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The analgesic properties of intravenous pethidine and pethidine plus levallorphan were compared in a group of seventy-two fit obstetric patients. The assessment was made by graded pressure on the tibia. A double blind four-point assay plus placebo technique was used. The trial failed to distinguish between the analgesic effect of the narcotic and the placebo. It is concluded that this method of assessment is inapplicable to the pregnant patient. The commonest side dect noted was dizziness but the incidence of side effects was related more to increased dosage of drugs rather than Werences between pethidine and pethidine plus levallorphan.

An investigation, in volunteers, into the sensory effects of nitrous oxide and methoxyflurane showed that the subjective changes of reduction in visual awareness and heightened auditory awareness were not supported by objective measurement. Vision remained normal until the subjects became unresponsive, whilst hearing was in fact diminished. The analgesia produced by nitrous oxide was late in appearance relative to the other sensory changes and it disappeared very rapidly upon recovery. In contrast, analgesia appeared early with methoxyflurane and persisted well into the recovery period. The principal changes found were alterations in orientation in space, of intellectual attitudes, of mood and of emotional attitudes. The emotional attitudes were easily disturbed by extraneous noise or conversation and the need for a quiet approach not only to the induction of anaesthesia but also to the recovery from anaesthesia is stressed.

A possible means of rapid cooling in the emergency treatment of malignant hyperpyrexia, peritoneal dialysis using a cold dialysate, is described. Experimental observations in a young man on a regular peritoneal dialysis regime showed that significant heat extraction can be obtained when either a cool (20 degrees C) or cold (9 degrees C) dialysis fluid is used. The maximum heat exchange observed was 17.5 kJ/min when 2 litre of cold dialysis was instilled for a mean time of 10 min. This rate of heat exchange is within the 10--40 kJ/min range of excess heat production that occurs in malignant hyperpyrexia. Since peritoneal dialysis is, technically, a very quick and simple procedure, it is suggested that it might play a very useful role in the emergency treatment of malignant hyperpyrexia. The dialysis treatment would also correct some of the biochemical disturbances that occur in this condition.

SUMMARY During induction of anaesthesia with nitrous oxide and 21 per cent oxygen in subjects in the sitting position there was a rise in alveolar oxygen tension proportional to the inspired nitrous oxide concentration. The mean rise in alveolar oxygen tension was 30 mm Hg after breathing 79 per cent nitrous oxide for 80 seconds. There was little change in alveolar carbon dioxide tension. There was a rise in arterial oxygen tension in the three subjects studied; the alveolar/arterial oxygen difference increased from 9 to more than 20 mm Hg in two of the subjects. The changes in alveolar and arterial oxygen tensions are due to lung shrinkage and a greater inspired to expired tidal volume ratio consequent upon nitrous oxide uptake. The increase in alveolar/arterial difference is a consequence of an increase in alveolar oxygen in the presence of non-uniformity of ventilation-perfusion ratios. The increase in alveolar/arterial difference was accompanied by a fall in functional residual capacity. The reduction in functional residual capacity was found to be proportional to the inspired nitrous oxide concentration.

SUMMARY The effects of emotional stress, nitrous oxide and halothane anaesthesia, a 1-minute period of hypoxia, and surgery, on the blood sugar, plasma free fatty acids (FFA) and insulin were investigated. The emotional stress of being brought to the operating theatre and the stress of surgery seem to be more important than anaesthesia in causing a rise in blood sugar and plasma FFA. There was a corresponding fall in levels of plasma insulin. The infusion of Phentolamine in two patients did not prevent the failure of insulin response to injected glucose during surgery. The clinical significance of this temporary state of glucose intolerance is discussed.

Duplicate determinations of arterial oxygen and carbon dioxide tensions were made in seventy adult patients of both sexes awaiting elective surgery. No difference in arterial oxygen tension was noted between the sexes but a marked inverse correlation between age and arterial oxygen tension was demonstrated. When this relationship was evaluated from the duplicate estimations the resultant regression equation was such that Pao2 = 102.5–0.22 (age). No statistically significant differences were noted between the Paco2 values of patients of different sexes and age groups.