Objective: Epidural anesthesia for the parturient is often provided in a clinical context where rapid onset of segmental analgesia is important; however, little is published on the ideal local anesthetic to safely achieve this onset. To fi ll this gap in knowledge, we studied bupivacaine and lidocaine, two local anesthetics (LA) commonly used for labor epidural activation, either as a single drug or in combination to determine the onset of epidural analgesia.
Methods: In this double-blinded study, seventy-five patients were randomized into three groups (n = 25 each) for labor epidural activation: 10 mL of 0.25% bupivacaine, 10 mL of 1% lidocaine, or 5 mL of 0.25% bupivacaine plus 5 mL of 1% lidocaine. Patients were assessed for the fi rst 20 min after drug administration at 5-min intervals. Data collected included sensory level to pinprick, maternal blood pressure, vasopressor administration, and peak motor blockade.
Results: Data were analyzed on 71 of 75 patients. Time to loss of sensation to pinprick at the T10 dermatome in the bupivacaine group was signifi cantly longer than the lidocaine group (p = 0.006), but the time to loss of sensation to pinprick at the T10 dermatome did not signifi cantly differ in the bupivacaine plus lidocaine group when compared to both the bupivacaine (p = 0.114) as well as the lidocaine (p = 0.203) groups. Phenylephrine usage did not signifi cantly differ amongst the three groups (p = 0.062).
Conclusion: Lidocaine provides statistically signifi cant faster onset of epidural analgesia when compared to bupivacaine only. Combining the two LA did not signifi cantly affect onset.
Keywords: epidural analgesia; labor pain; local anesthetics; obstetrical analgesia.