAP/(SV/T)]+c2, and

C=ln(k3*SV/EI)

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

5. The method of monitoring cardiac parameters according to claim 1 further comprising the step of 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.

6. The method of monitoring cardiac parameters according to claim 5 further comprising an additional step of displaying a three dimensional object defining a safe zone indicative of a safe hemodynamic state.

7. The method of monitoring cardiac parameters according to claim 6 wherein the first axis, the second axis, the third axis and the three dimensional object are each displayed with a predetermined color.

8. The method of monitoring cardiac parameters according to claim 1 further comprising an additional step of displaying a vector cross product between the vector and a predetermined vector indicating an amount of physiologic stress.

9. The method of monitoring cardiac parameters according to claim 1 further comprising an additional step of determining a fitness level of the subject based upon the invasive cardiac analogues.

10. The method of monitoring cardiac parameters according to claim 1 further comprising an additional step of determining management of an anesthetic-related procedure of the subject based upon the invasive cardiac analogues.

11. The method of monitoring cardiac parameters according to claim 1 further comprising an additional step of determining an abnormal cardiac condition of the subject based upon the invasive cardiac analogues.

12. The method of monitoring cardiac parameters according to claim 1 further comprising an additional step of transferring the non-invasive cardiac parameters from one location to another location before converting the non-invasive cardiac parameters into the invasive cardiac analogues.

13. The method of monitoring cardiac parameters according to claim 12 further comprising an additional step of evaluating a cardiac condition of the subject based upon the invasive cardiac analogues.

14. The method of monitoring cardiac parameters according to claim 1 wherein C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner.

15. A system for monitoring cardiac parameters comprising:

a calibration unit for calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner;

a non-invasive cardiac parameter measuring unit connected to said calibration unit for non-invasively measuring from a subject a plurality of predetermined non-invasive cardiac parameters including the SV, the MAP, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

a conversion unit connected to said non-invasive cardiac parameter measuring unit for converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C in a monotonically increasing one-to-one and onto manner; and

a display unit connected to said conversion unit for displaying a vector indicative of a hemodynamic state.

16. The system for monitoring cardiac parameters according to claim 15 wherein said non-invasive cardiac parameter measuring unit measures the predetermined non-invasive cardiac parameters from a human.

17. The system for monitoring cardiac parameters according to claim 15 wherein said non-invasive cardiac parameter measuring unit measures the predetermined non-invasive cardiac parameters from an animal.

18. The system for monitoring cardiac parameters according to claim 15 wherein said non-invasive cardiac parameter measuring unit further comprises a vibration sensing device including at least one of a Doppler ultrasound device, an optical plethysmographic device and a fiber optic device.

19. The system for monitoring cardiac parameters according to claim 15 wherein said conversion unit determines the P, the A and the C based upon predetermined conversion equations including

P=k1*[(DI)(MAP)/ln(SV/EI)]+c1,

A=k2*[MAP/(SV/T)]+c2, and

C=ln(k3*SV/EI)

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

20. The system for monitoring cardiac parameters according to claim 15 wherein said display unit additionally displays a three dimensional object defining a safe zone indicative of a safe hemodynamic state.

21. The system for monitoring cardiac parameters according to claim 15 wherein said display unit displays the first axis, the second axis, the third axis and the safe zone respectively in a predetermined color.

22. The system for monitoring cardiac parameters according to claim 15 wherein said display unit additionally displays a vector cross product between the vector and a predetermined vector indicative of an amount of physiologic stress.

23. The system for monitoring cardiac parameters according to claim 15 further comprising a determination unit connected to said conversion unit for determining a fitness level of the subject based upon the invasive cardiac analogues.

24. The system for monitoring cardiac parameters according to claim 15 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.

25. The system for monitoring cardiac parameters according to claim 15 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.

26. The system for monitoring cardiac parameters according to claim 15 further comprising a data communication unit connected to said non-invasive cardiac parameter measuring unit at one location for transferring the non-invasive cardiac parameters to said conversion unit at another location before converting the non-invasive cardiac parameters into the invasive cardiac analogues.

27. The system for monitoring cardiac parameters according to claim 15 wherein said data communication unit transfers the non-invasive cardiac parameters to said conversion unit via the Internet.

28. The system for monitoring cardiac parameters according to claim 15 wherein said data communication unit transfers the non-invasive cardiac parameters to said conversion unit via telecommunication.

29. The system for monitoring cardiac parameters according to claim 15 wherein said non-invasive cardiac parameter measuring unit is portable.

30. The system for monitoring cardiac parameters according to claim 15 wherein said conversion unit is retrofitted to an existing one of said non-invasive cardiac parameter measuring unit.

