Cerebral Oxygen Saturation Measured by Near-infrared Spectroscopy and Jugular Venous Bulb Oxygen Saturation during Arthroscopic Shoulder Surgery in Beach Chair Position under Sevoflurane-Nitrous Oxide or Propofol-Remifentanil Anesthesia

Background: We examined the effects of different anesthetics on cerebral oxygenation and systemic hemodynamics in patients undergoing surgery in beach chair position (BCP). Jugular venous bulb oxygen saturation (SjvO 2 ) and regional cerebral tissue oxygen saturation (SctO 2 ) were determined while patients were placed from the supine to BCP. Whether SctO 2 andSjvO 2 areinterchangeableinassessingthecerebral oxygenation was also examined. Methods: Forty patients undergoing shoulder surgery in BCP were randomly assigned to receive sevoflurane-nitrous oxide (S/N) or propofol-remifentanil (P/R) anesthesia. Four patients taking angiotensin II receptor antagonists were excluded post hoc. Mean arterial pressure and heart rate, as well as SjvO 2 and SctO 2 , were measured before (postinduction baseline in supine position) and after BCP. Results: Mean arterial pressure decreased by BCP in both groups.Itwas,however,significantlyhigherinS/N(n19) than in P/R group (n 17) at 7 to 8 min after the positioning. SjvO 2 also significantly decreased after BCP in both groups, the magnitude of which was lower in S/N than in P/R group (11 10% vs. 23 9%, P 0.0006). The incidences of SjvO 2 50% and mean arterial pressure less than 50 mmHg were lower in S/N group, but SctO2and the incidence of cerebral desaturation (more than 20% decrease from baseline) did not significantly differ between the groups. SctO 2 and SjvO 2 were only weakly correlated ( 0.218, r 2 0.133). Bland-Altman analysis showed a mean difference of 7.2% with 95% limit of agreement between 38.2% and 23.8%. Conclusions:Themarginofsafetyagainstimpairedcerebral oxygenation is greater and SjvO2is more preserved with S/N than with P/R anesthesia. SctO2 may not be reliable in detecting a low SjvO2 during the surgery in BCP.