Urinary markers of pain in children in neonatal intensive care units: a cross-section study

Introduction: Repetitive exposition to pain negatively affects newborns development. Procedural pain in newborn in Neonatal Intensive Care Unit (NICU) triggers a series of physiological, behavioral and hormonal disorders that may set off the impairment of the neurological development in preterm infants, who undergo long periods of hospitalization at a moment of physiological immaturity and fast brain development. Objective: This study aimed not only to observe the pain score in newborns and infants when undergoing painful procedures in neonatal intensive care units but also to analyse urinary IL-8 and cortisol levels at such stressful moments. Methods: Patients were submitted to venipuncture and to other methods of blood collection. Cortisol and IL-8 levels were measured by immunometric assay and chemiluminescence detection. For the collection of data regarding observation of neonatal pain, the Neonatal Infant Pain Scale was used with immediate results. To describe the qualitative variables, absolute and relative frequencies were used. For the quantitative variables with normal distribution, mean, standard deviation, minimum and maximum were used. Results: A total of 81 patients were included: 47 were submitted to venipuncture and 36 to other methods of blood collection. Significance for cortisol can be seen (p=0.04); however, IL-8 levels, when associated with the pain scale, were not sensitive enough (p=0.11). Conclusion: The results showed that cortisol is a better marker for pain than IL-8, and its accumulation in urine may help the detection and interpretation of pain. Conclusion: Based on this information, nurses can step in to reduce the discomfort brought by painful procedures, and thus highlight humanistic practices in nursing assistance.