Can Oxygen Really Reduce Tourniquet-Associated Pain in Patients Undergoing Hand Surgery?

Sir: In a double-blind, randomized, controlled trial assessing the effect of supplemental oxygen on tourniquet-associated pain, White et al.1 showed that, compared with air placebo, 50% inhaled oxygen was associated with a significant pain reduction and a significant prolongation of tourniquet tolerance time. Accordingly, they recommend oxygen to facilitate hand surgery under a tourniquet. Although many aspects of this study were well conducted, we believe that a limitation of study design restrains extrapolation of their findings to clinical practice. This study was performed on healthy volunteers without regional anesthesia and sedation management. In contrast, hand surgery with tourniquet application is commonly executed under regional anesthesia and sedation management. It has been shown that regional anesthesia can attenuate tissue metabolism changes (e.g., increases in lipid peroxidation, creatine phosphokinase, and uric acid levels) and ischemia-reperfusion injury connected with tourniquet application in extremity surgery.2,3 Also, sedation drugs used frequently in clinical practice, such as propofol, midazolam, ketamine, and dexmedetomidine, can reduce tissue markers of ischemia resulting from tourniquet use and attenuate tourniquet-associated pain on healthy volunteers and patients undergoing extremity surgery.4–8 Actually, in this study, supplemental oxygen merely provides a moderate beneficial effect on tourniquet-associated pain, namely, a 29 percent mean reduction in tourniquet-associated pain on visual analogue scale scoring and a 6.5-minute prolongation of the tourniquet tolerance time to a visual analogue scale score of 40 mm or more. Because of the above study limitation, it is unclear whether this modest favorable effect can be achieved in patients undergoing hand surgery with tourniquet application under regional anesthesia and sedation management. Therefore, we argue that, before supplemental oxygen is recommended as an adjunct to attenuate tourniquet-associated pain in patients undergoing a procedure under an upper limb tourniquet, randomized controlled clinical trials are still required. If further clinical studies show a consistent beneficial effect of supplemental oxygen on tourniquet-associated pain, the implications for practice are vast. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. No external funding was received. Fu S. Xue, M.D. Gao P. Liu, M.D. Chao Sun, M.D.