The seated position in patent foramen ovale?

Anesthetic management of patients presenting for posterior cranial fossa surgery in the seated position includes detection and treatment of venous air embolism. Atrial positioning of a central venous (cv) line may be verified by either X-ray or an atrial ECG tracing. We report a case where a chest X-ray film proved superior. A 26-year-old white female was scheduled for posterior cranial fossa exploration. A cv line was inserted via the left antecubital vein; the chest X-ray film documented correct positioning of the catheter tip within the atrium but an aberrant course of the superior vena cava. Echocardiography was performed in the induction room and indicated a patent foramen ovale. In view of the risk of paradoxical air embolism, surgery was postponed. Subsequent cardiologic and radiologic examinations revealed a patent foramen ovale and a persisting left superior vena cava draining into a dilated coronary sinus. Surgery was rescheduled and carried out uneventfully in the prone position. This case demonstrates: 1) an advantage of a thoracic-X-ray film compared to atrial ECG tracing as not only the catheter tip position, but also the course of the catheter can be identified; and 2) the usefulness of preoperative screening for a patent foramen ovale in patients scheduled for surgery in the seated position.