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

We have compared the haemodynamic and catecholamine responses to laryn goscopy and tracheal intubation in 43 patients after induction of anae sthesia 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 pretreatme nt. Heart rate increased significantly above baseline after induction and intubation in both groups, but there were no differences between g roups. Arterial pressure increased significantly at 1 min after intuba tion in both groups and at 2 min in the thiopentone group only. Plasma concentrations of adrenaline increased significantly compared with co ncentrations before induction, 1 min after intubation in both groups a nd at 2 min in the thiopentone group only. Plasma concentrations of ad renaline were significantly greater in the thiopentone group than in t he propofol group at both 1 and 2 min after intubation. Plasma concent rations 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 thiopent one or propofol sufficient to obtund the eyelash reflex with suxametho nium 1 mg kg(-1) alone do not adequately block the catecholamine and h ypertensive responses to laryngoscopy and intubation in normal patient s and although propofol suppressed increases in catecholamines to a gr eater extent than thiopentone, there were no clinical advantages.