Assessing pain in our tiniest patients

Babies in the NICU can feel pain

An infant rests in the Neonatal Intensive Care Unit (NICU), recovering from elective surgery. She’s crying, but is it because the procedure caused pain, because she’s hungry or for some other reason? An inspired research collaboration between the NICU and the Division of Pain Medicine at Boston Children’s Hospital is determined to find out.

As recently as the last century, physicians weren’t sure how much pain infants experienced — or if they felt pain at all. As a result, many procedures were performed without anesthesia or analgesics. Today, it’s widely accepted that newborns do feel pain, but there’s still much we don’t understand about the severity of that pain. Although the Neonatal Infant Pain Scale can help clinicians access pain through behavioral cues such as crying, breathing patterns and facial expressions, it isn’t always reliable, particularly when infants are premature, ill or require medications that alter their perceptible response to pain.

To better understand pain in neonates, investigators at Boston Children’s Hospital are moving beyond visual indicators of the problem by studying multiple aspects of pain expression. The team includes Anne Hansen, MD, medical director of the NICU; Charles Berde, MD, PhD, chief of the Division of Pain Medicine; Christos Papadelis, PhD, an associate researcher in the hospital’s Fetal-Neonatal Neuroimaging and Developmental Science Center and Laura Cornelissen, a research associate in the Division of Pain Medicine.

“Though our pain scores are tried and true, they are limited to external expressions, and they can be subjective,” explains Hansen. “We hope to augment our current assessment with newer technologies to optimally treat our patients.”

A special population

Infants who require care in the NICU after undergoing surgery present a special challenge for clinicians. “These babies feel considerable pain and are more vulnerable to even minor painful clinical procedures, possibly because their somatosensory system is more unregulated than that of healthy infants,” explains Papadelis. Post-surgical discomfort is believed to have a significant impact on babies’ lives and later development, making early assessment and treatment crucial for this population.

To gain insight into pain processing in these young patients, the Boston Children’s team is performing electroencephalography (EEG) so that they can non-invasively assess their direct neurologic response to pain. They are also assessing other signs of autonomic nervous system changes, such as skin conductance, which measures the amount that infants sweat when experiencing discomfort. In addition, an advanced technique that recognizes sub-dermal blood flow from video recordings of the infants’ faces is used to extract data on their response to painful clinical stimuli. Finally, for the subset of patients who are muscle-relaxed — and therefore the most difficult to assess for pain and agitation — they are assessing facial electromyographic responses in order to determine if the infants display a facial grimace that is not evident to the naked eye.

“Our findings from these tests will help us to assess the level of pain that post-operative infants the NICU experience,” says Papadelis. “This could help guide the pharmacological treatment of these patients with analgesic agents, sedatives, muscle relaxants or a combination of these approaches.”

The promise of research

The researchers plan to gather information on a total of 40 infants, 10 controls and 10 each from three groups undergoing major surgery that is anticipated to cause pain and agitation, including one group who will receive postsurgical neuromuscular blockage. “We’re still in the early stages of the project,” says Papadelis, who predicts that the study will be completed a year from now. “But the initial data look really promising.”

We have learned that both pain and agitation, as well as the medications to treat pain and agitation, are unhealthy. Therefore, it is critical to be able to assess pain and agitation as accurately as possible,” says Hansen. “Given our expertise here at Boston Children’s, we believe we are in a strong position to make a valuable contribution to the field. Our goal is to be able to use advanced, noninvasive technologies to tailor our treatment of NICU patients to avoid both under- and over-treating their pain and agitation. We know that this is a top priority for parents, as it is for us.”

Learn more about the Neonatal Intensive Care Unit.