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

Cairo University40 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Ketamine Oculocardiac Reflex Ophthalmic Surgery

Interventions

0.5 mg/kg intravenous ketamineDRUG

Patients will receive 0.5 mg/kg intravenous ketamine hydrochloride.

0.75 mg/kg intravenous ketamineDRUG

Patients will receive 0.75 mg/kg intravenous ketamine hydrochloride.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

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.

Locations (1)

Cairo University

Cairo, Egypt

RECRUITING

Outcomes

Primary Outcomes

Incidence of oculocardiac reflex

Incidence of oculocardiac reflex (OCR) in each group \[defined as ≥20% heart rate decrease from baseline or absolute bradycardia (HR\<50 bpm)\] sustained during extraocular muscles (EOMs) traction.

Time frame: During extraocular muscle traction (intraoperative)

Secondary Outcomes

Lowest recorded intraoperative heart rate

The lowest recorded intraoperative heart rate will be recorded.

Time frame: Intraoperatively

Incidence of use of atropine

If oculocardiac reflex (OCR) (defined as \>20% drop in heart rate from the baseline or absolute bradycardia \<50 bpm) occurs, the surgeon will be ordered to stop extraocular muscle traction, and atropine increments (0.3 mg IV) will be administered.

Time frame: Intraoperatively

Mean arterial pressure

Mean arterial pressure (MAP) will be recorded throughout surgery, measured every 15 minutes.

Time frame: Every 15 minutes till the end of surgery (Up to two hours)

Heart rate

Heart rate (HR) will be recorded throughout surgery, measured every 15 minutes.

Time frame: Every 15 minutes till the end of surgery (Up to two hours)

Time to emergence

Time to emergence from anesthesia will be recorded from the conclusion of anesthesia to eye opening.

Time frame: To eye opening (Up to one hour)

Incidence of postoperative complications

Incidence of postoperative complications such as nausea, vomiting, or hallucinations will be recorded.

Central Contacts

Hebatullah S Abdelhamid, MD

CONTACT

00201044512277 drhebasalah593@gmail.com

Data from ClinicalTrials.gov

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