Subtenon and Intravenous Dexmedetomidine Effect on Patients Undergoing Cataract Surgery

Study Overview
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Brief Summary
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The study designed to compare the effects and the safety of adding dexmedetomidine to local anesthetics and its intravenous administration in subtenon block in patients undergoing cataract surgery.

Detailed Description
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Ophthalmological surgery can be performed under topical, regional or general anesthesia. Recently, the majority of ocular surgeries performed by regional rather than general anesthesia, because of the regional anesthesia is more economic, easy to perform, and the risk involved is less. Orbital regional anesthesia can be done using a retrobulbar (intra-conal) block, peribulbar (extra-conal) block or sub-Tenon's block. The STBs or episcleral block was first described by Turnbull in 1884 and it was repopularized in the 1990s as a simple and safe alternative to needle-based eye blocks. The STB becomes the most widely practiced regional technique for cataract surgery, because it produces satisfactory anesthesia for most intraocular procedures, and avoids the inherent risks of needle-based blocks, such as globe perforation and optic nerve injury. Dexmedetomidine is a selective α-2 receptor agonist that produces sedation and analgesia without causing respiratory depression. It also allows patients to respond to verbal commands during the sedation; easy conversion from sleeping to awakening is possible. Therefore, dexmedetomidine has been used as sedative in various clinical fields in intensive care unit and surgery and an adjuvant to local anesthetics. Many studies were done to evaluate its effect as sedative or anlgesic when administered either intravenously or when added to local anesthesia in ophthalmic block. But no one, till now comparing its effect when used as adjuvant to local anesthetics or administered intravenously in subtenon block.

Official Title
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The Effect of Subtenon and Intravenous Dexmedetomidine on Patients Undergoing Cataract Surgery: A Comparative Randomized Controlled Double Blind Study

Conditions
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Acute Postoperative Pain

Intervention / Treatment
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* Drug: Dexmedetomidine
* Drug: lidocaine 2%
* Drug: bupivacine 0.5%
* Drug: Normal saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA grade I-III Aged 18-70 years Both sex Scheduled for elective phacoemulsification cataract surgery Exclusion Criteria: Coagulation abnormalities Impaired mental status Refusal of the patient Uncontrolled glaucoma Recent surgical procedure on the same eye

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

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
Interventional Model Description: 75 Patients were assigned into three equal groups, all patients received 2.5 ml of local anesthetic mixture through subtenon block and IV infusion of drugs as follows: Group C (control group): received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ saline 0.9% (0.5 ml) and IV infusion of saline 0.9% over 10 min. before subtenon block. Group SD ( subtenon dexmedetomidine): received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ 0.5 μg/kg dexmedetomidine (0.5 ml) and IV infusion of saline 0.9% over 10 min. before subtenon block. Group ID (iv dexmedetomidine): received received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ saline 0.9% (0.5 ml) and IV infusion of 0.5 μg/kg dexmedetomidine over 10 min. before subtenon block.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Group C (control group)<br>Group C (control group): received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ saline 0.9% (0.5 ml) and IV infusion of saline 0.9% over 10 min. before subtenon block. | Drug: lidocaine 2%<br>* subtenon injection<br>Drug: bupivacine 0.5%<br>* subtenon injection<br>Drug: Normal saline<br>* either subtenon or iv<br>|
| Active Comparator: Group SD (subtenon dexmedetomiine)<br>Group SD ( subtenon dexmedetomidine): received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ 0.5 μg/kg dexmedetomidine (0.5 ml) and IV infusion of saline 0.9% over 10 min. before subtenon block. | Drug: Dexmedetomidine<br>* the drug administered either subtenon ot iv<br>Drug: lidocaine 2%<br>* subtenon injection<br>Drug: bupivacine 0.5%<br>* subtenon injection<br>Drug: Normal saline<br>* either subtenon or iv<br>|
| Active Comparator: Group ID (iv dexmedetomidine)<br>Group ID (iv dexmedetomidine): received received subtenon LA mixture of bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml)+ saline 0.9% (0.5 ml) and IV infusion of 0.5 μg/kg dexmedetomidine over 10 min. before subtenon block. | Drug: Dexmedetomidine<br>* the drug administered either subtenon ot iv<br>Drug: lidocaine 2%<br>* subtenon injection<br>Drug: bupivacine 0.5%<br>* subtenon injection<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| duration of sensory block | time from injection of local anesthetic mixture to complete recovery from pain sensation or the first need of rescue analgesia | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| duration of motor block | time from injection of local anesthetic to complete recovery of motor function in all ocular muscles. | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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subtenon, dexmedetomidine, cataract surgery