Comparison of the effects of pneumoperitoneum and position changes on optic nerve sheath diameters in laparoscopic and open nephrectomies

Objectives: Objectives: Laparoscopic nephrectomy is one of the most common operations among urological interventions. However, lateral trandelenburg position and pneumoperitoneum during surgery are known to cause intracranial pressure increases. Measurement of optic nerve sheath dimension (ONSD) using ultrasonography is a noninvasive and rather sensitive intervention that can be easily performed as a bedside assessment in the diagnosis of increased intracranial pressure. In this study we aimed to evaluate the ONSD measurement changes in patients undergoing laparoscopic or open nephrectomie operations. Material and Methods: Twenty-five patients who underwent laparoscopic nephrectomy and fourteen patients who underwent open nephrectomy were included in this prospective, observational study after ethics board approval (08/01/2018) was granted. In laparoscopic procedure, longitudinal and transverse measurements were performed for each eye by inserting a 7.5-10 Hz linear probe over the eyeball, and the mean values were calculated. First calculation was performed in the supine position after administration of standard general anesthesia (T0). In the lateral 45° downward position (T1), after carbondioxide (CO2), pneumoperitoneum (T2), at 30-minute intervals during surgery (T3, T4, T5), in the lateral position after insufflation (T6), in the supine position at the end of surgery (T7), and in the 24th postoperative hour (T8). standard general anesthesia (T0). In the lateral 45° downward position (T1), at 30-minute intervals during surgery (T2, T3, T4, T5), in the last measurement lateral position (T6), in the supine position at the end of surgery (T7), and in the 24th postoperative hour (T8). Demographic and clinical characteristics, hemodynamic (heart rate, mean arterial pressure) and respiratory parameters (SpO2, ETCO2) were recorded. In the postoperative period, patients were questioned for postoperative complications (nausea, vomiting) at 1st and 24th hours. Results: Fourteen open and twenty three laparoscopic nephrectomy patients who underwent ONSD measurements completed the study. The lower eye's ONSD, in the patients with laparoscopic nephrectomy, measured as 4.27±0.49 mm at the time of T0. The highest diameter was reached in T4 (4.99 ± 0.59 mm). The upper eye's ONSD was measured as 4.24±0.46 mm at the time of T0. The highest diameter was reached at the T5 time period ( 4,72±0,77 mm). Except the 24th hour's ONSD, all ONSD values were statistically significant higher than T0 value (p<0,001). In open nephrectomy patients, lower eye ONSD values was measured as 4.65±0.52 mm at the T0 time period. The upper eye ONSD was measured as 4.73±0.67 mm at the time of T0. The lower eye ONSD values at T5 (5,12±0,49mm) and T6 (5,15±0,65mm) time periods were statistically significant higher than T0 value (p<0,05). Conclusions Ultrasonound-guided ONSD measurements revealed increment with in minutes after both lateral 450 trandelenburg position and CO2 pnomoperitoneum in laparoscopic nephrectomy surgeries. We believe that ONSD monitorization in patients with high neurologic risk is very useful technic for the early diagnosis of intracranial pressure increase. Keywords: laparoscopic nephrectomy, open nephrectomy, ONSD measurement, intracranial pressure increase, Trendelenburg position, robotic surgery