Segmented estimation method

• US 5,738,103 A
• Filed: 07/31/1996
• Issued: 04/14/1998
• Est. Priority Date: 07/31/1996
• Status: Expired due to Fees

• Current Assignee: Medwave, Inc.
• Original Assignee: Medwave, Inc.
• Inventors: Poliac, Marius O.
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US08/690,617
• Time in Patent Office: 622 Days
• Field of Search: 128/672-673, 128/687-690, 128/691, 128/677-683, 128/668
• US Class Current: 600/490
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence

Abstract

A method for determining blood pressure of an artery includes the steps of applying a pressure to the artery, sensing pressure data produced by the artery and deriving parameters from the sensed pressure data. The parameters are utilized for generating a first blood pressure value estimate using a first function of the parameters based upon a first range of pressure values and by generating at least one second blood pressure estimate using at least one second parameter function based upon a second pressure range different from the first pressure range. A blood pressure value is determined based upon the first blood pressure estimate and said at least one second blood pressure estimate.

Claims

1. A method for determining blood pressure of an artery, the method comprising:

applying pressure to the artery;

sensing pressure data produced by the artery;

deriving parameters from the sensed pressure data;

generating a first blood pressure estimate from the derived parameters using a first parameter function based upon a first pressure range of possible blood pressure values;

generating at least one second blood pressure estimate from the derived parameters using at least one second parameter function based upon a second pressure range of possible blood pressure values, in which the second pressure range is different from the first pressure range; and

determining a blood pressure value based upon the first blood pressure estimate and said at least one second blood pressure estimate.

2. The method of claim 1 wherein the step of generating at least one second blood pressure estimate includes:

generating at least one second blood pressure estimate using at least one second parameter function that corresponds to a subset of possible first blood pressure estimates.

3. The method of claim 1 wherein the step of determining a blood pressure value includes:

weighting said at least one second blood pressure estimate based upon the first blood pressure estimate.

4. A method for determining blood pressure of an artery, the method comprising:

applying a varying pressure to an artery of a plurality of patients having known blood pressures values;

sensing first pressure data produced by the artery;

deriving first values for a set of parameters from the sensed pressure data for each known blood pressure value;

ascertaining a first function based upon the first derived parameter values and the corresponding known blood pressure values, wherein the first function estimates a blood pressure value;

segmenting possible blood pressure values into a plurality of subsets;

ascertaining a second function for each subset based upon the first derived parameter values and corresponding known blood pressure values within each subset, wherein each second function estimates the blood pressure value;

applying a varying pressure to an artery of a patient having an unknown blood pressure value;

sensing second pressure data produced by the artery;

deriving second values for the set of parameters from the second sensed pressure data; and

determining the blood pressure value from the second derived parameter values by;

generating a first blood pressure value estimate using the first function;

generating at least one second blood pressure value estimate using at least one second function; and

determining the blood pressure value based upon the first blood pressure value estimate and said at least one second blood pressure value estimate.

5. The method of claim 4 wherein the step of determining the blood pressure value includes:

determining the blood pressure value using a second function that corresponds to a subset of possible blood pressure values including the first blood pressure value estimate.

6. The method of claim 4 wherein the step of determining the blood pressure value includes:

weighting each second blood pressure value estimate.

7. The method of claim 6 wherein the step of determining the blood pressure value includes:

summing each weighted second blood pressure value estimate.

8. The method of claim 4 wherein the step of determining the blood pressure value includes:

weighting each second blood pressure value estimate based upon the first blood pressure value estimate.

9. The method of claim 4 wherein the step of ascertaining a first function based upon the first derived parameter values and the corresponding known blood pressure values includes:

ascertaining a first function based upon the first derived parameter values that minimizes a sum of differences between the known blood pressure value and a corresponding estimate of the blood pressure value of the first function.

10. The method of claim 4 wherein the step of ascertaining a second function for each subset based upon the first derived parameter values and corresponding known blood pressure values includes:

ascertaining a second function for each range that minimizes a sum of differences between the known blood pressure value within its corresponding range and a corresponding estimate of the blood pressure value of the second function.

11. A method for determining blood pressure of an artery, the method comprising:

applying pressure to the artery;

sensing pressure data produced by the artery;

deriving parameters from the sensed pressure data;

generating a first blood pressure estimate using a first parameter function based upon a first pressure range;

generating a plurality of second blood pressure estimates using second parameter functions based upon second pressure ranges different from the first pressure range;

weighting the second blood pressure estimates based upon the first blood pressure estimate;

summing the weighted second blood pressure estimates; and

determining a blood pressure value based upon the summing of the weighted second blood pressure estimates.

12. A method for determining blood pressure of an artery, the method comprising:

applying pressure to the artery;

sensing pressure data produced by the artery;

deriving parameters from the sensed pressure data;

generating a global blood pressure estimate from the derived parameters using a global parameter function based upon a global pressure range of possible blood pressure values;

generating a plurality of local blood pressure estimates from the derived parameters using local parameter functions, each local parameter function being based upon a local pressure range of possible blood pressure values that is a subset of the global pressure range; and

determining a blood pressure value based upon the global blood pressure estimate and the local blood pressure estimates.

13. The method of claim 12, wherein the step of determining a blood pressure value includes:

weighting the local blood pressure estimates based upon the global blood pressure estimate.

14. The method of claim 13 including:

summing the weighted local blood pressure estimates to produce the blood pressure value.