Dexmedetomidine in Topical Versus Peribulbar Anesthesia for Cataract Surgery

Study Overview
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Brief Summary
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The aim of this study is to compare efficacy of dexmedetomidine as an additive to topical versus peribulbar anesthesia for cataract surgery

Detailed Description
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Ocular surgery may be performed under topical, regional, or general anesthesia. The first recorded use of regional anesthesia for surgery was the instillation of cocaine into the conjunctival sac in 1884 by an Austrian ophthalmologist. Davis and Mandel in 1986 described the peribulbar block, peribulbar block has delayed onset and need a higher volume of local anesthetic (LA) than a retrobulbar block. But the peribulbar block is away from intra-conal space and so produce fewer complication. Dexmedetomidine is used as adjuvant to LA drugs in peripheral nerve block, brachial plexus block and intrathecal anesthesia with satisfactory results. A more recent study using dexmedetomidine (50 μg) with the peribulbar block before cataract surgery demonstrated an IOP decrease similar to IV dexmedetomidine administration and greater than a peribulbar block without dexmedetomidine.

Official Title
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Dexmedetomidine as an Additive to Topical Versus Peribulbar Anesthesia for Cataract Surgery

Conditions
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Dexmedetomidine, Cataract Surgery, Peribulbar, Anesthesia

Intervention / Treatment
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* Drug: Topical dexmedetomidine
* Drug: Reginal dexmedetomidine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists (ASA) physical status classification I or II who scheduled for eye surgery Exclusion Criteria: Patients who are younger than 18 years The usual contraindications for regional anesthesia such as patients refusing LA Clotting abnormalities Impaired mental status Allergy to any of the study medications patients had the severe cardiac disease chronic obstructive lung disease and a history of sleep apnea contraindications to the use of dexmedetomidine history or significant cardiovascular disease risk factors significant coronary artery disease or any known genetic predisposition history of any kind of drug allergy drug abuse psychological or other emotional problems special diet or lifestyle clinically significant abnormal findings in physical examination electrocardiographic (ECG) or laboratory screening known systemic disease requiring the use of anticoagulants.

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Topical dexmedetomidine group<br>Patients will receive mixture of one milliliter of dexmedetomidine-HCl and local anesthetic | Drug: Topical dexmedetomidine<br>* Patients will receive mixture of one milliliter of dexmedetomidine-HCl and local anesthetic<br>|
| Active Comparator: Reginal dexmedetomidine group<br>Patients will receive mixture of bupivacaine 0.5% (4.5 ml) + lidocaine 2% (4.5 ml) + dexmedetomidine 50 μg (1 ml) in peribulbar block | Drug: Reginal dexmedetomidine<br>* Patients will receive mixture of bupivacaine 0.5% (4.5 ml) + lidocaine 2% (4.5 ml) + dexmedetomidine 50 μg (1 ml) in peribulbar block<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Inadvertent eye movement | Asses intra-ocular pressure (IOP) before injection of baseline and after a complete akinesia of the globe before surgical incision. | 2 hours postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Anesthesia-related complications | The patients will be asked whether the cataract surgery was more or less painful than having the needle used for intravenous infusions inserted into the back of the hand. | 2 hours postoperatively | 
| Sedation level | Numeric Rating Scale will be applied to grade the pain where 0 = no pain and 10 = extreme pain. | 2 hours postoperatively | 
| pain during and after the surgery | Immediately after surgery, patients will be asked to grade the pain felt during the operation, including the pain felt after delivery of topical or peribulbar anaesthesia. | 2 hours postoperatively | 
| Need for additional anesthesia during surgery and surgeon | The dose of additional needed anesthesia (fentanyl 0.5 µg/kg) during surgery will be recorded | During surgery | 
| Intraoperative difficulties | The surgeon will also be requested to grade any difficulties encountered during surgery immediately after the operation, using a 4-point scale, where 1 = no difficulty and 4 = extremely difficult | 2 hours postoperatively |