Ultrasonographic optic nerve sheath diameter for assessing the effect of pneumoperitoneum and Trendelenburg position on intracranial pressure during gynecologic surgery: a prospective observational study

Previous studies have shown that pneumoperitoneum and the Trendelenburg position can increase intracranial pressure (ICP). The optic nerve sheath diameter (ONSD) measurement using ultrasound has emerged as a simple, noninvasive, and reliable surrogate for invasive ICP measurement. This prospective study enrolled 121 patients undergoing gynecologic laparoscopic surgery under general anesthesia. ONSD was measured using ultrasonography at different time points during surgery. All patients were assessed Postoperative headache, nausea and vomiting, blurred vision, and cognitive dysfunction within 1 day of recovery. After establishing the pneumoperitoneum in the Trendelenburg position, ONSD increased over time and decreased significantly upon release of the pneumoperitoneum and return to the supine position (p < 0 .05). However, ONSD did not return to baseline levels 1 h after the release of the pneumoperitoneum and return to the supine position (4.63 mm vs. 4.52 mm, p < 0.05). Different Trendelenburg angles during the surgeries revealed a significant upward trend in ONSD with increasing tilt angles (p < 0.05). Patients with ONSD > 5 mm experienced higher rates of postoperative headache, nausea and vomiting, blurred vision, and cognitive dysfunction than those with ONSD ≤ 5 mm (p < 0.05 respectively). The combination of pneumoperitoneum and Trendelenburg position significantly increased ONSD during surgery. The longer the duration of the pneumoperitoneum and the steeper the Trendelenburg position, the more significant the increase in ONSD. Postoperative headache, nausea and vomiting, blurred vision, and cognitive dysfunction were significantly associated with an intraoperative ONSD > 5 mm.