Tourniquet for regulating applied pressures

• US 5,048,536 A
• Filed: 07/13/1989
• Issued: 09/17/1991
• Est. Priority Date: 04/03/1987
• Status: Expired due to Term

• Current Assignee: Abatis Medical Technologies Limited, Zimmer Orthopaedic Surgical Products (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Torromain Investments Limited
• Inventors: McEwen, James A.
• Primary Examiner(s): Hindenburg, Max
• Application Number:
  US07/388,699
• Time in Patent Office: 796 Days
• Field of Search: 128/686, 128/748, 128/774-782, 606/203, 606/202, 606/201, 200/83 N, 200/83 Y, 200/81.4, 200/211, 200/212, 200/214
• US Class Current: 600/561
• CPC Class Codes: A61B 17/132 Tourniquets sphygmomanometer A61B5/022
• CPC Class Codes: A61B 17/1355 Automated control means therefor
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61H 2201/5074 using electric pressure transducers with proportional output
• CPC Class Codes: H01H 35/24 Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow wherein the change of pressure is caused by change of temperature H01H37/36

Abstract

A tourniquet comprising: (a) an occlusive band for encircling a limb of a subject and for applying pressure to the limb wherein an inner surface of at the band faces the limb; and applied pressure sensing means located at a predetermined position on the inner surface of the band for producing an indication of the pressure applied by the band to the limb near the predetermined location. The applied pressure sensing means is comprised of material having a degree of flexibility and physical dimensions selected so that the sensing means conforms closely to the surface of the occlusive band and does not substantially displace the surface of the limb away from the band surface. The applied pressure sensing means produces an applied pressure signal representative of the pressure applied by the band to the limb near the predetermined location, the occlusive band is responsive to a varible pressure control signal, and pressure-regulating means responsive to the applied pressure signal is included for producing a pressure control signal to maintain the pressure applied by the band to the limb near a predetermined reference pressure.

Claims

1. Apparatus for controlling the pressure applied to a body tissue by pressure-applying means near a predetermined location relative to the pressure-applying means, comprising:

pressure-applying means responsive to a pressure control signal for applying pressure to a tissue;

transducing means comprised of;

a first flexible layer carrying a first electrical contact;

a second flexible layer carrying a second electrical contact and cooperating with the first flexible layer to define a flexible pressurizable chamber interposed between the tissue and the pressure-applying means, wherein the first and second electrical contacts are touching near a predetermined location relative to the pressure-applying means when the chamber is not pressurized; and

pressure estimation means for selectable pressurizing the chamber, and for producing an applied pressure signal representative of the lowest pressure at which the first and second electrical contacts are separated; and

pressure-regulating means responsive to the applied pressure signal for producing a pressure control signal to maintain the pressure applied to the tissue by the pressure-applying means near a predetermined reference pressure.

2. A tourniquet comprising:

an occlusive band responsive to a variable pressure control signal for encircling a limb of a subject and for applying pressures to the limb wherein an inner surface of at the band faces the limb;

applied pressure sensing means located at a predetermined location on the inner surface of the band for producing an applied pressure signal representative of the pressure applied by the band to the limb near the predetermined location wherein the applied pressure sensing means is comprised of;

a first flexible layer carrying a first electrical contact,

a second flexible layer carrying a second electrical contact and cooperating with the first flexible layer to define a flexible pressurizable chamber wherein the first and second electrical contacts are touching, near the predetermined location when the chamber is not pressurized, and

pressure estimation means for selectably pressurizing the chamber, and for producing an applied pressure signal representative of the lowest pressure at which the first and second electrical contacts are separated; and

pressure-regulating means responsive to the applied pressure signal for producing a pressure control signal to maintain the pressure applied to the limb near a predetermined reference pressure.

3. A tourniquet comprising:

an occlusive band responsive to a variable pressure control signal for encircling a limb of a subject and for applying pressures to the limb, wherein an inner surface of the band faces the limb;

applied pressure sensing means located at a plurality of predetermined locations on the inner surface of the band for producing a plurality of applied pressure signals representative of the pressures applied by the band to the limb near each of the predetermined locations wherein the applied pressure sensing means is comprised of;

a first flexible layer carrying a plurality of first electrical contacts,

a second flexible layer carrying a plurality of electrical contacts and cooperating with the first flexible layer to define a flexible pressurizable chamber wherein pairs of first and second electrical contacts are touching, near the plurality of predetermined locations when the chamber is not pressurized, and

pressure estimation means for selectably pressurizing the chamber, and for producing a plurality of applied pressure signals representative of the lowest pressures at which each pair of electrical contacts is separated; and

pressure-regulating means responsive to at least one of the applied pressure signals for producing a pressure control signal to maintain the pressure applied to the limb near at least one predetermined location near a predetermined reference pressure.

