The impact of persisting pain following surgery in neonates

Clinicians and researchers agree that neonates (infants between 0 and 27 days old following birth) admitted to the neonatal intensive care unit (NICU) experience pain. In addition to being a source of immediate distress and agitation for neonates, pain may also have consequences for neonates during their admission and also extending beyond discharge from the NICU. Researchers have hypothesised that early-life exposure to pain may alter the development of the brain, and thus hinder an infant’s ability to reach age-appropriate developmental milestones. Indeed, acute pain, or procedure-related pain, has been shown to result in long-lasting impacts on developmental outcomes such as brain development (neurodevelopment), growth, and psychosocial functioning. Specifically, researchers have suggested a dose-response relationship between pain in the NICU and poor long-term outcomes. Studies have shown that a greater frequency of painful procedures in the NICU may result in poor cognitive and motor development at eight and 18 months of age, poor cognitive outcomes at school age, increased sensitivity to pain in early childhood, higher rate of internalising behaviours at school age such as fearfulness and social withdrawal, and low weight and head circumference. Furthermore, the impact of painful experiences on the infant’s social wellbeing is unknown. In particular, the role of ongoing pain on the infant-to-parent relationship at such a critical period of relationship formation has not been investigated. Depending on their underlying medical condition, neonates and infants in the NICU undergo a wide range of interventions, some of which may contribute to ongoing pain and distress. It has been difficult to establish whether pain has a direct impact on the developmental trajectory of infants. In order to elucidate whether there is a dose-response relationship between pain experience and developmental outcomes, it is important to determine if there is an impact of the duration of treated pain on the developing infant. The primary objective of this study is to determine whether the persisting need for analgesia, operationalised as the duration of treated pain, during NICU admission has an impact on gross motor skills after discharge. Secondary objectives of this study are to determine whether the duration of treated pain during NICU admission has an impact on 1) other neurodevelopmental outcomes including cognition/problem-solving, fine motor skills, receptive and expressive language, and personal-social skills, 2) complications following surgery, 3) growth, and 4) psychosocial functioning, of the infant.