WEDNESDAY, Feb. 15, 2006 (HealthDay News) -- A dose of morphine given before the insertion of an intravenous line effectively relieves pain for newborn infants placed on mechanical ventilation, a new study finds.
"Babies do feel a lot of pain and we want to decrease that pain," said study author Anna Taddio, an assistant professor of pharmacy at the University of Toronto and a scientist at The Hospital for Sick Children in Toronto. "There wasn't a lot of information available on what's best to use. We wanted to know what works best and what are the actual risks?"
Reporting in the Feb. 15 issue of the Journal of the American Medical Association, her team found that morphine reduced the babies' pain response. They also report that a combination of morphine and the topical medication tetracaine was slightly more effective than morphine alone.
As many as one in six newborns needs to stay in the hospital after birth and undergo multiple, sometimes invasive, procedures, according to background information provided in the study. Until fairly recently, it was believed that an infant's underdeveloped nervous system wasn't capable of feeling pain as adults do. However, other studies, including some done by Taddio and her colleagues, have shown that infants do feel pain.
What's more, if infants are subjected to pain early on, it may cause lifelong changes in their pain sensitivity. Taddio said that no one knows for sure why such changes occur, but it's likely due to the fact that the infants' nervous systems are still developing, so experiencing discomfort during that developmental stage can trigger long-term changes.
However, giving pain medication to infants is a complex task. Opioid medications, such as morphine, are very effective at relieving pain but they can also slow breathing, sometimes to dangerously low levels.
Unfortunately, doctors don't have many other options for infant analgesia, Taddio said.
In this study, the Toronto researchers were able to test the efficacy of morphine in infants already placed on ventilators. That's important, Taddio said, because if the morphine did happen to cause a decrease in respiratory function, it could be compensated for with the ventilator.
The study included 132 newborn infants, some premature, others born at full-term. All of the infants needed a "central line," an intravenous line placed in one of the large veins that leads to the heart.
Forty-two babies received tetracaine, while 38 others were given morphine. Thirty-one infants received both morphine and tetracaine and 21 babies received neither medication for the procedure.
The researchers measured pain scores by assessing the infants' "brow bulge" or "facial grimacing" during various points in the procedure. They also measured the newborns' heart rates and oxygen levels.
Compared to babies who didn't receive analgesia, babies who received morphine and tetracaine grimaced for almost 50 percent less time during the procedure, the researchers report. Babies who received morphine alone grimaced 35 percent less time than babies who received no medication during the needle-puncture phase of the procedure. Infants who received tetracaine alone grimaced 20 percent less time than babies with no analgesia, according to the study.
Heart rates were also significantly lower during the procedure for babies who received any type of analgesia, though the effect was strongest for those babies who had morphine or morphine plus tetracaine.
As expected, babies who received morphine -- alone or in combination with tetracaine -- did need more help breathing for 12 hours after they received the medication. About 30 percent of the babies given tetracaine had a slight skin reaction to the drug.
"Using morphine decreased the pain response," concluded Taddio. "Morphine was better than the cream [tetracaine]. Morphine and the cream together weren't much better than morphine alone," she added.
Dr. Jesus Jaile-Marti is director of the division of neonatology at Nyack Hospital in Nyack, N.Y. He said, "This is an important study that highlights a very big issue in the care of these premature babies -- pain management. Babies do sense pain and we all have to be very cognizant of that and we have to provide support and pain relief."
He said he wasn't surprised to see that topical anesthetic wasn't very useful in this situation. Besides using opioid medications, local anesthetics injected under the skin are sometimes an option, Jaile-Marti said.
Both Taddio and Jaile-Marti believe that in very young infants, simple non-pharmaceutical interventions such as providing sugar water, giving physical comfort, and allowing a baby to suck can all sometimes help to reduce the pain response.
For more on infant pain, visit the University of Michigan Health System.