Detection of Venous Air Embolism in Nonsitting Craniotomy for Tumor Patients: A Retrospective Case Series.

Background: Venous air embolism (VAE) occurs when air enters the venous circulation. During nonsitting craniotomies with elevated VAE risk due to proximity to a venous sinus, our institutional practice is to employ precordial Doppler ultrasound (PDU) and transesophageal echocardiography (TEE) for monitoring, as well as central venous catheterization (CVC) for aspiration. We utilized an electronic medical record (EMR) database to assess the frequency of VAE occurrence, its clinical detection, and the use of VAE-specific monitoring modalities.

Methods: EMR review identified all patients who underwent nonsitting craniotomies for an intracranial tumor. To identify episodes of VAE occurrence, the EMR was screened for intraoperative VAE events as determined by clinical diagnosis (cVAE) as well as an EtCO2 drop >20% over a 2-minute interval, concerning for suspected VAE (sVAE). To identify patients who had VAE-specific monitoring, the EMR was scanned for placement of a CVC, TEE, or PDU.

Results: Three thousand nine hundred forty-five patients underwent a craniotomy for resection of tumor, and 3531 met study inclusion criteria. There were 14 episodes of intraoperative VAE diagnosed by a clinician (cVAE) and 86 episodes of suspected VAE (sVAE) based on review of anesthesia records for significant changes in EtCO2. There were 261 cases that used VAE-specific monitoring, with minimal overlap with sVAE cases.

Conclusions: We identified 100 episodes of VAE, diagnosed either clinically (cVAE) or by abrupt EtCO2 decrease (sVAE). Our data suggest that VAE in nonsitting craniotomy often occurs in instances where VAE-specific monitoring modalities are not used, and that our ability to preoperatively identify neurosurgical cases where VAE may occur is limited.