Lignocaine to aid the insertion of the laryngeal mask airway with thiopentone. A comparison between topical and intravenous administration.

Conditions for insertion of a laryngeal mask airway in 90 unpremedicated adult were patients were assessed in a randomised, single-blinded trial. Each patient received fentanyl 1 microgram.kg-1 and thiopentone 5 mg.kg-1, and this was preceded either by lignocaine 0.5 mg.kg-1 intravenously (group 1), lignocaine 1.5 mg.kg-1 intravenously (group 2) or 40 mg of topical lignocaine spray to the posterior pharyngeal wall (group 3). Conditions for laryngeal mask airway insertion were recorded. The group receiving topical lignocaine had a lower incidence of laryngospasm (p < 0.05), required fewer attempts for successful insertion of the laryngeal mask (p < 0.05) and coughed or gagged less frequently than either group receiving lignocaine intravenously (p > 0.05). Overall, the conditions for laryngeal mask airway insertion were better in the topical group (p < 0.05). There were no significant differences in haemodynamic response and apnoea between the three groups. Topical lignocaine spray prior to thiopentone provides conditions for insertion of a laryngeal mask that are superior to those provided by lignocaine and thiopentone intravenously.