PATIENT RESPONSE TO LARYNGEAL MASK INSERTION AFTER INDUCTION OF ANESTHESIA WITH PROPOFOL OR THIOPENTONE

The response to insertion of the laryngeal mask airway (LMA) following either propofol 2.5 mg . kg-1 or thiopentone 5 mg . kg-1 was assessed in two groups of patients. The purpose of the study was to ascertain which of these two induction agents provided the better conditions for insertion of the LMA. Anaesthesia was induced by propofol in 35 patie nts and by thiopentone in 37 Following induction, ventilation was assi sted for two minutes using 50% oxygen and nitrous oxide and 2% isoflur ane, before insertion of the LMA. The presence of gagging, coughing, l aryngospasm and movement was noted and graded. Thiopentone was associa ted with an adverse response in 76% of patients, compared with propofo l in 26% (P < 0.01). Gagging, laryngospasm and head movement were more common using thiopentone (P < 0.01, P < 0.05 and P < 0.05 respectivel y) and in 11% (P < 0.05) of the thiopentone group insertion of the LMA was impossible due to inadequate relaxation. We conclude that, using these doses, propofol is superior to thiopentone as an induction agent for insertion of the laryngeal mask airway.