The Effect of Epidural Epinephrine on Breakthrough Pain in Labor
Abstract Number: 11
Abstract Type: Original Research
Epidural bupivacaine is effective for the management of labor pain, but produces the undesirable side effects of hypotension and motor blockade. The addition of other analgesics, such as opioids and clonidine, added to local anesthetics reduces the concentration of bupivacaine required. Epidural epinephrine has been observed to prolong and enhance the analgesic effect of local anesthetics. The mechanism is thought to be due to its own analgesic properties and possibly a spinal adrenergic mechanism.(1)
The addition of epinephrine reduces the minimum local analgesic concentration of bupivicaine by 30%.(2) However; the effect of epinephrine during epidural infusion has not been evaluated. We undertook this study to assess whether the addition of epinephrine to epidural bupivicaine could decrease episodes of breakthrough pain during labor.
After IRB approval and written informed consent, ASA I and II paturients in active labor (<7 cm dilated) were enrolled. Exclusion criteria included previous opioid use, chronic pain, and DM. All patients received a combined spinal epidural. Spinal injectate was 2mg bupivacaine and 12.5mcg fentanyl. Subjects were randomized to receive: bupivicaine 0.4%/fentanyl 1.66mcg/ml (BF), or bupivicaine 0.4%/fentanyl 1.66mcg/ml/epinephrine 1:600,000 (BEF) as the epidural solution at 15ml/hr. Vital signs and visual analog scale (VAS) scores for pain were recorded at placement and at 15 minute intervals for the next 120 minutes. Primary outcome was the need to treatment of breakthrough pain, secondary outcomes included side effects, and labor outcome.
111 paturients were enrolled. Four were eliminated due to catheter replacement. There was no significant difference in demographic characteristics: age, height, weight, gestation, dilation at placement, use of oxytocin, and neonate weight. The BEF group required fewer boluses of supplement medication and had a lower bolus rate than the BF group (p=.035, p=.025). We found no significant difference in hypotension, episodes of nausea and vomiting, and duration of labor between the two groups. (Table 1)
The addition of epidural epinephrine 1:600,000 resulted in a significant reduction in supplemental bolus rate in parturients receiving CSE for labor. There were no significant increases in side effects or duration of labor.
1. Anesthesiology 1981;54:451-67.
2. Anesthesiology 2002:96:1123-8.