Aspects of intravenous anaesthesia

Abstract: Background:Developments in anaesthesia during the recent decades include new drugs with limited unwanted side effects and the need for anaesthesia in new interventions, together with new groups of patients that in the past were considered to be beyond help. Aims:Study I: To determine the bolus dose of remifentanil that depresses the ventilatory drive as deeply as 1 µg/kg of fentanyl.Study II: To test the hypothesis that the combination of rocuronium (0.2 mg/kg) with modest doses of propofol and remifentanil during anaesthesia induction always achieves good or excellent intubation conditions in infants.Study III: To compare the safety of propofol in a large cohort of patients with a known sensitization to soy and/or peanuts to that of non-propofol hypnotic use in a control group.Study IV: To assess muscular endurance from subparalyzing doses of rocuronium on awake subjects.Methods:Study I: A randomised, double-blinded, placebo-controlled study in healthy subjects comparing the effect on ventilation of three different doses of remifentanil and one dose of fentanyl.Study II: A randomised, double-blinded, placebo-controlled clinical trial investigating intubation conditions with and without a low-dose of rocuronium in combination with propofol and remifentanil.Study III: A retrospective observational cohort study in patients sensitised to peanut and/or soy anaesthetized with either propofol or another anaesthetic agent.Study IV: A randomised, double-blinded, placebo-controlled study where the effect on muscular endurance of subparalyzing doses of rocuronium was studied in healthy subjects.Results:A remifentanil bolus of 0.5 µg/kg give similar ventilatory depression as a fentanyl bolus of 1 µg/kg.Intubation conditions were classified as ‘poor’ in 14 of 34 (41 %) patients given placebo and in 10 of 36 (28 %) patients given rocuronium. There were no identifiable allergic reactions in either the propofol or in the non-propofol group in patients sensitised to soy and/or peanuts. The sustained handgrip strength after rocuronium (0.08 mg/kg) was one third compared to placebo.Conclusions:Remifentanil bolus is twice as potent as fentanyl bolus in producing ventilatory depression.Adding a low-dose rocuronium did not significantly improve intubation conditions compared to placebo. Propofol was safe to use in a cohort of patients sensitised to soy and/or peanut. Recommendations to withhold propofol because of soy or peanut allergy should be questioned. Low doses of rocuronium may partly exert its effect by reducing muscular endurance.