Background: Epidural local anesthetic medications are effective in producing labor pain relief, but the high concentrations required result in significant maternal side effects. The concentration of local anesthetic can be reduced by the addition of an opioid medication. Epinephrine can also act as an analgesic medication in addition to causing vasoconstriction. If epinephrine improves the initiation of pain control by analgesic mechanism might allow for a further reduction of the minimum local analgesic concentration (MLAC).
Methods: We conducted a randomized, double-blind, prospective dose-response study examining the initiation of labor pain relief in parturients with epidural catheters. Subjects were randomized to one of four groups: bupivacaine, bupivacaine-fentanyl 1.67 μg/mL, bupivacaine-epinephrine 1.67 μg/mL, and bupivacaine-fentanyl-epinephrine. We used the up-down sequential allocation technique to determine the MLAC of bupivacaine in each group. MLAC calculation was performed with the equation of Massey and Dixon and confirmed with probit analysis.
Results: We found that the MLAC of bupivacaine alone (0.119% ± 0.07%) was reduced when either fentanyl (0.048% ± 0.03%) or epinephrine (0.082% ± 0.05%) were added. The MLAC of bupivacaine was reduced further by the combination of both epinephrine and fentanyl (0.033% ± 0.02%). There were no significant side effects in either group.
Conclusion: The addition of either fentanyl, epinephrine or both medications in an epidural solution can reduce the effective dose of bupivacaine for the initiation of labor pain relief. The addition of these adjuvants allows for a further reduction of the concentration of bupivacaine, thereby reducing side effects. (Funded by the Beth Israel Anesthesia Foundation, Boston, USA.)
Author & Article info
Fentanyl and Epinephrine on the Minimum Local Analgesic Concentration of Epidural Bupivacaine for Labor Pain Relief
Yunping Li1, Sabrina Shu2, Cynthia Tirado3, and Philip E. Hess1
From the 1Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA; 2Advanced Solutions Pain Management, White Plains, NY, USA; 3UC Davis Medical Center, Sacramento, CA, USA.
Correspondence to Dr. Philip E. Hess at firstname.lastname@example.org.
Citation: Yunping Li, Sabrina Shu, Cynthia Tirado, Philip E. Hess. Fentanyl and Epinephrine on the Minimum Local Analgesic Concentration of Epidural Bupivacaine for Labor Pain Relief. J Anesth Perioper Med 2019; 6 : 8- 14.