Tourniquet

Abstract

A tourniquet for restricting the venous flow of blood is formed by a strip of elastic material having a series of spaced apertures adapted for selective engagement with an upstanding stud for holding the tourniquet tightened around a body member. The apertures are unevenly spaced to compensate for the stretch of the strip so that substantially the same constricting pressure is applied regardless of the size of the body member.

Description

BACKGROUND OF THE INVENTION

This invention relates to constricting devices for medical usages and more particularly it has reference to a tourniquet which is wrapped and tightened around an arm or limp of a person in order to distend the veins, generally the superficial but sometimes the deeper veins. This is necessary in order to facilitate the puncture of the veins with a needle for extracting a sample of blood or effecting intravenous injection of desired material. Under prior art practices, various types of tourniquets have been used such, for example, as a piece of rubber tubing or strip which is wrapped around a body member and tied or held in place with a clamp. Such devices, however, have been unsatisfactory since they do not consistently provide the optimum pressure to produce adequate distension of the veins to permit easy and accurate insertion of a needle, especially in the hands of relatively unskilled persons. In addition, some of the prior art tourniquets are reliable and cumbersome in use and frequently cause discomfort to the patient.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a tourniquet of the type described which will, when in use, apply to the arm or limb substantially the same predetermined optimum constricting pressure regardless of the size of the arm or limb so that the veins will be adequately distended to permit accurate and easy insertion of a needle. Other objects are to provide a tourniquet which will be relatively simple in structure yet efficient in operation and constructed so that it may be quickly and easily applied to or removed from a body member.

In accordance with the invention, a tourniquet is formed of a flat strip of elastic plastic material having fastening means such as an upstanding stud secured thereto adjacent to one end thereof. The strip is provided with a plurality of spaced apertures which extend lengthwise of the strip from a point spaced from the stud and are adapted for selective engagement with the stud for holding the tourniquet in constricting relation around a body member. In order to compensate for the greater stretch of the strip when applied to body members of larger sizes, the spacings between successive apertures increase progressively beginning with the aperture nearest to the stud. Because of this arrangement of the spacings and apertures, the tourniquet will, when in use, consistently provide substantially the same predetermined optimum constricting pressure, within a small range, so that adequate distension of the veins is produced regardless of the circumference of the body member to which it is applied.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view of the tourniquet embodying the invention.

FIG. 2 is an edge view thereof.

FIG. 3 is a perspective view showing the relation of the parts when the tourniquet is in use.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the invention is shown in the drawing wherein 10 indicates a tourniquet which is formed of a flat strip of elastic material. Secured to the end portion 11 of the strip is suitable fastening means such as the upstanding metal stud 12. A plurality of spaced apertures 13 are formed in the strip in substantial alignment with the stud 12 and extending lengthwise of the strip 10 from a point spaced from the stud 12 and thence towards the end portion 14 of the strip. The apertures 13 are adapted to be selectively engaged with the stud 12 to hold the strip 10 in tightened encircling relation with a body member. The spacings between successive apertures increase progressively in length beginning with the aperture which is nearest to the stud 12, for a purpose to be described hereinafter.

In use, the tourniquet is wrapped around a body member with portions of strip 10 in side-by-side parallel relation snugly engaging the member and with an aperture substantially adjacent to the stud 12. With an end of the strip 10 held in each hand, the strip is tightened by an amount which is produced by moving the strip a distance equivalent to about 2 or 21/2 spacings, for example, and then securing the strip in tightened position by forcing the adjacent aperture down over the stud 12. The tourniquet may be quickly released by raising the strip 10 to move the engaged aperture off the stud 12.

The average arterial blood pressure for a adult varies between about 100-200 mm. of mercury whereas the average venous pressure for an adult is about 15-25 mm. of mercury. In order to produce adequate distention of the superficial veins for the easy and accurate insertion of a needle, the tourniquet should not produce a constricting pressure greater than about 90 mm. Hg. since such a greater pressure would unduly impede or stop the arterial flow of blood. The tourniquet must, however, produce a pressure which exceeds the venous pressure and also overcomes the resistance provided by tissue, such as fat, in the body member to which it is applied. The optimum pressure produced by a tourniquet for the adequate distention of the superficial veins to permit easy and accurate insertion of a needle varies from about 60-90 mm. Hg. for an adult.

For optimum results, the constricting pressure of 60-90 mm. Hg. should be provided consistently whether the tourniquet is applied to a body member having a large or small circumference. The predetermined optimum constricting pressure on a body member of any size can be obtained by tightening the strip 10 through relative movement of adjacent parts of the encircling strip 10 a distance equal to, for example, two or two and one-half spacings between successive apertures 13.

