TCI Eleveld

The goal of this clinical trial is to compare the effects of Opioid Free Anesthesia (OFA) with and without volatile anesthetics (in this case desflurane) in patients undergoing bariatric surgery. The main question it aims to answer : -Will there be a difference in the perioperative stress between patients receiving OFA with and without desflurane? Participants will undergoing sleeve gastrectomy or gastric by pass, will be administered OFA with and without desflurane and blood tests (cortisole, ACTH,dopamine, PRL, adrenaline, noradrenaline, lactate) will be collected perioperatively to compare stress in the two groups.