1. Medical Gases Group, Air Liquide Santé International, Centre de Recherche Claude-Delorme, Les Loges-en-Josas, France.
2. National Institute of Health Research Biomedical Research Unit in Respiratory Disease, Southampton, UK.
3. Department of Medical Physics and Bioengineering, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
4. Faculty of Health Sciences, University of Southampton, Southampton, UK.
5. Department of Mechanical Engineering, Lafayette College, Easton, PA, USA.