In this paper, we summarise the physiology of lactation and discuss the pathophysiology brought about by fasting, stress and anaesthetic drugs. Drug secretion into breast milk and subsequent absorption by the infant is considered. Maternal hydration must be well maintained with intravenous fluids, allowing an added 500 to 1000 ml for daily fluid loss in lactation. Maternal premedication, general anaesthesia and routine postoperative analgesics are also discussed as to the effects on the breast-fed infant. Drug side-effects may be avoided by timing breast feeding just before the next due dose. Sedatives with long half-lives should not be used. Endocrine and metabolic responses to anaesthesia and surgery are less with regional anaesthesia than with general, hence regional anaesthesia is preferred where it is a reasonable alternative technique.

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Ketamine 1 · 0 mg/kg and diazepam 0 · 3 mg/kg was used to induce anaesthesia in patients requiring pericardiectomy. A significant rise in blood pressure in patients receiving ketamine was noted. In contrast, a fall in blood pressure was seen when diazepam was administered. Changes in cardiac output, cardiac index, central venous pressure and systemic vascular resistance are discussed. Ketamine appears to be a more satisfactory agent for induction of anaesthesia in patients for pericardiectomy, whereas diazepam should be used with caution.

The pharmacokinetic behaviour of alcuronium was studied in three patients undergoing resection of an aortic aneurysm, and in another two patients undergoing total hip replacement (group I). A control group of five elderly patients undergoing relatively minor surgery was included (group II). In group I patients, the values of the pharmacokinetic parameters such as plasma clearance, elimination half-life and the apparent volume of distribution of the drug were found to be comparable to those obtained in normal young patients in previous studies. The group II patients, however, were found to have a prolonged elimination half-life as a result of reduced plasma clearance, possibly an age-related effect. The differences between these two groups of patients may be explained by the differences in the extent of haemorrhage and fluid replacement or changes in blood circulation, or both. However, alcuronium must still be used cautiously in both groups of patients, especially in the light of a recent finding that patients undergoing aortic reconstructive surgery have a high frequency of functional renal failure after operation.