Method of positioning a sensor for determining blood pressure of an artery

• US 5,938,618 A
• Filed: 08/08/1997
• Issued: 08/17/1999
• Est. Priority Date: 02/16/1995
• Status: Expired due to Fees

• Current Assignee: Medwave, Inc.
• Original Assignee: Medwave, Inc.
• Inventors: Thede, Roger C., Curran, Timothy G., Poliac, Marius O., Archibald, G. Kent, Danielson, Orland H.
• Primary Examiner(s): Cohen, Lee
• Assistant Examiner(s): YARNELL, BRYAN KEITH
• Application Number:
  US08/907,611
• Time in Patent Office: 739 Days
• Field of Search: 600/485, 600/490, 600/493, 600/500, 600/501, 600/502
• US Class Current: 600/485
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence

Abstract

The present invention is a method for locating a sensor over an underlying artery having a blood pulse. The sensor is positioned at a plurality of locations above a known appoximate location of the artery while applying a constant hold down pressure to the artery. The sensor is finally positioned at the location which exhibits the largest maximum pressure ampltiude.

Claims

1. A method of locating a blood pressure sensor over an underlying artery having a pulse, the method comprising:

positioning the blood pressure sensor at each of a plurality of locations above a known approximate location of the artery while applying hold down pressure at each location;

wherein the blood pressure sensor has an active area which contacts a patient'"'"'s body and has a width greater than a width of the artery, and wherein the blood pressure sensor produces a single time-varying signal representative of pressure applied to the active area by the artery during a cardiac cycle;

sensing pressure applied to the active area by the artery during a cardiac cycle with the sensor at each of the locations to produce at each location the time-varying signal representative of the pressure applied to the active area by the artery; and

displaying an indication of maximum pressure signal sensed during each cardiac cycle at each location to aid in final positioning of the sensor.

2. The method of claim 1 wherein displaying an indication includes:

deriving waveform pressure data from the time-varying signal deriving a value from the waveform pressure data at each of the plurality of locations, the value comprising a maximum pressure amplitude exerted by the pulse during a cardiac cycle in response to hold down pressure applied to the artery; and

displaying the value at each of the plurality of locations.

3. The method of claim 2 wherein displaying the value includes providing a digital output of the value.

4. The method of claim 1 wherein the pulse exerts a pressure upon the sensor which varies over time during an individual cardiac cycle and wherein displaying an indication includes:

visually displaying the pressure exerted by the pulse upon the sensor as a function of time during an individual cardiac cycle.

5. The method of claim 1 wherein the pulse exerts a pressure upon the sensor which varies over time in the shape of a pressure waveform having a systolic portion and a diastolic portion during an individual cardiac cycle, wherein the diastolic portion has a known characteristic shape and wherein the hold down pressure applied to the sensor is as large as possible without the known characteristic shape of the diastolic portion of the waveform distorting.

6. The method of claim 1 wherein the step of sensing pressure during a cardiac cycle includes:

continually sensing pressure during a cardiac cycle with the sensor at each of the locations.

7. A method of locating a sensor over an underlying artery having a blood pressure pulse, the method comprising:

positioning the sensor at each one of a plurality of locations above a known approximate location of the artery while applying hold down pressure to the artery, wherein the sensor has an active area which contacts a patient'"'"'s body and has a width greater than a width of the artery, and wherein the sensor produces a single time-varying signal representative of pressure applied to the active area by the artery during a cardiac cycle;

sensing pressure applied to the active area by the artery during a cardiac cycle with the sensor at each of the locations to produce at each location the time-varying signal representative of the pressure applied to the active area by the artery;

deriving waveform pressure data from the time varying signal; and

positioning the sensor over the underlying artery based upon the sensed waveform pressure data at each one of the plurality of locations.

8. The method of claim 7 including:

providing an indicator based upon the sensed waveform pressure data at each one of the plurality of locations to aid in final positioning of the sensor.

9. The method of claim 8 wherein providing an indicator includes:

deriving a value from the waveform pressure data at each of the plurality of locations; and

displaying the value at each of the plurality of locations.

10. The method of claim 9 wherein the value comprises a maximum pressure amplitude exerted by the pulse during a cardiac cycle in response to hold down pressure applied to the artery.

11. The method of claim 9 wherein displaying the value includes providing a digital output of the value.

12. The method of claim 8 wherein the pulse exerts a pressure upon the sensor which varies over time during an individual cardiac cycle and wherein providing an indicator includes:

visually displaying the pressure exerted by the pulse upon the sensor as a function of time during an individual cardiac cycle.

13. The method of claim 7 wherein the pulse exerts a pressure upon the sensor which varies over time in the shape of a pressure waveform having a systolic portion and a diastolic portion during an individual cardiac cycle, wherein the diastolic portion has a known characteristic shape and wherein the hold down pressure applied to the sensor is as large as possible without the known characteristic shape of the diastolic portion of the waveform distorting.

14. The method of claim 7 wherein the step of sensing pressure during a cardiac cycle includes:

continually sensing pressure during a cardiac cycle with the sensor at each of the locations.