Process and apparatus for measurement and monitoring of muscle compartment pressure

• US 4,817,629 A
• Filed: 02/18/1987
• Issued: 04/04/1989
• Est. Priority Date: 01/03/1986
• Status: Expired due to Term

• Current Assignee: Stryker Corporation
• Original Assignee: Stryker Corporation
• Inventors: Booth, William M. III, Warfield, Wayne N., Davis, Scott J.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/015,835
• Time in Patent Office: 776 Days
• Field of Search: 128/672.3, 128/675, 128/748, 604/236-237, 604/160
• US Class Current: 600/561
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• 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

Abstract

Portable apparatus for measuring and monitoring muscle compartment pressures comprising a system of a disposable assembly of a syringe, a pressure chamber having a diaphragm, and means to penetrate the skin of a patient, and a measuring and reading device comprising a transducer, whereby accurate measurement of such pressures can be easily made.

Claims

1. A tissue fluid pressure measuring and monitoring system, comprising a syringe, a pressure chamber member having a bottom, and a tissue penetrating means aligned in series, said syringe and tissue penetrating means having flow passages, said pressure chamber member being a one piece member coaxially aligned between said syringe and tissue penetrating means;

a cap fitted to the bottom of said pressure chamber member, said pressure chamber member and cap cooperating to define an internal chamber having a top wall, said wall and bottom wall, said bottom wall being annular and having a central opening therethrough, L-shaped connecting passages in said top wall respectively connecting said flow passages with said internal chamber, said L-shaped passages having generally aligned but spaced apart legs respectively connected to said flow passages in said syringe and tissue penetrating means, said L-shaped passages further having respective downward extending parallel, spaced apart legs connecting respective aligned legs with said internal chamber at two points spaced from the center of the chamber, the top wall of said chamber being domed in the central portion thereof and having a substantially square cross section annular recess at the perimeter thereof, said pressure chamber member being free of any valve structure in and between said connecting passages and chamber;

a diaphragm of semitoroidal shape and hence of generally W-shaped cross section, said diaphragm separating top and bottom portions of said chamber, said diaphragm having a rim, a raised central head and a deeply depressed annular suspension portion radially interposed between the rim and central head, said rim being of substantially square cross section and substantially thicker than the rest of said diaphragm, said rim being snugly received in said annular recess in said top of said chamber, the radially outer portion of said rim defining a downward facing annular step, said cap having an upstanding annular cylindrical wall snugly telescopingly received in an annular side wall of said member and at its upper edge abutting said annular step of said diaphragm rim, the edge of said domed portion of said top wall of said member lying at an intermediate level in the height of said rim, all four sides of said rim being in sealing engagement with opposed surfaces of said pressure chamber member and cap, said depressed annular suspension portion being of deep U-shaped cross section and extending from said rim down to near the bottom wall of said chamber, said central head having a rest (no pressure differential thereacross) position at about the level of said step of the rim and spaced above the bottom of said annular suspension portion, said downwardly extending legs of said L-shaped connecting passages opening through the top wall of said chamber vertically opposite said depressed annular suspension portion and substantially flush with said rim and the radially outer wall of said annular suspension portion of said diaphragm to prevent trapping air between the diaphragm and chamber top wall when the syringe is activated to drive liquid through said pressure chamber member and tissue penetrating means, the central opening in the bottom wall of said chamber being spaced opposite said raised central head of said diaphragm by more than the depth of said depressed annular suspension portion and said depressed annular suspension portion being radially outboard of said central opening in said bottom wall so that said central opening is free of blocking by said diaphragm;

a pressure transducer positionable at said central opening, whereby movement of said diaphragm caused by pressure in said tissue is detected by said pressure transducer.

2. A tissue pressure measuring and monitoring system as recited in claim 1, wherein said syringe, said pressure chamber member and said tissue penetrating means are separable from said pressure transducer and are disposable after use.

3. A tissue pressure measuring and monitoring system as recited in claim 2, wherein said tissue penetrating means comprises a needle.

4. A tissue pressure measuring and monitoring system as recited in claim 2, wherein said tissue penetrating means comprises a catheter and a cannula.

5. A tissue pressure measuring and monitoring system as recited in claim 1, including a measuring device including a housing having a support surface on which to lay said syringe, said pressure transducer being located on said housing adjacent said support surface and having a projection sealingly receivable in said central opening in said annular bottom wall of said cap with said syringe laid on said support surface of said housing, said housing having a cover closable over said support surface to hold said syringe in place on said support surface and said cap in place on said transducer, said housing having oppositely open holes through which a manually actuable portion of said syringe projects and from which oppositely projects said tissue penetrating means, said housing having pressure read out means outside and adjacent said cover for reading out the pressure in said chamber.

