[1] Univ Derby, Human Sci Res Ctr, Derby, England
[2] Cambridge Univ Hosp, Cambridge Resp Physiol, Cambridge, England
[3] Royal Papworth Hosp, Cambridge, England
[4] NHSFT, Lung Funct & Sleep Univ Hosp Birmingham, Birmingham, W Midlands, England
[5] Royal Brompton Hosp, Dept Resp Med, London, England