1. Intensive Care Medicine, St James’s University Hospital, Dublin, Ireland
2. Department of Respiratory Medicine, South Texas Veterans Health Care System and the University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
3. Department of Intensive Care Medicine, Polyvalent Intensive Care Unit, São Francisco Xavier Hospital, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal
4. Nova Medical School, CEDOC, New University of Lisbon, Lisbon, Portugal
5. Department of Clinical Medicine, Trinity College, Welcome Trust-HRB Clinical Research Facility, St James Hospital, Dublin, Ireland