Impact of controlled intraabdominal pressure on the optic nerve sheath diameter during laparoscopic procedures

Acute elevations of intraabdominal pressure (IAP) are seen in many clinical scenarios with a consequent elevation in intracranial pressure (ICP). With the optic nerve sheath (ONS) being a part of the dura mater and the optic nerve surrounded by cerebral spinal fluid, a change in pressure within the subarachnoid space would be detected by ultrasonography, and invasive methods could be avoided. The study objective was to evaluate ultrasonographic modifications observed on the optic nerve sheath diameter during acute elevations of IAP in patients undergoing laparoscopic procedures.

We prospectively collected data from patients who underwent laparoscopic procedures between July and August 2013. The optic nerve sheath diameter was measured sagittally with a 12-MHz transducer. The measurements were obtained at baseline, 15 and 30 min, and at the end of surgery.

There were 16 females (36.4%) and 28 males (63.6%), with a mean age of 44.22 ± 10.44 years (range 23-66) and body mass index of 29.45 ± 6.53 kg/m(2) (range 21-39). The mean optic nerve sheath diameter was 4.8 ± 1.0 mm at baseline, 5.5 ± 1.1 mm at 15 min, 5.9 ± 1.0 mm at 30 min, and 5.1 ± 1.2 mm after deflation of pneumoperitoneum. The diameter increased significantly at 15 min by a median of 0.6 mm (interquartile range 0.3, 0.8; p < 0.0001) and at 30 min by a median of 1.0 mm (interquartile range 0.7, 1.4; p < 0.0001), returning close to baseline after surgery.

The acute elevation in IAP during laparoscopy significantly increased the optic nerve sheath diameter. The changes in the ONSD reflect a temporary and reversible increase in the ICP due to the acute elevation of IAP.