The effect of topical lignocaine on intubating conditions after propofol-alfentanil induction

Recent studies have found satisfactory conditions for intubation of the trachea without using muscle relaxants using an intravenous technique combining propofol and alfentanil. In this study we evaluate intubating conditions with this method and either lignocaine applied topically in the larynx and trachea or placebo.

Sixty adult patients of ASA class I were premedicated with diazepam 15-20 mg and randomly allocated to one of two groups. For induction of anaesthesia both groups were given propofol 2.5 mg/kg and alfentanil 30 micrograms/kg. One group received 4 ml of lignocaine 40 mg/ml (< or = 3 mg/kg) topically into the larynx and trachea (group L), the other group an equal amount of isotonic saline (group S) in a double-blind design. Intubation conditions were assessed as excellent, good, moderately good, poor or impossible, scored on the basis of jaw relaxation, ease of insertion of the tube and coughing on intubation.

The total score for group L was significantly better than the score for group S (P < 0.0001) with significant differences with respect to ease of intubation and coughing after intubation.

Induction of anaesthesia with propofol 2.5 mg/kg and alfentanil 30 micrograms/kg combined with 4 ml of lignocainespray 40 mg/ml into the larynx and trachea offered consistent and satisfactory intubation conditions. We thus recommend this method for tracheal intubation, where the use of muscle relaxants is not indicated.