FUNDING This study, including the protocol, will be upload in clinicaltrials.com and supported by the Centro de Investigaciones Biomédicas en Red; (CIBER of Respiratory Diseases (CIBER de Enfermedades Respiratorias del Instituto Carlos III) and the Respiratory Group from the Spanish Society of Intensive Care Medicine (Grupo de Respiratorio de la Sociedad Española de Cuidados Intensivos y Unidades Coronarias, SEMICYUC).