Abstract

Early clinical studies with etidocaine indicated that this new local anesthetic was unique among all local anesthetics in that it produced a motor block that outlasted the sensory block. A doubleblind, randomized comparison of the onset and duration of sensory and motor blockade following subclavian perivascular brachial block carried out with 0.5% etidocaine and 1% lidocaine, both containing 1:200,000 epinephrine, indicated that the duration of paresis exceeds the duration of analgesia with both drugs, by approximately 18% with Iidocaine and etidocaine in mantle fibers and by 17% with Iidocaine and by 27% with etidocaine in core fibers. Probably the reason that this phenomenon, so apparent and alarming with etidocaine, has gone unnoticed in clinical practice with Iidocaine is due to the fact that the time during which an identifiable degree of paresis exists without analgesia is short enough with Iidocaine that the patient does not notice it, whereas the time during which the patient already has postoperative pain and still cannot move the arm is very long with etidocaine. Therefore, this phenomenon is not unique to etidocaine.