Two Intravenous Doses of Ketamine in Reducing the Oculocardiac Reflex in Adult Patients Undergoing Ophthalmic Surgery

Evaluation of Two Intravenous Doses of Ketamine in Reducing the Oculocardiac Reflex in Adult Patients Undergoing Ophthalmic Surgery: A Randomized Controlled Double-Blinded Trial

This study aims to evaluate whether a lower dose of ketamine (0.5 mg/kg IV) may be as effective as a higher dose (0.75 mg/kg IV) in reducing oculocardiac reflex (OCR) incidence in adult patients undergoing ophthalmic surgery.

The oculocardiac reflex (OCR) is a trigeminovagal reflex that can occur intraoperatively due to traction on extraocular muscles or pressure on the globe, resulting in bradycardia, arrhythmias, or asystole. Defined as a heart rate drop exceeding 20% from baseline, OCR is most frequently described in pediatric strabismus surgery, though its relevance persists in adult ophthalmic interventions involving similar stimuli.

Optimal ketamine dosing in adults remains underexplored. Higher doses may enhance OCR protection but could also prolong emergence or increase psychomimetic effects.

Inclusion Criteria:

• Age from 18 to 65 years old.
• Both sexes.
• American Society of Anesthesiologists (ASA) physical status I, II.
• Scheduled for elective ophthalmic surgery involving extraocular muscle traction under general anesthesia.

Exclusion Criteria:

• Ketamine contraindications (e.g., hypersensitivity, uncontrolled hypertension)
• History of cardiac arrhythmia or conduction disorder
• Glaucoma or raised intraocular pressure
• ASA status greater than II
• Patient refusal.