Interscalene versus supraclavicular plexus block for the prevention of postoperative pain after shoulder surgery A systematic review and meta-analysis

BACKGROUND Interscalene brachial plexus blockade is the most common regional anaesthesia technique for alleviating pain after shoulder surgery, but complications occur, including ipsilateral hemidiaphragmatic paresis, Horner's syndrome and hoarseness. The supraclavicular approach might be an effective alternative with fewer adverse effects. OBJECTIVES The aim of this study was to determine whether there is a difference in postoperative pain scores and morphine equivalents between interscalene and supraclavicular brachial plexus blocks. Secondary endpoints were serious adverse events. DESIGN A systematic review and meta-analysis of randomised controlled trials. DATA SOURCES A comprehensive literature search of Embase, CENTRAL, MEDLINE and Web of Science was performed from the earliest record to December 2018. ELIGIBILITY CRITERIA Prospective randomised controlled trials that compare interscalene and supraclavicular brachial plexus blocks in patients undergoing shoulder surgery were eligible for inclusion. Only studies that reported their methods transparently and comprehensibly were included. Conference abstracts or meeting abstracts were not excluded a priori. Risk of bias was assessed using Cochrane methodology. RESULTS Twelve studies were eligible for meta-analysis. The supraclavicular approach showed overall comparable 24-h pain scores (mean difference -0.34; 95% CI -0.75 to 0.07, P = 0.11) and comparable morphine equivalent consumption (mean difference 1.84 mg per 24 h; 95% CI -0.00 to 3.69, P = 0.05). Secondary endpoint analysis revealed a significantly lower rate of hemidiaphragmatic paresis (risk ratio 0.56; 95% CI 0.39 to 0.82, P = 0.003) and Horner's syndrome (risk ratio 0.29; 95% CI 0.19 to 0.44, P<0.00001) for the supraclavicular approach. There was no significant difference in hoarseness (risk ratio 0.73; 95% CI 0.48 to 1.13, P = 0.16). CONCLUSION After 24 postoperative hours, pain scores and consumption of morphine equivalents were comparable. Adverse effects were less common with the supraclavicular approach. The supraclavicular approach might be an efficient alternative to the interscalene approach for shoulder surgery. However, the available evidence is inadequate and prevents a firm conclusion.