PRESSURE CUFF

Abstract: A pressure cuff (10) of the type for use with a sphygmomanometer wherein the cuff is adapted to fit snugly about the limb (12) of a patient in accommodation with the particular tapered contour of the limb. The pressure cuff comprises a relatively wide, elongated flexible strap (32) having an inner portion (34) for wrapping about the patient's limb and for supporting an inflatable bladder (38) and a microphone (42) against the limb for use in detecting arterial blood pressure. The inner strap portion is joined to an outer portion (36) and carries a slotted hanger bracket (50) through which the outer portion is pulled to fit the cuff snugly about the patient's limb in accordance with the circumference and tapered contour of the limb, whereupon the outer strap portion is folded back upon the inner portion for locking engagement therewith by use of Velcro-Type fastening strips (58) or the like. The slotted hanger bracket is mounted on the inner portion of the strap for pivoting movement to permit the outer strap portion to be folded back in substantial overlapping alignment with the inner portion, regardless of the tapered contour of the patient's limb.

Description: PRESSURE CUE BACKGROUND OF THE INVENTION This invention relates generally to pressure cuffs for wrapping snugly about the limb of a patient, such as pressure cuff's of the type for use in sphygmoman- ometers. More specifically, this invention relates to an improved pressure cuff designed to fit snugly about a patient's limb in adjustable accommodation with the particular circumference and tapered contour of the limb. Sphygmomanometers in general are known in the art and typically include a so-called pressure cuff or tourniquet which carries an inflatable bladder and a microphone for use in detecting arterial blood pressure in a patient. The pressure cuff is wrapped snugly about a limb of the patient, normally about the biceps muscle of the upper arm to position the bladder and the microphone against the limb, whereupon the bladder is inflated to a pressure sufficient to cause cessation of arterial blood flow. The pressure in the bladder is then released slowly to permit resumption of arterial blood flow, the sound of which is readily detected by .use of the microphone. -The audible blood flow sounds are correlated with the bladder pressures at which they occur to obtain an indication of the patient's systolic and diastolic arterial blood pressure. Pressure cuffs in the prior art commonly comprise a relatively wide strap of a flexible fabric or the like having a length sufficient to be wrapped approximately one and one-half to two times about a • patient's limb of average size. The strap thus has a length sufficient to overlap itself at least partially when wrapped about the patient's limb. Fastening members, such as -Velcro-type fastening strips are provided for locking the overlapped strap portions with respect to each other to secure the strap snugly about the patient's limb. Importantly, the fastening members must secure the strap relatively tightly about the limb such that inflation of the bladder results in £UREA OMPI sufficient application of pressure to the limb to stop arterial blood flow, and with a fastening force sufficient to withstand the pressure ap- plied to the limb. To this end, in an effort to secure the strap more tightly about a patient's limb, some pressure cuffs have been proposed where¬ in the outer overlapping portion of the strap is looped through a bracket on an inner strap portion and pulled tightly against the bracket in a re- verse direction overlapping the inner strap portion for locking engagement of fastening members. For an example of this type of pressure cuff, see U.S. Patent 4,106,499. Significant problems arise, however, when the patient*s limb exhibits a pronounced tapered contour, such as the upper arm of a par¬ ticularly muscular patient. More specifically, when the pressure cuff is wrapped about a tapered limb of a patient, the inner portion of the strap must assume a generally conical contour in order to fit tightly about the limb for proper operation in detecting arterial blood pressure. However, when the inner strap portion assumes this conical shape, the outer overlapping strap portion is necessarily misaligned angularly with respect to the inner strap portion, with the degree of mis¬ alignment being directly related to the magnitude of tapered contour of the limb. This misalign¬ ment between the strap portions results in a corre- - sponding misalignment of the fastening members to affect adversely the ability to secure the cuff tightly about the patient's limb, which can result in the application of nonuniform circumferential pressure to the limb when the bladder is inflated wherein blood pressure readings may be distorted. Moreover, when the fastening members