Parasympathetic evaluation for procedural pain assessment in neonatology.

Introduction: The Newborn Infant Parasympathetic Evaluation (NIPE) index is an instrument that enables continuous, fast and objective assessment of neonatal discomfort. The aim of the study was to analyse changes in NIPE values after performance of blood draws and the factors involved in this variation.

Material And Methods: We conducted a prospective observational study. We included infants admitted to the neonatal intensive care unit between June and December 2021 who underwent blood draws. We recorded demographic data, aspects related to the procedure, the NIPE index and the heart rate at baseline and 1, 2, 3, 4, 5, 10 and 15 min after the procedure.

Results: The study included 86 records for 49 patients. In the first 4 min after the procedure, there was a significant decrease in the NIPE index, with a maximum decrease of 22.8% relative to baseline and the nadir at 2.79 min. The decrease in NIPE values was greater in infants born preterm, male, with lower 5-min Apgar scores and following procedures that had been performed previously, after caesarean section or in the morning. There were no differences when the blood draw was obtained during kangaroo care. The correlation between the NIPE index and the heart rate was weak.

Conclusions: After a painful procedure, such as a blood draw, the NIPE monitor showed a significant decrease in the first 4 min, which was more pronounced in preterm infants, in repeated procedures or after caesarean delivery. The NIPE index could help identify infants experiencing acute procedural pain, complementing clinical rating scales.