ABSTRACT & COMMENTARY
Synopsis: Combined spinal-epidural analgesia in labor does not result in fewer cesarean deliveries than does traditional epidural analgesia.
Source: Nageotte MP, et al. N Engl J Med 1997;337: 1715-1719.Epidural analgesia during labor is effective and safe but has been linked with dystocia. Alternative forms of regional analgesia are of clear interest to clinicians. This study was a randomized trial of traditional epidural analgesia vs. a "walking epidural" alternative. Combined spinal-epidural analgesia uses lower doses of opioids and local anesthetics, causing less motor block than traditional epidural analgesia and allowing ambulation that was hoped to benefit laboring women in this protocol.
Nageotte and colleagues randomized 761 primiparous women in spontaneous labor either to conventional epidural analgesia or to a low-dose combination of spinal (intrathecal) and epidural analgesia. All women were at term, and all received bupivacaine and fentanyl. Half of the spinal-epidural group was encouraged to walk at least five minutes per hour, while the other half was discouraged.
Among the three groups, no significant differences were found in the cesarean section rate, the incidence of dystocia, patient satisfaction, five-minute Apgar scores, or other birth outcomes. Nageotte et al identified three risk factors for dystocia necessitating cesarean section: administering epidural analgesia with the fetal vertex at a negative station (relative risk, 2.0; 95% confidence interval [CI], 1.3-3.9), administering epidural analgesia before the cervix is dilated to 4 cm (relative risk, 1.8; 95% CI, 1.1-3.7), and lack of ambulation (relative risk, 1.6; 95% CI, 0.9-3.3). An interesting observation was that, among the women who received the combined spinal-epidural analgesia, only 66% of those encouraged to walk actually walked, while 15% of those discouraged from walking chose to walk.
COMMENT BY ELIZABETH MORRISON, MDMany maternity care clinicians hope that walking epidural analgesia could provide safe, effective pain relief while avoiding the increased risk of dystocia associated with traditional epidural regimens. At first glance, this important study by Nageotte et al dims our hopes-at least as far as dystocia is concerned. Despite the lower doses of narcotics and local anesthetics used in the combined spinal-epidural group, women in this group did not undergo fewer cesarean sections for dystocia.
On closer inspection, this study may not be so discouraging after all. It validates combined spinal-epidural analgesia as a safe, effective way to relieve labor pain. Patients found the walking epidural as acceptable as the traditional epidural, despite the lower doses of analgesics.
Fewer of these patients required instrumental vaginal delivery, a clear benefit. As the spinal-epidural technique becomes available at more medical centers, birth attendants will find it an attractive addition to their analgesic repertoire.
The issue of ambulation merits further analysis. Nageotte et al point out that their data did not permit detailed assessment of how walking affects labor or dystocia. Many of the walkers in the study did not walk long. Clearly, it can be difficult to get patients to comply with instructions about walking, so perhaps this study's "intention to walk" analysis is a good approximation of real life in the labor suite. However, it would be fascinating to know whether the ambulation group in this study, if they had all walked and walked longer, could have expected less dystocia and a lower risk of cesarean section. One also wonders whether ambulation is the real answer, as it intuitively seems to be. Women who self-select to walk in labor may have other unrecognized factors that help them achieve vaginal births.
To my mind, the best qualities of the walking epidural are that it limits
analgesic doses while allowing laboring women the option to walk if they
so choose. Future studies can address how more extensive ambulation affects
labor and birth outcomes, how multiparas react to spinal-epidural analgesia,
and whether other doses or combinations are associated with less dystocia.
Meanwhile, Nageotte et al have broadened our understanding of a valuable
new method of regional pain relief for women in labor.