comprise Velcro-type fastening strips, the overlapping sur¬ face areas of the fastening strips can be reduced significantly to reduce the locking force the strips. With some patients, the locking force provided by the fastening strips is sufficient to withstand the pressure application to the limb when the bladder is inflated, whereby the fasten- ing strips separate and the cuff falls from the patient's limb. The present invention overcomes the prob¬ lems and disadvantages of the prior art by providing an improved pressure cuff adapted to fit snugly about a patient's limb with an outer overlapping strap portion in locking engagement with an inner strap portion by use of Velcro-type fastening strips or the like, wherein the outer strap por¬ tion can be wrapped about the inner portion in sub- stantial overlapping alignment therewith, regard¬ less of the particular tapered contour of the patient's limb. SUMMARY OF THE INVENTION In accordance with the invention, an improved pressure cuff is provided particularly for use in a sphygmomanometer for obtaining measurements of arterial blood pressure in a patient. The pres¬ sure cuff comprises an elongated flexible strap designed to wrap snugly about the limb of a patient according to the circumferential " size and tapered contour of the limb. An outer portion of the strap is received through a slotted hanger bracket mounted pivotally on an inner portion of the strap to form a limb-receiving loop which is adjustably cinched to fit tightly about the limb by pulling the outer strap portion against the bracket, whereupon the outer strap portion is wrapped in overlapping re¬ lation with the inner strap portion and secured thereto by interengaging fastening members, such as Velcro-type fastening strips. The pivoting nature of the hanger bracket permits the outer strap por¬ tion to overlap the inner strap portion in substan- - • tial alignment therewith, regardless of the par¬ ticular tapered contour of the limb. BϋR t AcT O PI BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In such drawings: FIGURE 1 is a fragmented perspective view illustrating a prior art pressure cuff and the disadvantages arising by use thereof; FIGURE 2 is a fragmented perspective view illustrating use of a pressure cuff of the present invention wrapped snugly about the arm of a patient; FIGURE 3 is an enlarged perspective view illustrating the pressure cuff in a generally tapered or truncated conical configuration for accommodating a patient's limb having a tapered contour; FIGURE 4 is an elevation view showing an outside face of the pressure cuff; FIGURE 5 is an elevation view showing an inside face of the pressure cuff; FIGURE 6 is an enlarged exploded per¬ spective view illustrating construction details of the slotted hanger bracket; FIGURE 7 is an enlarged fragmented ele¬ vation view showing a portion of the inside face of the pressure cuff, with portions broken away to illustrate mounting of the hanger bracket at one end of the cuff; FIGURE 8 is an enlarged end elevation view of a retainer clip for use with the hanger bracket, as viewed generally on the line 7-7 of FIG. 6; and FIGURE 9 is a bottom plan view of the retainer clip. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A pressure cuff of this invention, de¬ signated generally by the re erence numeral 10 in the accompanying drawings, is provided for fitting snugly about a limb 12 of a patient 14 in adjustable accommodation with the circumferential size and tapered contour of the patient's limb. The pressure cuff 10 is particularly useful in a sphygmomanometer for controlling arterial blood flow wherein alter¬ ations in arterial blood flow are sensed to provide an indication of systolic and diastolic arterial blood pressure in a patient. Accordingly, while the pressure cuff 10 of this invention is illustrated for use in a sphygmomanometer environment, other uses of the cuff are possible, such as, for example, a tourniquet for applying uniform circumferential pressure to the limb of a patient. The pressure cuff 10, illustrated in an operative position about the limb 12 of a patient 14 in FIGURE 2 comprises a substantial improvement over pressure cuffs of the general type found throughout the prior art. More particularly, with reference to FIG. 1, a typical prior art pressure cuff 16 is illustrated in the form of an elongated flexible strap 18 which is wrapped about the limb 20 of a patient 22, such as the biceps muscle region of the upper arm. The strap 18 has a length sufficient for wrapping about the limb 20 more than one revolution, whereby an outer end portion 24 of the strap overlaps an inner portion of the strap. In some pressure cuffs, such as the type shown in U.S. Patent 4,106,499, the outer end portion is pulled through a buckle on the inner portion and wrapped in a reverse direction overlapping