Patent or persistent ductus arteriosus is a vascular connection between the pulmonary artery and the aorta, causing a L→R shunt. The ductus is a normal part of the antenatal circulation and usually closes in the first few days of life. Persistence is more common in premature babies. Pulmonary vascular resistance decreases in the first few weeks of life, increasing shunt volume and therefore pulmonary overcirculation, resulting in tachypnoea and pulmonary oedema. Anaesthetic management aims to avoid a decrease in pulmonary vascular resistance with air and mild hypoventilation and avoid an increase in systemic blood pressure.