Maria Pureza Laudiano-Dray, Rebecca Pillai Riddell, Laura Jones, Rajeshwari Iyer, Kimberley Whitehead, Maria Fitzgerald, Lorenzo Fabrizi, Judith Meek

Institution(s): Department of Neuroscience, Physiology & Pharmacology, University College London, Department of Psychology, York University (Toronto), Elizabeth Garrett Anderson Obstetric Wing, University College London Hospitals

Introduction (include hypothesis)
Long-term outcomes for infants born prematurely are adversely affected by repeated exposure to noxious procedures1. These interventions vary widely, for example, in the extent of damage caused and duration. Skin and tissue breaking procedures are therefore likely to each contribute differently to the overall pain burden of neonates, ultimately having a different impact on their development.

Methods
In order to quantify the total pain burden experienced by infants on NICU retrospectively, we aimed to estimate the pain severity of common NICU procedures using published pain scores. We extracted pain scores over the first minute (pain reactivity) from the literature, using 59 randomized controlled trials for 15 different procedures. We calculated the averaged mean scores per procedure and ran a hierarchical cluster analysis to see how they would be significantly separated into degrees of severity. The study was funded by MRC UK, IASP’s Collaborative Research Grant and CHRP.

Results
The average pain scores clustered into five discrete severity groups; mild (n=1; eye drops instillation), mild to moderate (n=3; orogastric tube insertion, nasal prongs insertion for CPAP, urethral catheterization), moderate (n=7; heel lance, nasogastric tube insertion, tape removal, naso/oropharyngeal suction, venepuncture, endotracheal suction, eye examination), severe (n=3; intramuscular injection, endotracheal intubation, peripheral arterial puncture) and very severe (n=1; lumbar puncture). The estimate of the severity of individual procedures provided new insight into infant pain reactivity which is not always directly related to the invasiveness and duration of a procedure

Conclusions
This estimate of procedural pain severity, based on pain reactivity scores, provides a novel platform for retrospective quantification of the total pain burden in NICU patients. Other measures that reflect the recovery from each individual procedure, such as brain activity and behaviour, would further improve pain estimation.

References
1 Grunau R. E. (2013). Neonatal pain in very preterm infants: long-term effects on brain, neurodevelopment and pain reactivity. Rambam Maimonides medical journal, 4(4), e0025. doi:10.5041/RMMJ.10132