2026 FSA Podium and Poster Abstracts

Background: Venous air embolism (VAE) remains a significant complication of posterior fossa surgery in the sitting position, with incidence rates of up to 56% when sensitive monitoring is employed.1 Fenestrated central venous catheters are commonly placed for air aspiration, though their efficacy can be compromised by thrombosis. Cancer patients undergoing neurosurgery face elevated thrombotic risk, particularly those with metastatic disease.2 This case involves recurrent VAE during sitting position craniotomy complicated by catheter thrombosis in a patient with metastatic malignancy.

Case Description: A 62-year-old female with newly diagnosed posterior fossa mass, tongue base mass, and lung nodules presented with obstructive hydrocephalus requiring suboccipital craniotomy for fourth ventricular tumor resection. Given the sitting surgical position and inability to place TEE due to the tongue mass, monitoring included precordial Doppler, ETCO2, and a fenestrated central venous catheter. 

Two hours into surgery, sudden ETCO2 drop and precordial Doppler changes, and hemodynamic instability suggested VAE. Immediate aspiration through the fenestrated catheter yielded blood with air bubbles. Hypotension was treated with phenylephrine. Lidocaine 100 mg and magnesium infusion were administered for bigeminy. The surgical field was flooded with water. The fenestrated catheter subsequently clotted and could no longer aspirate effectively. ETCO2 normalized and hemodynamics stabilized. 

Two additional VAE episodes occurred roughly 60 and 90 minutes post-initial event. Attempts to aspirate through the occluded catheter were unsuccessful. Each episode was managed with surgical field flooding and vasopressor support with successful hemodynamic recovery. The procedure was completed without conversion to supine positioning. 

The patient was extubated and transferred to SICU hemodynamically stable. Final pathology revealed primary tongue base pleomorphic mesenchymal malignant tumor with metastases to brain and lung. During the hospitalization, she developed an acute calf DVT and was started on apixaban by hematology prior to discharge.

Discussion/Conclusion: This case illustrates successful VAE management despite loss of aspiration capability through catheter thrombosis. While fenestrated catheters are traditionally placed for air aspiration during sitting position cases, their utility may be limited by thrombosis, particularly in hypercoagulable cancer patients. The patient's underlying metastatic malignancy likely contributed to both intraoperative catheter thrombosis and postoperative DVT. 

Standard VAE management principles such as flooding the surgical field, hemodynamic support, and surgical team notification proved effective despite inability to aspirate air. Precordial Doppler and ETCO2 monitoring provided sufficient VAE detection when TEE was contraindicated. 

Strategies to prevent catheter thrombosis may continuous infusion through the fenestrated catheter or pressure transduction with a pressurized flush system. Continuous low-speed infusion techniques significantly reduce catheter occlusion rates (17.4% vs 43.5%) compared to intermittent flushing.3 Transducing the catheter with a pressure bag provides continuous positive pressure to prevent blood backflow and thrombosis while maintaining CVP monitoring capability. These preventive measures may be particularly important in cancer patients with elevated thrombotic risk undergoing prolonged procedures that need reliable venous access.

This case highlights that fenestrated catheter thrombosis does not preclude safe VAE management when alternative monitoring and supportive measures are employed. Anesthesiologists should maintain heightened awareness for catheter dysfunction in cancer patients and consider prophylactic strategies to maintain catheter patency.