Optimal dose of succinylcholine for tracheal intubation in patients during inhalation induction with sevoflurane: a randomized controlled trial.

STUDY OBJECTIVE:To determine the dose of succinylcholine during inhalation induction of a patient. DESIGNED:Prospective, double-blind, randomized study. SETTING:Operating room of a university hospital. PATIENTS:180 adult, ASA physical status 1 and 2 patients with a suspected difficult airway, who were scheduled for surgery. INTERVENTIONS:Nonpremedicated patients were anesthetized with inhalation of 8% sevoflurane, followed by succinylcholine. Group 1 received intravenous (IV) succinylcholine 0.3 mg/kg, Group 2 had IV succinylcholine 0.6 mg/kg, and Group 3 was given IV succinylcholine 1.0 mg/kg. Direct laryngoscopy and tracheal intubation were performed after onset of succinylcholine. MEASUREMENTS:Intubation conditions were scored as excellent, good, or poor. The recovery time of spontaneous respiration, end-tidal carbon dioxide partial pressure (PETCO2), and pulse oxygen saturation (SpO2) were recorded. MAIN RESULTS:Acceptable conditions (excellent and good) for intubation were rated in 80% of Group 1 patients (0.3 mg/kg succhinylcholine), 91.7% of Group 2 patients (0.6 mg/kg), and 93.3% of Group 3 patients (1.0 mg/kg), respectively. Intubation scores were similar in Groups 2 and 3, and were significantly higher than in Group 1 patients (0.3 mg; P < 0.01). Time to recovery of spontaneous respiration in Group 3 was significantly prolonged compared with Groups 1 and 2 (238 ± 59 sec vs 132 ± 43 sec, P < 0.001; 238 ± 59 sec vs 151 ± 47 sec, P < 0.001, respectively). SpO2 in Group 3 did not differ significantly from Group 1 and 2 values. However, PETCO2 in Group 3 was significantly higher than in Groups 1 or 2. CONCLUSIONS:Succinylcholine at a dose of 0.6 mg/kg IV provided intubation conditions similar to succinylcholine at 1.0 mg/kg IV, and recovery of spontaneous respiration following a 0.6 mg/kg dose of succinylcholine was significantly shorter.