tourniquet test

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a device for compression of an artery or vein; uses include stopping of the excessive bleeding of a hemorrhage, maintenance of a nearly bloodless operative field, prevention of spread of snake venom after a snakebite, and aiding in obtaining blood samples or giving intravenous injections.

For hemorrhage, a tourniquet should be used only as a last resort, when the bleeding is so severe that it is threatening the life of the injured person and cannot be stopped by direct pressure. In the case of snakebite, a moderately tight tourniquet may be applied to impede the spread of venom while not stopping arterial blood flow. For an intravenous injection, a loosely applied tourniquet inhibits blood flow in the superficial veins, making them more prominent so that a vein can be found for the injection. For maintenance of a nearly bloodless operative field, pneumatic tourniquets are often used. The American Association of Operating Room Nurses (AORN) has published guidelines for the use of tourniquets during surgery; see their web site at
To apply a tourniquet for control of arterial bleeding from the arm: Wrap a gauze pad twice with a strip of cloth just below the armpit and tie with a half knot; tie a stick at the knot with a square knot. Slowly twist stick to tighten.
tourniquet test one involving the application of a tourniquet to a limb, as in determination of capillary fragility (denoted by the appearance of petechiae) or of the status of the collateral circulation.

cap·il·lar·y fra·gil·i·ty test

a tourniquet test used to determine the presence of vitamin C deficiency or thrombocytopenia; a circle 2.5 cm in diameter, the upper edge of which is 4 cm below the crease of the elbow, is drawn on the inner aspect of the forearm, pressure midway between the systolic and diastolic blood pressure is applied above the elbow for 15 minutes, and a count of petechiae within the circle is made: 10, normal; 10-20, marginal; more than 20, abnormal.

tourniquet test

a test of capillary fragility, caused by an abnormality in the capillary wall or thrombocytopenia, in which a blood pressure cuff is applied for 5 minutes to a person's arm and inflated to a pressure halfway between the diastolic and systolic blood pressure. The number of petechiae within a circumscribed area of the skin may be counted, or the results may be reported in a range from negative (no petechiae) to +4 positive (confluent petechiae).

tourniquet test

A test used to determine pain thresholds or, alternately, capillary fragility. A blood pressure cuff is inflated sufficiently to occlude venous return. It is kept in place for a set time. The anesthetic effect, or the impact on skin integrity, is subsequently assessed.