Ketamine, Oculocardiac Reflex, Ophthalmic Surgery
Conditions
Brief summary
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.
Detailed description
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.
Interventions
DRUG0.5 mg/kg intravenous ketamine
Patients will receive 0.5 mg/kg intravenous ketamine hydrochloride.
DRUG0.75 mg/kg intravenous ketamine
Patients will receive 0.75 mg/kg intravenous ketamine hydrochloride.
Sponsors
Cairo University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of oculocardiac reflex | During extraocular muscle traction (intraoperative) | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Lowest recorded intraoperative heart rate | Intraoperatively | The lowest recorded intraoperative heart rate will be recorded. |
| Incidence of use of atropine | Intraoperatively | 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. |
| Mean arterial pressure | Every 15 minutes till the end of surgery (Up to two hours) | Mean arterial pressure (MAP) will be recorded throughout surgery, measured every 15 minutes. |
| Heart rate | Every 15 minutes till the end of surgery (Up to two hours) | Heart rate (HR) will be recorded throughout surgery, measured every 15 minutes. |
| Time to emergence | To eye opening (Up to one hour) | Time to emergence from anesthesia will be recorded from the conclusion of anesthesia to eye opening. |
| Incidence of postoperative complications | 24 hours postoperatively | Incidence of postoperative complications such as nausea, vomiting, or hallucinations will be recorded. |
Countries
Egypt
Contacts
CONTACTHebatullah S Abdelhamid, MD
Outcome results
None listed