GB2048683A - Tourniquet for venepuncture - Google Patents

Abstract

A venepuncture tourniquet comprising an elongated flat band 13 having a connector 15 at one end and spaced graduated shoulders 25 along one surface thereof. The connector 15 has a portion 19 which extends transversely of the band 13 and is selectively engageable with the shoulders 25, and has a finger-engageable portion 21 which ensures easy engagement and disengagement of the transverse connector portion 19 and shoulders 25. The tourniquet can be wrapped around a limb 27. <IMAGE>

Description

SPECIFICATION Torniquet for venepuncture In the art of venepuncture, a needle or a special cannula is inserted into a vein and is used to withdraw blood, to administer medication, insert probes, orto monitor functions such as blood pressure. In order to make the venepuncture process as easy and painless as possible, the one who inserts the needle or cannula, sometimes called a phlebotomist, first distends the vein by applying a tourniquet to constrict the limb at a position between the puncture target site and the heart. This restricts flow of blood in the vein and distends it making the venepuncture target larger.

ideally, it is desirable that the constricting pressure applied to the limb when using a tourniquet be predictable in order that the target vein will be properly distended but that an adjacent artery is not constricted or obstructed. A normal adult has a systolic pressure of about 120mm Hg and a diastolic pressure of about 70mm Hg, the difference in these pressures normally being referred to as the pulse pressure. Venous pressure is significantly less than 30-40mm Hg. Therefore, an ideal constricting pressure by a venepuncture tourniquet is about 40mm Hg.

With the present tourniquets available, it is difficult to repetitively achieve an accurate constricting pressure, and those which are capable of some repetitive accuracy are often difficult and cumbersome to apply and remove and sometimes result in patient discomfort.

Currently used tourniquets include a simple stretchable piece of rubber tubing or rubber strap which is wrapped around the limb and haphazardly fixed in place by tying a knot. Other tourniquets sometimes used include blood pressure cuffs which are secured in place around the limb and then inflated using air pressure. Still further, other more sophisticated tourniquets include bands having adjustable fastener means such as "Velcro" fasteners, or headed pins and complementary apertures on opposite ends thereof.

With the knotted tubing, blood pressure cuffs, and tourniquets using "Velcro" fasteners, the limb is often overconstricted which is uncomfortable and possibly even dangerous to the patient. With the positive-type fastener means currently available, e.g.

those using headed pins and apertures to secure the tourniquet in place, the tourniquet is difficult to secure on the limb and to remove from it, and often causes the patient's skin to be pinched.

The present invention overcomes the aforementioned drawbacks and disadvantages. In this invention, there is provided a venepuncture tourniquet which translates the optimum constricting pressure into a relationship of the relaxed circumference of a limb and its corresponding cross-sectional area when relaxed, and the percentage of reduction in circumference and cross-sectional area when proper constriction is achieved.

In addition, the venepuncture tourniquet of this invention is one which is simply and easily attached in place around a patient's limb and produces repetitive and predictable constricting pressures, and which facilitates quick, easy and one-hand removal from the limb with little or no resulting discomfort to the patient, and even may be removed by the patient himself.

Further, and importantly, the venepuncture tourniquet of this invention achieves uniform constricting pressures on limbs of different circumferences and cross sections.

Accordingly, it is the primary object of this invention to provide a new and improved venepuncture tourniquet which facilitates repetitive and predictable constricting pressures on human limbs of different sizes.

It is a further important object of this invention to provide a venepuncture tourniquet which is capable of being secured in place around and removed from a limb by a simple operation and which minimizes or eliminates the likelihood of discomfort to the patient.

It is a still further object of this invention to provide a venepuncture tourniquet which is relatively inexpensive, rugged in construction, and reliable in use.

Additional objects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.# The objects and advantages of the invention may be realized and attained by means of the instrumen taiities and combinations particularly pointed out in the appended claims.

To achieve the foregoing objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the tourniquet of this invention comprises an elongated flat strap, connector means at one end of the strap and having a transverse connector portion extending transversely of the strap, graduated means including a plurality of spaced lugs formed on one surface of the strap and along a major portion of its length, each of the lugs defining a shoulder extending transversely of the strap, adjacent ones of the lug shoulders being spaced apart varying distances from each other along the strap with the adjacent lug shoulders nearest the connector means being the closest to each other and adjacent lug shoulders becoming gradually further apart in a direction away from the connector means, the transverse connector portion being selectively engageable with the lug shoulders when the strap is wrapped around a human limb, the connector means including finger engageable means operable in use to facilitate engagement and disengagement of the transverse connector portion with the lug shoulders, whereby the tourniquet can be positioned around a human limb and then pulled tightly about the limb by holding the end of the strap opposite the one end and pulling on the finger engageable portion of the connector to position the transverse connector portion behind and in engagement with the desired lug shoulder, the tourniquet being removable from the limb by pulling laterally on the finger engageable portion to release the transverse connector portion from the lug shoulder.

