The Addition of Morphine Prolongs Fentanyl-Bupivacaine Spinal Analgesia for the Relief of Labor Pain

Abstract

The combination intrathecal fentanyl (25 μg) and bupivacaine (2.5 mg) provides effective labor analgesia for approximately 90 minutes. The purpose of this prospective, randomized, double-blinded investigation was to determine if the addition of morphine (150 μg) to the intrathecal combination of fentanyl (25 μg) and bupivacaine (2.5 mg) would prolong labor analgesia. By using the combined spinal epidural technique, 95 healthy primiparous laboring women in early labor received 2 mL of one of the two intrathecal study solutions, either FB (n = 48): fentanyl (25 μg) and bupivacaine (2.5 mg); or FBM (n = 47): fentanyl (25 μg) and bupivacaine (2.5 mg) plus morphine (150 μg). 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 regarding the sensory levels, the incidence of nausea, vomiting, pruritus, hypotension, or operative delivery. In conclusion, the addition of 150 μg of morphine to the intrathecal combination of fentanyl plus bupivacaine prolonged the duration of labor analgesia duration without increasing adverse effects.