Lidocaine given intravenously improves conditions for laryngeal mask airway insertion during propofol target-controlled infusion.

BACKGROUND AND OBJECTIVE: Patient response to laryngeal mask airway insertion during propofol induction depends on many factors. Lidocaine has been used to reduce cardiovascular responses, coughing, and bucking induced by tracheal intubation. The aim of this study was to determine the effects of intravenous lidocaine on laryngeal mask airway insertion conditions during the induction of anaesthesia with propofol target-controlled infusion.

METHODS: Eighty patients, 16-54 years of age, weighing between 45 and 100 kg, who underwent minor surgery, were randomly divided into two groups (the lidocaine and control groups). Anaesthesia was induced with propofol target-controlled infusion at a target plasma concentration of 6 microg ml. The lidocaine group received 1.5 mg kg of lidocaine 50 s after starting target-controlled infusion and the control group received an equivalent volume of saline. Laryngeal mask airways were inserted when propofol effect-site concentrations reached 2.5 microg ml. Laryngeal mask airway insertion conditions (mouth opening, gagging, coughing, movements, laryngospasm, overall ease of insertion, and hiccups) were assessed, and haemodynamic responses were monitored for 3 min after laryngeal mask airway insertion.

RESULTS: No significant differences were observed between the two groups in terms of haemodynamic responses. However, the lidocaine group showed lower incidences of coughing (5 vs. 22.5%), gagging (25 vs. 55%), and laryngospasm (2.5 vs. 17.5%) (P < 0.05).

CONCLUSION: Pretreatment with intravenous lidocaine 1.5 mg kg during induction with propofol target-controlled infusion improves laryngeal mask airway insertion conditions.