Blood pressure cuffs

Abstract

A blood pressure cuff includes: (a) a flexible, hollow bladder adapted to surround the arm of the patient, which has an inside surface adapted to apply pressure to a surface of the arm above an artery, an outside surface opposite this inside surface, and an inlet line for receiving a fluid to cause the bladder to expand;(b) at least one first sensor element arranged on a inside and/or outside surface of the bladder in a location adjacent the artery when the bladder is in its operative position surrounding the patient's arm; and possibly also(c) at least one second sensor element arranged on a surface of the bladder that is opposite to the surface on which the first sensor element is disposed, and in a location adjacent the artery when the bladder is in its operative position surrounding the patient's arm. The sensor elements each comprise an elongate thin-film strip which transduces mechanical vibrations and produces an electrical signal representing these vibrations, normally in the range of 0 to 100 Hz.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a blood pressure cuff having both an inside sensor element and an outside sensor element according to a first preferred embodiment of the present invention.

FIG. 2 is a perspective view of a blood pressure cuff having multiple inside sensor elements according to a second preferred embodiment of the present invention.

FIG. 3 is a schematic view of a two-channel sensor system for a blood pressure cuff according to a third preferred embodiment of the present invention.

FIG. 4 is a block diagram of an electronic circuit for a blood pressure cuff according to the invention, which circuit converts the analog outputs of the sensor elements into digital signals and transmits the digital data to a computer for storage, retrieval and analysis.

FIG. 5 is a representational diagram of a connector and plug for both a pneumatic line and electronic leads in a blood pressure cuff according to the invention.

FIG. 6 illustrates typical sensor signals during blood pressure cuff deflation (volts vs. time in seconds) for both an inside sensor element and an outside sensor element.

FIG. 7 is a graph of a high frequency inside sensor signal (right axis) and cuff pressure (left axis) vs. time in seconds.

FIG. 8 is a graph showing positional and interbeat variablility of an outside sensor element.

FIG. 9 is a graph of sensor element signals showing a succession of mean supra-systolic beats.

FIG. 10 is a graph of sensor element signals showing a mean sub-diastolic beat.

FIG. 11 is a representational diagram of the components of a pressure wave represented by the sensor element output.

FIG. 12 is a representational diagram showing an initial step in the manufacture of a blood pressure cuff according to the invention.

FIG. 13 is a representational diagram showing a next following step in the manufacture of a blood pressure cuff according to the invention.

FIG. 14 is a representational diagram showing still another next step in the manufacture of a blood pressure cuff according to the invention.

FIG. 15 is a representational diagram showing a final step in the manufacture of a blood pressure cuff according to the invention.

Claims

1. Blood pressure cuff apparatus for constricting an artery in a peripheral limb of a mammal and sensing cardiovascular performance of the mammal, said blood pressure cuff comprising, in combination: (a) a flexible, hollow bladder adapted to surround the limb with the artery, said bladder having an inside external surface adapted to apply pressure to a surface of the limb, an outside external surface on the side opposite said inside surface, and an inlet for receiving a fluid to cause the bladder to expand;(b) at least one first sensor element disposed on at least one of said inside surface and outside surface of the bladder in a location adjacent said artery when said bladder is in an operative position surrounding said limb, said first sensor element including an elongate thin-film strip for transducing mechanical vibrations and producing electrical signals representing said vibrations.

2. The blood pressure cuff recited in claim 1, wherein said limb of a mammal is an arm of a human patient and said artery is a brachial artery.

3. The blood pressure cuff defined in claim 1, wherein said first sensor element includes a piezo-electric, thin film material.

4. The blood pressure cuff defined in claim 3, wherein said material is PVDF.

5. The blood pressure cuff defined in claim 1, wherein said first sensor element transduces strain in said surface of the bladder on which it is disposed and produces an electric signal representing said strain.

6. The blood pressure cuff defined in claim 1, further comprising at least one second sensor element disposed on at least one of said inside surface and said outside surface of the bladder that is opposite to the surface on which said first sensor element is disposed, said second sensor element including an elongate thin-film strip which transduces mechanical vibrations and produces an electrical signal representing these vibrations.

7. The blood pressure cuff defined in claim 6, wherein said second sensor element includes a piezo-electric, thin film material.

8. The blood pressure cuff defined in claim 7, wherein said material is PVDF.

9. The blood pressure cuff defined in claim 6, wherein said second sensor element transduces strain in said surface of the bladder on which it is disposed and produces an electric signal representing said strain.

10. The blood pressure cuff defined in claim 1, wherein said elongate strip of said first sensor element is disposed substantially parallel to a direction of the artery when said blood pressure cuff is positioned on said limb.

11. The blood pressure cuff defined in claim 1, wherein said first sensor element comprises at least two elongate strips which extend substantially parallel to each other.

12. The blood pressure cuff defined in claim 11, wherein said at least two elongate strips extend substantially parallel to a direction of the artery when said blood pressure cuff is in an operative position surrounding said limb.

13. The blood pressure cuff defined in claim 11, wherein said at least two elongate strips extend substantially transverse to a direction of the artery when said blood pressure cuff is in an operative position surrounding said limb.

14. The blood pressure cuff defined in claim 11, wherein said at least two elongate strips are connected in series.

15. The blood pressure cuff defined in claim 11, wherein said at least two elongate strips are connected in parallel.

16. The blood pressure cuff defined in claim 1, wherein said bladder has a proximal end and a distal end when it surrounds said limb, and wherein said first sensor element is disposed adjacent the distal end of said bladder.

17. The blood pressure cuff defined in claim 6, wherein said elongate strip of said second sensor element is disposed substantially parallel to a direction of the artery when said blood pressure cuff is positioned in an operative position surrounding said limb.

18. The blood pressure cuff defined in claim 6, wherein said elongate strip of said second sensor element is disposed substantially transverse to a direction of the artery when said blood pressure cuff is positioned in an operative position surrounding said limb.

19. The blood pressure cuff defined in claim 1, wherein said first sensor element is attached to said surface of the bladder by means of at least one of an adhesive and welding.

20. The blood pressure cuff defined in claim 1, wherein said first sensor element is held in place by a cover film which is attached to the surface of the bladder.

21. The blood pressure cuff defined in claim 1, wherein each first sensor element is connected to an analog-to-digital (A/D) converter.

22. The blood pressure cuff defined in claim 21, wherein the A/D converter is connected to a digital communication manager (DCM) which converts the output of the A/D converter to a standard communication protocol for transmission to a digital computer.

23. The blood pressure cuff defined in claim 22, wherein the first sensor element is electrically connected to a connector jack, and wherein the A/D converter and DCM are disposed in a plug which is connectable electrically to the connector jack.

24. The blood pressure cuff defined in claim 23, wherein the plug is connectable by a cable to a computer.

25. The blood pressure cuff defined in claim 24, wherein the connector jack also has a receptacle for a fluid connection to the bladder, and wherein the plug is connectable fluidically to the receptacle.

26. The blood pressure cuff defined in claim 25, wherein the plug is connectable to a source of fluid under pressure by a flexible hose.