title: Author reply.
authors.affiliation: The Prince Charles Hospital, Heart and Lung Institute, Brisbane, Queensland, Australia.|University of Queensland, Brisbane, Queensland, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Markham
authors.affiliation: The Prince Charles Hospital, Heart and Lung Institute, Brisbane, Queensland, Australia.|University of Queensland, Brisbane, Queensland, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Murdoch
authors.affiliation: The Prince Charles Hospital, Heart and Lung Institute, Brisbane, Queensland, Australia.|University of Queensland, Brisbane, Queensland, Australia.
authors.forename: D L
authors.initials: DL
authors.lastname: Walters
authors.affiliation: The Prince Charles Hospital, Heart and Lung Institute, Brisbane, Queensland, Australia.|University of Queensland, Brisbane, Queensland, Australia.|University of Washington, Seattle, Washington, USA.
authors.forename: C
authors.initials: C
authors.lastname: Hamilton-Craig