Large visible gas bubbles in the internal jugular vein: a common occurrence during supine radical neck surgery?

To establish the frequency of large visible bubbles or collections of bubbles in the jugular vein during radical neck dissection in the supine position.

Prospective observation by at least two investigators of random consecutive patients scheduled for radical neck surgery.

Operating room suite in a university hospital specializing in head and neck cancer surgery.

Twelve consecutive ASA physical status II and III patients undergoing modified radical dissection for cancer.

General anesthesia with fentanyl, oxygen (O2) 30% to 40%, nitrous oxide (N2O) 60% to 70%, and isoflurane 0.5% to 1.5%, with mechanical ventilation. Table position horizontal. Modified radical neck dissections performed by attending surgeons. Surgical field (jugular vein) carefully observed by the surgeons and an independent anesthesiologist investigator for the presence of bubbles during the dissection.

Easily visible bubbles were observed in the jugular veins of 42% (5 of 12) of the consecutive radical neck dissection patients studied. Some of the collections of bubbles were large (greater than 2.5 cm in diameter). In one case, the appearance and subsequent disappearance of bubbles was followed by a transient drop in arterial blood pressure (BP) and in end-tidal carbon dioxide (PETCO2), which was suggestive of a diagnosis of central venous air embolization.

We theorize that some unexplained, undesirable intraoperative events (hypotension, arrhythmia, and hypoxemia) during radical neck dissection could be a result of venous air embolus or paradoxical air embolus. The anesthesia community should be aware of the high frequency of these visible bubbles in the jugular veins during radical neck surgery, even in the supine position. At minimum, this phenomenon is a frequent event of intellectual interest. At worst, these bubbles may be harbingers of significant central air embolism.