CHANGES IN CEREBRAL OXYGENATION AT DIFFERENT BEACH CHAIR POSITION ANGLES AS A PREDICTOR OF EARLY POSTOPERATIVE NEUROCOGNITIVE DISORDERS

Abstract

The beach chair position during shoulder surgery may lead to reduced cerebral oxygenation due to the hydrostatic gradient and anesthesia-induced vasodilation. Increasing the tilt angle potentially elevates the risk of cerebral hypoxia and early postoperative cognitive impairment. Objective. To investigate the effect of body tilt angle in the beach chair position on cerebral oxygenation parameters and the risk of early postoperative cognitive impairment. Methods. In this prospective randomized study, 75 ASA I–II patients undergoing shoulder surgery were assigned to a beach chair position at either 80° (n = 35) or 60° (n = 40). Regional cerebral oxygen saturation (rSO2) was monitored using near-infrared spectroscopy (NIRS), along with hemodynamic parameters and BIS. Cognitive function was assessed using the MMSE preoperatively and 24 hours postoperatively. Quality of recovery was evaluated using the QoR-15 questionnaire, and discharge readiness using the Modified Aldrete score. Statistical analysis was performed using Student’s t-test. Results. After positioning, mean rSO2 was lower in the 80° group (71.9 ± 6.6 %) compared with the 60° group (83.3 ± 5.3 %; p < 0.001), with no significant differences in mean arterial pressure. At 24 hours, MMSE scores were lower in the 80° group (25.1 ± 1.5 vs 28.1 ± 1.3; p < 0.001). This group also demonstrated poorer QoR-15 scores and longer extubation time (p <0.001). Conclusions. A tilt angle of 80° is associated with greater reductions in rSO2 and worse early cognitive outcomes.