“My patient’s an airhead!” Management of air embolism during sitting craniotomy

The case A 52-year-old man presents to the preop area for a craniotomy for tumor. You reviewed the patient's records the prior day and noted that he was previously healthy but has recently developed severe headaches. Imaging of the head revealed a sizable mass compressing the brain stem, with some cerebral edema involving the pons. Your attending for the day doesn't usually do neuro cases, especially craniotomies. The surgeon wants maximal operative exposure and really wants this to be an “awake crani” so that the patient can be quickly assessed for new neuro deficits. He strongly requests an awake crani in the sitting position. Your attending says, “Sure, whatever you want.” You remember from your studies that these procedures are dangerous, but you can't really remember why. You convince your attending to put in both a central line and an arterial line. These are placed, with some sedation, into the right internal jugular vein and left radial artery, respectively. The patient is positioned and sedated to a zombielike state with a dexmedetomidine drip. You've given the patient 1 g/kg of mannitol, 10 mg of dexamethasone, and 750 cc of normal saline. Incision goes well, partly due to your superb bilateral scalp block. You notice that the surgical field is rather dry, once the skull flap is removed. You're now smiling and excited. Things are going well! Thirty minutes later, the surgeon tells you that he got into the venous sinus but that he thinks he can control things quickly.