The use of low-dose mivacurium to facilitate insertion of the laryngeal mask airway

Ninety patients were assigned randomly in a double-blind manner to receive 0.9% sodium chloride, mivacurium 0.04 mg.kg⁻¹ or mivacurium 0.08 mg.kg⁻¹ intravenously, followed by propofol 2.5 mg.kg⁻¹. A laryngeal mask airway (LMA) was inserted 90 s later. The LMA was positioned correctly during the first attempt in 87% of patients and this was not significantly altered by the use of mivacurium. However, mivacurium decreased the incidence of swallowing, coughing, movement and laryngospasm (p < 0.05). LMA insertion was graded as easy in 88% of patients who had mivacurium, compared with 50% in patients who had propofol alone (p < 0.05). The conditions during LMA insertion were similar after 0.04 or 0.08 mg.kg⁻¹ of mivacurium. Patients were apnoeic for a mean (SD) time of 0.67 (0.72) min after propofol alone, compared with 1.72 (1.06) min and 3.05 (1.36) min in patients who also received mivacurium 0.04 and 0.08 mg.kg⁻¹, respectively (p < 0.01). Patients who received mivacurium had a lower incidence of postoperative sore throat (24–30% vs. 53%) (p < 0.05). In conclusion, low-dose mivacurium facilitates LMA insertion and decreases the incidence of postoperative sore throat.