The aim of this study was to evaluate the sensory and motor nerve block achieved by epidural anesthesia using 0.475% ropivacaine and 0.75% ropivacaine.

Fifty-six patients undergoing cesarean section were randomly allocated to group I (0.75% ropivacaine) or group II (0.475% ropivacaine). We assessed changes in sensory and motor block using the Bromage scale over 180 minutes after epidural anesthesia. The incidence of nausea, vomiting and the total dosage of ephedrine used were also recorded. Sensory changes, motor blockade and the total dosage of ephedrine used were compared using the t-test (P < 0.05).

No significant differences were found between the two groups at the sensory block level except at 30 and 60 minutes after epidural anesthesia. However, the motor blockade of group I was significantly more intense than that of group II at 15, 20, 25, 30, 60, 120 and 180 minutes after epidural anesthesia. No significant differences were observed between the two groups in the incidences of nausea, vomiting or the total dosage of ephedrine used.

The use of 0.475% ropivacaine instead of 0.75% ropivacaine in epidural anesthesia for cesarean section did not reduce the incidence of nausea, vomiting or the total dosage of ephedrine used. The sensory block achieved using 0.75% ropivacaine was similar, but the motor blockade achieved using 0.475% ropivacaine was less intense with a shorter duration and an earlier recovery to normal than that of 0.75% ropivacaine. These results suggest that 0.475% ropivacaine may be more useful in epidural anesthesia for cesarean section than 0.75% ropivacaine.