When the tourniquet is applied to and tightened on a large arm, the strip 10 will be stretched or expanded more than when applied to a smaller arm. Hence, if substantially the same constricting pressure of 60-90 mm. Hg. is to be applied to an arm regardless of its circumference, it is essential that some compensation or allowance be made for the additional stretch of the strip 10. This is accomplished by spacing the apertures 13 unevenly so that beginning with aperture A, nearest the stud 12, the spacings between successive apertures increase progressively. Since the stretch of the material in strip 10 substantially varies directly as the force applied, the optimum results are provided by making the spacings between successive apertures 13 increase by a substantially fixed increment, such, for example, as 0.015 inch in the specific embodiment of the invention hereinafter described. Spacings between apertures may be varied depending on the size and material of the strip but it is essential that there be some progressive increase in spacing lengths between at least some of the apertures with the longest spacing being near to the end portion 14 of the strip.

In one embodiment of the invention which has been made and used successfully, the tourniquet is formed of a flat extruded strip of polyurethane 80A Durometer. The strip is 24 inches long, 0.656 inches wide and 0.078 inches thick. The upstanding metal stud 12 is located about 4 inches from the strip end 11 and the apertures 13 each have a diameter of about 0.156 inches so that they may be forced into releaseable holding engagement with the head on stud 12. The row of apertures 13 extends lengthwise of and along the central portion of the strip 10 and in alignment with stud 12. The aperture indicated at A is nearest to and about 7 inches from the stud 12. The distance between the centers of A and the next aperture B is 0.530 inches; the distance between the centers of aperture B and the next aperture C is 0.545 inches; the distance between the aperture C and the next aperture D is 0.560 inches and so on with the distance between successive apertures increasing progressively by a substantially constant increment of 0.015 inches.

In order that the optimum constricting pressure of 60-90 mm. Hg. will be provided when the tourniquet of the next preceding paragraph is tightened around a body member of minimum size with the aperture A engaged over the stud 12, the elasticity of the plastic strip is modified by providing eight parallel pairs of holes 15 each having a diameter of 0.109 inches and located between the aperture A and the stud 12. Suppose, for example, that the tourniquet is wrapped around a larger body member so that the strip snugly engages the member and the aperture A is adjacent to the stud 12. Then a tightening of the tourniquet by pulling the ends of the strip so that the aperture C is engaged over the stud 12 will serve to produce the optimum constricting pressure of 60-90 mm. Hg. Because of the progressively increasing lengths of the spaces between the apertures 13, beginning with the first aperture A, a substantially constant predetermined pressure, within a range of 60-90 mm. Hg., will be provided regardless of the circumference of the body member to which the tourniquet is applied. The structural dimensions and data for the above-described tourniquet were determined experimentally and resulted in a device which has been very successful in use.

The tourniquet may be made of any suitable elastic material and the strip may be made in any suitable thickness, width and length. A plastic material such as polyurethane has proven to be highly satisfactory because of its resistance to deterioration and consequent retention of its elastic properties. Whether in the hands of skilled or unskilled technicians, the tourniquet of the invention will consistently provide a predetermined optimum constricting pressure on a body member regardless of its size. The tourniquet is wrapped snugly around a body member with the end portions of the strip in side-by-side relation and, using the stud 12 as a guide, the strip is tightened by pulling the ends of the strip to move a distance of a substantially fixed number of spaces to consistently provide the optimum constricting pressure. For the tourniquet which has been described specifically herein, the optimum pressure is provided by tightening the strip by a movement equivalent to two or two and one half spaces between apertures.

The series of apertures may be serially numbered on the strip 10 to facilitate the application of the tightening pull by moving the parts a certain fixed number of spaces such as two to two and one half in the example herein given. The number of spaces to be moved to provide a consistent predetermined optimum constricting pressure will of course, depend on the dimensions and material of the strip 10 and the spacings between the apertures. For use on a child, the tourniquet would, of course, be appropriately modified in structure. Various modifications may be made without departing from the spirit of the invention as pointed out in the appended claims.

Claims

I claim:

1. A tourniquet adapted to be placed in encircling relation on a body member for restricting the venous flow of blood comprising a strip of elastic material, fastening means carried by the strip adjacent to a first end portion thereof, said strip having a plurality of spaced apertures extending lengthwise thereof from a point spaced from the fastening means and thence towards the second end portion of the strip, said apertures being adapted for selective engagement with the fastening means for exerting on a body member a constricting pressure for restricting the venous flow of blood, the optimum constricting pressure being provided when the strip is tightened around a body member with the aperture nearest to the fastening means in engagement therewith, the remaining apertures being unevenly spaced to compensate for the stretch of the strip when it is tightened around body members of larger sizes, the spacings between successive apertures increasing in length progressively by a substantially fixed increment beginning with the spacing nearest to the fastening means whereby substantially the same optimum predetermined constricting pressure will be exerted on a body member regardless of its circumference.