4. A tourniquet comprising:

an occlusive band responsive to a variable pressure control signal for encircling a limb of a subject and for applying pressures to the limb wherein an inner surface of at the band faces the limb;

applied pressure sensing means located at a predetermined location on the inner surface of the band for producing an applied pressure signal representative of the pressure applied by the band to the limb near the predetermined location wherein the applied pressure sensing means is comprised of;

a first flexible layer carrying a first electrical contact,

a second flexible layer carrying a second electrical contact and cooperating with the first flexible layer to define a flexible pressurizable chamber wherein the first and second electrical contacts are touching, near the predetermined location when the chamber is not pressurized, and

pressure estimation means for selectably depressurizing the chamber from a level at which the contacts are separated, and for producing an applied pressure signal representative of the highest pressure at which the contacts touch; and

pressure-regulating means responsive to the applied pressure signal for producing a pressure control signal to maintain the pressure applied to the limb near a predetermined reference pressure.

5. A tourniquet comprising:

an occlusive band responsive to a variable pressure control signal for encircling a limb of a subject and for applying pressures to the limb, wherein an inner surface of the band faces the limb;

applied pressure sensing means located at a plurality of predetermined locations on the inner surface of the band for producing a plurality of applied pressure signals representative of the pressures applied by the band to the limb near each of the predetermined locations wherein the applied pressure sensing means is comprised of;

a first flexible layer carrying a plurality of first electrical contacts,

a second flexible layer carrying a plurality of electrical contacts and cooperating with the first flexible layer to define a flexible pressurizable chamber wherein pairs of first and second electrical contacts are touching, near the plurality of predetermined locations when the chamber is not pressurized, and

pressure estimation means for selectably depressurizing the chamber from a level at which all pairs of contacts are separated, and for producing a plurality of applied pressure signals representative of the highest pressures at which each pair of contacts touch; and

pressure-regulating means responsive to at least one of the applied pressure signals for producing a pressure control signal to maintain the pressure applied to the limb near at least one predetermined location near a predetermined reference pressure.

6. A tourniquet for occluding blood flow into a limb over a time period suitably long for the performance of a surgical procedure, comprising:

an occlusive band for encircling a limb of a subject and for applying pressure to the encircled limb to occlude blood flow into the limb distal to the band wherein an inner surface of the band faces the limb; and

applied pressure sensing means located at a predetermined location fixed relative to and in contact with the inner surface of the band for producing an indication of the pressure applied by the band to the surface of the limb in a normal direction at the predetermined location.

7. A tourniquet as defined in claim 6, wherein the applied pressure sensing means produces an applied pressure signal representative of the pressure applied by the band to the limb near the predetermined location, wherein the occlusive band is responsive to a variable pressure control signal, and including pressure-regulating means responsive to the applied pressure signal for producing a pressure control signal to maintain the pressure applied to the limb near a predetermined reference pressure.

8. A tourniquet for establishing a bloodless surgical field to facilitate limb surgery, comprising:

a cuff, attachable to a limb for applying pressure to the limb to occlude blood flow into the limb distal to the band, the cuff having an inner surface positionable in contact with the limb; and

a plurality of sensors fastened to the inner surface of the cuff for detecting the pressure applied by the cuff to the surface of the limb at a plurality of locations in a direction normal to the cuff at each of the locations.

9. A tourniquet as defined in claim 8 wherein the sensors produce a plurality of applied pressure signals representative of the pressure applied by the cuff to the limb near each of the locations, wherein the cuff is responsive to a variable pressure control signal, and including pressure-regulating means responsive to at least one of the applied pressure signals for producing a pressure control signal to maintain the pressure applied to the limb near at least one location near a predetermined reference pressure.

10. A tourniquet for establishing a bloodless surgical field to facilitate limb surgery comprising:

an occlusive band for encircling a limb of a subject and for simultaneously applying a plurality of pressures to the encircled limb to occlude blood flow into the limb distal to the band, wherein an inner surface of the band faces the limb;

applied pressure sensing means for producing an indication of the pressure applied by the band to the surface of the limb in a direction normal to the inner surface of the band at a predetermined location on the inner surface of the band; and

fixing means for fixing the location of the applied pressure sensing means relative to the predetermined location on the inner surface of the band over a time period suitably long for the performance of a surgical procedure.

11. A tourniquet for establishing a bloodless surgical field to facilitate limb surgery, comprising:

an occlusive band for encircling a limb of a subject;

pressure means for simultaneously applying a plurality of selected pressures to the surface of the encircled limb to occlude blood flow into the limb distal to the band; and

pressure sensing means for producing an indication of the pressure applied by the pressure means to the surface of the limb near any of a plurality of locations near the band.