the inner portion. In any event, this overlapping outer end portion 24 is secured to the inner portion, conventionally by use of interengaging Velcro-type fastening strips 26 and 28 carried by the strap portions, to retain the strap relatively tightly about the patient's limb. However, when the pa- tient's limb 20 exhibits a pronounced tapered con¬ tour as viewed in FIG. 1, the inner portion of the strap must assume generally the same tapered contour to fit tightly about the limb. The outer overlapping strap portion 24 is thereby angularly misaligned with the inner portion to result in par- tial engagement or nonengagement of the fastening strips 26 and 28. When the pressure cuff 16 is in. place about the patient's limb 20, an inflatable bladder (not shown in FIG. 1) is inflated by passage of air through an air tube 30 to apply pressure to the limb for causing cessation of arterial blood flow. How¬ ever, the misaligned partial engagement between the fastening strips 26 and 28 can result in ήonuniform circumferential pressure applied to the limb where¬ by the blood pressure reading obtained may be dis¬ torted. Moreover, the misalignment substantially reduces the locking force between the fastening strips, possibly resulting in a disengagement of the fastening strips when the bladder is inflated. The pressure cuff 10 of this invention is adapted to accommodate the specific tapered contour of a patient's limb without any significant reduc- tion in the locking forces provided by interacting fastening members. This feature is achieved by use of a flexible strap having a pivoting bracket which permits an outer, overlapping portion of the strap to be angularly aligned with an inner strap for substantial alignment between fastening members carried thereby, regardless of the particular tapered contour of the patien 's limb. The pressure cuff 10 of this invention is shown in detail in FIGS. 2-9 and comprises an elon- gated strap 32 formed from a flexible material, such as a woven fabric or the like.- The strap 32 has a relatively broad width, such as on the order of about five inches, for engagement with a substantial sur¬ face area of a patient's limb 12, such as the biceps muscle region of the upper arm, as viewed in FIG. 2. In addition, the strap 32 has a substantial length sufficient for wrapping circumferentially about an average-sized limb of a patient from about one and one-half to about two times. For example, a typical length for the strap when used to wrap about the upper arm of a patient is on the order of about 60 cm'. The flexible strap 32 is composed gen- erally of an inner portion 34 for wrapping about the patient's limb 12 and an outer portion 36 which is wrapped about the inner portion in an overlapping or superimposed relationship for lock¬ ing engagement with the inner strap portion. As viewed best in FIG. 5, the inner portion 34 of the strap supports an inflatable bladder 38 having a generally rectangular shape with a width generally corresponding with the width of the strap, and a length sufficient to wrap circumferentially about at least a substantial part of the patient's limb 12. The bladder 58 is secured to an inside face 40 of the strap 32 by appropriate fastening means, such as a suitable adhesive, for bearing engagement with the patient's limb when the strap is wrapped thereabout. The inner portion 34 of the flexible strap 32 further supports a microphone 42 against the bladder 38, such as by use of an appropriate adhesive tape 44. The microphone 42 is of a conventional construction for use in sphygmomanometers for detec¬ ting variations in arterial blood flow and for supplying an output via a conductor 46 to appropriate audio or electronic devices for use in obtaining a readout of the patient's arterial blood pressure. Accordingly, the particular construction and oper¬ ation of the microphone 42 is not shown or described in detail herein. The flexible strap 32 is wrapped about the patient's limb 12 by positioning the inner portion 34 of the strap against the limb with the bladder 38 in bearing engagement with the limb and the micro¬ phone in close proximity with a major artery. The outer portion 36 of the strap 32 has its free end 48 threaded through a slotted hanger bracket 50 mounted generally at the free end 52 of the inner strap - • portion 34 to define a closed loop wrapped about the limb 12. This slotted hanger bracket includes a transversely elongated slot 54 sized for smooth sliding reception of the outer strap portion 36. Conveniently, the free end 48 of the outer strap portion 36 tapers to a point 56 to facilitate threading thereof through the bracket slot 54. The thus-formed closed loop is drawn tightly about the patient's limb 12 by pulling the outer strap portion 36 through the slotted hanger bracket 50 to reduce the size of the loop. The amount of the