Double tourniquet with linked mercury manometers for hand surgery.

Double tourniquets linked to separate Freon cannisters and two mercury manometers have been effective in maintaining ischemia in over 1,000 consecutive hand surgery operations. The mercury manometers permit constant accurate monitoring of the tourniquet pressure. The cuffs are used alternately. Each is inflated for up to 1 hour in order to limit the duration of nerve compression deep to the cuff. If there is malfunction of either cuff, the other cuff may be inflated at once. This system has permitted sustained ischemia in the upper extremity for up to 3 1/2 hours at a constant tourniquet pressure with no permanent clinically apparent sequellae. There has been no permanent nerve injury, although patients with more than 2 hours of tourniquet time often note hypoesthesia or paresthesia for 1 or 2 days. The alternating double tourniquet linked to a mercury manometer permits up to 3 1/2 hours of continuous ischemia of the upper limb with little risk of nerve damage.