Is an alkalinized lignocaine solution a better topical anaesthetic for intratracheal application?

Topical anaesthesia of the trachea is used to avoid coughing during emergence from anaesthesia. This study was designed to compare the effects of an alkalinized lignocaine and plain lignocaine solution given intratracheally. After institutional approval and written informed consent, 30 patients were randomized into three groups and received in a double-blind fashion: lignocaine, alkalinized lignocaine and normal saline for control. After application of normal or alkalinized lignocaine the tolerance to the tube was significantly better during extubation (P = 0.001). Noradrenaline levels were significantly diminished in the lignocaine groups (P < 0.05). Plain and alkalinized lignocaine solutions for topical anaesthesia significantly improved tolerance to the tracheal tube during emergence from anaesthesia. Plain and alkalinized lignocaine given directly before intubation reduced the sympathomimetic stress response resulting in a lower noradrenaline concentration and a reduced heart rate.