RAPID INDUCTION OF HALOTHANE ANAESTHESIA IN MAN

The inhalation induction of general anaesthesia is usually avoided by both patients and anaesthetists, since a prolonged induction may terrify both adults and children. In addition, the anaesthetist may have difficulty maintaining the airway and restraining the muscular patient if excitement occurs. Intravenous induction is popular because these complications are usually avoided. However, venous access may be impossible in some patients and the slow termina-tion of action of i.v. agents may delay the awakening of patients following outpatient surgery. In the past, cyclopropane offered an alternative (Bourne, 1954): loss of consciousness was rapid, arterial pressure was well maintained and emergence was rapid. The risk of explosion has, however, forced most anaesthetists to discard this method of rapid induction. To provide a better method of gaseous induction of anaesthesia in co-operative adults, we devised a new halothane in oxygen technique. The patient takes a vital capacity breath of 4 % halothane in oxy-gen and attempts to hold his breath until he is unconscious. The method has been used in approxi-mately 200 patients in the past 5 years and appears to be effective, safe and acceptable. To understand this technique better, we attempted to anaesthetize heal-thy volunteers using vital capacity breath-holds of various concentrations of halothane in oxygen as delivered by clinical equipment, while monitoring cardiopulmonary responses