Blood pressure cuff with integral acoustic pickup cup

• US 4,890,625 A
• Filed: 03/24/1988
• Issued: 01/02/1990
• Est. Priority Date: 03/24/1988
• Status: Expired due to Fees

• Current Assignee: Spacelabs, Inc. (OSI Systems Incorporated)
• Original Assignee: Spacelabs, Inc. (OSI Systems Incorporated)
• Inventors: Sorensen, Jay R.
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US07/172,718
• Time in Patent Office: 649 Days
• Field of Search: 128/672, 128/677-686, 128/715
• US Class Current: 600/493
• CPC Class Codes: A61B 5/02208 using the Korotkoff method
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 7/045 Detection of Korotkoff sounds A61B5/0225 takes precedence; measuring blood pressure A61B5/021

Abstract

A blood pressure cuff having an internal acoustic pickup cup. In one embodiment, the cup communicates with the interior of the blood pressure cuff bladder through an aperture that is sufficiently large to allow pressure equalization between the interior of the bladder and the cup and sufficiently small to prevent Karotkoff sounds from being coupled from the cup to the interior of the bladder. A single pneumatic tube extends from the cup and through the wall of the bladder to a first enclosure that is coupled to a second enclosure through a conduit. The first enclosure contains a microphone for converting the acoustic signals picked up by the cup into a corresponding electrical signal. The second enclosure contains a pressure transducer for providing an electrical signal indicative of the pressure in the bladder. In a second embodiment, the cup and bladder are isolated from each other and separate tubes extend from the bladder and the cup to separate enclosures. The enclosure communicating through one of the conduits with the cup contains a microphone, while the enclosure communicating through the other tube with the bladder contains a pressure transducer.

Claims

1. A blood pressure cuff comprising:

a flexible casing having a rectangular pocket formed therein;

a relatively thin, flexible rectangular bladder positioned in the pocket of said casing;

an acoustic pickup cup mounted in said bladder in a manner that allow said cup to pick up Korotkoff sounds when said blood pressure cuff is placed on a patient, said cup having an aperture formed therein between the interior of said cup and the interior of said bladder to allow the pressure in the interior of said cup to equalize; and

a pneumatic tube extending from the interior of said cup through said bladder, whereby the pressure in said bladder and acoustic signals picked up by said cup are both coupled through said tube.

2. The blood pressure cuff of claim 1 wherein said aperture has a diameter of about 0.1 inch.

3. A system for measuring blood pressure, comprising:

a blood pressure cuff including a flexible casing having a rectangular pocket formed therein, a flexible rectangular bladder positioned in the pocket of said casing, and an acoustic pickup cup to pick up Korotkoff sounds when said blood pressure cuff is placed on a patient, said cup having an aperture formed therein between the interior of said cup and the interior of said bladder to equalize the pressure in said bladder with the pressure in said cup;

an enclosure having a pressure transducer generating an electrical signal indicative of the pressure in said enclosure and an electrical signal corresponding to an acoustic signal coupled to said enclosure; and

a pneumatic tube extending from the interior of said acoustic pickup cup through said bladder to said enclosure for coupling the pressure in said bladder and acoustic signals picked up by said cup into the interior of said enclosure.

4. The blood pressure measuring system of claim 3 wherein said pressure transducer comprises a microphone generating said electrical signal corresponding to said acoustic signal;

and

pressure transducer means generating said signal indicative of the pressure in said enclosure.

5. The blood pressure measuring system of claim 4 wherein said microphone and said pressure transducer means are mounted in separate respective first and second enclosures that are coupled to each other.

6. The blood pressure measuring system of claim 5 wherein said penumatic tube means comprise a first pneumatic tube extending from the interior of said cup through said bladder to said first enclosure and a second pneumatic tube extending from the interior of said bladder to said second enclosure.

7. The blood pressure measuring system of claim 6 wherein said acoustic pickup cup is open to the atmosphere and wherein said acoustic pickup cup has sufficient rigidity to withstand the pressure differential across said cup when said bladder is inflated.

8. The blood pressure measuring system of claim 3 wherein said aperture has a diameter of about 0.1 inch.

9. A method of measuring blood pressure, comprising:

providing a blood pressure cuff having a flexible casing with a rectangular pocket formed therein, a flexible rectangular bladder positioned in the pocket of said casing, and an acoustic pickup cup mounted in said bladder in a manner that allows said pickup cup to pick up Korotkoff sounds when said blood pressure cuff is placed on a patient;

placing said blood pressure cuff around the limb of a patient and selectively inflating or deflating said bladder so that Korotkoff sounds generate relatively high-frequency pressure signals in said pickup cup;

venting the interior of said pickup cup to the interior of said bladder so that the pressure in said cup and the pressure in said bladder are substantially equalized; and

measuring the pressure in said pickup cup to both detect Korotkoff sound-induced pressure signals in said pickup cup and determine the fluid pressure in said bladder.

10. The method of claim 9 wherein the pressure in said pickup cup is measured by connecting the interior of said pickup cup to a pressure transducer with a pneumatic tube extending from the interior of said acoustic pickup cup through said bladder and to said pressure transducer without allowing said pneumatic tube to communicate directly with the interior of said bladder.

11. The method of claim 9 wherein said acoustic pickup cup is mounted within said bladder, and further comprising forming an aperture in said acoustic pickup cup between the interior of said acoustic pickup cup and the interior of said bladder to vent the interior of the acoustic pickup cup to the interior of the bladder, said aperture having a diameter that is sufficiently small to substantially prevent Korotkoff sound-induced pressure signals in said pickup cup from being coupled to the interior of said bladder.

12. The method of claim 11 wherein the diameter of said aperture is about 0.1 inch.