A survey of the incidence of postoperative vomiting in 1476 children was conducted over a two-month period as part of our quality assurance programme. The incidence of vomiting was 24 %, and was highest in children over three years of age and in those receiving opioids. The incidence is lower than that recorded in an earlier (1981) survey in our hospital. Changes in anaesthetic practices may have contributed to this decrease.

Objective-To study the dose response characteristics of prostaglandin El and epoprostenol (prostacyclin) and directly to compare their effectiveness as pulmonary vasodilators in infants with pulmonary hypertension. Design-A crossover design with each patient receiving both drugs in random order.Setting-Infants were studied in the intensive care unit while they were sedated, paralysed, and ventilated.Patients-Twenty infants who had undergone corrective cardiac surgery and who were in sinus rhythm, had stable haemodynamic function, and had a pulmonary artery catheter in place. All infants were receiving dopamine and phenoxybenzamine.Interventions-Baseline haemodynamic measurements were taken and an infusion of the first drug was started at the lowest dose: after 20 Conclusions-Neither drug showed pulmonary specificity.heart disease who are ductus dependent,6 but there are few published reports of its use as a pulmonary vasodilator in infants and children. 78 Prostacyclin, identified in 1976, is the main arachidonic acid metabolite formed by vascular endothelium.2 It is a more potent inhibitor of platelet aggregation than PGE, and may also play a part in modulating pulmonary vascular tone, thereby contributing to the thromboresistance of endothelial cells.2 Early reports of its use in children suggested that it caused highly selective pulmonary vasodilatation9 10; however, in larger studies PGI2 was a consistent but non-selective vasodilator.'1'3 As epoprostenol, prostacyclin is used clinically both to assess the reversibility of pulmonary vasoconstriction before surgery1' 14 and as long term treatment for patients with primary pulmonary hypertension."5In infants with cardiac lesions associated with high pulmonary blood flow severe pulmonary vasoconstriction can develop in response to adverse factors after operation.'6 17 PGE, and epoprostenol are both used in the management of reactive pulmonary hypertension but there is no reported comparison of their efficacy in infants. This study was conducted to document the dose response characteristics of PGE, and epoprostenol and directly to compare their effectiveness as pulmonary vasodilators. Patients and methods PATIENTSThe mean age of the 20 patients we studied was 2 8 months (range 3 days-6 months), and their mean weight was 4-2 kg (3 2-62 kg). The diagnoses were ventricular septal defect (nine cases), complete atrioventricular canal (five cases), total anomalous pulmonary veins (four cases), transposition of the great vessels (one case), and truncus arteriosus (one case).