No abstract

We have demonstrated the value of task analysis in improving anaesthetic practice. Task analysis facilitates the identification of relevant human factors issues and suggests ways in which these issues can be addressed. The output of the task analysis will be of use in focusing future interventions and research in this area.

SummaryWe determined the effective time to satisfactory intubation conditions after the administration of rocuronium 0.6 mg.kg À1 to 120 unpremedicated adult patients anaesthetised with propofol 2.5 mg.kg À1 or thiopentone 5 mg.kg À1. Intubation conditions were assessed in 10 subgroups of 12 patients at 30, 40, 50, 60 and 70 s. The effective times to satisfactory intubation conditions in 50 and 90% of patients were obtained by the method of maximum likelihood after log time-probit response transformations. Intubation conditions after induction of anaesthesia with propofol were satisfactory in 5/12 patients at 30 s, 7/12 at 40 s, 10/12 at 50 s, 11/12 at 60 s and 11/12 at 70 s compared with 1/12 patients at 30 s, 2/12 at 40 s, 5/12 at 50 s, 7/12 at 60 s and 8/12 at 70 s after induction with thiopentone. The effective times to satisfactory intubation conditions in 50% and 90% (95% confidence intervals) of patients after rocuronium 0.6 mg.kg À1 were 34 (26-40) s and 61 (50-81) s in patients given propofol compared with 57 (48-69) s and 101 (79-167) s in patients given thiopentone. We conclude that rocuronium 0.6 mg.kg À1 may be a suitable alternative to suxamethonium during rapid sequence induction of anaesthesia with propofol in situations where suxamethonium is contraindicated.Keywords Anaesthetics, intravenous; propofol, thiopentone. Anaesthetic techniques; rapid sequence intubation. Intubation; tracheal. Neuromuscular relaxants; rocuronium.. ..................................................................................... Correspondence to: Dr A. McCluskey Accepted: 6 June 1998 Since its introduction into clinical practice nearly 50 years ago, suxamethonium has been the 'gold standard' neuromuscular relaxant for rapid sequence induction of anaesthesia. Unfortunately, suxamethonium has numerous undesirable side-effects, some of which may be life-threatening [1]. Rocuronium is a newer steroid nondepolarising neuromuscular blocker with a rapid onset and may be a suitable alternative to suxamethonium for rapid sequence induction of anaesthesia [2][3][4]. The choice of induction agent may influence the rate of onset of satisfactory intubation conditions. Propofol is known to depress laryngeal reflexes [5][6][7][8] and may therefore be a more appropriate induction agent than thiopentone when rocuronium is used in a rapid sequence technique. We recently described a method for determining the effective time to satisfactory intubation conditions after injection of a neuromuscular blocker [9]. In the present study, we determined the effective times to satisfactory intubation conditions in 50 and 90% of patients (ET 50 and ET 90 ) after rapid sequence induction of anaesthesia with either propofol or thiopentone and rocuronium 0.6 mg.kg À1 . The intubator, who was blinded to both the choice of induction agent and the intubation time, was instructed to commence laryngoscopy 10 s before the allotted intubation time. The precise intubation time was indicated by an audible alarm, at which the attempt was made to pass t...

We determined the dose-response curves and effective doses of propofol for insertion of the laryngeal mask airway (LMA) in 50 unpremedicated children and in 60 children premedicated with midazolam, aged 3-12 yr. One of several doses of propofol was administered i.v. over 15 s to groups of 10 children, and conditions for LMA insertion were assessed at 60 s. The dose-response curves were parallel (P = 0.94), but the curve for premedicated children was shifted significantly to the left of that for unpremedicated children and propofol requirements were reduced by one-third (P < 0.0001). The doses required for satisfactory LMA insertion in 50% and 90% of unpremedicated patients (ED50, ED90) (95% confidence interval) were 3.8 (3.4-4.2) mg kg-1 and 5.4 (4.7-6.8) mg kg-1, respectively; those for premedicated patients were 2.6 (2.2-2.8) mg kg-1 and 3.6 (3.2-4.3) mg kg-1, respectively.

Although children were more anxious during i.v. induction than inhalation induction, there was no difference in the incidence of behavioural disturbances in the first 2 weeks postoperatively.