Should intrathecal narcotics be used as a sole labor analgesic? A prospective comparison of spinal opioids and epidural bupivacaine

OBJECTIVE: Intrathecal narcotics (ITNs) are being used in some settings as a sole labor analgesic. However, they have not been directly compared to epidural analgesia. STUDY DESIGN: We used a prospective observational design. POPULATION: Eighty-two women with uncomplicated full-term pregnancies were enrolled upon analgesia request during spontaneous labor with cervical dilation 3 to 7 cm. Sixty-three chose ITNs (morphine and fentanyl), and 19 chose epidural analgesia (continuous infusion of bupivacaine and fentanyl). OUTCOMES MEASURED: Pain scores were documented using a visual analog scale. Satisfaction and side effects were rated with Likert scales during a structured interview on the first postpartum day. Outcomes were analyzed with multivariate regression techniques. RESULTS: Intrathecal narcotics were associated with significantly higher pain scores than was epidural analgesia during the first and second stages of labor and on an overall postpartum rating. The median effective duration of action for ITNs was between 60 and 120 minutes; however, ITNs provided excellent analgesia for a subgroup of women who delivered within 2 to 3 hours of receiving them. Although women in both groups were satisfied with their pain management, women receiving ITNs had statistically lower overall satisfaction scores. CONCLUSIONS: Within the limitations of a nonrandomized study, a single intrathecal injection of morphine and fentanyl has a shorter duration of action and provides less effective pain control than a continuous epidural infusion of bupivacaine and fentanyl. However, ITNs may have a role in settings with limited support from anesthesiologists or for women whose labors are progressing rapidly.