Patients with obstructive sleep apnea tend to be more sensitive to what would otherwise be non-obstructive doses of drugs. That's a risk that he should be aware of. Another way to provide comfort during surgery is regional anesthesia, especially for extremities like arms and legs, and some abdominal procedures. Parts of the body can be numbed without giving any centrally acting drugs. Normally narcotics are used to relieve pain.
Narcotics suppress everyone's drive to breathe.
If one has a lower respiratory drive to begin with, narcotics can make that even more dramatic. By numbing just the part of the body being operated on, there is no need to give centrally acting drugs. Epidural is quite often used to relieve the pain of labor. Many surgeries below the ribcage can be done with epidural. For patients with sleep apnea, this is an especially nice way to work, because it provides comfort and safety without affecting the respiratory drive or the musculature of the pharynx.