Preferably, the lugs and shoulders extend the full width of the strap, and the tourniquet strap material is selected, as are the distances adjacent lug shoulders are spaced apart, such that when the strap is snugly wrapped around a limb and the transverse connector portion aligned with any one of the lug shoulders, the strap circumference is reduced sub stantiallythe same percentage when the transverse connector portion is moved to align with the next adjacent lug shoulder for limbs of different cross section. This provides that the same constricting pressure can be achieved repetitively on limbs of different circumference and cross section.

The strap can be constructed of elastomeric material which facilitates spacing of the strap from the limb at the area of the connector means and lug shoulder when connection between the connector means and lug is made. This helps prevent accidental pinching during application.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a plan view showing a preferred form of venepuncture tourniquet constructed in accordance with the teachings of this invention; FIG. 2 is a side elevational view of the construction of FIG. 1; FIG. 3 is a view of the preferred form of tourniquet of this invention and shown in position on a limb with the connector means engaged with a shoulder on one of the lugs; FIG. 4 is a view similar to FIG. 3 and showing the connector means released from the lug shoulder; FIG. 5 is an enlarged view of a portion of a tourniquet according to the invention showing a modified form of connector means; and FIG. 6 is a side elevational view of FIG. 5.

Referring now to FIGS. 1 and 2, a preferred form of the tourniquet ofthis invention is illustrated generally at 11 and is seen to include an elongated flat strap 13. Although not critical, the strap 13 is constructed of a pliable material, preferably an elastomeric material, i.e., one which stretches and can return to its original length. Suitable elastomeric materials for use in this invention are well-known to those skilled in the art.

In accordance with the invention, connector means is provided at one end of the strap and has a transverse connector portion which extends transversely of the strap. As embodied herein, the connector means includes a wire form 15 having a base leg 17 extending through a transverse opening in one end of the strap 13. The connector 15 has a return bent, transverse connector portion 19 which extends transversely of the strap 13 and is bent to form a loop 21 sized to receive a human index finger.

Preferably, as shown in FIGS. 1 and 2, the wire form connector 15 lies in a single plane.

In accordance with the invention, graduated means is formed on the tourniquet strap which is selectively engageable with the connector means to releasably hold the tourniquet in place around a human limb. As embodied herein, the graduated means includes a plurality of outwardly projecting, spaced lugs 23 formed on one surface of the strap 13 and along a major portion of its length. The lugs 23 extend the full width of the strap and each defines a shoulder 25 which is generally perpendicular to the length of the strap 13.

In accordance with the invention, the adjacent ones of the shoulders are spaced apart varying distances from each other with the shoulders adjacent the connector means being the closest to each other and adjacent lug shoulders becoming gradually further apart in a direction away from the connector means. As embodied herein, each set of adjacent shoulders 25 are spaced apart a distance which is related to their position along the strap 13 so that when the effective circumference of the tourniquet, i.e. the length of the tourniquet from the transverse connector portion 19 to one of the shoulders 25 is reduced by an amount equal to the distance to the next adjacent shoulder, the percentage reduction in the effective tourniquet circumference is always the same.

It has been discovered that by reducing the size of a tourniquet by a predetermined percentage when it is applied to a limb, an accurate and repetitive constricting pressure can be obtained. Specifically, the elasticity of the material used in the strap, the strap length, and the distance adjacent lug shoulders 25 are spaced apart, are selected such that when the tourniquet is wrapped snugly around a limb and the transverse connector portion 19 aligned with a lug shoulder 25, and then the tourniquet strap 13 pulled tightly, or in the case where it is elastomeric, stretched to align and engage the transverse connector portion 19 with the next adjacent lug shoulder 25, the tourniquet applies the desired constricting pressure to the limb.This makes use of the tourniquet of this invention virtually foolproof in achieving proper constricting pressure, and renders it unlikely that the tourniquet will be applied to develop excessive constricting pressure.

