SummaryA randomised, prospective trial was conducted to assess the efficacy of various means of alleviating the pain of subcutaneous lidocaine infiltration. One hundred and twenty-two patients were randomly allocated to different groups to receive buffered lidocaine 1%, warmed lidocaine 1% or infiltration by the counter-irritation technique. A visual analogue pain score was recorded at different stages of cannulation and results showed that pain scores were significantly lower in the group receiving buffered lidocaine 1% (p`0.02) and in the counter-irritation group (p`0.05). Thus buffering lidocaine 1% and administration of lidocaine 1% by the counter-irritation technique is effective in relieving the pain of lidocaine infiltration.Keywords Anaesthetic, local; lidocaine. Procedures, venepuncture. ...................................................................................... Correspondence to: Dr E. L. Ong Accepted: 27 February 1999 It is common practice for anaesthetists to use a subcutaneous infiltration of lidocaine to alleviate the pain of venepuncture with a cannula. While previous studies have shown this to be less painful than insertion of a cannula, even one as small as 22-gauge [1], the pain associated with lidocaine infiltration has at times led to debate about this procedure. It was, therefore, the need to alleviate the 'lidocaine sting' that prompted this study, which compares various means of reducing this pain. Well-tested methods include alkalinisation of lidocaine with sodium bicarbonate solution and warming the lidocaine to body temperature. A less well-known method, counter-irritation, has been suggested to be effective [2]. Previous studies with volunteers have performed testing on the forearm [3, 4], this study aims to test the efficacy of these pain-reducing methods on the dorsum of the hand of patients, which is the common site of venous cannulation. A previous study has shown that the skin sensitivity of different parts of the arm vary with the dorsum of the hand being less sensitive than the volar aspect of the arm. If this is the case it may not be necessary to go to lengths to alleviate lidocaine sting [5].
MethodsAfter approval by the hospital ethics committee and informed consent, 122 unpremedicated ASA grade I and II patients were enrolled into the study. Exclusion criteria included allergy to local anaesthetics and pregnancy. The patients were randomly assigned to one of four treatment groups. Groups A and D received 1% lidocaine at room temperature (20 ЊC) as was the standard practice. Group B received 1% lidocaine buffered by adding 8.4% sodium bicarbonate in the ratio of 1-10 of lidocaine. Group C received 1% lidocaine warmed to 37 ЊC by means of a thermostatically controlled water bath available in all operating theatres.The dorsum of the nondominant hand was cleansed with an alcohol swab and allowed to dry. A quantity (0.5 ml) of the prepared solution in a 2.5-ml syringe was infiltrated subcutaneously via a 27-gauge needle over 5 s. In group D, counter-irritation ...
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