A 39 year old woman with bronchial asthma collapsed following an acute asthma attack. She was admitted to the medical intensive care unit in status asthmaticus requiring mechanical ventilation and severe anoxic encephalopathy. On the 10th hospital day a right subclavian catheter was removed. Within three minutes severe bradycardia was noticed associated with pronounced ST elevation in the inferior wall (panel A) and prominent ST depression in L1 and avL (precordial leads are not available). The patient was placed on 100% oxygen, and in the Trendelenburg and left lateral decubitus position. ST elevation and bradycardia completely resolved within five minutes (panel B). Cardiac troponin T and creatine phosphokinase remained normal.

Air embolus during the insertion or removal of central venous catheters and positive pressure mechanical ventilation is an increasingly recognised problem. The exact frequency of this potentially fatal complication is unknown and difficult to assess. It is believed that many unexplained decompensations in critically ill patients may be attributed to air embolisation. Manifestations are predominantly respiratory, cardiovascular, and neurologic. Once suspected, patients should be placed on 100% oxygen to facilitate gas absorption and in the Trendelenburg left lateral decubitus position to prevent air migration into the pulmonary circulation and systemic embolisation. The present case probably illustrates a rather rare manifestation of air embolus into the coronary circulation resulting in severe transient myocardial ischaemia.

A limb lead ECG, performed within three minutes, showing pronounced 12 mm ST elevation in the inferior wall and 10 mm ST depression in L1 and avL.

A limb lead ECG, performed 10 minutes later, showing normalisation of ST segments.