Jeong H et al. – The margin of safety against impaired cerebral oxygenation is greater and ugular venous bulb oxygen saturation (SjvO2) is more preserved with sevoflurane–nitrous oxide (S/N) than with P/R anesthesia. SctO2 may not be reliable in detecting a low SjvO2 during the surgery in beach chair position (BCP).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 SjvO2 and SctO2, were measured before (postinduction baseline in supine position) and after BCP.
- Mean arterial pressure decreased by BCP in both groups.
- It was, however, significantly higher in S/N (n=19) than in P/R group (n=17) at 7 to 8min after the positioning.
- SjvO2 also significantly decreased after BCP in both groups, the magnitude of which was lower in S/N than in P/R group (11&plismn;10% vs. 23±9%, P=0.0006).
- The incidences of SjvO2 <50% and mean arterial pressure less than 50mmHg 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.
- SctO2 and SjvO2 were only weakly correlated (β=0.218, r2=0.133).
- Bland-Altman analysis showed a mean difference of -7.2% with 95% limit of agreement between -38.2% and 23.8%.