Chronic Critical Illness (CCI) is a condition associated to patients surviving an acute phase of disease and respiratory failure (ARF) although remaining dependent on mechanical ventilation (MV). The prevalence and the underlying mechanisms of CCI have not been elucidated in this population.An observational prospective cohort study was undertaken at the Respiratory Intensive Care Unit (RICU) of the University Hospital of Modena (Italy) from January 2016 to January 2018. Patients mechanically ventilated with ARF in this unit were enrolled. Demographics, diagnosis, severity scores (APACHEII, SOFA, SAPSII) and clinical conditions (septic shock, infections, acute respiratory distress syndrome [ARDS]) were recorded on admission. Respiratory mechanics and inflammatory-metabolic blood parameters were recorded on admission and within the first seven days of stay. All these variables were tested as potential predictors of CCI through appropriate univariate and multivariate analysis.

Inclusion Criteria:

• older than 18 years of age
• consecutively admitted to RICU due to acute respiratory failure (ARF) requiring mechanical ventilation.

Exclusion Criteria:

• refractory shock (death < 24h)
• patient goals of care not consistent with aggressive management
• end stage COPD requiring home oxygen long term therapy or home non invasive ventilation support
• presence of interstitial lung disease
• history of neuromuscular disease
• chest wall deformities
• pregnancy
• chemotherapy or radiotherapy within the past 30 days
• evidence of neurologic injury on CT scan and GCS < 8
• tracheostomy.

Observational cohort