The protective role of local hypothermia in tourniquet-induced ischaemia of muscle.

The protective effect of local hypothermia was studied in pig's limbs made ischaemic by long, repeated application of a pneumatic tourniquet. Twenty-one Landrace pigs were anaesthetised on two separate occasions six days apart and a pneumatic tourniquet at 500 mmHg pressure was applied to the same forelimb for three and two hours respectively. Ten of the pigs had local hypothermia from cold gel packs placed around the limb during the first tourniquet application; the other 11 had the ischaemic limb exposed to room temperature. In comparison with the normothermic limbs, the hypothermic ischaemic limbs had significant slowing of metabolism. The hypothermic limbs also showed less inflammatory response and a faster rate of recovery, both immediately after removal of the tourniquet, and by the end of the experiment, 10 days after the first tourniquet. Local hypothermia produced by this technique was shown to be safe and effective, while appearing to protect muscles exposed to prolonged tourniquet-induced ischaemia.