A comparative study between bupivacaine (S75-R25) and ropivacaine in spinal anesthesia for labor analgesia.

BACKGROUND AND OBJECTIVES Spinal anesthesia is used for relief of pain during labor and it is associated with low indices of complications. Studies with levorotatory enantiomers of local anesthetics demonstrate higher safety due to the lower cardiotoxicity. The objective of this study was to evaluate the latency and duration of analgesia and maternal and fetal repercussions with bupivacaine (S75-R25) and ropivacaine in spinal anesthesia for labor analgesia. METHODS A prospective, double-blind, randomized clinical assay was undertaken with 49 labouring parturients with low risk, with indication of vaginal delivery, ages 15 to 35 years, ASA I or II, divided into two groups: GI - 0.25% bupivacaine (S75-R25); GII - 0.20% ropivacaine. RESULTS A statistically significant difference was observed between the two groups 30 minutes after the spinal anesthesia, and pain scores were higher in the ropivacaine group. Statistically significant differences were not observed regarding the latency of analgesia, sensorial level of the blockade, volume of local anesthetic, rescue dose, duration of labor and analgesia, frequency of instrument-assisted labor, hemodynamic changes, Apgar scores or umbilical cord blood pH, and incidence of adverse events. CONCLUSIONS The use of bupivacaine (S75-R25) and ropivacaine in labor analgesia provided good conditions for spinal anesthesia with small indices of adverse events.