[Experimental and clinical study of safe prolongation of tourniquet time by hypothermia of an upper limb (author's transl)].

In order to establish a practical method by which the tourniquet can be safely kept on for more than 2 hours, i.e., the safe limit in the conventional method, the author initially made an experimental and then a clinical investigation as follows.

METHODS

Thirty-five adult mongrel dogs were used including a control group. One hour immersion of hind limb in ice water lowers the temperature of leg muscles from ca. 38 degrees C to 16 degrees--18 decrees C. Thereafter, maintenance of tourniquet exsanguination of the cooled hind limb for 5 hours elevates the muscle temperature several degrees, but still keeps it much lower than in the control group. Edema and limping appeared after release of the tourniquet and subsided much faster in the cooled group than in the control group. Result in 12 CASES: Cooling of an upper limb after general anesthesia or nerve block with ice bags for 30 minutes lowers the temperature of the forearm muscles from 30 degrees--35 degrees C to 16 degrees--25 degrees C. Tourniquet applied thereafter at the upper arm was kept inflated maximally for four hours and 7 minutes. An average of 3 hours and 30 minutes did not cause any serious side effects but only temporary dysesthesia at the finger tips in 2 cases and a Tinel's sign at the site where tourniquet was applied in one case.

CONCLUSIONS

These results proved that tourniquet time could be safely prolonged for 4 hours. The most important problem in the future is to clarify how far it can be safely prolonged.