Patient Safety Section Editor: Sorin J. Brull The Effects of Steep Trendelenburg Positioning on Intraocular Pressure During Robotic Radical Prostatectomy Hamdy Awad, MD* Scott Santilli, BA† Matthew Ohr, MD‡ Andrew Roth, MD* Wendy Yan, MD§ Soledad Fernandez, PhD Steven Roth, MD¶ Vipul Patel, MD# BACKGROUND: Intraocular pressure (IOP) increases in steep Trendelenburg position- ing, but the magnitude of the increase has not been quantified. In addition, the factors contributing to this increase have not been studied in robot-assisted prostatectomy cases. In this study, we sought to quantify the changes in IOP and examine perioperative factors responsible for these changes while patients are in the steep Trendelenburg position during robotic prostatectomy. METHODS: In this prospective study, we measured IOP using a Tono-pen XL in 33 patients undergoing robot-assisted prostatectomy. The IOP was measured bef- ore anesthesia while supine and awake (baseline T1), anesthetized and supine (T2), anesthetized after insufflation of the abdomen with carbon dioxide (CO 2 ) (T3), anesthetized in steep Trendelenburg (T4), anesthetized in steep Trendelenburg at the end of the procedure (T5), anesthetized supine before awakening (T6), and 1 hr after awakening in the supine position (T7). RESULTS: On average, IOP was 13.3  0.58 (mean  se) mm Hg higher at the end of the period of steep Trendelenburg position (T5) compared with supine position T1 (P  0.0001). The least square estimates for each time point in mm Hg were as follows: T1 = 15.7, T2 = 10.7, T3 = 14.6, T4 = 25.2, T5 = 29.0, T6 = 22.2, T7 = 17.0. Using univariate mixed effects models for the T1–T5 time periods, peak airway pressure, mean arterial blood pressure, ETco 2 , and time were significant predictors of the IOP increase, whereas age, body mass index, blood loss, volume of IV fluid administered, mean airway pressure, and desflurane concentration were not predic- tive. In T4 –T5, which involved no significant positional or perioperative interventions, we performed a multivariate analysis to evaluate predictors of IOP increases. Surgical duration (in minutes) and ETco 2 were the only significant variables predicting changes in IOP during stable and prolonged Trendelenburg positioning. On average, IOP increased 0.21 mm Hg per mm Hg increase in ETco 2 after adjusting for time. An increase of 0.05 mm Hg in IOP per minute of surgery on average was observed during this period in the Trendelenburg position after adjusting for ETco 2 . CONCLUSIONS: IOP reached peak levels at the end of steep Trendelenburg position (T5), on average 13 mm Hg higher than the preanesthesia induction (T1) value. Surgical duration and ETco 2 were the only significant predictors of IOP increase in the Trendelenburg position (T4 –T5). (Anesth Analg 2009;109:473–8) After skin cancer, prostate cancer is the most com- mon cancer in men in the United States and the third leading cause of cancer death in this group. 1 There are many treatment options available, and robotic- assisted radical prostatectomy is one of the newest and most technically advanced. Its advantages include decreased blood loss and postoperative pain, shorter hospital stay, and faster recovery time. 2 Demand for the procedure is increasing worldwide. Many urologic procedures, including robotic radi- cal prostatectomy, require specific body positioning in which the patient must be placed in steep Trendelen- burg position (25– 45 degree head down). 3 This posi- tioning uses gravity to pull the abdominal viscera away from the operative field, but is nonphysiologic and may have significant negative physiologic effects when maintained for long periods of time. Few stud- ies have addressed the impact of placing surgical patients in this position for extended periods. Compli- cations of radical robotic prostatectomy positioning were reported in two patients: postextubation respira- tory distress attributed to laryngeal edema in one, and From the *Department of Anesthesiology, The Ohio State Univer- sity Medical Center; †The Ohio State University College of Medicine; ‡The Ohio State University Medical Center, Columbus, Ohio; §UC Davis Department of Anesthesiology and Pain Medicine, Sacramento, California; Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, Ohio; ¶Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois; and #Florida Celebration Hospital, Global Robotics Institute, Celebration, Florida. Accepted for publication February 20, 2009. Supported by Department of Anesthesiology, The Ohio State University Medical Center. Reprints will not be available from the author. Address correspondence to Hamdy Awad, MD, Department of Anesthesiology, The Ohio State University, 410 W. 10th Ave. N411, Columbus, OH 43210. Address e-mail to Hamdy.Elsayed-Awad@ osumc.edu. Copyright © 2009 International Anesthesia Research Society DOI: 10.1213/ane.0b013e3181a9098f Vol. 109, No. 2, August 2009 473