Occurrence and Severity of Venous Air Embolism During Neurosurgical Procedures: Semisitting Versus Supine Position

Abstract

Background: At our institution, patients undergoing neurosurgical procedures in the posterior cranial fossa are placed either in the semisitting or in the supine position. The major risk of the semisitting positioning is a venous air embolism (VAE), which may, however, also occur in the supine position.

Methods: In a prospective single-center study with 137 patients, we evaluated the occurrence of VAEs in patients in the supine and in the semisitting position during the period from January 2014 until April 2015. All patients were monitored for VAE by the use of a transesophageal echocardiography (TEE).

Results: In total, 50% of the patients experienced a VAE (56% of these patients underwent surgery in the semisitting and 11% in the supine position). In total, 86% of the VAEs were detected by the use of a TEE and did not lead to any changes in the end-expiratory CO₂. We only observed VAEs with a decrease in end-expiratory CO₂ in the semisitting position. However, none of the patients had any hemodynamic changes due to the VAE.

Conclusions: The semisitting position with TEE monitoring and a standardized protocol is a safe and advantageous technique, taking account of a significant rate of VAEs. VAEs also occur in the supine position, but less frequently.

Keywords: Neurosurgery; Posterior cranial fossa; Semisitting position; Supine position; Transesophageal echocardiography; Vestibular schwannoma.