Intravenous Magnesium Sulphate Versus Dexmedetomidine for Prevention of Emergence Agitation in Adult Otorhinolaryngologic Surgery

Comparison on the Effectiveness of Intravenous Magnesium Sulphate and Intravenous Dexmedetomidine in Reducing Emergence Agitation in Adults Undergoing Otorhinolaryngology Surgery

The goal of this clinical trial is to learn whether intravenous magnesium sulphate can reduce emergence agitation as effectively as intravenous dexmedetomidine in adult patients undergoing otorhinolaryngology surgery under general anesthesia.

The main questions it aims to answer are:

- Is intravenous magnesium sulphate non-inferior to intravenous - dexmedetomidine in reducing the proportion of emergence agitation (defined as Richmond Agitation-Sedation Scale [RASS] ≥2)? Are there differences between the two drugs in terms of hemodynamic stability, severity, onset and duration of emergence agitation, and recovery profile? Researchers will compare continuous intravenous magnesium sulphate infusion (20 mg/kg/hour) with continuous intravenous dexmedetomidine infusion (0.5 µg/kg/hour) to see if magnesium sulphate provides similar protection against emergence agitation with fewer hemodynamic side effects.

Participants will:

• Be randomized to receive either magnesium sulphate or dexmedetomidine infusion from induction of anesthesia until the end of surgery.
• Undergo standardized general anesthesia with sevoflurane, fentanyl, and rocuronium.
• Be assessed for emergence agitation using the Richmond Agitation-Sedation Scale (RASS) after discontinuation of anesthetic agents.
• Have intraoperative heart rate, mean arterial pressure, anesthetic consumption, and vasoactive drug use recorded.
• Be evaluated postoperatively for pain, opioid requirement, and extubation time.

This multicenter, double-blinded, randomized controlled trial was designed to evaluate two intraoperative pharmacologic strategies used during general anesthesia for adult otorhinolaryngologic surgery.

The study is based on differing pharmacodynamic mechanisms: dexmedetomidine provides central sympatholysis via selective α2-adrenergic receptor activation, while magnesium sulphate modulates neuronal excitability primarily through NMDA receptor antagonism and calcium channel blockade. Both agents are administered as continuous infusions during surgery without a loading dose to allow steady-state effects and minimize abrupt hemodynamic changes.

Randomization is performed using a computer-generated sequence with allocation concealment. Study medications are prepared by independent pharmacy personnel in identical syringes to maintain blinding of anesthesia providers, patients, and investigators. Perioperative anesthetic management is standardized across sites to reduce variability in clinical practice.

Physiologic parameters are recorded at predefined perioperative intervals using structured case report forms. Data are analyzed using appropriate statistical methods based on distribution characteristics, including longitudinal modeling to account for repeated intra-subject measurements. A two-sided significance threshold is prespecified for all analyses.

Inclusion Criteria:

• Adult patients aged 18-70 years
• ASA physical status I or II
• Undergoing elective otorhinolaryngology surgery under general anesthesia
• Willing to participate and provide informed consent

Exclusion Criteria:

• Pregnant patients
• Severe cognitive impairment
• Known allergy to study drugs
• Contraindications to study drugs (atrioventricular block, sinoatrial node dysfunction, renal failure)
• Neuromuscular disorders
• Regular use of beta-blockers or clonidine
• Not extubated in the operating room or post-anesthesia care unit after procedure
• Body mass index (BMI) ≥ 40