Ultrasound Guided Peribulbar Anaesthesia - A Novel Dual Quadrant Injection Technique

Study Overview
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Brief Summary
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Peribulbar anaesthesia for ocular surgery depends on the spread of local anaesthetic throught the orbit to be successful and has a relatively high failure rate. This study will examine a novel ultrasound guided approach to peribulbar anaesthesia which should extend the depostion of local anaesthetic by using a dual quadrant injection technique. The study will assess the feasibility of this technique, how successful it is and whether any obvious safety issues arise with its use.

Detailed Description
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Peribulbar anesthesia is widely used for anterior and posterior chamber ophthalmic procedures. It is a blind technique which is traditionally carried out by inserting a needle in the infero-lateral aspect of the orbit below the globe and injecting a volume of 8 - 12 mL of local anesthetic in the periorbital space. The goal of this inejction is to achieve akinesia and anesthesia of the eye sufficient for surgery. The technique has a relatively high failure rate of up to 30%. A failure or insufficient block requires a second or rarely a third peribulbar injection to achieve success. Ultrasound can be used to guide needles in the human body and has been successfully used in many anatomic locations for anaesthesia. This study will assess whether ultrasound can guide the block needle in ophthalmic anesthesia to deliver local anesthetic via a single entry into two discrete locations within the periorbital space - the first in the infero-lateral quadrant and the second in the infero-medial quadrant. If this can be done the investigators may achieve a higher success rate for this block with a lower volume potentially improving the quality of the block and its safety.

Official Title
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Ultrasound Guided Peribulbar Anaesthesia: a Real-time Ultrasound Guided Technique With a Novel Dual Quadrant Injection

Conditions
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Eye Diseases

Intervention / Treatment
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* Procedure: Ultrasound guided Dual Quadrant Peribulbar Anaesthesia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA score less than III and ability to provide a written informed consent 22 patients presenting for opthalmic surgery Exclusion Criteria: Coagulation disorder or anticoagulated with INR > 1.5 Platelet count < 75 X 10*9/L Significant Myopia (axial length > 28mm) Patients unable to lie supine for 2 hours Patients with recent gas or silicone injections in/around the eye

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 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

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: US Guided Dual Quadrant Peribulbar block<br>Ultrasound guided Dual Quadrant Peribulbar Anaesthesia | Procedure: Ultrasound guided Dual Quadrant Peribulbar Anaesthesia<br>* Landmark Guided single injection vs Ultrasound guided dual quadrant injection<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block Success | Block will be deemed a failure if a supplementary block is required for the operative procedure | 10 minutes post intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block Quality (standardized Ocular Scoring System for akinesia and anaesthesia) | Block will be assessed according to a standardized Ocular Scoring System for akinesia and anaesthesia at 5 minutes and 10 minutes post block. This is a composite measure | 5 and 10 minutes | 
| Block Volume | Total volume of local anaesthetic will be recorded. Volume for each part of the dual injection technique will also be recorded. This is a composite measure. | 1 minute | 
| Duration of Procedure | The duration of the entire procedure will be recorded | 1 to 10 minutes | 
| Complications | Any complications during the procedure or in follow up clinical visits will be recorded | 6 Weeks | 
| Image Visualization | Operator's ability to see the needle in both the infero-lateral and infero-medial injection will be recorded. Ability to see perineural, retrobulbar and medial rectus spread of local anaesthetic will be recorded. This is a composite qualitative measure. | 1 minute | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ultrasound guided peribulbar anesthesia