The impact of cumulative pain/stress on neurobehavioral development of preterm infants in the NICU

Abstract

Background: Vulnerable preterm infants experience repeated and prolonged pain/stress stimulation during a critical period in their development while in the neonatal intensive care unit (NICU). The contribution of cumulative pain/stressors to altered neurodevelopment remains unclear. The study purpose was to investigate the impact of early life painful/stressful experiences on neurobehavioral outcomes of preterm infants in the NICU.

Methods: A prospective exploratory study was conducted with fifty preterm infants (28 0/7-32 6/7weeks gestational age) recruited at birth and followed for four weeks. Cumulative pain/stressors (NICU Infant Stressor Scale) were measured daily and neurodevelopmental outcomes (NICU Network Neurobehavioral Scale) were examined at 36-37weeks post-menstrual age. Data analyses were conducted on the distribution of pain/stressors experienced over time and the linkages among pain/stressors and neurobehavioral outcomes.

Results: Preterm infants experienced a high degree of pain/stressors in the NICU, both in numbers of daily acute events (22.97±2.30 procedures) and cumulative times of chronic/stressful exposure (42.59±15.02h). Both acute and chronic pain/stress experienced during early life significantly contributed to the neurobehavioral outcomes, particularly in stress/abstinence (p<0.05) and habituation responses (p<0.01), meanwhile, direct breastfeeding and skin-to-skin holding were also significantly associated with habituation (p<0.01-0.05).

Conclusion: Understanding mechanisms by which early life experience alters neurodevelopment will assist clinicians in developing targeted neuroprotective strategies and individualized interventions to improve infant developmental outcomes.

Keywords: Neonatal intensive care; Neurobehavioral outcomes; Pain; Preterm infants; Stress.

Copyright © 2017 Elsevier B.V. All rights reserved.

Figures

Figure 1

Unweighted daily mean pain/stressors during the first 28 postnatal days decomposed by pain/stress severity levels. 1A - Acute pain/stressors (frequency); 1B - Chronic pain/stressors (hours); Pain/stress severity levels: Acute2/Chronic2 = a little; Acute3/Chronic3 = moderate; Acute4/Chronic4 = very; and Acute5 = extremely painful/stressful.

Figure 2

Unweighted weekly mean pain/stressors during the first four weeks decomposed by pain/stress severity levels. 2A - Average weekly mean (frequency) acute pain/stress experience; 2B - Average weekly mean (hours) chronic pain/stress experience. Pain/stress severity levels: Acute2/Chronic2 = a little; Acute3/Chronic3 = moderate; Acute4/Chronic4 = very; and Acute5 = extremely painful/stressful.

Figure 3

Common daily pain/stressors experienced during the first 28 postnatal days in the NICU. 3A - Acute procedures (frequency); 3B – Daily chronic events (hours); Pain/stress severity levels: Acute2/Chronic2 = a little; Acute3/Chronic3 = moderate; Acute4/Chronic4 = very; and Acute5 = extremely painful/stressful.