The Effect of Nitrous Oxide on the Intraocular Pressure in Patients Undergoing Abdominal Surgery under Sevoflurane and Remifentanil Anesthesia

Abstract

Introduction: Although inhalational anesthesia and nitrousoxide (N 2 O) are known to affect the intraocular pressure (IOP), little is known about the effect of nitrousoxide on the IOP during sevoflurane and remifentanil anesthesia. In the present study, we examined the effect of balanced anesthesia on the IOP. Materials and Methods: After obtaining informed consent, the patients undergoing abdominal surgery under general anesthesia were divided into two groups: N 2 O group (n = 10) and control group (n = 12). General anesthesia was maintained with remifentanil (0.05 -0.3 µg/kg/min), 33% O 2 and 1.2% sevoflurane to keep ETCO 2 of 35 -40 mmHg following tracheal intubation. After baseline measurement of IOP (T0, 20 minutes after injection of anesthesia), the patients in the N 2 O group received 67% nitrousoxide, and the patients in the control group received air, with O 2 and 1.2% sevoflurane. Then, IOP was measured at 1 hour (T1), 2 hours (T2), and 3 hours (T3) after anesthesia induction in the supineposition. Blood pressure and heart rate were recorded at the same time interval. Results: There was no significant difference in the IOP at any period between the two groups. In both groups, the IOP at the T3 was significantly higher than that at T0. Conclusion: These results suggest that N 2 O does not affect the IOP in patients undergoing abdominal surgery under sevoflurane and remifentanil anesthesia.