RESUMO
UNLABELLED: During propofol/fentanyl anesthesia, a large percentage of patients have jugular bulb oxygen saturation (SjO(2)) <50%. The incidence is less with isoflurane/N(2)O. We evaluated the effect of N(2)O on SjO(2) during remifentanil-based anesthesia with concurrent propofol or sevoflurane in 20 adults undergoing brain tumor surgery. Anesthesia was randomized: Group 1 (n = 10), target-controlled infusion propofol; and Group 2 (n = 10), thiopental 2-3 mg/kg followed by sevoflurane 0.9% end-tidal. Jugular bulb and arterial blood samples for gas analysis were withdrawn during the administration of oxygen 33% with nitrogen 67% and then with N(2)O 67%. All samples were drawn before surgery and 20 min after the addition of the study gas and with an ETCO(2) 26-28 mm Hg and mean arterial pressure >90 mm Hg. Both groups had similar demographic and physiologic data. In the Propofol group, SjO(2) was 50% +/- 10% with nitrogen and 52% +/- 9% with N(2)O (not significant); in the Sevoflurane group, however, N(2)O 67% increased SjO(2) from 56% +/- 13% to 66% +/- 12% (P < 0.01). This indicates that N(2)O does not reduce the incidence of low SjO(2) values during propofol anesthesia. IMPLICATIONS: This study demonstrates that nitrous oxide can increase jugular bulb venous oxygen saturation when added to sevoflurane/remifentanil anesthesia, but not to propofol/remifentanil anesthesia, in patients with brain tumors.
