SUMMARY

The induction and maintenance of anaesthesia with ether using a combined intravenous infusion and a constant low inspired concentration are described. Predictions from a mathematical model were checked against animal experiments. Anaesthesia occurred within 5 min. The method obviates the need for explosive mixtures. Ether is still the most commonly used anaesthetic agent in many countries in spite of the disadvantages of the explosion risk, a slow and difficult induction, and the stimulation of secretions, vomiting and laryngeal spasm. Artusio (1954) reported that complete analgesia and amnesia may be obtained at ether concentrations below the explosion limit. One of us (R. G.-M.) has confirmed the report by Artusio (1954) that surgical anaesthesia may be obtained at an expired concen-tration of 1.8 vol % using air-ether mixtures or 1.0 vol % using oxygen-nitrous oxide-ether mixtures. By administering ether i.v., and avoiding the risk of explosion, it was possible to reach this concentration rapidly. Intravenous ether anaesthesia was first described by Burkhardt (1909a, b). Eger and others (1962) reported a series of experiments using electroence-phalographic changes as an index of ether concentra-tions. In spite of the promising results from Butt and his colleagues (1965), there has not been general acceptance of the method. The absence of adverse effects of ether on cardio-respiratory function has been confirmed by the recent investigation by Roberts and others (1974). This is a report of combined inhalation and intravenous ether anaesthesia