[1] Univ Sydney, Sydney Med Sch, Fac Med & Hlth, Sydney, NSW, Australia
[2] Concord Hosp, Dept Resp & Sleep Med, Concord, Australia
[3] Royal Prince Alfred Hosp, Dept Resp & Sleep Med, Camperdown, NSW, Australia
[4] Royal Prince Alfred Hosp, Physiotherapy Dept, Camperdown, NSW, Australia
[5] Univ Sydney, Sydney Sch Hlth Sci, Fac Med & Hlth, Sydney, NSW, Australia