Drug Gives Relief During Labor and Delivery Without Uncomfortable Numbness, Yale Study Shows

A pain reliever traditionally used for post-operative pain, when diluted and given through an epidural, provides pain relief during labor and delivery without the uncomfortable numbness that makes it difficult for women to push or feel the baby emerge, a Yale study has found.

“The drug hydromorphone, or Dilaudid, is given in very small amounts and provides nearly complete pain relief without the need for excessive amounts of numbing local anesthetic medication,” said Raymond Sinatra, M.D., professor of anesthesiology at Yale School of Medicine and lead author of the study published in the May issue of the journal Anesthesia & Analgesia. “By reducing the amount of local anesthetics in the epidural, women are able to push more vigorously and can actually feel the baby being born, without feeling pain.”

Sinatra and his research team tested a continuous epidural infusion containing a dilute solution of hydromorphone and local anesthetic (0.03 percent bupivacaine) in 1,830 women who requested pain relief during labor and delivery. An epidural usually involves injecting a significant amount of local anesthetic into the epidural space of the spinal column to achieve regional anesthesia of the abdominal, genital or pelvic area.

Sinatra said prior studies at Yale have evaluated hydromorphone for use during labor and delivery, but this is the first to test it on such a wide scale.

“Women treated with hydromorphone reported superior pain control and required less need for the local anesthetic bupivacaine and less analgesic supplementation than has been our experience with the pain reliever fentanyl, which is most commonly used in this setting,” he said.

“On the basis of these findings, and clinical experience gained over several years, hydromorphone is the epidural opioid of choice for labor and delivery analgesia at our institution,” he said. The women who received the epidural were initially given 100 micrograms hydromorphone, which is a very small amount, plus bupivacaine followed by a continuous infusion of the two pain relievers.

After delivery, the women’s level of pain was assessed in an interview. The overall quality of labor analgesia was rated excellent by 91 percent of the women, good by seven percent, and poor by two percent of the patients.

Earlier studies found that the hydromorphone, when not diluted, caused nausea in about one third of the women who received it. Sinatra said the reduction in the drug used in this large-scale trial reduced the number of women who actually experienced nausea to an acceptable level of only two percent, yet it did not influence its effectiveness as an analgesic. As labor progressed, fewer than 22 percent of the women requested supplemental epidural doses of more concentrated local anesthetic.

There were no observable serious side effects such as excessive sedation, slower breathing, very low blood pressure or the slowing of the fetus’ heartbeat. The number of patients experiencing other side effects to the use of hydromorphone, among them nausea and severe itching, was small.

Sinatra said ongoing research is underway to assess the effect of the two drugs on the duration and outcome of labor and delivery. Nevertheless, over 10,000 women requesting epidural analgesia for labor and delivery at Yale-New Haven Hospital have received the dilute hydromorphone solution.

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