Comparative study to evaluate the effect of alkalinization of lignocaine hydrochioride on supra-clavicular brachial pllexus block

Alkalinization of 2% lignocaine hydrochloride with adrenaline leads to alteration in its onset of action and duration of action. 60 patients requiring upper limb surgery between the age group of 20-60 years of either sex, ASA grade I and II were randomly allocated into three equal groups. Group I received 20 ml of standard 2% lignocaine hydrochloride with adrenaline [pH=3.21]. Group II received 20 ml of freshly prepared solution by addition of 1 ml 8.4% sodium bicarbonate [w/v] to the standard solution [pH=6.21]. Group III received 20 ml of alkalinized standard solution prepared by addition of 2 ml 8.4% sidium bicarbonat [w/v] [pH=6.67]. Supra clavicular brachial plexus block technique was used for drug administration. Onset of sensory block, onset of motor block, quality of block and duration of block was assessed using standard parameters. It was obsrved that raising the pH of the solution from 3.21 to 6.21produced a reduction in latency of sensory block [from 18.35 mins to 10.35mins], a reduction in latency of motor block [from 20.65 mins to 12.2 mins] and increased the duration of block. Further increased of pH from 6.21 to 6.67 did not confer any added advantage. Frequency of complete block in solution with pH 6.21 was seen to increase as compared to pH 3.21 solution [35% to 80%]

effect of local anesthetic temperature on the pain of peribulbar anesthesia

Peribulbar anesthesia is the preferred technique of local anesthesia of the majority of cataract surgeons. Local anesthetic injections at other sites in the body proved to be less painful if the solution is warmed to body temperature before injection. Forty patients undergoing routine cataract surgery were randomized into two groups [twenty patients each] and received local anesthesia at 20C or 37C. The injection contained a solution of 5 ml 2% lignocaine, 5 ml 0.5% bupivacaine in a 10 ml syringe in a 25 mm, 20 gauge needle. The solution [7 ml] was given transcutaneously at the junction of the lateral and medial thirds of the lower lid. The patients graded the pain of injection using the visual analogue scale. The pain sensation of local anesthetic is less when the solution is warmed to body temperature compared with room temperature