Effects of positive end-expiratory pressure on intraocular pressure and optic nerve sheath diameter in robot-assisted laparoscopic radical prostatectomy

Background: There has been no study of the effect of post end-expiratory pressure (PEEP) on intraocular or intracranial pressure during pneumoperitoneum with steep Trendelenburg positioning. We investigated the effects of 5cmH2O of PEEP on intraocular pressure and optic nerve sheath diameter as a surrogate for intracranial pressure in robot-assisted laparoscopic radical prostatectomy. Methods: Fifty patients scheduled for robot-assisted laparoscopic radical prostatectomy were divided into a zero-PEEP (ZEEP) group and a 5cmH2O of PEEP (PEEP) group. Intraocular pressure, optic nerve sheath diameter, and respiratory and hemodynamic parameters were measured before induction (T0), 10minutes after induction of general anesthesia in the supine position before CO2 insufflation (T1), 5minutes (T2), and 30minutes (T3) after steep Trendelenburg positioning with pneumoperitoneum, after desufflation of pneumoperitoneum in the supine position (T4), and after 30minutes in the recovery room postoperatively (T5). Results: There was no significant difference in intraocular pressure or optic nerve sheath diameter between the groups during the study. The partial pressure of arterial oxygen and dynamic lung compliance at T1, T2, T3, and T4 were significantly higher in the PEEP than in the ZEEP group. There was no difference in mean arterial pressure or heart rate between groups at any time. Conclusion: Applying 5cmH2O of PEEP did not increase intraocular pressure or optic nerve sheath diameter during pneumoperitoneum with steep Trendelenburg positioning in robot-assisted laparoscopic radical prostatectomy. These results suggest that low PEEP can be safely applied during surgery with pneumoperitoneum and steep Trendelenburg positioning in patients without preexisting eye disease and brain pathology.