BACKGROUND Why do limb tourniquets cause pain? If ischemia is the mechanism, can supplemental oxygen reduce pain? The Reducing Tourniquet Associated Pain study investigated whether this simple treatment could extend tourniquet tolerance time to facilitate hand surgery under local or regional anesthesia. METHODS The Reducing Tourniquet Associated Pain study was a double-blind, randomized, controlled trial of healthy volunteers. Participants received either 50% inhaled oxygen or air placebo via a face mask for 3 minutes before and up to 30 minutes after upper arm tourniquet inflation to 250 mmHg. Pain scores were recorded at 2-minute intervals using a validated 100-mm visual analogue scale. The primary outcomes were (1) difference in visual analogue scale score and (2) difference in time taken to reach visual analogue score of 40 mm or more in oxygen and air groups. RESULTS Fifty participants enrolled and, after exclusion criteria were applied, 46 were analyzed (oxygen, n = 23; air, n = 23). Oxygen supplementation was associated with a 29 percent mean reduction in pain on visual analogue scoring compared with air placebo over the entire period of inhalation (p = 0.027). Oxygen also extended the time to visual analogue scale score of 40 mm or more by a mean of 6½ minutes compared with air placebo (p = 0.008). CONCLUSIONS Oxygen is a readily available, low-risk, low-cost treatment that significantly reduced tourniquet-associated pain in this study and significantly increased the time taken to reach visual analogue scale score of 40 or more. The authors recommend oxygen to facilitate hand surgery under a tourniquet and when a regional block fails to control tourniquet pain.
Oxygen reduces tourniquet-associated pain: a double-blind, randomized, controlled trial for application in hand surgery.