Comparison of 0.5% articaine and 0.5% prilocaine in intravenous regional anesthesia of the arm: A cross-over study in volunteers

Background and Objectives. Earlier studies of the use of articaine in intra venous regional anesthesia (IVRA) are conflicting. In fact, despite similar physicochemical properties and regional anesthetic action, significant dif ferences between articaine and prilocaine in IVRA have been reported. Artic aine, being a potent local anesthetic with low degree of toxicity and being rapidly metabolized by esterases, could be a useful local anesthetic parti cularly in IVRA and, perhaps, could challenge prilocaine, the present local anesthetic of choice for this technique. Methods. A double-blind, cross-ov er study of IVRA of the upper extremity in 10 healthy volunteers was perfor med. There was at least a 1-week interval between the use of the two anesth etics in each volunteer. After exsanguination with an Esmarch bandage, IVRA was induced either with preservative-free 0.5% articaine (5% Ultracaine, H oechst, Germany, diluted with 0.9% NaCl) or 0.5% prilocaine (Citanest, Astr a, Sodertalje, Sweden) (35-50 mt, according to weight), injected in 2 minut es. Sensation at defined skin spots that were innervated by the median, mus culocutaneous, radial, and ulnar nerves was tested by pinprick; motor funct ion was tested by the movements of the wrist. After 20 minutes, the tourniq uet cuff was deflated in one step. Circulatory,toxic, and skin reactions we re registered. At least 1 week after the second IVRA intracutaneous allergy testing with 0.5% articaine, 0.5% prilocaine, histamine, and saline was pe rformed. Results. There were no significant differences between the two loc al anesthetics in the onset of analgesia or anesthesia, degree of motor blo ck, and recovery of NRA. Onset of analgesia occurred 4.2-5.6 minutes, on av erage, after the injection. One volunteer had short-lasting tinnitus after tourniquet cuff deflation when prilocaine was used. Erythematous nonitching skin rashes developed in 8 of 10 volunteers when articaine was used, and t wo volunteers had rashes when prilocaine was used. These rashes disappeared within an hour, and negative intracutaneous test results confirmed their n onallergic origin. Conclusion. Both 0.5% articaine and 0.5% prilocaine, in a median dose of 40 mt in adults, injected in 2 minutes, are effective and equipotent local anesthetics in IVRA of the arm. An earlier reported four-t ime faster onset time of the block by articaine in comparison with prilocai ne may be caused by a very rapid injection rate (40 mL/30 sec) by the inves tigators of that study. The erythematous skin rashes after IVRA, in particu lar when articaine was used, may be a sign of venous endothelial irritation .