The addition of morphine prolongs fentanyl-bupivacaine spinal analgesia for the relief of labor pain

The combination intrathecal fentanyl (25 mug) and bupivacaine (2.5 mg) prov ides effective labor analgesia for approximately 90 minutes. The purpose of this prospective, randomized, double-blinded investigation was to determin e if the addition of morphine (150 mug) to the intrathecal combination of f entanyl (25 mug) and bupivacaine (2.5 mg) would prolong labor analgesia. By using the combined spinal epidural technique, 95 healthy primiparous labor ing women in early labor received 2 mL of one of the two intrathecal study solutions, either FB (n = 48): fentanyl (25 mug) and bupivacaine (2.5 mg); or FBM (n = 47): fentanyl (25 mug) and bupivacaine (2.5 mg) plus morphine ( 150 mug). The mean duration of labor analgesia was significantly longer in the FBM group than in the FB group (252 +/- 63 min vs 148 +/- 44 min, P < 0 .01). There were no significant differences between the two groups regardin g the sensory levels, the incidence of nausea, vomiting, pruritus, hypotens ion, or operative delivery. In conclusion, the addition of 150 <mu>g of mor phine to the intrathecal combination of fentanyl plus bupivacaine prolonged the duration of labor analgesia duration without increasing adverse effect s.