1 Paediatric Emergency Medicine Leicester Academic (PEMLA) Group, Children's Emergency Department, Leicester Royal Infirmary, Leicester, UK.
2 SAPPHIRE Group, Health Sciences, Leicester University, Leicester, UK.
3 Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, UK.
4 NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.