1. Royal Brompton Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London SW3 6NP, UK
2. National Hospital for Neurology and Neurosurgery, University College London, London WC1N 3BG, UK
3. Lane Fox Respiratory Service St Thomas’ Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London SE1 7EH, UK
4. Lane Fox Clinical Respiratory Physiology Research Unit, Centre for Human and Applied Physiological Science, King’s College London, London SE1 7EH, UK