1 Intensive Care Clinical Unit, Hospital Universitario Virgen Macarena, Seville, Spain. Electronic address: luisabulnes@hotmail.com.
2 Department of Intensive Care Medicine, Multidisciplinary Intensive Care Research Organisation (MICRO), St James's Hospital, Dublin, Ireland; Trinity College Dublin, Dublin, Ireland; CIBER of Respiratory Diseases (CIBERES), Institute of Health Carlos III, Madrid, Spain; Pulmonary Department, Hospital Clinic, Universitat de Barcelona, IDIBAPS, ICREA, Barcelona, Spain.