Local hypothermia to prolong safe tourniquet time. Local hypothermia was studied as a method to safely prolong tourniquet time for reconstructive procedures of the upper extremity. An ice blanket constructed of flannel cloth and cold gel packs was applied to the limb for 45 minutes preoperatively. Seventy-eight patients were evaluated for complications resulting from hypothermia and prolonged tourniquet application. The duration of continuous tourniquet ischemia averaged two hours and 25 minutes. Intraoperative muscle temperature recordings indicated that the iced limbs were an average of 12.9 degrees cooler than noniced limbs before tourniquet inflation. Electron microscopic studies of biopsied muscle showed no evidence of ischemic changes. There were no postoperative complications associated with prolonged tourniquet inflation or the hypothermia blanket technique. Local hypothermia appears to be a safe and effective method of decreasing the adverse effects of tourniquet ischemia and allowing continuous tourniquet inflation time to extend safely beyond the customary two-hour limit. 