Lidocaine, Dexmedetomidine, Esmolol and Magnesium Effect on Optic Nerve Sheath Diameter After Laryngoscopy

This study compares four different medications — lidocaine, dexmedetomidine, esmolol, and magnesium — used to reduce the body's stress response during the insertion of a breathing tube (endotracheal intubation) for general anesthesia. The goal is to find which drug best prevents the dangerous spike in heart rate and blood pressure that can occur during this procedure. **You may be eligible if...** - You are aged 18–80 and scheduled for a surgical procedure requiring general anesthesia with a breathing tube - You have an ASA physical status of I, II, or III (generally healthy to mild-moderately ill) **You may NOT be eligible if...** - You are allergic to dexmedetomidine, esmolol, lidocaine, or magnesium - You have uncontrolled high blood pressure or severe heart failure - You have a heart rhythm disorder (arrhythmia) - You have severe kidney or liver disease - You have a known brain or neurological condition, or a history of seizures - Your airway was difficult to manage during intubation Talk to your doctor to see if this trial is right for you.