6. A tissue pressure measuring and monitoring system as recited in claim 1 in which the side wall of said chamber is concavely curved downward and then radially inward to meet the bottom wall of said chamber, so that the portion of said chamber occupied by said annular suspension portion of said diaphragm has a rounded cup like shape, the curvature of said chamber side wall conforming substantially to the curvature that a radially outer portion of said U-cross section depressed annular suspension portion tends to take in response to an increase in pressure above the diaphragm tending to force same downward in the chamber, the top edge portion of the radially outer portion of the annular suspension portion depending from said rim and downward flush along a top portion of said side wall and diverging radially inward away from said side wall with the diaphragm in its normal, rest, raised position in the chamber, said diaphragm depressed portion radially outer portion being responsive to an increase in pressure above said diaphragm to unroll progressively downward close along the concavely curved side wall of said chamber to a lower operating position in the chamber and with a downwardly opening, narrow angular squish area advancing downward between the side wall of the chamber and the radially outer portion of the U-shaped annular suspension portion brought together by an increase in pressure above the diaphragm, the curvature of said chamber side wall corresponding substantially to the curvature that the diaphragm naturally assumes in response to increasing pressure above it in the chamber, such that the curved side wall of the chamber supports the radially outer portion of the U-shaped annular suspension portion of the diaphragm as it unrolls downward therealong, so as to avoid stretching of the diaphragm material or trapped air pockets between the curved side wall of the chamber and the radially outer portion of the diaphragm.

7. The apparatus of claim 1 in which said central opening in said chamber bottom wall is tapered, being narrower at its inboard end, said transducer having a projection which is tapered at a lesser angle than said central opening, the minimum diameter of said projection being slightly less than that of said central opening and related thereto such that the projection is freely insertable up into said central opening with adequate space therebetween for air escape from the portion of said chamber beneath said diaphragm until said projection is nearly fully inserted into said central opening, whereat a slight further axial insertion causes said projection to block said central opening in an air tight manner, whereby preloading of the bottom of the diaphragm, due to insertion of said projection into said central opening is minimized.

8. A tissue pressure measuring and monitoring system as recited in claim 1 in which said side wall of said chamber is curved into the bottom wall thereof in a concave manner conforming substantially to the shape of the radially outer wall of said U-shaped depressed portion of said diaphragm when the latter is subjected to increased liquid pressure in the top portion of said chamber, said diaphragm having a depressed lower position within said chamber corresponding to a maximum usable pressure reading for liquid in said chamber above said diaphragm, in which lower position the air volume in the chamber below the diaphragm is minimized and very substantially less than the liquid volume in said chamber above said diaphragm, such that the pressure of liquid above said diaphragm is transferred through a minimum volume of air to said pressure transducer in said central opening.

9. A tissue measuring and monitoring system as recited in claim 1 including a tubular valve housing having one end fixedly extending from said pressure chamber member in coaxial relation with the aligned legs of said connecting passages, said syringe being releasably connected to a remote end of said tubular valve housing, means defining an automatic one way valve in said tubular valve housing for permitting fluid flow from the syringe to and through said interior chamber and through said tissue penetrating means but automatically preventing back flow of any fluid from said interior chamber to said syringe.

10. Apparatus for measuring fluid pressures and fluctuations thereof in tissues, comprising:

a pressure receiving device and a separate pressure measuring device;

said pressure receiving device comprising a member defining a pressure chamber having a top wall, side wall and a bottom wall, said bottom wall having an opening therein;

a pressure responsive flexible diaphragm within said chamber and dividing said chamber into separate liquid and air subchambers;

means for connecting said liquid subchamber to tissues in which fluid pressure is to be measured;

means to purge said liquid subchamber of said pressure receiving device with air and fill it with liquid;

said pressure measuring device comprising a pressure transducer having a protrusion insertable in said opening in said bottom wall, said opening in said bottom wall opening to said air subchamber, such that said protrusion is shielded from liquid contact by said diaphragm but as applied thereto the pressure of liquid in said liquid subchamber through action of the diaphragm and correspondingly pressurizing the air in said air subchamber, said measuring device including a housing having a support surface on which to lay said purge means, said pressure transducer being located on said housing adjacent said support surface, said transducer projection being sealingly received in said opening in said bottom wall of said chamber member with said purge means laid on said support surface of said housing, a cover fitted to said housing and adapted to close over said member defining said pressure chamber in a manner to hold same fixedly on said housing and with respect to said projection, said housing and cover together defining a closed surround containing said pressure chamber defining member, said closed surround having opposed openings through which snugly project said purge means and said means for connecting said liquid subchamber to tissue, said pressure chamber defining member, purge means and means connecting said liquid subchamber to tissue being as a unit implacable in and removable from said enclosed relation by said housing and cover and being operable to inject liquid into tissue while so enclosed, said housing having a pressure read out means exposed outside said cover for reading out the pressure in said chamber and located adjacent said support surface.

