Apparatus and method for determination of stroke volume using the brachial artery

• US 20050283088A1
• Filed: 06/16/2004
• Published: 12/22/2005
• Est. Priority Date: 06/16/2004
• Status: Active Grant

• Current Assignee: Donald P. Bernstein
• Original Assignee: Donald P. Bernstein
• Inventors: Bernstein, Donald P.
• Granted Patent: US 7,261,697 B2
• Time in Patent Office: Days
• US Class Current: 600/506
• 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 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Provided herein are methods and apparatus for stroke volume determination by bioimpedance from a patient'"'"'s upper arm, or brachium, utilizing pulsations of the brachial artery contained therein. The apparatus includes two or more spaced apart alternating current flow electrodes positioned on the patient'"'"'s arm proximate the brachial artery and two or more spaced apart voltage sensing electrodes positioned on the patient'"'"'s arm proximate the brachial artery. The voltage sensing electrodes are positioned between the alternating current flow electrodes on the arm. An alternating current source is electrically connected to the alternating current flow electrodes and a voltmeter electrically is connected to the voltage sensing electrodes. A data input device is provided along with a processing unit in communication with the data input device, the alternating current source, alternating current flow electrodes, the voltmeter, and voltage sensing electrodes. The processing unit is capable of using data from the data input device and voltage sensing electrodes to calculate the stroke volume of the patient.

Claims

1. An apparatus for determining stroke volume by bioimpedance from a patient'"'"'s brachial artery, comprising:

two or more spaced apart alternating current flow electrodes positioned on the patient'"'"'s arm proximate the brachial artery;

two or more spaced apart voltage sensing electrodes positioned on the patient'"'"'s arm proximate the brachial artery, the voltage sensing electrodes being positioned between the alternating current flow electrodes;

an alternating current source electrically connected to the alternating current flow electrodes,

a voltmeter electrically connected to the voltage sensing electrodes;

a data input device; and

a processing unit in communication with the data input device, the alternating current source, alternating current flow electrodes, the voltmeter, and voltage sensing electrodes, the processing unit capable of using data from the data input device and voltage sensing electrodes to calculate the stroke volume of the patient.

2. The apparatus of claim 1, further comprising an arm band or cuff, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within the arm cuff.

3. The apparatus of claim 1, further comprising an adhesive strip, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within the adhesive strip.

4. The apparatus of claim 1, further comprising:

a first arm band, wherein at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within the first band; and

a second arm band, wherein at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within the second band.

5. The apparatus of claim 1, wherein the electrodes include an adhesive surface capable of attachment to the patient'"'"'s arm.

6. The apparatus of claim 1, wherein the processing unit uses the equation:

SV_(brachium)=V_c(brachium)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve to determine stroke volume.

7. The apparatus of claim 6, wherein V_c(brachium) is determined by a calibration factor, V_c(cal), using the equation:

V_c(brachium)=V_c(cal)=(V_c(thorax)·

√

[(dZ/dt_max)/Z₀]_(thorax))/(√

[(dZ/dt_max)/Z₀]_(brachium)).

and the stroke volume equation is;

SV_(brachium)=V_c(cal)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve.

8. The apparatus of claim 6, wherein T_lve is obtained from a dZ/dt waveform.

9. The apparatus of claim 8, wherein a trigger for initiating processing of the transbrachial dZ/dt waveform is obtained from an R wave of an antecedent ECG waveform.

10. The apparatus of claim 8, wherein a trigger for initiating processing of the transbrachial dZ/dt waveform is obtained from a C wave of an antecedent dZ/dt waveform.

11. The apparatus of claim 6, wherein T_lve is obtained from a pulse oximetry waveform (Δ

SpO₂(t)), or its first time-derivative, dSpO₂(t)/dt.

12. The apparatus of claim 6, wherein T_lve is obtained from an applanation tonometry (pressure) waveform (Δ

P(t)), or its first time-derivative dP(t)/dt.

13. The apparatus of claim 6, wherein T_lve is obtained from regression equations.

14. The apparatus of claim 13, wherein the regression equations are:

T_lve=−

0.0017 heart rate (HR)+0.413 for Male patients and T_lve=−

0.0016 HR+0.418 for Female patients.

15. A method of determining stroke volume by bioimpedance from a patient'"'"'s brachial artery, comprising:

positioning two or more spaced apart alternating current flow electrodes to the patient'"'"'s arm proximate the brachial artery;

positioning two or more of spaced apart voltage sensing electrodes to the patient'"'"'s arm proximate the brachial artery, the voltage sensing electrodes being positioned between the alternating current flow electrodes;

providing a constant magnitude alternating current flow (I(t)) through the electrically conductive electrodes creating a current field;

measuring the voltage (U(t)) between the voltage sensing electrodes within the current field; and

calculating the stroke volume (SV) of the patient using the measured voltage and data from a data input device.

16. The method of claim 15, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within an arm band or cuff that is attached to the patient'"'"'s arm.

17. The method of claim 15, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within an adhesive strip that is attached to the patient'"'"'s arm.

18. The method of claim 15, wherein:

at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within a first arm band attached to the patient'"'"'s arm; and

at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within a second arm band attached to the patient'"'"'s arm spaced apart from the first arm band.

19. The method of claim 15, wherein attaching the electrodes includes an adhesive on the electrodes capable of attachment to the patient'"'"'s arm.

20. The method of claim 15, wherein calculating the stroke volume includes:

determining the electrical impedance Z(t) by the ratio U(t)/I(t);

determining the peak first derivative of transbrachial dZ/dt, i.e., transbrachial dZ(t)/dt_MAX;

determining a transbrachial base impedance Z₀;

determining a left ventricular ejection time, T_lve;

determining a volume conductor V_C; and

calculating the stroke volume SV of the patient using the equation;

SV=V_c(brachium)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve.

