Low-dose succinylcholine facilitates laryngeal mask airway insertion during thiopental anaesthesia

We have assessed the optimal dose of succinylcholine to provide satisfactory conditions for insertion of a laryngeal mask airway (LMA) without causing myalgia during induction of anaesthesia with thiopental. We studied 60 adult patients, allocated randomly to one of three groups: group 1 (n = 20) received normal saline, group 2 (n = 20) received succinylcholine 0.25 mg kg-1 and group 3 (n = 20) received succinylcholine 0.5 mg kg-1. Insertion of the LMA was performed 1 min after administration of succinylcholine or saline. Insertion conditions were significantly better in group 3 compared with groups 1 and 2. The incidence of adverse responses on insertion was significantly higher in groups 1 and 2 than in group 3. Four of 20 patients (20%) in group 3 complained of myalgia, which was higher than that in group 1 (0%) and group 2 (10%), but there were no significant differences between groups on the day of operation. On day 3 after operation, seven patients (35%) in group 3 complained of myalgia, which was significantly higher than that in group 1 (5%) and group 2 (20%). Time from administration of succinylcholine to resumption of spontaneous respiration was significantly longer in groups 2 (194.9 (SD 50.4) s) and 3 (234.2 (34.3) s) than in group 1 (84.7 (32.4) s). There was also a significant difference between groups 3 and 2 for duration of apnoea.