11. The apparatus of claim 10 in which said opening in said bottom wall is tapered toward said air subchamber, said projection being tapered at a lesser angle toward the end thereof and insertable in said opening, the minimum diameters of said opening and projection being related such that air is free to flow out of said air subchamber through said opening during insertion of said projection into said opening and until said projection is substantially fully inserted in said opening whereupon only a very small fractional further increment of insertion of said projection into said opening is required to effect sealing between the minimum diameter end of said projection and the minimum diameter end of said opening.

12. Apparatus for measuring fluid pressures and fluctuations thereof in tissues, comprising:

a member defining a pressure chamber having a top wall, side wall and a bottom wall, said bottom wall having an opening therein for measuring of the pressure in said chamber;

a pressure responsive flexible diaphragm within said chamber and dividing said chamber into separate liquid and air subchambers, said diaphragm having a depressed annular suspension portion of U-cross section depending from an annular rim and a central head;

means for connecting said liquid subchamber to tissues in which fluid pressure is to be measured;

means to purge said liquid subchamber of air and fill it with liquid;

the side wall of said chamber being concavely curved downward and then radially inward to meet the bottom wall of said chamber, so that the portion of said chamber occupied by said annular suspension portion of said diaphragm has a rounded cup like shape, the curvature of said chamber side wall conforming substantially to the curvature that a radially outer portion of said U-cross section depressed annular suspension portion tends to take in response to an increase in pressure above the diaphragm tending to force same downward in the chamber, the top edge portion of the radially outer portion of the annular suspension portion depending from said rim and downward flush along a top portion of said side wall and diverging radially inward away from said side wall with the diaphragm in its normal, rest, raised position in the chamber, said diaphragm depressed portion radially outer portion being responsive to an increase in pressure above said diaphragm to unroll progressively downward close along the concavely curved side wall of said chamber to a lower operating position in the chamber and with a downwardly opening, narrow angular squish area advancing downward between the side wall of the chamber and the radially outer portion of the U-shaped annular suspension portion brought together by an increase in pressure above the diaphragm, the curvature of said chamber side wall corresponding substantially to the curvature that the diaphragm naturally assumes in response to increasing pressure above it in the chamber, such that the curved side wall of the chamber supports the radially outer portion of the U-shaped annular suspension portion of the diaphragm as it unrolls downward therealong, so as to avoid stretching of the diaphragm material or trapped air pockets between the curved side wall of the chamber and the radially outer portion of the diaphragm.

13. A disposable device for use in measuring fluid pressures and changes thereof in tissues, comprising:

a pressure chamber member defining a pressure chamber;

a pressure sensitive diaphragm disposed in said chamber and dividing it into liquid and air subchambers;

insertion means freely openly connected to said liquid subchamber and arranged for insertion into said tissues;

a syringe connected to said liquid subchamber and having plunger means for advancing liquid from said syringe through said liquid subchamber and insertion means to said tissues; and

automatic means interposed between said syringe and said liquid subchamber and automatically responsive to pressure drops thereacross for (1) automatically permitting liquid to flow freely from said syringe through said pressure chamber to said insertion means but (2) automatically preventing escape of pressure from said pressure chamber and insertion means by pushing back said plunger means in said syringe and (3) automatically preventing contamination of said syringe by blocking back flow of liquid into said syringe from said insertion means and tissue, said automatic means including a tubular valve housing extending from said syringe to said pressure chamber member, said automatic means also including an automatic one way valve member shiftable in said tubular valve housing for permitting free liquid flow from the syringe to and through said liquid subchamber and through said insertion means but automatically preventing back flow of any fluid from said liquid subchamber to said syringe.

14. A disposable device for use in measuring fluid pressures and changes thereof in tissues, comprising:

a syringe and a plunger therein;

a pressure chamber member defining a pressure chamber having top, bottom, and side walls;

a pressure sensitive diaphragm disposed in said chamber and dividing it into upper liquid and lower air subchambers; and

insertion means for insertion into said tissues, said device being substantially T-shaped with said pressure chamber member at the base of the T and said syringe and at least an adjacent portion of said insertion means as arms of the T, said top wall having passages comprising coaxial lateral blind legs entering from opposite sides thereof and having adjacent blind ends spaced by a central portion of said top wall, said lateral legs communicating with coaxial passages in said syringe and insertion means, said diaphragm being of reentrant type having a rim recessed in the side walls of said pressure chamber at said top wall, said diaphragm having a flexible wall depending in a flush manner from said rim down from said top wall and close along said side walls of the air subchamber, said top wall passages having respective depending legs opening down into said liquid subchamber substantially flush with adjacent portions of said rim and diaphragm flexible wall to avoid entrapment of air in said liquid subchamber when the device is positioned with the insertion means uppermost and the syringe is actuated to drive liquid through said liquid subchamber and insertion means.