SummaryThe induction characteristics of sevoflurane in nitrous oxide and oxygen were compared with sevoflurane in oxygen alone and a propofol infusion. A vital capacity technique was used for the gaseous induction groups using a Mapleson A system and a 4-litre reservoir bag. Four end-points of anaesthesia were recorded: time to cessation of finger tapping, time to loss of eyelash reflex, time to jaw relaxation and time to regular settled breathing after laryngeal mask airway insertion. We also recorded sequential blood pressure and pulse rate, the incidence of adverse airway events and the acceptability of the induction technique. Propofol had a faster time to cessation of finger tapping (p < 0:05) and jaw relaxation (p < 0:01). These differences disappeared with the final induction stage and sevoflurane in nitrous oxide and oxygen had the faster time to regular settled breathing, though this did not reach statistical significance. Cardiovascular stability was good and comparable in all groups. There were few adverse airway events in any group and none caused oxygen saturation to fall below 96%. There was more excitation in the gaseous induction groups, though this did not interfere with induction. Patient satisfaction with induction was high.

SummaryWe have examined the differences in ventilatory characteristics between halothane and sevoflurane when used for adult vital capacity induction of anaesthesia. The study was conducted in a randomized, double-blind manner. After 13 patients had been enrolled, the study was curtailed because the blinded observer thought that there was an unacceptably high incidence of adverse events. After the randomization code was revealed, the adverse events were found to be in the halothane group. Although the sample size was small, minute volumes appeared to be maintained in the sevoflurane group. Ventilatory frequencies were similar in the two groups after insertion of the laryngeal mask airway, but tidal volumes were significantly greater in the sevoflurane group (P:0.0013). (Br.

We have investigated the effects of clonidine on gastric emptying of liquids in 30 patients. In a double-blind, randomized design, clonidine 150 micrograms, morphine 10 mg or saline in 1 ml was given i.m. One hour later, the patient drank a paracetamol solution (1.5 g in 50 ml water). Venous blood samples were obtained every 15 min for 90 min thereafter. Plasma paracetamol concentrations were measured using high-pressure liquid chromatography and the area under the concentration-time curve was calculated. The degree of sedation and complications were recorded. The area under the curve for 0-60 min was significantly smaller in the morphine group than in the saline group (P = 0.002; 95% confidence interval (CI) for difference -1237 to -502 micrograms min ml-1), whereas it was greater in the clonidine group compared with the saline group, although this was not significant (95% CI for difference -423 to 1264 micrograms min ml-1). Arterial pressure was significantly lower in the clonidine group compared with the saline group. Both clonidine and morphine appeared to cause mild sedation. We conclude that clonidine 150 micrograms i.m. does not delay gastric emptying of liquids in a similar manner to morphine.

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