Epidural analgesia during labor--0.5% lidocaine with fentanyl vs. 0.08% ropivacaine with fentanyl.

Background: Although lidocaine is a cheap and globally available local anesthetic, yet it is not a popular drug for labor analgesia. This is claimed to its higher intensity of motor block, possibility of transient neurological symptoms (TNS) and its placental transfer with probable drawbacks on fetal well-being. However, these effects could be concentration dependent and, the evidence linking them to lidocaine is still lacking. This study was designed to evaluate the efficacy and safety of 0.5% epidural lidocaine plus fentanyl during labor.

Methods: One hundred and twenty healthy full term nulliparous women in early labor with a single fetus presented by the vertex were enrolled in this randomized, double-blind clinical trial. Parturient were assigned to receive epidural analgesia either with lidocaine 0.5% plus fentanyl 2 microg(-1 mL) (LF), or ropivacaine 0.08% plus fentanyl 2 microg(-1 ml) (RF) when their cervix was dilated to 4 centimeters. Analgesia was provided with 20 ml bolus of the study solution and maintained at 10 ml(-1) h. Upper level of sensory loss to cold, Visual Analogue Pain Score (VAPS), motor block (modified Bromage score), the duration of the first and second stages of labor, numbers of instrumental vaginal and cesarean deliveries, the neonatal apgar score, patient satisfaction and side effects, were recorded.

Results: There were no significant differences in sensory level, pain scores, duration of the first and second stages of labor, numbers of instrumental and cesarean deliveries, the neonatal apgar scores, patient satisfaction or side effect between groups. Although motor block was significantly high in lidocaine group compared to ropivacaine group (p < 0.05), all parturient were moving satisfactorily in bed.

Conclusions: Dilute epidural lidocaine (0.5%) with fentanyl effectively and safely initiates epidural analgesia clinically indistinguishable from 0.08% epidural ropivacaine with fentanyl. Although it induces significant motor block compared to ropivacaine, it still preserves maternal ability to move satisfactorily in bed. Whether further reduction in lidocaine concentration could trim down the motor block, remains to be investigated.