Endotracheal intubation may cause significant increases in blood pressure, heart rate, and intracranial pressure, particularly in patients undergoing cerebral aneurysm coil embolization. Remifentanil and esmolol are commonly used agents to attenuate these responses during anesthesia induction.

This randomized controlled trial aims to compare the effects of remifentanil and esmolol administered before endotracheal intubation on optic nerve sheath diameter/eyeball transverse diameter ratio (ONSD/ETD), a noninvasive surrogate marker of intracranial pressure, as well as hemodynamic responses in patients undergoing elective cerebral aneurysm coil embolization.

The findings may help identify the most effective strategy for minimizing intubation-related intracranial pressure changes and hemodynamic fluctuations in neurointerventional anesthesia practice.

Endotracheal intubation is one of the most stimulating periods during induction of general anesthesia and is associated with transient increases in blood pressure, heart rate, and intracranial pressure. These responses may be particularly important in patients undergoing cerebral aneurysm coil embolization, where excessive hemodynamic fluctuations and increases in intracranial pressure may adversely affect procedural safety.

Optic nerve sheath diameter (ONSD) measured by ultrasonography has emerged as a noninvasive marker of intracranial pressure. The optic nerve sheath diameter-to-eyeball transverse diameter ratio (ONSD/ETD) has been proposed as a more standardized parameter that may reduce interindividual variability.

Remifentanil and esmolol are widely used agents for attenuation of the hemodynamic response to endotracheal intubation. Although both agents have been shown to reduce sympathetic activation during airway manipulation, their comparative effects on ONSD/ETD ratio and intubation-related intracranial pressure changes in patients undergoing neurointerventional procedures remain unclear.

The aim of this prospective randomized controlled trial is to compare the effects of remifentanil and esmolol administered before endotracheal intubation on ONSD/ETD ratio and hemodynamic parameters in adult patients undergoing elective cerebral aneurysm coil embolization. Participants will be randomized in a 1:1 ratio to receive either remifentanil (0.5-1 µg/kg IV) or esmolol (0.5-1 mg/kg IV) administered over 90 seconds before intubation.

ONSD/ETD measurements and hemodynamic parameters will be recorded before intubation (T0), 5 minutes after intubation (T1), and 10 minutes after intubation (T2). The primary outcome will be the change in ONSD/ETD ratio at 5 minutes after intubation. Secondary outcomes include changes in ONSD/ETD ratio at 10 minutes, mean arterial pressure, heart rate, and vasopressor requirements.

The results of this study may provide evidence regarding the optimal pharmacological strategy for attenuating intubation-related intracranial pressure changes and hemodynamic responses in patients undergoing cerebral aneurysm coil embolization.

Inclusion Criteria:

• Age ≥18 years
• American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled for elective cerebral aneurysm coil embolization under general anesthesia
• Planned endotracheal intubation
• Ability to provide written informed consent

Exclusion Criteria:

• Emergency procedures
• Hemodynamic instability before induction of anesthesia
• Severe cardiac conduction abnormalities or clinically significant arrhythmias
• Contraindication or allergy to remifentanil or esmolol
• Chronic opioid use or opioid dependence
• Known orbital disease, ocular trauma, or conditions interfering with optic nerve sheath diameter measurements
• Anticipated difficult airway
• Pregnancy
• Refusal to participate in the study

There is no plan to make individual participant data (IPD) publicly available.