COMPARISON OF THE HEMODYNAMIC-RESPONSE TO LARYNGEAL MASK INSERTION AND OROTRACHEAL INTUBATION

This prospective study was designed to compare the haemodynamic respon se to insertion of either a laryngeal mask or an orotracheal tube. Twe nty patients scheduled for orthopaedic surgery were randomly assigned to two groups : laryngeal mask group (n = 10) and orotracheal tube gro up (n = 10). Patients were premedicated with flunitrazepam (1 mg i.m.) and anaesthesia was induced with propofol (bolus of 2.5 mg . kg-1, fo llowed by a continuous infusion of 10 mg . kg-1 . h-1) and vecuronium (0.1 mg . kg-1). Heart rate and mean arterial pressure were assessed n on-invasively before and after induction of anaesthesia and immediatel y after tube or laryngeal mask insertion. Orotracheal intubation elici ted a significant increase in heart rate (92 +/- 16 vs 77 +/- 19 b . m in-1, p < 0.05) and in mean arterial pressure (117 +/- 21 vs 85 +/- 16 mmHg, p < 0.05), whereas there was significant increase in heart rate (74 +/- 11 vs 72 +/- 12 b . min-1) and mean arterial pressure (86 +/- 8 vs 81 +/- 10 mmHg) after insertion of the laryngeal mask. In both g roups, plasma catecholamine concentrations were not significantly modi fied after tube or laryngeal mask insertion. It is concluded that, und er propofol anaesthesia, laryngeal mask insertion does not induce any significant haemodynamic response in ASA 1 patients. In the opposite, orotracheal intubation increases both heart rate and mean arterial pre ssure.