Effect of verapamil on the cardiovascular responses to tracheal intubation

We have studied the efficacy of verapamil in attenuating the cardiovascular responses to tracheal intubation in three groups of ASA grade I patients given verapamil 0.05 mg kg-1 or 0.1 mg kg-1 or saline 45 s before the start of laryngoscopy. Anaesthesia was induced with thiopentone 5 mg kg-1 i.v. and tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% enflurane and 50% nitrous oxide in oxygen. In patients who received saline, there was a significant increase in mean arterial pressure and rate-pressure product associated with tracheal intubation. The increases were significantly less in verapamil-treated patients compared with those in the control group, although verapamil failed to prevent tachycardia caused by laryngoscopy and intubation.