The effect of obesity on optic nerve sheath diameter in patients undergoing laparoscopic gynecological surgery: a prospective observational study

Abstract

Purpose: Pneumoperitoneum and the steep Trendelenburg position during laparoscopic gynecological surgery may increase intracranial pressure, which can be estimated using ultrasound measurement of the optic nerve sheath diameter (ONSD). In this study, we evaluated the effect of obesity on ONSD in patients undergoing laparoscopic gynecological surgery.

Methods: Sixty-eight patients who underwent laparoscopic gynecological surgery were allocated to either the non-obese (n = 34) or obese (n = 34) groups. ONSD was assessed using ultrasound after anesthesia induction, at 30 and 60 min after pneumoperitoneum and Trendelenburg positioning, and at 10 and 60 min, and 24 h after desufflation and return to the supine position. Postoperative nausea and vomiting (PONV) and headache were evaluated 1 and 24 h after surgery.

Results: ONSD increased significantly during pneumoperitoneum and Trendelenburg positioning in both groups (P < 0.001, respectively) and was higher in the obese group at each time point throughout and after surgery (P < 0.007, respectively). The increased ONSD during surgery returned to baseline 24 h after desufflation in the non-obese group, but not in the obese group. The incidence of PONV 1 h after surgery was significantly higher in the obese group than in the non-obese group (59% vs. 21%, respectively; P = 0.001). The incidence of PONV 24 h after surgery and postoperative headaches were not different between the two groups.

Conclusion: ONSD was significantly higher in the obese group than in the non-obese group throughout and after laparoscopic gynecological surgery. The increased ONSD during surgery did not return to baseline even 24 h after desufflation in the obese group.

Keywords: Obesity; Optic nerve sheath diameter; Pneumoperitoneum; Trendelenburg position.

Fig. 1

Ultrasound measurement of the optic nerve sheath diameter (ONSD). The probe was applied in the transverse plane on the eyelid, and the optic nerve was observed longitudinally behind the orbit at its widest diameter. The ONSD was assessed as the distance between the external borders of the hyperechoic area surrounding the optic nerve, 3 mm behind the retina

Fig. 2

Study flow diagram. ONSD, optic nerve sheath diameter

Fig. 3

The change in optic nerve sheath diameter (ONSD) (mm) throughout and after surgery. Data are expressed as means. The error bars represent one SD. T_Induction, baseline after induction of anesthesia before artificial pneumoperitoneum and in the supine position; T_{Pneumo+Tren15m}, 15 min after artificial pneumoperitoneum with CO₂ insufflation and Trendelenburg position; T_{Pneumo+Tren30m}, 30 min after pneumoperitoneum and Trendelenburg position; T_{Pneumo+Tren60m}, 60 min after pneumoperitoneum and Trendelenburg position; T_{Desuff+Sup10m}, 10 min after deflation and return to the supine position; T_{Desuff+Sup60m}, 60 min after desufflation and return to the supine position; T_{Desuff+Sup24h}, 24 h after deflation and return to the supine position. *P < 0.008 vs. T_Induction in each group, †P < 0.007 vs. non-obese group

Fig. 4

The change in mean arterial pressure, end-tidal CO₂, and peak inspiratory pressure during perioperative period. Data are expressed as means. The error bars represent one SD. T_Induction, baseline after induction of anesthesia before artificial pneumoperitoneum and in the supine position; T_{Pneumo+Tren15m}, 15 min after artificial pneumoperitoneum with CO₂ insufflation and Trendelenburg position; T_{Pneumo+Tren30m}, 30 min after pneumoperitoneum and Trendelenburg position; T_{Pneumo+Tren60m}, 60 min after pneumoperitoneum and Trendelenburg position; T_{Desuff+Sup10m}, 10 min after deflation and return to the supine position; T_{Desuff+Sup60m}, 60 min after desufflation and return to the supine position; T_{Desuff+Sup24h}, 24 h after deflation and return to the supine position. *P < 0.05 vs. T_Induction in each group, †P < 0.05 vs. non-obese group