Even routine tests can up newborns' pain response

Newborn babies lie in their cots in a hospital in Hanoi August 13, 2009.

NEW YORK (Reuters Health) - Even a routine heel-stick test can be painful enough for some newborns to trigger an increase in potentially harmful free radicals in the blood, a new study suggests.

The findings, published in the journal Pain, do not mean that a single heel stick -- done routinely to test newborns for certain genetic disorders -- will cause harm. But researchers say they do raise concerns about newborns in neonatal intensive care units (NICUs), who undergo many painful procedures each day.

The study underscores the need to ensure that newborns have adequate pain relief during medical procedures, lead researcher Dr. Carlo Bellieni, of the University of Siena in Italy, told Reuters Health in an email.

It was once widely thought that newborns essentially do not feel pain from routine medical procedures. Research has proven that belief to be wrong, and guidelines from groups like the American Academy of Pediatrics call on NICUs to do everything they can to limit tiny infants' pain -- including using topical anesthetics and non-drug tactics, like pacifiers dipped in sugar solutions.

But recent studies indicate that newborn pain management is "still far from satisfactory," Bellieni and his colleagues note in their report.

This is concerning not only because of the immediate pain and stress tiny infants suffer, but also because research suggests that repeated exposure to pain and stress early in life may have lasting effects -- including increased pain sensitivity later in life.

For their study, Bellieni and his colleagues measured two markers of free-radical production in 64 newborns having a routine heel stick to draw blood samples. Free radicals are potentially cell-damaging substances that may be generated in response to injury and stress; it has not been clear whether minor medical procedures boost their production in newborns.

The researchers found that, as a group, the infants showed no significant increase in free-radical production from the beginning of the heel-stick procedure to the end.

However, the findings were different when Bellieni's team focused on the 34 infants who showed a high pain response during the heel stick -- as measured by the babies' crying and distress.

These newborns did show an increase in free-radical generation.

The potential consequences of this increase are not clear, according to Bellieni. "Free radicals can provoke brain damage," he explained, "but no study has been performed to measure the threshold above which they may harm the baby."

A single heel stick would not be enough to cause damage, the researcher said. But he added that infants in the NICU may receive more than a dozen procedures a day, which may result in repeated free radical production -- the possible effects of which are unknown.

The findings, according to Bellieni, further the case for better pain management in NICUs.

Recent studies have pointed to a number of non-drug approaches that may calm newborns' pain response during routine procedures -- including sugar solutions, skin-to-skin contact with mom and soothing music.

Bellieni said he and his colleagues have developed a technique called "sensorial saturation," where oral sugar solutions, massage and the mother's voice are all used to distract and soothe babies.

SOURCE: Pain, December 15, 2009.