21. The method of claim 20, wherein the V_c(brachium) is determined by a calibration factor, V_c(cal), using the equation:

V_c(brachium)=V_c(cal)=(V_c(thorax)·

√

[(dZ/dt_max)/Z₀]_(thorax))/(√

[(dZ/dt_max)/Z₀]_(brachium)).

and the stroke volume equation is;

SV=V_c(cal)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve.

22. The method of claim 20, wherein the left ventricular ejection time, T_lve is obtained from a dZ/dt waveform.

23. The method of claim 20, further comprising triggering the processing of a transbrachial dZ/dt curve from the R wave of the antecedent ECG waveform.

24. The method of claim 20, further comprising triggering the processing of a transbrachial dZ/dt curve from the C wave of the antecedent transbrachial dZ/dt waveform.

25. The method of claim 20, wherein T_lve is obtained from a pulse oximetry waveform (Δ

SpO₂(t)), or its first time-derivative, dSpO₂(t)/dt.

26. The method of claim 20, wherein T_lve is obtained from a applanation tonometry (pressure) waveform (Δ

P(t)), or its first time-derivative dP(t)/dt.

27. The method of claim 20, further wherein T_lve is obtained from regression equations.

28. The method of claim 27, further comprising determining the patient'"'"'s left ventricular ejection time (LVET) from the regression equations:

T_LVE=−

0.0017 HR+0.413 for Male patients and T_LVE=−

0.0016 HR+0.418 for Female patients.

29. A method for determining stroke volume by bioimpedance from a patient'"'"'s brachial artery, comprising:

applying a constant magnitude alternating current flow (I(t)) to the patient'"'"'s arm proximate the brachial artery creating a current field;

measuring the voltage (U(t)) within the current field; and

calculating the stroke volume SV of the patient using the measured voltage and applied A.C.

30. The method of claim 29, wherein calculating the stroke volume SV of the patient using the equation:

SV=V_c(brachium)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve.

31. The method of claim 29, wherein applying a constant magnitude alternating current flow includes positioning two or more spaced apart alternating current flow electrodes on the patient'"'"'s arm proximate the brachial artery.

32. An apparatus for determining stroke volume by bioimpedance from a patient'"'"'s brachial artery, comprising:

two or more spaced apart alternating current flow electrodes positionable on the patient'"'"'s arm proximate the brachial artery;

two or more spaced apart voltage sensing electrodes positionable on the patient'"'"'s arm proximate the brachial artery, the voltage sensing electrodes being positionable between the alternating current flow electrodes;

an alternating current source electrically connected to the alternating current flow electrodes,

a voltmeter electrically connected to the voltage sensing electrodes;

a data input device; and

a processing unit in communication with the data input device, the alternating current source, the alternating current flow electrodes, the voltmeter, and the voltage sensing electrodes, wherein the processing unit is capable of using data from the data input device and a voltage sensed by the voltage sensing electrodes to calculate the stroke volume of the patient.

33. The apparatus of claim 32, further comprising an arm band or cuff, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within the arm cuff.

34. The apparatus of claim 32, further comprising an adhesive strip, wherein the alternating current flow electrodes and the voltage sensing electrodes are positioned on or within the adhesive strip.

35. The apparatus of claim 32, further comprising:

a first arm band, wherein at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within the first band; and

a second arm band, wherein at least one of the alternating current flow electrodes and one of the voltage sensing electrodes being positioned on or within the second band.

36. The apparatus of claim 32, wherein the electrodes include an adhesive surface capable of attachment to the patient'"'"'s arm.

37. The apparatus of claim 32, wherein the processing unit uses the equation:

SV_(brachium)=V_c(brachium)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve to calculate the stroke volume,

where SV_(brachium) is the stroke volume, V_c(brachium) is a volume of electrically participating brachial tissue, dZ/dt_max is a peak rate of change of a measured cardiogenically induced transbrachial impedance variation, Z₀ is a quasi-static transbrachial base impedance, and T_lve is a left ventricular ejection time.

38. The apparatus of claim 37, wherein V_c(brachium) is determined by a calibration factor, V_c(cal), using the equation:

V_c(brachium)=V_c(cal)=(V_c(thorax)·

√

[(dZ/dt_max)/Z₀]_(thorax))/(√

[(dZ/dt_max)/Z₀]_(brachium)),

and the stroke volume equation is;

SV_(brachium)=V_c(cal)·

√

[(dZ/dt_max)/Z₀]_(brachium)·

T_lve.

39. The apparatus of claim 37, wherein T_lve is obtained from a dZ/dt waveform.

40. The apparatus of claim 39, wherein a trigger for initiating processing of the transbrachial dZ/dt waveform is obtained from an R wave of an antecedent ECG waveform.

41. The apparatus of claim 39, wherein a trigger for initiating processing of the transbrachial dZ/dt waveform is obtained from a C wave of an antecedent dZ/dt waveform.

42. The apparatus of claim 37, wherein T_lve is obtained from a pulse oximetry waveform (Δ

SpO₂(t)), or its first time-derivative, dSpO₂(t)/dt.

43. The apparatus of claim 37, wherein T_lve is obtained from an applanation tonometry (pressure) waveform (Δ

P(t)), or its first time-derivative dP(t)/dt.

44. The apparatus of claim 37, wherein T_lve is obtained from regression equations.

45. The apparatus of claim 44, wherein the regression equations are:

T_lve=−

0.0017 heart rate (HR)+0.413 for Male patients and T_lve=−

0.0016 HR+0.418 for Female patients.