Isobolographic Analysis of the Hypnotic Interaction Between Propofol and Thiopental

Introduction: Giving two intravenous anaesthetic agents simultaneously generally results in an additive effect. The aim of this study was to investigate the interaction between propofoland thiopental when given to patients who have had sedative premedication. Methods: Fifty patients were admitted into the study. All patients received oral midazolam 3.75mg and intravenous fentanyl 100mg before induction of anaesthesia. Twenty patients received an infusion of their propofol or thiopental while 30 patients received an infusion of an admixture of both drugs. Results: The interaction between propofol and thiopental was additive. The average dose at loss of the eyelash reflex for propofol and thiopental was 0.71mg kg-1 and 1.54mg kg-1 respectively. Premedication decreased the induction dose by 38.2%. Conclusion: Propofol and thiopental interact in an additive fashion when given at induction of anaesthesia

Comparison Between the Effects of High Secoflurance Concentration during Induction of Anaesthesia Using Vital Capacity Breath and Tidal Breathing Techniques in Adults

Introduction: The aims of this randomised study were to compare the induction characteristics of sevoflurane using vital capacity breath technique to that of tidal breathingtechnique in adults undergoing day-care surgery., and to compare patients' acceptance of these two techniques. Methods: Sixty ASA I and II adult patients undergoing day-care surgery were randomly allocated to receive either the vital capacity breath or tidal breathing technique for induction of anaesthesia with 7.5% sevoflurane in nitrous oxide and oxygen. Haemodynamic changes, induction characteristics and patients' acceptance were compared. Results: The mean time for induction was significantly faster with the vital capacity breath technique. There were no significant differences in haemodynamic changes and oxygenation during induction between these two groups. There was a significant increase in incidence of exictatory movement in patients receiving the tidal breathing technique. Either technique was found to be acceptable by most of the patients studied. Conclusion: The vital capacity breath technique appears to be better tolerated with shorter onset time and less movement during induction of anaesthesia. As it is well accepted by the patients and has a stable haemodynamic profile, its use should be encouraged.