SummaryA .study hos heen undertoken of a combined thiopentont-t-tomidate sequence of anaesthesia f o r termination ofpregnancy. The side-effects of pain on injection und abnormol movements have been minimised by the technique. The pattern of recovery is satis{octor.v but the optimum dosage of thiopentone requires further study.
Key wordsAnoesthetirs. introvenous; etomidate.N o intravenous anaesthetic agent isentirely satisfactory and whilst thiopentone is probably the nearest approach to the ideal available at present, its relatively long duration of action makes many anaesthetists avoid its use for short stay patients.Etomidate has recently been introduced as a shortacting induction agent, yet whilst its minimal cardiovascular effects indicate a place for it in our armamentarium many anaesthetists have abandoned its use because of pain on injection and irregular voluntary muscle movements which render surgery difficult. ' This study was undertaken to see whether a small preceding dose of thiopentone would reduce those sideeffects associated with etomidate.
MethodThe protocol of this trial was first agreed by the Lewisham District Ethical Committee.The study was conducted on patients attending for termination of pregnancy at the day stay ward at Lewisham Hospital. Patients below 50 kg or over 75 kg were excluded to enable a standardised dosage of induction agents to be used. One patient on monoamine-oxidase inhibitors and another with little understanding of the English language were also excluded. Patients were allocated alternately to the thiopentone (A) or thiopentone-etomidate sequence (B).The patients were visited by one of us directly after admission to the day stay ward and the nature of the anaesthetic procedure was explained to them before their consent to be entered into the trial was sought. Each patient was then given fourinstructions to remember (Table I) Ask the patient to repeat the instructions given before the anaesthetic. and also the instructions given I h after the anaesthetic fossa. Fentanyl 0.1 mg was injected via the cannula followed by oxytocin 5 units. Thiopentone 250 mg was then injected slowly intravenously and 70% nitrous oxide with oxygen administered by face mask. An oropharyngeal airway was only used if the patient's airway could not otherwise be maintained. The patient was transferred to the operating theatre and anaesthesia maintained with 70% N 2 0 and 0: supplemented by either 4 mg increments of etomidate or SO mg increments of thiopentone as required by response of the patient to stimulation. A record was kept of the amounts of increments required and of the number of patients responding to stimuli. Similarly, the number
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