Optimizing epidural fentanyl loading dose for early labor pain

Objective: Sufficient sensory blockade between L1 and T10 is required to relieve visceral pain during early labor. We examined whether the addition of fentanyl to a loading dose of 0.0625% bupivacaine could provide dose-dependent analgesic effects on early-stage labor pain. Methods: Sixty parturients who requested epidural analgesia for labor pain were enrolled and randomly allocated to one of three groups. Group A (n=20) received 10 mL of 0.0625% epidural bupivacaine as a loading dose alone. Group B (n=20) received the same bupivacaine loading dose in combination with 2 μg/mL fentanyl. Group C (n=20) received the same loading bupivacaine dose plus 4 μg/mL fentanyl. All patients received diluted bupivacaine plus 2 μg/mL fentanyl at a rate of 10 mL/hr as a maintenance dose. Fifteen minutes later, we recorded the highest cephalic and lowest caudal anesthetized dermatomes, side effects, and the number of patients who asked for supplemental analgesia. Results: The highest anesthetized cephalic dermatome was at the level of T12 (T9-L1) in Group A, T9 (T8-T12) in Group B and T7 (T5-T9) in Group C (p<0.05 among the three groups). Eleven patients (55%) requested supplemental bupivacaine for inadequate analgesia in Group A, six in Group B (30%), and none in Group C (0%). Pruritus was reported by seven (35%) patients in Group B and eight (40%) patients in Group C, but none in Group A. Conclusion: The addition of fentanyl to epidural bupivacaine dose-dependently increased the analgesic effect and higher loading doses of fentanyl increased the dermatomic coverage. We suggest that 0.0625% bupivacaine plus 4 μg/mL fentanyl is the ideal loading dose to provide the greatest segmental analgesia for early labor pain with minimal side effects.