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Updated: Mar 20, 2026
Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition
Published on: August 18, 2023
Changes in Optic Nerve Sheath Diameter With Lateral Decubitus Positioning and Pneumoperitoneum Pressure During
Serkan Akan1, Umut Arslan1,2, Ahmet Tasci1,3
1Department of Urology, University of Health Sciences, Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.
Objectives:
The aim of this study is to assess the effects of the 45° lateral decubitus positioning and CO2 pneumoperitoneum pressure increases on the intracranial pressure via sonographically measured optic nerve sheath diameter (ONSD) in patients undergoing laparoscopic partial nephrectomy (LPN).
Methods:
In this prospective observational study, all patients underwent an LPN procedure. By using ocular ultrasonography, vertical and horizontal ONSDs were measured for each eye in the supine position preoperatively (T0), 10 min after the anesthesia induction in the supine position (T1), before the insufflation in the 45° lateral decubitus position (T2), after the insufflation with incremental pressures during the procedure (T3-T4-T5-T6-T7), and before awakening from anesthesia in the supine position (T8). Between the T3 and T7 measurement points, the pneumoperitoneum pressures were gradually increased from the level of 12 mmHg up to 20 mmHg by 2 mmHg in each step.
Results:
A total of 103 patients, whose ages ranged from 25 to 69 years, were included in the study. A significant increase in the ONSDs was found in each measurement point from T0 to T7 (p < 0.05). The mean ONSDs were 4.4, 5.7, and 5.8 mm in T0, T6, and T7, respectively. However, as a result of a decrease in T8, the mean ONSD was similar to that in T2 (p > 0.05).
Conclusion:
Our study demonstrated that in the 45° lateral decubitus position, pneumoperitoneum pressures of 18-20 mmHg during LPN caused ONSD values to approach the threshold for elevated intracranial pressure.
