الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Local anaesthesia is currently performed for many ophthalmic procedures as it is associated with reduced morbidity and mortality when compared with general anaesthesia. Additional benefits include early patient mobilization, improved patient satisfaction and reduced hospital stay.
Peribulbar anaesthesia is a safe, simple, quick to perform, and effective method of anaesthesia.However, it has the disadvantage of a slow onset of orbital akinesia and the frequent need for block supplementation. To overcome these limitations, many adjuvant drugs such as adrenaline, sodium bicarbonate, and hyaluronidase have been added to the local anaesthetic mixture used for peribulbar block in order to augment its efficacy and hasten its speed of onset.
Hyaluronidase is an enzyme that reversibly liquefies the interstitial barrier between cells by depolymerisation of hyaluronic acid to a tetrasaccharide, thereby enhancing the diffusion of molecules through tissue planes. It has been shown to improve the onset and enhance the quality of retrobulbar, peribulbar and sub-Tenon’s block.
Local anaesthetics are weak bases. The addition of bicarbonate increases the pH, which in turn, increases the amount of local anesthetic in the uncharged base form allowing more rapid influx into the neuronal cells. Thus, alkalinization has a proven impact in decreasing onset time, prolonging the duration of action and also decreasing the pain experienced by the patient during injection of the local anaesthetic.
The study was carried out on 40 eyes of unpremedicated patients of both sexes undergoing peribulbar block and were subjected to cataract extraction using phacoemulsification technique with intraocular lens implantation by the same surgeon.The patients were randomized into four groups to receive one of four local anesthetic solutions for peribulbar anesthesia:
group 1 received peribulbar block with a plain solution of 6 ml of 2% Lidocaine.
group 2 received a peribulbar block with 6 ml of 2% Lidocaine mixed with 15 IU/ml units of sodium hyaluronidase.
group 3 received a peribulbar block with 6 ml of 2% Lidocaine mixed with sodium bicarbonate.
group 4 received a peribulbar block with 6 ml of 2% Lidocaine mixed with 15 IU/ml units of sodium hyaluronidase and sodium bicarbonate.
Every patient was subjected to preoperative preparationwhichincluded psychological preparation, preoperative assessment, review of preoperative tests, optimization of medical conditions and explanation of anesthetic risk.
Single transcutaneous infero-lateral injection peribulbar technique was performed. The time taken for onset of akinesia was measured.Analgesia,globe and lid akinesia scoreswere measured at 1,5 and 10 minutes after injection.Duration of surgery and the block were measured.Need for second injection was recorded.Anaesthesia related ocular or systemic complications were recorded.
Akinesia of the globe was achieved significantly earlier with Lidocaine solutionscontaining hyaluronidase but not with alkalinized Lidocaine solution.Greater eyelid anesthesia with the alkinized local anaesthetic. Surgical pain, pressure and discomfort were less withthe alkinized local anaesthetic.