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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 (SjvO2) and regional cerebral tissue oxygen saturation (SctO2) were determined while patients were placed from the supine to BCP. Whether SctO2 and SjvO2 are interchangeable in assessing the cerebral 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 SjvO2 and SctO2, were measured before (postinduction baseline in supine position) and after BCP. Results 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 8 min 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 ± 10% vs. 23 ± 9%, P = 0.0006). The incidences of SjvO2 Conclusions The margin of safety against impaired cerebral oxygenation is greater and SjvO2 is 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.

Background Endotracheal intubation in patients undergoing general anesthesia often causes hypertension and tachycardia, which may be altered when the efferent sympathetic fiber to the cardiovascular system is interrupted. The aim of the current study was to investigate the effects of different levels of spinal cord injury on the cardiovascular responses to intubation. Methods Fifty-four patients with traumatic complete cord injuries requiring tracheal intubation were grouped into quadriplegics (above C7; n = 22), high paraplegics (T1-T4, n = 8), and low paraplegics (below T5, n = 24) according to the level of injury. Twenty patients without spinal injury served as controls. Arterial pressure, heart rate, and rhythm were recorded at intervals for up to 5 min after intubation. Plasma concentrations of catecholamines were also measured. Results The intubation increased the systolic blood pressure similarly in control, high-paraplegic, and low-paraplegic groups (P < 0.05), whereas it did not alter the blood pressure in the quadriplegic group. Heart rate was significantly increased in all groups; however, the magnitude was more pronounced in the high-paraplegic group (67%) than in the control (38%) and quadriplegic (33%) groups. Plasma concentrations of norepinephrine were significantly increased after intubation in all groups; however, values were lower in the quadriplegic group and higher in the low-paraplegic group compared with those in the control group. Incidence of arrhythmias did not differ among groups. Conclusions The cardiovascular and plasma catecholamine changes associated with endotracheal intubation may differ according to the affected level in patients with complete spinal cord injuries.