31. The system for monitoring cardiac parameters according to claim 15 wherein C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner.

32. A method of monitoring cardiac parameters, comprising the steps of:

measuring in a substantially non-invasive manner from a subject a plurality of predetermined non-invasive cardiac parameters including a stroke volume as denoted by SV, mean arterial pressure as denoted by MAP, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C in a monotonically increasing one-to-one and onto manner; and

displaying a vector indicating a hemodynamic state.

33. The method of monitoring cardiac parameters according to claim 32 wherein C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner.

34. A system for monitoring cardiac parameters comprising:

a non-invasive cardiac parameter measuring unit for measuring in a substantially non-invasive manner from a subject a plurality of predetermined non-invasive cardiac parameters including a stroke volume as denoted by SV, mean arterial pressure as denoted by MAP, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

a conversion unit connected to said non-invasive cardiac parameter measuring unit for converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C based in a monotonically increasing one-to-one and onto manner; and

a display unit connected to said conversion unit for displaying a vector indicative of a hemodynamic state.

35. The system for monitoring cardiac parameters according to claim 34 wherein C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner.

36. A method of evaluating a patient based upon non-invasively measured parameters of myocardial contractility, comprising the steps of:

measuring in a substantially non-invasive manner from the patient a plurality of predetermined non-invasive cardiac parameters including a stroke volume as denoted by SV and an ejection interval as denoted by EI at rest and under duress; and

equating one of SV/EI and ln(SV/EI) to the myocardial contractility.

37. The method of evaluating a patient based upon non-invasively measured parameters according to claim 36 wherein said equating step equates the measured SV/EI to a level of myocardial contractile reserve and further comprising an additional step of making pre-anesthetic assessment based upon the level of the myocardial contractile reserve.

38. The method of evaluating a patient based upon non-invasively measured parameters according to claim 37 wherein the pre-anesthetic assessment is made over a wide range Systemic Vascular Resistance (SVR) and Left Ventricular End-Diastolic Pressure (LVEDP).

39. The method of evaluating a patient based upon non-invasively measured parameters according to claim 36 wherein said equating step equates the measured SV/EI to a level of myocardial contractility and further comprising an additional step of making intra-anesthetic assessment based upon the myocardial contractility.

40. The method of evaluating a patient based upon non-invasively measured parameters according to claim 36 wherein said equating step equates the measured SV/EI to a level of myocardial contractility and further comprising an additional step of making peri-anesthetic assessment based upon the myocardial contractility.

41. A system for making pre-anesthetic assessment of a patient based upon measure of myocardial contractility, comprising:

a cardiac parameter measuring unit for measuring in a substantially non-invasive manner from the patient a plurality of predetermined non-invasive cardiac parameters including a stroke volume as denoted by SV and an ejection interval as denoted by EI; and

a determination unit connected to said non-invasive cardiac parameter measuring unit for equating one of SV/EI and ln(SV/EI) to myocardial contractility.

42. The system for making pre-anesthetic assessment of a patient according to claim 41 wherein said determination unit equates the measured SV/EI to a level of myocardial contractile reserve and makes pre-anesthetic assessment based upon the level of the myocardial contractile reserve.

43. The system for making pre-anesthetic assessment of a patient according to claim 42 wherein said determination unit makes the pre-anesthetic assessment over a wide range Systemic Vascular Resistance (SVR) and Left Ventricular End-Diastolic Pressure (LVEDP).

44. The system for making pre-anesthetic assessment of a patient according to claim 41 wherein said determination unit equates the measured SV/EI to a level of the myocardial contractility and makes intra-anesthetic assessment based upon the level of the myocardial contractility.

45. The system for making pre-anesthetic assessment of a patient according to claim 41 wherein said determination unit equates the measured SV/EI to a level of the myocardial contractility and makes peri-anesthetic assessment based upon the level of the myocardial contractility.

46. A method of detecting myocardial ischemia in a patient based upon non-invasively measured parameters, comprising the steps of:

calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner for the patient;

non-invasively measuring from the patient a plurality of predetermined non-invasive cardiac parameters including the MAP, the SV, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

approximating the rate of change in volume with respect to the rate of change in pressure in the left ventricle (dV/dP) by the change in LV volume divided by the change in LV pressure during diastolic filling (Δ

V/Δ

P); and

evaluating the Δ

V/Δ

P by the non-invasively measured cardiac parameters; and

detecting ischemia in the patient based upon the evaluated Δ

V/Δ

P.

47. The method of detecting myocardial ischemia according to claim 46 wherein said evaluating step utilizes a relation, Δ

V/Δ

PΨ

SV/{(DI)(MAP)/ln(SV/EI)}.

