Changes in cerebral oxygenation assessed by near-infrared spectroscopy during shoulder arthroscopy in the beach chair position after brachial plexus block

Abstract

Background: It is well known that patients undergoing shoulder surgery in the Beach Chair Position (BCP) have a potential risk for cerebral ischemia. Using Near-Infrared Spectroscopy (NIRS), this study aimed to test whether cerebral oxygenation in these patients was impaired by brachial plexus block accompanied with general anesthesia. Methods: Ultrasound-guided interscalene brachial plexus block was performed in 26 patients undergoing elective arthroscopic shoulder surgery under general anesthesia. In all subjects, cerebral oxygenation during anesthesia was evaluated by measuring the Tissue Oxygenation Index (TOI) with NIRS. Results: No differences were seen in TOI values between Pre-BCP and Post-BCP periods in both block and non-block sides, despite a decrease in mean blood pressure (P<0.05, repeated measures one-way ANOVA by the Bonferroni post hoc test). Additionally, no differences were seen in TOI values between block and non-block sides at any time point. Conclusion: Changing from the supine position to the BCP did not appear to impair cerebral oxygenation, regardless of brachial plexus block, in patients undergoing shoulder arthroscopy under general anesthesia. © 2013 Aso C, et al.