HEMODYNAMIC AND CATECHOLAMINE CHANGES AFTER INDUCTION OF ANESTHESIA WITH EITHER THIOPENTONE OR PROPOFOL WITH SUXAMETHONIUM

We have compared the haemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in 43 patients after induction of anaesthesia with either thiopentone 5.1 (SD 0.9) mg kg(-1) or propofol 2.2(0.1) mg kg(-1), each with suxamethonium and without opioid pretreatment. Heart rate increased significantly above baseline after induction and intubation in both groups, but there were no differences between groups. Arterial pressure increased significantly at 1 min after intubation in both groups and at 2 min in the thiopentone group only. Plasma concentrations of adrenaline increased significantly compared with concentrations before induction, 1 min after intubation in both groups and at 2 min in the thiopentone group only. Plasma concentrations of adrenaline were significantly greater in the thiopentone group than in the propofol group at both 1 and 2 min after intubation. Plasma concentrations of noradrenaline showed no significant time-based within-group changes, but were significantly greater in the thiopentone group at 1 and 2 min after intubation. We conclude that doses of either thiopentone or propofol sufficient to obtund the eyelash reflex with suxamethonium 1 mg kg(-1) alone do not adequately block the catecholamine and hypertensive responses to laryngoscopy and intubation in normal patients and although propofol suppressed increases in catecholamines to a greater extent than thiopentone, there were no clinical advantages.