The Newborn Infant Parasympathetic Evaluation Index for Assessment of Procedural Pain and Discomfort in Mechanically Ventilated Pediatric Intensive Care Patients: A Prospective, Exploratory, Observational Study

Background: The heart rate variability-based Newborn Infant Parasympathetic Evaluation (NIPE) Index is a continuous noninvasive tool for the assessment of pain and discomfort in infants. Little is known about its performance in the pediatric intensive care unit (PICU) setting, where assessment of pain/discomfort is usually based on discontinuous observational scoring systems or personal experience of medical staff. Aim: Evaluation of the performance of NIPE as an indicator of procedural pain and/or discomfort in conscious mechanically ventilated PICU patients. Methods: Procedural pain/discomfort was simultaneously assessed during pain- or stressful procedures by two validated discontinuous clinical scoring systems (FLACC and COMFORT-B scale) and the NIPE. Results: NIPE values, FLACC- and COMFORT-B scores were recorded in 17 infants with a mean age of 1.2 (range 0.8-5.9) months. NIPE values associated with positive FLACC- (>= 4; indicative of pain) and/or COMFORT-B (>= 17, indicative of discomfort) scores were lower (p<0.001) than when associated with negative FLACC (<4) and/or COMFORT-B (<17) scores with 95% CI's of a difference of -14 to -11 (FLACC), -13 to -11 (COMFORT-B) and -14 to -11 (FLACC and COMFORT-B), with significant interindividual variability in NIPE values. Logistic regression analyses revealed odds ratios between 0.84 and 0.85; the adjacent receiver operating curve analyses showed areas under the curve between 0.83 and 0.88. NIPE data recording failure occurred during 49.3% of the periods with a FLACC >= 4% and 40.7% with a COMFORT-B >= 17. Conclusions: The NIPE detects procedural pain and discomfort in conscious mechanically ventilated infants with an accuracy comparable to established clinical scoring systems. However, because of significant interindividual variability of NIPE values and frequent data recording failure associated with patient movement, we believe it is premature to recommend its use in conscious infants.