Method and apparatus for noninvasive determination of peripheral arterial lumenal area

• US 6,309,359 B1
• Filed: 12/03/1998
• Issued: 10/30/2001
• Est. Priority Date: 06/01/1998
• Status: Expired due to Term

• Current Assignee: Advanced Cardiovascular Systems Incorporated, Rutgers University
• Original Assignee: Rutgers University
• Inventors: Whitt, Michael D., Drzewiecki, Gary M., Pilla, James J.
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US09/205,042
• Time in Patent Office: 1,062 Days
• Field of Search: 600/485, 600/481, 600/490, 600/492, 600/493-496, 600/500, 600/507, 600/526, 600/499, 600/504
• US Class Current: 600/507
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

An occlusive cuff is placed around a limb (e.g. an arm) of a patient. A fluid, such as air, is pumped into the cuff, and the pressure in the cuff is measured. The pressure variation in the cuff with respect to time is caused by the pump and expansion/contraction of the arm caused by blood being pumped therethrough by the patient'"'"'s heart. This variation in pressure is used to calculate systolic and diastolic pressure, artery lumen area compliance and artery volume compliance, artery lumen area, and the blood flow rate through the patient'"'"'s arteries (e.g. the brachial artery for the case of the patient'"'"'s arm, or the femoral artery or the case of the patient'"'"'s leg).

Claims

1. A method for collecting data concerning a patient comprising the steps of:

providing a cuff around a portion of a patient;

pumping a fluid into said cuff;

measuring the pressure variation in said cuff, a first portion of said pressure variation being a function of said fluid being pumped into said cuff, a second portion of said pressure variation being a function of the expansion and contraction of said portion of said patient caused by blood flowing through said portion of said patient;

determining the volume of fluid pumped into said cuff per pump stroke;

determining the relation between cuff volume and cuff pressure based on said determination of said volume of fluid pumped into said cuff per pump stroke; and

determining the change in volume of said portion of said patient caused by blood flowing through said portion of said patient by monitoring said second portion of said pressure variation.

2. The method of claim 1 wherein said step of pumping a fluid is performed using a pump having a substantially flat volume vs. pressure curve in the pressure range used.

3. The method of claim 1 wherein said pump pumps at a frequency substantially greater than the heart rate of said patient.

4. The method of claim 1 further comprising the step of calculating the lumen area of an artery in said patient by determining the lumen area compliance of said artery across a range of transmural pressures and integrating said lumen area compliance with respect to said transmural pressure to arrive at the lumen area.

5. The method of claim 1 further comprising the step of calculating the blood flow rate through an artery of said patient based on said second portion of said pressure variation.

6. The method of claim 1 further comprising the step of calculating the phase lag between the pressure vs. time waveform and the blood volume flow vs. time waveform.

7. The method of claim 1 wherein said step of determining the volume is performed using a flow meter.

8. An apparatus comprising:

a cuff for surrounding a portion of a patient;

a pump for pumping a fluid into and out of said cuff;

a flow meter coupled to said pump for measuring the volume of said fluid being pumped into and out of said cuff and determining a pump stroke volume for said pump;

a transducer for measuring the pressure of the fluid in the cuff;

filter circuitry for providing a measure of the change in cuff pressure caused by said pump and the change in cuff pressure caused by said patient'"'"'s pulse; and

circuitry for calculating a cuff compliance based on said pump stroke volume and said chance in cuff pressure caused by said pump and for calculating the change in the size of said portion of said patient caused by said patient'"'"'s pulse based on said change in cuff pressure caused by said patient'"'"'s pulse.

9. The apparatus of claim 8 wherein said circuitry calculates the chance in the area of the lumen of an artery of said patient caused by said patient'"'"'s pulse.

10. An apparatus comprising:

a cuff for surrounding a portion of a patient;

a pump for pumping a fluid into and out of said cuff;

a flow meter coupled to said pump for measuring the volume of said fluid being pumped into and out of said cuff and determining a pump stroke volume for said pump;

a transducer for measuring the pressure of the fluid in the cuff;

means for measuring the change in cuff pressure caused by said pump and the change in cuff pressure caused by said patient'"'"'s pulse; and

means for calculating a cuff compliance based on said pump stroke volume and said change in cuff pressure caused by said pump, and for calculating the change in the size of said portion of said patient caused by said patient'"'"'s pulse based on said change in cuff pressure caused by said patient'"'"'s pulse.

11. A method comprising the steps of

providing a cuff including a plurality of bladders around a portion of a patient;

inflating said bladders one at a time so that one of said bladders are in an inflated state;

pumping a fluid in and out of each of said bladders when said bladders are inflated;

measuring the pressure in said bladders when said bladders are inflated; and

using said pressure to determine the area of the lumen of an artery extending through each bladder.

12. The method of claim 11 further comprising the steps of:

measuring the volume of said fluid pumped in and out of said bladders;

determining the bladder compliance based on said measure of the volume of said fluid and the measure of said pressure; and

generating a measure of the change in cuff volume caused by a patient'"'"'s pulse.

13. An apparatus comprising:

a cuff comprising a plurality of bladders therein;

a manifold for selectively connecting a selected one of said bladders to a pump, said pump pumping fluid in and out of said bladder; and

a transducer for measuring the pressure at said selected bladder, said transducer being used to calculate lumen area of an artery.

14. An apparatus comprising:

a cuff comprising a plurality of bladders therein;

first means for selectively connecting a selected one of said bladders to a pump, said pump pumping fluid in and out of said bladder; and

second means for measuring the pressure at said selected bladder, said second means calculating the lumen area of an artery.