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