Effect of Epinephrine Addition to Epidural Morphine in Obstetric Analgesia

Abstract

We studied, in a double-blind manner, the effect of epinephrine added to a 2-mg morphine sulfate solution for epidural analgesia in obstetrics. Seventy-five primagravida (ASA class I) were randomly divided into five groups. Group 1 received morphine sulfate 2 mg with epinephrine 1:200,000 in 0.9 NaCI. Group 2 received morphine sulfate 2 mg and bupivacaine 25 mg. Group 3 received morphine sulfate 2 mg, bupivacaine 25 mg, and epinephrine 1:200,000. Group 4 received bupivacaine 25 mg. Group 5 received bupivacaine 25 mg and epinephrine 1:200,000. Group 1 patients had significantly less pain relief than the other four groups. The degree of pain relief was similar in the other four groups. The time between the first epidural injection and reinjection was significantly shorter in Group 1 patients. Moreover, patients who received morphine had significantly more nausea and pruritus than patients not receiving morphine. We conclude that epinephrine is not effective with a small dose of morphine (2 mg) in obstetric epidural analgesia and that the combination of bupivacaine and morphine does not offer any advantage that would justify its use in obstetric epidural analgesia.