Discussion
bradycardia, labor, pruritus, lower motor blockade, nausea, vomiting
ADVERSE EVENTS, COMPLICATIONS
In our study we have observed that levobupivacaine and ropivacaine in infusions at lower concentrations than traditionally considered [However, we have also observed that these effects are not equivalent, but they differ in terms of intensity of motor blockade and analgesic efficacy. It seems that ropivacaine produced an increased dissociative analgesia (increased analgesia and lower motor blockade) than levobupivacaine. This fact would result from the lower liposolubility of the ropivacaine, which would have a lower penetration on richly myelinated motoneuron fibers, otherwise known as type A fibers [Traditionally, ropivacaine has always been considered as less potent than levobupivacaine (at least in analgesic terms), which has led to studies that claim that with ropivacaine infusions, rescue boluses are more requested [Furthermore, safety of both LA during labor have been studied and it have been observed that ropivacaine would present a quicker onset and lower hemodynamic adverse events, lowering cesareans rate [In addition, we did not register nausea, vomiting or pruritus episodes due to the epidural infusion (in fact, lower LA concentrations would decrease maternal adverse events). No neonatal complications (bradycardia or low Apgar scores) were registered.However, the present study has some limitations. First, our patients were from the same hospital and perhaps our results might not be extensible to the general population due to socio-cultural influences. Finally, we did not manage to obtain statistical significancy when we evaluated variables corresponding to a labor duration superior to 4 h, perhaps because a considerable proportion of each group terminated their labor before 4 h, hence reducing our statistical potency.