Randomized blinded control trial into tourniquet tolerance in awake volunteers

The ability to tolerate a tourniquet is often the limiting factor to elective and emergent procedures of the upper limb performed under local anaesthesia. This study aims to demonstrate that upper limb tourniquets are more predictably and better tolerated when inflated to 200 mmHg than to the traditional inflation pressure of 250 mmHg in awake, unsedated subjects.

Forty healthy volunteers were randomized to have a tourniquet applied at either 200 or 250 mmHg for 20 min. Vital signs and pain scores were measured pre-test, at intervals throughout the time the tourniquet was inflated and post-deflation until the parameters normalized. Grip strength was measured pre-test, immediately post-deflation of the tourniquet and every 2 min until return of normal strength.

All subjects were able to tolerate a tourniquet inflated for the allocated 20 min irrespective of the inflation pressure; however, there was a statistically significant lower average pain score in the group where the tourniquet was inflated to 200 mmHg compared with 250 mmHg. There was a quicker return of normal grip strength, although this was not shown to be statistically significant.

Tourniquets inflated to 200 mmHg are better tolerated in awake, unsedated subjects that would allow predictably short procedures of the hand, wrist and forearm to be performed under local anaesthesia. It represents a pilot study prior to a further clinical study investigating the efficacy of tourniquets inflated to a lower pressure in maintaining an effective bloodless field.