The effect of dexmedetomidine on S-100 β in beach chair position for arthroscopic shoulder surgery. A randomized controlled trial

Objective: This study was designed to determine whether S-100 beta is released during arthroscopic shoulder surgery in the beach chair position (BCP). The primary aim was to evaluate the pattern of S-100 beta release after BCP and the secondary aim was to explore the effect of dexmedetomidine (DEX) as an adjuvant of interscalene block on the release of S-100 beta. Methods: Fifty patients, undergoing arthroscopic rotator cuff repair in the BCP under general anesthesia, were randomly allocated to two groups. Ultrasound-guided interscalene block was performed using 9 ml of 0.75% ropivacaine with 1 ml of normal saline (Group R) or 100 mu g of DEX (Group RD). For the S-100 beta assay, venous blood was taken at admission and 1, 6, 24, and 48 hours after surgery. Results: Initial S-100 beta levels (pg/ml) were 15.13 +/- 14.19 (Group R) and 13.74 +/- 9.18 (Group RD). They showed peak elevation at 1 hour after surgery [40.78 +/- 21.01 (Group R), 28.19 +/- 12.63 (Group RD)] and decreased gradually. There was an overall significant difference in the change in S-100 beta over time between the two groups (P = 0.029). Conclusions: The S-100 beta level was elevated more than two-fold 1 hour after arthroscopic shoulder surgery in the BCP and decreased gradually during the postoperative period, but remained within the normal range. Perineural DEX suppressed the release of serum S-100 beta and may serve as a protective agent against cerebral ischemic changes in high-risk patients undergoing arthroscopic shoulder surgery in the BCP.