Utility of optic nerve sheath ultrasound during laparoscopic colorectal surgery

Abdominal laparoscopic surgery to treat colorectal cancer has been shown to be more effective than open surgery in terms of mobility, hospital stay, tumour recurrence and long-term survival. This surgical approach requires pneumoperitoneum and the Trendelenburg position (35-45º), both of which have a negative effect on the cardiovascular system and can even change the cerebrovascular physiology, leading to an increase in intracranial pressure (ICP). Ultrasound measurement of optic nerve sheath (ONS) diameter has shown excellent correlation with invasive ICP measurement.

To correlate the increase in ONS diameter with surgical time and time to emergence after anaesthesia. The incidence of visual disturbances (visual acuity) and/or neurological complications (agitation, cognitive dysfunction) in the immediate postoperative period was also evaluated.

30 consecutive patients undergoing laparoscopic surgery for rectal or sigmoid adenocarcinoma were recruited. Pre-, intra- and postoperative ONS measurements were obtained and the Snellen test for visual acuity, Mini Mental Test for cognitive function, and the Richmond Agitation and Sedation Scale (RASS) were administered.

ONS increased intraoperatively in both eyes compared to baseline. However, this was not correlated with total surgical time or time to emergence, and there was no statistically significant correlation between ONS and postoperative neurological or visual alterations.