Profound hypercapnia due to disconnection within an anaesthetic machine

A 25-year-old patient received general anaesthesia for an emergency Caesarean section. Arterial blood gases obtained because of prolonged postoperative coma demonstrated profound hypercapnia (PaCO2 246 mmHg). Examination of the anaesthetic machine revealed a complete disconnection of the metal components of the main gas line downstream from the vaporizer, in a location that was obscured from the anaesthetist's view. Causes of profound hypercapnia are reviewed and preventive measures are discussed.