OBSTETRIC ANESTHESIA DIGEST

Based on studies that found an association between epidural analgesia given early in labor and an increase in cesarean deliveries (CS), recommendations have been to delay administration of neuraxial anesthesia in nulliparous women until cervical dilation is ≥4.0 cm. It is unclear, however, whether epidural anesthesia influences the progress of labor or requests for early-labor analgesia is a marker for another risk factor for CS, such as dysfunctional labor. Women requesting pain relief in early labor often receive systemic opioid analgesia, which may be inadequate and has potential side effects for mother and fetus (including respiratory depression). In this large, randomized, controlled trial, the authors investigated the hypothesis that initiating and maintaining neuraxial analgesia early in labor with intrathecal (IT) opioid as part of a low-dose local anesthetic technique would not increase the risk of CS, compared with use of systemic opioids. Between November 2000 and December 2003, healthy nulliparous women with uncomplicated term, singleton pregnancies in spontaneous labor or with spontaneous rupture of membranes (with <4.0 cm dilation) and requesting neuraxial analgesia were enrolled. Women were randomly assigned to receive either IT fentanyl (25 μg + epidural test dose) or systemic hydromorphone (1 mg IV + 1 mg IM) at first request for analgesia. Patient-controlled epidural analgesia (15 mL bupivacaine 0.625 mg/mL + fentanyl 2 μg/mL) was initiated in the IT group at second request for analgesia and in the systemic group at >4.0 cm dilation or at third request. Of 884 women enrolled, 728 met all inclusion criteria—366 in the IT analgesia group and 362 in the systemic group. At baseline, groups were similar except that the systemic group had a greater percentage of women with dilation <1.5 cm (although the median dilation for both groups was 2.0 cm and fetal station was similar) and a higher number with rupture of membranes >12 h before oxytocin administration. The rates of CS and instrumental vaginal deliveries were not significantly different (17.8% after IT analgesia, vs. 20.7% after systemic analgesia; 95% confidence interval [CI] –9.0–3.0; P=0.31). The median time from initiation of analgesia to complete dilation was significantly shorter in the IT group (295 min, vs. 385 min; P<0.001), as was time to vaginal delivery (398 min, vs. 479 min; P<0.001). Pain scores after the first intervention were significantly lower with IT analgesia (2, vs. 6; P<0.001), and the incidence of 1 min Apgar scores <7 was significantly lower in the IT group (16.7%, vs. 24.0%; P=0.01). Incidence and severity of nausea/vomiting was lower and duration of analgesia was longer in the IT group The authors concluded that nulliparous women in spontaneous labor or with spontaneous rupture of membranes requesting pain relief could safely receive neuraxial analgesia early in labor without adverse consequences. When compared with systemic opioid analgesia, early epidural analgesia does not increase the risk of CS and may shorten labor and improve maternal satisfaction. They point out that different techniques for administering neuraxial analgesia and different obstetrical providers may affect the outcome of labor differently. Further, the protocol used in this study may not be applicable to differing obstetric populations.