For this particular case, you should be able to perform it under light injectable anesthesia. I recommend placing an IV catheter and providing mask/flow-by with oxygen in the perioperative period. I would also have a laryngoscope and multiple endotracheal tubes (sized for the patient) to secure an airway if the patient becomes apneic or hypoxemic despite oxygen supplementation. The patient can then be maintained on inhalant gas (isoflurane/sevoflurane) or intermittent boluses of propofol.

Protocol:
Butorphanol 0.2 mg/kg IM (for catheter placement)
Propofol 2 mg/kg IV with repeat boluses of 0.5 mg/kg IV as needed
Ophthalmic tetracaine

Monitoring:
Pulse oximetry, ECG and non-invasive blood pressure.