Postcesarean Analgesia With Epidural Morphine After Epidural 2-Chloroprocaine: A Randomized Noninferiority Trial.

Background: Previous studies have suggested that administration of epidural 3% 2-chloroprocaine (CP) before epidural morphine results in decreased analgesic efficacy of epidural morphine. We sought to determine whether these observations were a result of antagonism or a window period between the conclusion of surgical anesthesia for cesarean delivery and the peak onset time of epidural morphine, and whether a method to preserve the analgesic efficacy of epidural morphine exists.

Methods: Term parturients scheduled for nonemergent, unscheduled cesarean delivery with preexisting labor epidural catheters were recruited for this exploratory, randomized, single-blinded, noninferiority trial.