The Effect of the modified Z Trendelenburg position on intraocular pressure during robotic assisted laparoscopic radical prostatectomy : a randomized, controlled study

Purpose: The Trendelenburg position has a dramatic effect on circulation, consequently increasing cerebral and intraocular pressure. We evaluated whether modifying the Trendelenburg position would minimize the increase in intraocular pressure. Materials and Methods: In this prospective, randomized, controlled study we compared intraocular pressure in patients undergoing robot-assisted laparoscopic radical prostatectomy while in the Trendelenburg position or the modified Z Trendelenburg position. In group 1 intraocular pressure, blood pressure and endotracheal CO₂ were measured in the patient at anesthesia induction (time 1), before positioning (time 2), and while in the Trendelenburg position (time 3) and in the modified Z Trendelenburg position (time 4). They were also measured after pneumoperitoneum (time 5), every 30 minutes (times 6 to 16), while supine at the end of pneumoperitoneum (time 17) and before awakening (time 18). We modified the Trendelenburg position by placing the head and shoulders horizontally. Results: Group 1 included 29 patients in the modified Z Trendelenburg position. Group 2 included 21 patients in the Trendelenburg position. No difference was found in patient demographics or surgical outcomes. Median intraocular pressure was in the low normal range at times 1 and 2, and increased in time 3 in each group. From time 4 intraocular pressure decreased and at all time points it was significantly lower in group 1 by a mean of 4.61 mm Hg (95% CI −6.90–2.30, p