[1] Sir Charles Gairdner Hosp, Dept Pulm Physiol, W Australian Sleep Disorders Res Inst, Perth, WA, Australia
[2] Univ Western Australia, Sch Anat & Human Biol, Perth, WA 6009, Australia
[3] Royal Brompton Hosp, Interstitial Lung Dis Unit, London SW3 6LY, England
[4] UCL, Ctr Resp Res, London, England
[5] Natl Heart & Lung Inst, London, England
[6] Hong Kong Sanat & Hosp, Hong Kong, Hong Kong, Peoples R China