A rare cause of intra-operative hypoxaemia

A 25-year-old man underwent left inguinal hernia repair. Following induction of anaesthesia, desaturation below 90% was noted which persisted despite correct placement of an endotracheal tube and ventilation with 100% oxygen. Surgery was allowed to continue, and the suspected diagnosis of pulmonary arterio-venous malformation was confirmed post-operatively by computerized axial tomography and arteriography. The investigation and treatment are described, and the diagnostic value of pulse oximetry in this case is emphasized.