Compara??o entre bupivacaína racêmica (S50-R50) e mistura enantiomérica de bupivacaína (S75-R25), ambas isobáricas, a 0,5% em raquianestesia. Estudo em cirurgias ortopédicas

摘要

BACKGROUND AND OBJECTIVES: Commercially available bupivacaine is a racemic mixture of S(-) and R(+)-enantiomers. Although S(-) bupivacaine is less toxic to the cardiovascular and central nervous systems than R(+) bupivacaine, its relative efficacy has not been determined in spinal anesthesia. This study compared the same levobupivacaine and bupivacaine doses in spinal anesthesia for lower limb orthopedic surgeries. METHODS: Participated in this study 120 patients aged 16 to 94 years, physical status ASA I and II, scheduled for lower limb orthopedic surgery under spinal anesthesia. Patients were randomly assigned to two groups (n=60): Group S75-R25 (levobupivacaine) received 3 ml (15 mg) of a 0.5% mixture containing 75% S(-)bupivacaine and 25% R(+)bupivacine, and Group S50-R50 received 3 ml (15 mg) of 0.5% plain bupivacaine. The following parameters were evaluated and compared: analgesia onset time, motor block, duration of effects, cephalad spread of analgesia, cardiovascular changes and transient neurological symptoms. RESULTS: Levobupivacaine and bupivacaine produced comparable effects following intrathecal administration. There were no significant differences in the upper blockade level between groups. Motor block onset time was shorter for bupivacaine. Motor block was not complete in all patients. The incidence of hypotension was similar for both solutions. Transient neurological toxicity was not observed. CONCLUSIONS: Plain intrathecal 0.5% levobupivacaine produced a similar sensory and motor block effect to that of 0.5% bupivacaine for orthopedic surgeries. The possibility of a significant differential blockade with levobupivacaine as compared to bupivacaine warrants further studies.