Influence of carbon dioxide insufflation of the neck on intraocular pressure during robot-assisted endoscopic thyroidectomy: a comparison with open thyroidectomy.

BACKGROUND: Increased intraocular pressure (IOP) during surgery can result in serious ophthalmic complications. We hypothesized that carbon dioxide (CO2) insufflation of the neck during endoscopic thyroidectomy would constrict the jugular veins mechanically, causing elevated venous pressure and thus elevated IOP. We compared IOP changes at each step of open thyroidectomy (OT) versus robot-assisted endoscopic thyroidectomy (RET) METHODS: Perioperatively, IOP was measured at six time points in patients undergoing OT (n = 18) or RET with CO2 insufflation (n = 19). Anesthesia, ventilatory strategy, intravenous infusions, and surgical positioning were standardized RESULTS: In both groups, induction of anesthesia reduced IOP, but surgical positioning with the neck in extension had no effect on IOP. In the OT group, IOP remained unchanged during anesthesia. In the RET group, CO2 insufflation significantly increased IOP to an average of 3.6 ± 3.0 mmHg higher than the previous measurement (P < 0.001), and this IOP increase persisted immediately before gas deflation. These elevated IOP values during CO2 insufflation in the RET group were significantly higher than those at corresponding time points in the OT group. However, these elevated IOP values were similar to the pre-anesthetic baseline IOP CONCLUSION: CO2 insufflation of the neck at pressure of 6 mmHg increased the IOP significantly compared with open thyroidectomy. However, this increase in IOP could be balanced by an anesthetic-induced IOP-lowering effect, thereby having no clinical significance in patients with normal IOP undergoing robot-assisted endoscopic thyroidectomy.