The Newborn Infant Parasympathetic Evaluation (NIPE™) monitor predicts post-operative pain in children undergoing day-procedures: A prospective observational study

Background: Pain assessment is essential for the administration of appropriate analgesia. Currently, clinicians use surrogate methods, such as heart rate or behavioural pain scales, to estimate pain in neonates and infants. The Newborn and Infant Parasympathetic Evaluation (NIPE™) monitor aims to provide an objective numeric value (NIPE index) of pain through a continuous assessment of the patient's parasympathetic activity. The aim of this study was to determine if the intraoperative NIPE index monitoring could predict postoperative pain in neonates and infants. Methods: This prospective observational pilot study included neonates and infants undergoing elective day-surgical procedures (n = 50). Intraoperatively, NIPE indices at 0 (NIPE₀), 10 (NIPE₁₀), 20 (NIPE₂₀), 30 (NIPE₃₀) minutes and at completion of surgery (NIPEe), were recorded; the median NIPE index (NIPEm) was calculated for the entire procedure. Postoperative Face, Legs, Activity, Cry, Consolability (FLACC) scale scores were calculated by the nursing staff blinded to the intraoperative NIPE indices. Results: Linear regression documented an association between the NIPEm and postoperative FLACC score at 0 (r = 0.31, p = 0.03) and 10 min (r = 0.36, p = 0.01). No significant associations were observed for FLACC scores at 20 (r = 0.21, p = 0.2) and 30 min (r = 0.36, p > 0.9). Multiple regression analysis revealed that intraoperative NIPE₁₀, NIPE₂₀, NIPE₃₀ and NIPEe also predicted the FLACC score at 0 min (p = 0.003). Conclusion: The intraoperative NIPE index is predictive of pain in the immediate postoperative period. This association was lost at 20 min likely due to nursing intervention to administer analgesia. NIPE monitoring could be useful in facilitating postoperative pain management in infants. Level of evidence: II. Type of study: Study of Diagnostic Test.