Changes in Optic Nerve Sheath Diameter with Dexmedetomidine During Laparoscopic Surgery in Steep Trendelenburg Position: A Prospective Randomized Controlled Trial

Steep Trendelenburg positioning combined with carbon dioxide insufflation during laparoscopic surgery is associated with an increase in intracranial pressure (ICP). Dexmedetomidine, a selective α2-adrenoceptor agonist, may attenuate this rise. This study evaluated the effect of intravenous dexmedetomidine on optic nerve sheath diameter (ONSD) with a primary objective to assess the change at 1 hour after the Trendelenburg position. The secondary objectives were to compare the mean ONSD at various time points, hemodynamic parameters, and postoperative pain. Dexmedetomidine on ICP using ONSD as a surrogate marker. This prospective, randomized, double-blind, placebo-controlled trial included 50 American Society of Anesthesiologists (ASA) physical status I–II patients undergoing elective laparoscopic surgery requiring steep Trendelenburg position (15°–45°). Patients were randomized to receive dexmedetomidine (Group D, n = 25; 1 µg/kg over 10 minutes followed by 0.4 µg/kg/h infusion) or normal saline (Group N, n = 25). Ultrasonographic ONSD was measured at baseline, 5 minutes after Trendelenburg positioning, 1 hour after positioning, and 5 minutes after peritoneum deflation. The mean ONSD was significantly lower in Group D compared with Group N at 1 hour after Trendelenburg positioning (5.8 ± 0.9 vs. 6.7 ± 0.5 mm; p < 0.001). Hemodynamic parameters remained comparable between groups. Postoperative pain scores showed statistically significantly lower values till the first postoperative hour. Intravenous dexmedetomidine significantly reduces the ONSD during laparoscopic surgery in a steep Trendelenburg position as early as 1 hour after pneumoperitoneum and Trendelenburg position when compared with placebo.