Propofol dosage achieving spontaneous breathing during balanced regional anesthesia with the laryngeal mask airway

Study Objective: To assess an anesthetic technique achieving spontaneous br eathing through the laryngeal mask airway (LMA) during combined epidural bl ock and propofol anesthesia. Design: Prospective, consecutive case series study. Setting: Operating room at a general hospital. Patients: 112 ASA physical status I and II adult surgery patients; 32 patie nts for lower extremity surgery are enrolled into study 1, and 30 patients for lower extremity surgery and 50 patients for lower abdominal gynecology surgery are enrolled into study 2. Interventions: In study 1, patients were given 1.5 to 2.0 mg/kg followed by a 3 mg/kg/h of infusion of propofol, af ter epidural block, and they were fitted with the LMA. Thirty minutes after induction, the dose of propofol was increased to 4,5,6, and 7 mg/kg/h ever y 15 minutes. In study 2, the patients were given 1.5 to 2.0 mg/kg and 5 mg /kg/h of propofol and the LMA insertion, after epidural block. Measurements and Main Results: PaO2/FlO(2), PCO2, tidal volume or respirato ry rate, blood pressure, heart rate, and eye opening and motor response sca les in conformity with Glasgow coma scale were recorded. Study 1 suggested an induction dose of 1.5 to 2.0 mg/kg and an infusion of 5 mg/kg/h as an ap propriate dose to preserve spontaneous breathing with the LMA and to mainta in reasonable depth of anesthesia, and other data related to anesthesia wer e clinically acceptable. Conclusions: The best infusion dose of propofol to achieve spontaneous brea thing with the LMA seems to be 5 mg/kg/h, and the present balanced regional anesthesia with the LMA, using propofol infusion at 1.5 to 2.0 mg/kg and 5 mg/kg/h combined with epidural block, may be useful in clinical practice f or lower extremity and lower abdominal gynecologic operations. (C) 2000 by Elsevier Science Inc.