Surgery – Instruments – External pressure applicator
Patent
1994-07-25
1996-11-26
Buiz, Michael Powell
Surgery
Instruments
External pressure applicator
606201, A61B 1700
Patent
active
055780555
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention pertains to cuffs for occluding flow in blood vessels in human limbs encircled by the cuffs. The invention particularly pertains to an overlapping occlusive cuff for improved application of pressure to a limb in order to facilitate the performance of a surgical procedure, comprising: an inflatable bladder; a sheath for containing the inflatable bladder wherein the sheath has a length sufficient to encircle the limb and overlap upon itself in a substantially circumferential direction around the limb; sheath securing means for securing the overlapped sheath around the limb; and stiffening means for superimposing over a region of the overlapped and secured sheath to constrain the shape of the sheath beneath the region when the bladder is inflated. The stiffening means may include securing means for securing the overlapping sheath in a substantially circumferential direction around the limb independently of the sheath securing means such that the sheath remains overlapped and secured in a substantially circumferential direction if the sheath securing means is not engaged or becomes ineffective while the bladder is inflated.
BACKGROUND OF THE INVENTION
The use of an inflatable cuff to occlude blood flow into a subject's limb, thereby providing a bloodless surgical field in the portion of the limb distal to the cuff over a time period suitably long for the performance of a surgical procedure, is well known in surgical practice. When employed to provide a bloodless surgical field, occlusive cuffs constitute one element of a surgical tourniquet system. Tourniquet systems typically include the following basic elements: a source of pressurized gas, an inflatable cuff for encircling a limb at a selected location, and a pressure regulating mechanism for controlling and maintaining the pressure of gas in the inflatable cuff and thus the pressure applied by the cuff to the limb which the cuff encircles. The recent advent of automatic tourniquet systems which employ digital electronic technology in the regulation of pressure and in the detection of certain hazardous conditions ions has led to significant improvements in the safety and accuracy of surgical procedures performed with an occlusive cuff applied proximally on a limb. These automatic tourniquet systems typically allow the surgeon to safely maintain a constant inflation pressure in the inflatable cuff which he or she estimates to apply pressures to the limb near the minimum required to safely occlude blood flow past the cuff. Recently, McEwen has described, in the U.S. patents and patent applications cited below, improved automatic tourniquet systems which provide for sensing and regulation of the pressures actually applied to the limb by a cuff, in contrast to merely sensing and regulation of the inflation pressure in the cuff.
However, despite improvements in electronic pressure regulation and applied pressure sensing, major limitations exist with respect to safety and efficacy of occlusive cuffs used as part of automatic tourniquet systems. These limitations in prior art occlusive cuffs have persisted despite the increasing use of such cuffs in more demanding surgical procedures, particularly those involving the use of intravenous regional anesthesia (IVRA). In surgical procedures performed under IVRA, the occlusive cuff must be effective in preventing the flow of blood into the field of surgical dissection as well as preventing the premature release of potentially toxic intravenous anesthetics from the veins of the operative limb into the general circulation.
In the design of most prior art cuffs, little attention has been paid to the actual spatial distribution of pressures applied to the limb beneath the cuffs, in both a circumferential direction around the limb, and a direction along the longitudinal axis of the limb, when the cuffs are inflated to various inflation pressures. This lack of attention has largely been due to the lack of suitable pressure transducers for measuring the applied pressures. However, in c
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Buiz Michael Powell
Dawson Glenn
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