BACKGROUND: Although controlled ventilation can shorten the induction time during vital capacity inhalation induction (VCII) with sevoflurane, it may associated with decrease in blood pressure and hyperventilation-related hyperdynamic responses such as hypertension and tachycardia. This study was designed to compare the clinical effects between controlled ventilation (CV) within acceptable ranges of PETCO2 and spontaneous breathing (SB) during VCII. METHODS: 100 patients were randomly allocated to the one of two groups. After the loss of consciousness during VCII with sevoflurane, controlled ventilation was applied in CV group within acceptable ranges of PETCO2 and spontaneous breathing was maintained in SB group. Alfentanil 4 mcg/kg was given i.v. 2 minutes prior to intubation. PETCO2, mean arterial pressure (MAP), heart rate (HR), SPO2, and BIS were measured at 1, 2 and 3 minute after the loss of consciousness (LOC). Clinical side effects were evaluated. RESULTS: MAP and HR were significantly decreased and increased in CV group compare to the baseline values at 1 minute after LOC. There were statistical differences of MAP and HR between two groups at 1 and 2 minutes after LOC. 46 of 50 (92%) showed delayed expiration with holding their breath > 20 s in SB group. No differences of other clinical side effects except hypotension between two groups. CONCLUSIONS: We conclude that spontaneous breathing provides a stable hemodynamic status and relatively acceptable ventilation profile compare to controlled ventilation during VCII.
Alfentanil ; Arterial Pressure ; Blood Pressure ; Heart Rate ; Hemodynamics ; Humans ; Hypertension ; Hypotension ; Inhalation* ; Intubation ; Respiration* ; Tachycardia ; Unconsciousness ; Ventilation* ; Vital Capacity*

BACKGROUND: Although nitrous oxide (N2O) is used commonly during anesthesia, the roles of N2O in postanesthetic recovery and emetic sequelae are not well established in the ambulatory surgery. The goal of this study was to compare outcomes in patients anesthetized with propofol/air versus propofol/N2O using BIS. METHODS: Patients for ambulatory laryngomicrosurgery were randomly allocated to the group of anesthesia with propofol/air (Air, n = 44) or propofol/67% N2O (N2O, n = 44). The target concentration of propofol was controlled to maintain the BIS values between 35 and 40. By the end of surgery, anesthetics were discontinued and the time to eyes-open (TTEO) on verbal command was measured. The BIS values, effect site concentration (ESC), and total propofol doses were measured at eyes-open. Time to first drink (TTD), walk (TTW), and PONV were evaluated by blinded observers in the phase II recovery room. All data were analyzed using the student t-test and the Chi-Square Test. RESULTS: In the Air group, TTEO was significantly shorter than in the N2O group (7.6+/-3.1 min vs 9.5+/-2.3 min) despite the higher ESC of propofol (1.8+/-0.4 mcg/ml vs 1.5+/-0.3 mcg/ml). The propofol doses, BIS scores at eyes-open, TTD and TTW, and the incidence of PONV were no different in the two groups. Females showed faster emergence from anesthesia than males in the operating room, but showed slower recovery in the phase II recovery room. CONCLUSIONS: N2O does not affect significantly postanesthetic recovery and emetic sequelae. Since N2O has no effect on BIS values, propofol doses may be titrated accordingly.
Ambulatory Surgical Procedures ; Anesthesia ; Anesthetics ; Consciousness Monitors* ; Female ; Humans ; Incidence ; Male ; Nitrous Oxide* ; Operating Rooms ; Postoperative Nausea and Vomiting ; Propofol* ; Recovery Room