A case of intrapulmonary transmission of air while transitioning a patient from a sitting to a supine position after venous air embolism during a craniotomy.

PURPOSE: Since certain surgical procedures still require a sitting or reverse Trendelenburg position, it remains important to evaluate the risk for paradoxical embolization. Intracardiac shunting, the most common cause being a patent foramen ovale, can be excluded by contrast-enhanced transesophageal echocardiography. There are, however, less described cases which result from patency of intrapulmonary functional arteriovenous anastomoses and lead to extra-cardiac paradoxical air embolism during anesthesia. We report a unique case to increase awareness of this real and potentially dangerous complication.

CLINICAL FEATURES: A 52-yr-old male was scheduled for resection of a tumour at the cerebellopontine angle. Preoperative evaluation excluded intracardiac shunts. During a craniotomy in the sitting position, recurrent venous air emboli entered the patient's right heart, leading to a sudden decline in end-tidal CO(2), an increase in PaCO(2), and a reduction of PaO(2). The exact source of surgical entrance could not be identified; therefore, the surgical wound was closed provisionally and the patient was repositioned supine to prevent further venous air emboli. During transition to the supine position, we observed clinically significant crossover of air into the left heart originating from the left pulmonary vein, as detected by transesophageal echocardiography. In all likelihood, the etiology was an opening of intrapulmonary right-to-left anastomoses. The patient recovered without neurological or pulmonary sequelae.

CONCLUSION: In the presence of massive venous air emboli, intrapulmonary right-to-left paradoxical air emboli can occur while intraoperatively transitioning a patient from the sitting to the supine position.