Validity of behavioral and physiologic parameters for acute pain assessment of term newborn infants.

CONTEXT The subjectivity of pain causes enormous difficulties in evaluating neonatal pain with a single, practical and easy-to-apply tool. Pain evaluation in the neonatal period should be performed by valid, safe, useful and feasible methods. OBJECTIVE To evaluate the validity of the Neonatal Facial Coding System (NFCS), Neonatal Infant Pain Scale (NIPS), heart rate (HR) and O2 saturation (O2 sat) for neonatal pain assessment. DESIGN Prospective, double-blind randomized trial. SETTING A secondary level maternity hospital. PARTICIPANTS 70 healthy neonates requiring bilirubin dosage were randomly assigned to receive a venous puncture (P: n = 33, BW 3.2 kg, SD 0.6; GA 39 wk, SD 1; 59 h of life, SD 25) or an alcohol swab friction (F: n = 37; BW 3.1 kg, SD 0.5; GA 39 wk, SD 1; 52 h of life, SD 17). INTERVENTION All measurements were taken prior to (PRE), during (TO), and 1 (T1), 3(T3), 5(T5) and 10(T10) minutes after the procedure. MEASUREMENTS A neonatologist evaluated NFCS, NIPS, HR and O2 sat by pulse oxymetry. RESULTS Median NFCS and NIPS results at T0, T1 and T3 were higher in P group, compared to F. More P neonates presented NFCS > 2 and/or NIPS > 3 at T0, T1 and T3. HR was lower in P group at T1. Average O2 sat was above 90% during the whole study period in both groups. CONCLUSION NFCS and NIPS are suitable instruments for neonatal pain evaluation. Heart rate and O2 saturation can be used only as auxiliary methods.