48. The method of detecting myocardial ischemia according to claim 46 wherein said detecting step includes any number of signs in decreased contractility, increased SVR, increased LVEDP, decreased CO and decreased SV, which are derived from the non-invasively measured cardiac parameters.

49. A system for detecting myocardial ischemia in a patient based upon non-invasively measured parameters, comprising:

a calibration unit for calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner for the patient;

a non-invasively measuring unit connected to said calibration unit for non-invasively measuring from the patient a plurality of predetermined non-invasive cardiac parameters including the MAP, the SV, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI; and

a determination unit connected to said non-invasively measuring unit for approximating the rate of change in volume with respect to the rate of change in pressure in the left ventricle (dV/dP) by the change in LV volume divided by the change in LV pressure during diastolic filling (Δ

V/Δ

P) to evaluating the Δ

V/Δ

P by the non-invasively measured cardiac parameters, said determination unit detecting ischemia in the patient based upon the evaluated Δ

V/Δ

P.

50. The system for detecting myocardial ischemia according to claim 49 wherein said determination unit evaluates Δ

V/Δ

P based upon SV/{(DI)(MAP)/ln(SV/EI)}.

51. The method of detecting myocardial ischemia according to claim 49 wherein said determination unit uses any number of signs in decreased contractility, increased SVR, increased LVEDP, decreased CO and decreased SV, which are derived from the non-invasively measured cardiac parameters.

52. A method of quantifying a subject'"'"'s ability to effect perfusion homeostasis through the physiologic modulation of myocardial contractility, comprising of the steps of:

measuring beat-to-beat SV/EI data over time in a substantially non-invasive manner;

obtaining a running average of the beat-to-beat SV/EI data, where the number of beats in the running average equals the number of beats in one respiratory cycle or at least two consecutive respiratory cycles;

determining variations in the SV/EI data with respect to the running averaged SV/EI data;

determining an average of the variations and a standard deviation of the variations to generate a contractile function metric; and

determining based upon the contractile function metric as to whether or not the subject experiences myocardial contractile decompensation.

53. The method of quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 52 wherein the variations in the SV/EI data is a time period of each of the contractility cycles.

54. The method of quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 53 wherein the contractility cycle is in the order of between 10 and 100 seconds.

55. The method of quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 52 wherein the variations in the SV/EI data is an amplitude of each of the contractility cycles.

56. A system for quantifying a subject'"'"'s ability to effect perfusion homeostasis through the physiologic modulation of myocardial contractility, comprising:

a measuring unit for measuring beat-to-beat SV/EI data over time in a substantially non-invasive manner;

a determination unit connected to said measuring unit obtaining a running average of the beat-to-beat SV/EI data, where the number of beats in the running average equals the number of beats in one respiratory cycle or at least two consecutive respiratory cycles, said determination unit determining variations in the SV/EI data with respect to the running averaged SV/EI data and an average of the variations and a standard deviation of the variations to generate a contractile function metric; and

a display unit connected to said determination unit for displaying the contractile function metric for determining whether or not the subject experiences myocardial contractile decompensation.

57. The system for quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 56 wherein the variations in the SV/EI data is a time period of each of the contractility cycles.

58. The system for quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 57 wherein the contractility cycle is in the order of between 10 and 100 seconds.

59. The system for quantifying a subject'"'"'s ability to effect perfusion homeostasis according to claim 56 wherein the variations in the SV/EI data is an amplitude of each of the contractility cycles.

60. A method of monitoring cardiac parameters, comprising the steps of:

calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner;

non-invasively measuring from a subject a plurality of predetermined non-invasive cardiac parameters including the MAP, the SV, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C in a monotonically increasing one-to-one and onto manner, C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner; and

displaying a vector indicating a hemodynamic state.

61. A system for monitoring cardiac parameters comprising:

a calibration unit for calibrating a stroke volume as denoted by SV and mean arterial pressure as denoted by MAP in a minimally invasive manner;

a non-invasive cardiac parameter measuring unit connected to said calibration unit for non-invasively measuring from a subject a plurality of predetermined non-invasive cardiac parameters including the SV, the MAP, a cardiac period as denoted by T, a diastolic filling interval from the opening to the closing of the mitral valve as denoted by DI and an ejection interval as denoted by EI;

a conversion unit connected to said non-invasive cardiac parameter measuring unit for converting the non-invasive cardiac parameters into a plurality of invasive cardiac analogues including preload as denoted by P, afterload as denoted by A and contractility as denoted by C in a monotonically increasing one-to-one and onto manner, C ∝

ln(SV/EI), wherein SV is obtained in a non-invasive manner; and

a display unit connected to said conversion unit for displaying a vector indicative of a hemodynamic state.