Intraocular pressure in pediatric patients during prone surgery.

BACKGROUND Intraoperative intraocular pressure (IOP) in the prone position and IOP changes over time have not been evaluated in pediatric surgical patients. We sought to determine time-dependent changes in IOP in children undergoing surgery in prone position. METHODS Thirty patients undergoing neurosurgical procedures in prone position were included. Using a pulse-mode pneumatonometer, IOP was measured in supine position after induction and before emergence of anesthesia and in prone position before the start and after the end of surgery. IOP changes over time in the prone position were assessed with a linear mixed model (i.e., random slope and intercept model) to adjust for the within-patient correlation. RESULTS IOP in prone position increased by an average of 2.2 mm Hg per hour (P < 0.001). Sixty-three percent of patients (95% confidence interval [CI], 46%-81%) had at least 1 IOP value exceeding 30 mm Hg, and 13% (95% CI, 1%-25%) had at least 1 IOP value exceeding 40 mm Hg while prone. Mean IOP increased 7 mm Hg (95% CI, 6-9) during the position change from supine to prone (P < 0.001) and decreased 10 mm Hg (95% CI, 9-12) after changing the position from prone back to supine (P < 0.001). CONCLUSIONS Changing position from supine to prone significantly increases IOP in anesthetized pediatric patients. Moreover, the IOP continued to increase during surgery and reached potentially harmful values, especially when combined with low mean arterial blood pressures that are common during major surgery.