Effect of early procedural pain experience on subsequent pain responses among premature infants

Abstract

Background and objectivesPreterm newborns are exposed to repeated procedural pain during their NICU stay. Acute pain has negative short-term effects and may have adverse neurodevelopmental sequelae. Disagreement among researchers exists in the direction of pain responses. We aimed at evaluating the short-term effects of early procedural pain exposure on subsequent behavioral and physiological responses among preterm infants; and to define possible contributing factors. Patients and methodsA prospective study included 203 preterm newborns recruited from 2 community centers, excluding cases having conditions that may affect pain responses. They were categorized into: group I including cases who were exposed to painful procedures; and group II were not exposed. Pain response to heel-stick procedure was assessed by Neonatal Infant Pain Scale to measure behavioral response, and changes in heart rate and oxygen saturation to evaluate physiological responses. ResultsHistory of pain exposure and number of procedures were the only independent variables that predicted subsequent pain responses while other contextual factors had no significant impact. The behavioral pain responses were blunted in group I with lower pain scores during and after the heel-stick test, while physiological responses were exaggerated with a higher heart rate and oxygen saturation variability. ConclusionOn studying the physiological and behavioral responses to pain in the premature infants, it was found that prior pain exposure and the number of procedures predict dampened behavioral and exaggerated physiologic subsequent pain responses. Protocols for minimization of pain exposure and pain control need to be implemented to avoid infant distress and long-term neurodevelopmental sequelae.