Method for the measurement of post arteriolar pressure

• US 6,997,877 B2
• Filed: 08/30/2002
• Issued: 02/14/2006
• Est. Priority Date: 08/30/2001
• Status: Expired due to Fees

• Current Assignee: Lidco Group, PLC (Masimo Corporation)
• Original Assignee: Lidco Group, PLC (Masimo Corporation)
• Inventors: O'Brien, Terence Kevin, Band, David Marston, Wolff, Christopher Bancroft
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US10/486,926
• Publication Number:
  US 20040254480A1
• Time in Patent Office: 1,264 Days
• Field of Search: 600/481, 600/490, 600483-486, 600492-496, 600500-503, 600/508, 600/526
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

A method for the measurement of post arteriolar pressure in a patient which is determined from information regarding the blood pressure (BP), systemic vascular resistance (R) and cardiac output (CO) by plotting the regression line for the equation BP=R×Q+c where c is the post arteriolar pressure, and determining the value of c from the regression line.

Claims

1. A method for determining the post arteriolar pressure in a patient, which method comprises the steps of:

(i) recording and storing the arterial blood pressure waveform of a patient from a blood pressure monitoring device over a period of time;

(ii) determining the nominal or actual stroke volume associated with each arterial blood pressure waveform;

(iii) obtaining the nominal or actual cardiac output from the data in step (ii); and

(iv) plotting the regression line for the equation

BP=R×

Q+c

 

where

BP is the blood pressure,

R is the systemic vascular resistance,

Q is the cardiac output, and

c is the post arteriolar pressure, and

(v) determining the value of the post arteriolar pressure from the regression line.

2. A method as claimed in claim 1 wherein the arterial blood pressure is plotted in step (i) for a period of up to ten seconds.

3. A method as claimed in claim 1 wherein the arterial blood pressure is analysed on a beat-to-beat basis.

4. A method as claimed in claim 1 wherein the stroke volume in step (ii) is determined via a cardiac output measuring method.

5. A method as claimed in claim 4 wherein the cardiac output measuring method is a pressure waveform analysis.

6. A method as claimed in claim 5 wherein the data obtained in step (i) is subjected to Fourier analysis in order to obtain the modulus of the first harmonic and the nominal stroke volume is obtained from the modulus of the first harmonic and data relating to the arterial blood pressure and the heart rate.

7. A method as claimed in claim 6 wherein the nominal stroke volume is obtained from the following equation $\mathrm{nominal}$

⁢

stroke⁢

⁢

volume=modulus⁢

⁢

of⁢

⁢

first⁢

⁢

harmonic⁢

⁢

ofblood⁢

⁢

pressure⁢

⁢

waveforme+0.0092×

MAP×

HR

where

e is the base of natural logarithms

MAP is the mean arterial blood pressure, and

HR is the heart rate.

8. A method as claimed in claim 1 wherein the regression line in step (iv) is plotted by means of a computer.

9. A method as claimed in claim 8 wherein the value of the post arteriolar pressure is displayed on a computer screen and optionally continuously updated.

10. A method as claimed in claim 2 wherein the arterial blood pressure is analysed on a beat-to-beat basis.

11. A method as claimed in 2 wherein the stroke volume in step (ii) is determined via a cardiac output measuring method.

12. A method as claimed in 3 wherein the stroke volume in step (ii) is determined via a cardiac output measuring method.

13. A method as claimed in 2 wherein the regression line in step (iv) is plotted by means of a computer.

14. A method as claimed in 3 wherein the regression line in step (iv) is plotted by means of a computer.

15. A method as claimed in 4 wherein the regression line in step (iv) is plotted by means of a computer.

16. A method as claimed in 5 wherein the regression line in step (iv) is plotted by means of a computer.

17. A method as claimed in 6 wherein the regression line in step (iv) is plotted by means of a computer.

18. A method as claimed in 7 wherein the regression line in step (iv) is plotted by means of a computer.