The Effect of Neostigmine and Sugammadex on the Optic Nerve Sheath Diameter

The study will be conducted prospectively, randomly, and double-blind on a total of 86 patients aged 18-65 years, classified as ASA 1-2, undergoing elective surgery at the Department of Anesthesiology and Reanimation, Faculty of Medicine, Çukurova University. Written and verbal informed consent will be obtained from all participants prior to the study.

The demographic data, such as age, gender, body weight, and height, as well as ASA score and information on comorbidities, will be recorded for the patients included in the study in the preoperative anesthesia care unit. All patients who will be taken to the operating room without premedication will undergo routine monitoring, including electrocardiography, noninvasive blood pressure monitoring, and peripheral oxygen saturation. During induction of anesthesia, propofol IV 2 mg/kg, rocuronium IV 0.6 mg/kg, and fentanyl IV 1 mcg/kg will be used. After observing adequate muscle relaxation with a TOF (Train-of-Four) monitor, tracheal intubation will be performed. All patients will receive mechanical ventilation after intubation. During anesthesia, a gas mixture of 2% sevoflurane, 60% nitrous oxide, and 40% oxygen will be administered at a flow rate of 2 L/min. To maintain muscle relaxation throughout the surgery, when a TOF of 2 is observed, 0.2 mg/kg of rocuronium IV will be administered. Tramadol 2 mg/kg IV will be given 45 minutes before the end of surgery for postoperative pain management. Ondansetron 8 mg IV will be planned as antiemetic treatment. At the end of the surgery, the maintenance gases will be discontinued, and according to the randomization, the anesthesiologist responsible for anesthesia administration will either administer 2 mg/kg Sugammadex IV or 0.05 mg/kg Neostigmine IV plus 0.02 mg/kg atropine sulfate IV. Patients who show a TOF value of 90% and clinically adequate respiration will be extubated.

In addition to the anesthesiologist responsible for administering anesthesia, one blinded evaluator for each group will perform three ultrasound measurements on both eyes to determine the Optic nerve sheath diameter at 5 minutes after endotracheal intubation, 5 minutes before extubation, and 5 minutes after extubation. The measurements will be recorded while the patient is in a supine position, with ultrasound gel applied to the eyelid, using a linear probe without applying pressure to the eyeball.

The diameter of the optic nerve sheath will be systematically measured at a point 3.0 mm posterior to the optic disc to ensure consistent anatomical evaluation.