Muhammad Naeem Khan, Nasreen Lair, Shahid Khan.
Peribulbar block: the effect of hyaluronidase and bicarbonate on the onset and quality of block.
Ann Pak Inst Med Sci Jan ;2(3):171-5.

Objective: The purpose of this study is to determine the effect of pH and the addition of hyaluronidase to a mixture of xylocaine and bupivacaine on the efficacy of peribulbar anaesthesia in patients undergoing cataract surgery. Design Study: Prospective comparative study of 100 cases. Place and Duration of Study: Study was done in operation theatre of LV Prasad Eye Institute Hyderabad India, during a period of 3 months i.e from Jan 2004 to March 2004. Patients and Methods: After approval from ethics committee of the institution, informed consent was taken from 100 patients of ASA class I, II and III scheduled to undergo elective cataract surgery under local anaesthesia. Exclusion criteria were patients with learning difficulties, profound deafness, dementia, high anxiety scores and those with a known hypersensitivity reaction to lignocaine or hyaluronidase. Patients were divided into two groups of 50 patients each, irrespective of age and sex. Group A (control) received 12m1 mixture of local anaesthetic containing 5ml of 2% xylocaine with adrenaline 1:100,000 (commercially prepared) and 7ml of 0.5% bupivacaine, while group B (pH / Hylase) received the same above mixture of local anaesthetics in addition to 50 IU of hyaluronidase and 1 ml of 0.4% sodium bicarbonate. Patients in both groups were assessed for the onset of akinesia and the quality of block at 5,10,15 and 20 minutes. Patients were also observed for any side effects throughout the procedure. Results: Onset of akinesia at 5,10,15 and 20 minutes in group A patients, where plain bupivacaine 0.5% and xylocaine 2% with adrenaline 1:100,000 was injected, was less pronounced compared to group B patients where hyaluronidase and sodium bicarbonate were added. Group B patients had faster onset of action i.e. 12.0 +/- 1.5 minutes and group A patients had a delay in onset of akinesia i.e. 15.2 +/- 1.4 minutes. P value was < 0.05 which is significant. None of our patients required supplemental blocks, almost all of our patients had good akinesia and they were able to undergo cataract surgery Conclusion: The addition of hyaluronidase and adjustment of pH by Sodium bicarbonate, fastens the onset time and improves the initial success rate of peribulbar block.

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