The effects of ropivacaine 0.0625% and levobupivacaine 0.0625% on uterine and abdominal muscle electromyographic activity during the second stage of labor.

Abstract

This study investigated the effect of ropivacaine on uterine and abdominal muscle electromyographic activity during the second stage of labor. A total of 161 patients, including 48 patients receiving 0.0625% ropivacaine for patient-controlled epidural analgesia (PCEA), 64 patients receiving 0.0625% levobupivacaine for PCEA, and 49 patients with no PCEA completed the study. Uterine and abdominal muscle electromyographic activity was continuously recorded from the abdominal surface during the second stage of labor. Maternal demographic and clinical characteristics, maternal and neonatal outcomes, and various electromyographic parameters were recorded. Second stage of labor was significantly prolonged (P=0.007) for levobupivacaine compared to ropivacaine or no PCEA. The root-mean-square and duration of uterine muscle electromyographic activity was significantly lower for levobupivacaine or ropivacaine compared to no PCEA. The root-mean-square and power of abdominal muscle electromyographic activity was significantly lower for levobupivacaine compared to ropivacaine or no PCEA; the peak frequency of abdominal muscle electromyographic activity was significantly higher for ropivacaine. Visual analogue scale pain scores in patients in the levobupivacaine group or ropivacaine group decreased significantly over time compared to patients in the no PCEA group. In conclusion 0.0625% ropivacaine does not suppress abdominal muscle electromyographic activity during the second stage of labor. Maternal and neonatal outcomes were similar in patients receiving ropivacaine or no PCEA.