outer strap portion 36 which can be drawn through the bracket 50 depends, of course, upon the circumferential size of the limb. When the loop is tightened sufficiently, the length of the outer strap portion 36 which has been drawn through the bracket 50 is wrapped in a reverse circumferential direction, as viewed best in FIG. 3, to overlap at least part of the underlying loop or inner strap portion 34. This reverse wrapping of the outer strap portion 36 brings a substantial surface area of an enlarged,- rectangular fastening strip 58, such as a loosely woven pad of cottom fibers sewn onto the outer face 60 of the strap, into overlapping and interlocking engagement with a rectangular fastening strip 62, such as a pad sewn, onto the outer face 60 of the strap and including a plurality of outwardly extending plastic hooks. The two fastening strips 58 and 62 thus comprise, in the preferred embodiment shown, so-called Velcro-type fastening strips, although other types of fastening members can be used, if desired. According to an important aspect of the invention, the slotted hanger bracket 50 is mounted for pivoting movement with respect to the free end 52 of the inner strap portion 34 to permit the outer strap portion 36 to be wrapped in sub- stantial alignment with the underlying inner strap 34, regardless of the tapered contour of the limb, to permit substantial locking surface area inter- engagement between the fastening strips 58 and 62. More specifically, when the patient's limb 12 has a significantly tapered contour, such as that shown in FIG. 2, the strap 32 must assume a tapered or truncated conical configuration for fitting snugly about the tapered limb. This conical strap con- figuration is illustrated in FIGS. 2 and 3. Impor¬ tantly, when this occurs, the hanger bracket 50 pivots to an angular position with respect to the adjacent free end 52, as viewed in FIG. 3, to per- mit the outer strap portion 36 to be wrapped about the loop-shaped conical inner strap portion in substantial angular alignment therewith to obtain broad contact area between the fastening straps. With this construction, the specific problems of insufficient forces locking the strap about the patient's limb, as described hereinabove with respect to the prior art cuff shown in FIG. 1, are avoided. One arrangement for pivotal mounting of the slotted hanger bracket 50 is shown in detail in FIGS. 5-9. As illustrated, the bracket 50 com¬ prises a relatively rigid mounting base 64 having a relatively ■ thin rectangular configuration and formed from a suitable plastic material or the like. The mounting base 64 is positioned to ex- tend transversely within a transverse pocket 66 located near the free end 52 of the inner strap portion 34. This pocket 66 is conveniently formed by folding over a relatively short flap 68 from the free end 52 to provide a portion of the strap hav- ing a double layer thickness, as viewed in detail in FIG. 7, and by sewing the two layers together with a pair of spaced parallel seams 70. The mounting base 64 is retained within the pocket 66 by securing the base to the inflat- able bladder 38. . In this regard, one end of the mounting base is formed integrally with an adapter fitting 72 which includes a first nipple 74 for fitting snugly into an adjacent corner of the bladder and a second nipple 76 for receiving the end of an air tube 78 through which air is sup¬ plied under pressure to inflate the bladder. Conveniently, the short flap 68 is cut back a short distance, as depicted by arrow 79 in FIG. 7, to accommodate the adapter fitting 72. In addition, the air tube 78 may be designed for connection to the microphone conductor 46 to in turn couple the conductor to appropriate audio or signal display apparatus, all in a well—known manner. A mounting post 80 is also formed in¬ tegrally with the mounting base 64 to extend from the base in an outboard direction through the ad¬ jacent inner strap portion 34. The mounting post 80 is oriented generally along a longitudinal centerline 82 (FIG. 4) of the strap and is received through a atingly-sized hole 84 in a relatively thin, generally rectangular-shaped buckle member 86. A spring clip 88 having a generally horseshoe-shaped lower flange 90 is seated within an annular groove 92 at the distal end of the mounting post to pre¬ vent undesired removal of the buckle member 86 therefrom. This spring clip 88, viewed in FIGS. 8 and 9, includes an upper closed cap 94 which cooper- ates with the lower flange 90 to define an open chamber 96 for receiving the upper end of the mount¬ ing post f with a tab 98 projecting outwardly from the clip to facilitate manual grasping thereof. The buckle member 86 includes the elon- gated transverse slot 54 for threaded reception of. the outer strap portion 36. According to the in¬ vention, the buckle member 86 is pivotally movable