I understand your fears I am planning on the gastric sleeve next month myself. As a recovery nurse I see patients of all sizes go through anesthesia. There can be complications for anyone no matter your weight. You have to remember what risk you face being over weight and not having the surgery and see that your risk are so much higher not having the surgery. In surgery you are monitored by a CRNA or anesthesiologist 100% of the time. They stay right with you and watch the monitors and vitals adjusting meds as need be. Having sleep apnea you should bring your machine and you might take a little longer coming off oxygen but that's no big deal. I send people up to the floor on oxygen daily and they are off by the next day. Bottom line it's scary. I totally agree but the end result is worth it. Hang in there and best of luck to you!