In use of the tourniquet, the strap 13 is wrapped snugly around a limb 27 (Fig 3) atthe desired location, i.e. between the venepuncture target and the heart, and the lug shoulder 25 with which the transverse connector portion 19 aligns is noted. The strap 13 is then pulled tightly or stretched by grasping the loop 21 with the index finger of one hand and the other end of the strap 13 with the other hand and the transverse connector portion 19 positioned behind and engaged with the next lug shoulder 25.

The loop 21 facilitates easy manipulation of the transverse connector portion 19 into engagement behind the appropriate lug shoulder 25. A strap 13 of elastomeric material is desirable because it can be pulled away from the patient's limb when engaging the transverse connector portion 19 and lug shoul dex 25.

It may be desirable, especially if very accurate constricting pressure is desired, to provide the lug shoulders 25 close together. This also has the advantage that it is more likely that the transverse connector portion 19 will align more accurately with one of the shoulders 25 when the strap 13 is snugly wrapped about the limb. In that case, it may be necessary to stretch the tourniquet a distance equal to the space between two or even more lug shoulders 25 to produce the desired constricting force on the limb. In such case, the instructions for using the tourniquet will be appropriately worded.

When it is desired to remove the tourniquet from the limb, the user need only grasp the loop 21 of the connector 15 with his index finger and pull it laterally of the strap 13. This releases the transverse connector portion 19 from the shoulder 25 and allows the tourniquet strap 13 to fall freely away from the limb without imposing additional stretch to the strap 13. Further, the connection between the transverse connector portion 19 and the shoulder 25 is positive and secure, but the tourniquet is released with only a relatively light lateral force on the connector 15 and does not result in any additional constricting force on the limb or frictional force on the skin, or any possibility that the patient's skin will be pinched.

Thus, the tourniquet can be quickly and easily removed from the limb with virtually no possibility of discomfort to the patient.

The modified form of the invention shown in FIGS.

5 and 6 is substantially the same as that illustrated and described above for FIGS. 1-4 with the exception that the wire form connector 15' has a finger loop 21' disposed in a plane which intersects the plane which includes the transverse connector portion 19 and the base leg 17. In some uses, it may be desirable to have the finger loop 21' so arranged for easier application and removal of the tourniquet. In all other respects, the embodiment of FIGS. 5 and 6 is the same as that of FIGS. 1-4, and like numerals represent similar parts in all the figures.

This invention provides a simple and inexpensive tourniquet which is capable of use in providing accurate and repetitive constricting pressures on a limb.

The tourniquet of this invention has a minimum of parts and is reliable, and safe in use. While preferred embodiments have an illustrated end described above, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention.

Claims (7)

1. A venepuncture tourniquet comprising an elongated flat strap, connector means at one end of said strap and having a transverse connector portion extending transversely of the strap, graduated means including a plurality of spaced lugs formed on one surface of said strap and along a major portion of its length, each of said lugs defining a shoulder extending transversely of said strap, adjacent ones of said lug shoulders being spaced apart varying distances from each other along the strap with the adjacent lug shoulders nearest said connector means being the closest to each other and adjacent lug shoulders becoming gradually further apart in a direction away from said connector means, said transverse connector portion being selectively engageable with said lug shoulders when said strap is wrapped around a human limb, said connector means including finger engageable means operable to facilitate engagement and disengagement of said transverse connector portion with said lug shoulders, whereby said tourniquet can be positioned around a human limb and then pulled tightly about the limb by holding the end of said strap opposite said one end and pulling on said finger-engageable portion of said connector to position said transverse connector portion behind and in engagement with the desired lug shoulder, said tourniquet being removable from the limb by pulling laterally on said finger-engageable portion to release said transverse connector portion from said lug shoulder.

2. Atourniquet as claimed in claim 1, said strap being constructed of an elastomeric material.

3. A tourniquet as claimed in claim 1, said strap being constructed of a material, and adjacent lug shoulders being spaced apart preselected distances such that, for limbs of different cross sections, when said strap is snugly wrapped around a limb and said transverse connector portion aligned with one of said lug shoulders and then is moved to align with the next adjacent lug shoulder, the circumference of said strap is reduced substantially the same percentage.

4. A tourniquet as claimed in claim 1, said connector means including a wire form having a closed loop forming said finger engageable means.

5. A tourniquet as claimed in claim 4, said transverse connector portion and said loop lying in a single plane.

6. A tourniquet as claimed in claim 5, said transverse connector portion and said loop lying in intersecting planes.

7. A venepuncture tourniquet substantially as hereinbefore described with reference to Figs. 1 to 4 of Figs. and 6 of the accompanying drawings.