Effect of Reverse Trendelenburg Position Applied Before Pneumoperitoneum on Optic Nerve Sheath Diameter in Laparoscopic Bariatric Surgery: A Randomized, Controlled Study

Background: Laparoscopic surgery is usually associated with increased levels of intracranial pressure (ICP). The impact of positional changes on ICP measurements via optic nerve sheath diameter (ONSD) in bariatric surgery has yet to be studied. We aimed at evaluating the impact of positional changes on ONSD values during the laparoscopic sleeve gastrectomy. Methods: One hundred and four obese patients who underwent laparoscopic sleeve gastrectomy were recruited. Patients were allocated into two groups based on initiating pneumoperitoneum in supine (Group SP, n = 51) and reverse Trendelenburg (Group RTP, n = 53) positions. Intraoperative ONSD measurements were performed at different time points: T0 (baseline, before anesthesia induction), T1 (after endotracheal intubation), T2 (after pneumoperitoneum in Group SP and after positioning in Group RTP), T3 (after positioning in Group SP and after pneumoperitoneum in Group RTP), T4 (intraoperative), and T5 (after desufflation). ONSD measurements at different time points and postoperative nausea-vomiting are the primary outcomes. Results: ONSD values at T2 in Group RTP were significantly lower than in Group SP (p < 0.001). For T4 and T5 time points, there were significantly lower ONSD values in Group RTP (p = 0.004 and p = 0.040). Conclusions: Initiation of pneumoperitoneum in reverse Trendelenburg position resulted in significantly lower values of ONSD during laparoscopic bariatric surgery.