about the axis of the mounting post 80, as illus¬ trated by the arrows 81 in FIGS. 4 and 6, in a plane closely adjacent to and generally parallel with the mounting base 64, and thus also generally in parallel with the plane of the strap. The buckle member 86 is thereby movable with respect to the strap to permit the outer strap portion 36 to be wrapped back about the inner strap portion in substantial alignment therewith. The buckle member 86 thereby makes possible broad surface area locking interengagement between the fastening strips 58 and 62, regardless of the tapered con¬ tour of the patient's limb. When the pressure cuff is snugly mounted about the patient's limb, the bladder is inflated by use of an air pump (not shown) to supply air under pressure through the air tube 78 and the adapter fitting 72 into the bladder. The extent of bladder inflation is chosen to apply sufficient pressure to the limb to- cause a cessation of arter¬ ial blood flow, as can be detected by use of the microphone 42. Importantly, the pressure cuff 10 ~ distributes this bladder pressure substantially uniformly about the circumference of the limb, with the surface interengagement between the fastening strips 58 and 60 being sufficient to withstand the bladder pressure reacting against the strap. By slowly releasing the bladder pressure in a con¬ ventional manner, arterial blood flow resumes and is audibly detected by the microphone and corre¬ lated with bladder pressure to provide an indication of systolic and diastolic arterial blood pressure. Various modifications and improvements to the improved pressure cuff of this invention are believed to be apparent to those skilled in the art. Accordingly, no limitation upon the invention is in- tended, except by way of the appended claims.

Claims: CIAIMS 1. A pressure cuff for fitting snugly about the limb of a patient, comprising: an elongated flexible strap having an inner portion for wrapping at least substantially about the patient's limb and an outer portion having a length sufficient to at least partially overlap said inner portion when the strap is wrapped about the patient*s limb; a pivoting hanger bracket mounted on said inner strap portion, said bracket being adapted to receive the free end of said outer strap portion to define a closed loop for receiving ^ the patient's.limb, said bracket being pivotally movable with respect to said inner strap portion to permit the outer strap portion received there¬ by to be overlappingly folded back upon at least part of said inner strap portion and in substantial alignment therewith, regardless of the tapered contour of the patien 's limb; and fastening members carried respectively by said inner and outer strap portions for substantially aligned locking interengagement when said outer strap portion is folded back upon said inner strap portion. 2. The pressure cuff of Claim 1 wherein said hanger bracket has a slot therein for relatively f-ree sliding reception of said free end of said outer strap portion. 3. The pressure cuff of Claim 1 wherein said hanger bracket is mounted for pivoting movement within a plane generally parallel with the plane of said inner strap portion. 4. The pressure cuff of Claims 2 or 3 wherein - said strap has a substantial width, and wherein said slot in said hanger bracket is transversely elongated -for sliding reception of said outer strap portion. 5. The pressure cuff of Claims 2 or 3 wherein said hanger bracket comprises a mounting base secured against rotation with respect to said inner strap portion , a mounting post projecting from said mounting base OMP generally in an outboard direction with respect to the patient's limb, a buckle member having said slot formed therein and carried on said mounting post for pivoting movement with respect thereto, and means for retaining said buckle member on said mounting post. 6. The pressure cuff of Claim 5 wherein said inner strap portion supports a bladder inflatable when said strap is snugly fitted about the patien 's limb to apply pressure to the limb for causing a cessation of arterial blood flow. 7. The pressure cuff of Claim 6 wherein said inner strap portion further supports a microphone for detecting variations in arterial blood flow. 8. The pressure cuff of Claims 1, 2 or 3 wherein said bracket is pivotally movable about an axis positioned generally at a longitudinal centerline of said strap. 9. The pressure cuff of Claims 1, 2 or 3 wherein said fastening members comprise an interlocking pair of hook and pile type fastening strips. 10. The pressure cuff of Claims 1, 2 or 3 wherein said hanger bracket is mounted on said inner strap portion generally at the free end thereof. - URE LT OMPI

Inventors: GEORGI HEINZ W, GEORGI, HEINZ, W.
Applicants: IVAC CORP, IVAC CORPORATION
Application year: 1982
Main classification: A61B5
IPC codes: A61B5