1 Department of Paediatric Respiratory Medicine, Staffordshire Children's Hospital at Royal Stoke, University Hospitals of North Midlands NHS Trust, Stoke-on-Trent, UK.
2 Institute of Applied Clinical Science, Keele University, Keele, UK.
3 Paediatric Intensive Care Unit, Leicester Children's Hospital, Leicester, UK.
4 Paediatric Psychology Service, North Staffordshire Combined Healthcare NHS Trust, Newcastle Under Lyme, Staffordshire, Derby, UK.