The use of mini-dose suxamethonium to facilitate the insertion of a laryngeal mask airway

Abstract

The use of mini-dose suxamethonium to facilitate the insertion of a laryngeal mask airway was investigated. Sixty patients were assigned randomly in a double-blind manner to receive 0.9% sodium chloride or suxamethonium 0.1 mg.kg-1 intravenously, following intravenous induction with propofol 2.5 mg.kg-1. The laryngeal mask was inserted after the first attempt in 87% of patients. Mini-dose suxamethonium improved the correct positioning of the laryngeal mask during the first attempt (93 vs. 67%: p < 0.02), decreased the incidence of swallowing (p < 0.001), gagging (p < 0.001) and head or limb movement (p < 0.05). Laryngeal mask insertion was graded as easy in 93% of patients who had mini-dose suxamethonium, compared with 60% in the placebo group (p < 0.01). The duration of apnoea between the two groups was not significantly different (0.54 vs. 0.61 min, p = 0.46). The total dose of propofol needed to insert the laryngeal mask was lower in the suxamethonium group (2.57 vs. 3.25 mg.kg-1, p < 0.01) and was associated with less hypotension (p < 0.05). Fasciculation (17%) and mild myalgia (23%) were common despite the small dose of suxamethonium used. In conclusion, mini-dose suxamethonium facilitates laryngeal mask insertion. Myalgia is common and the technique is not recommended for patients who are prone to suxamethonium myalgia.