Pneumonia is a recurrent element of COVID-19 infection, it is often associated with development of respiratory failure and patients frequently need various degrees of oxygen therapy up to non invasive ventilation (NIV-CPAP) and invasive mechanical ventilation (IMV).

Main purpose of this study is to evaluate with non invasive clinical instruments (pletysmography, Diffusion lung capacity for carbon monoxide -DLCO-, six minute walking test and dyspnea scores) and radiological tools (chest X-ray and chest CT scan) the development of medium-to-long term pulmonary sequelae caused by SARS-CoV-2 pneumonia.

SARS-CoV-2 related disease started in December 2019 in the Chinese city of Wuhan, rapidly spread and became an international health emergency.

Pneumonia is a frequent element of COVID-19, its pathogenic mechanisms are not entirely known and some patients develop various degrees of respiratory failure and need oxygen therapy up to NIV-CPAP) and IMV.

Some pathology studies in COVID-19 pneumonia show ARDS-like lesions associated to inflammatory reaction. It is known that pulmonary inflammatory damage can lead to fibrotic sequelae or to the development of pulmonary emphysema.

The main target of the study is to use non invasive methods (pletysmography, DLCO assessment, six minute walking test and dyspnea scores) and radiological tools (chest X-ray and chest CT scan) to identify pulmonary sequelae in patients hospitalised because of respiratory failure in COVID-19 pneumonia.

Study design: multicentre observational cohort study. Patients will be divided in three arms according to maximum ventilatory/oxygen support received during hospital stay:

1. patients who received only oxygen therapy
2. patients who received non invasive ventilation (NIV-CPAP)
3. patients who received invasive mechanical ventilation (IMV)

All patients undergo a clinical evaluation at 6 months from hospital discharge (T1) and a second clinical evaluation at 12 months from hospital discharge (T2).

During (T1) patients undergo spirometry with pletysmography and DLCO assessment, six minute walking test, standard chest X-ray, arterial blood gas analysis if SaO2 < 93% in room air, dyspnea score and presence and extension of lung sounds at pulmonary auscultation.

During (T2) patients will undergo spirometry with pletysmography and DLCO assessment, six minute walking test, High Resolution CT scan (HRTC) of the thorax, arterial blood gas analysis if SaO2 < 93% in room air, dyspnea score and presence and extension of lung sounds at pulmonary auscultation).

Inclusion Criteria:

• Age ≥ 18 and ≤ 80 years
• Able to sign informed consent to participate in the study
• Real time PCR diagnosis od SARS-CoV-2 infection
• Hospital admission due to clinical/instrumental diagnosis of interstitial pneumonia
• Presence of acute respiratory failure (PaO2/FiO2 <300 mm Hg) at the moment of hospital admission

Exclusion Criteria:

• Severe renal failure defined as glomerular filtration rate (GFR) < 30 ml/min at hospital discharge
• Cardiovascular failure NYHA class IV (patient unable to perform any activity) at hospital discharge
• Active solid or hematological malignancies at hospital discharge
• Prior diagnosis of chronic obstructive pulmonary disease (COPD), pulmonary emphysema, pulmonary fibrosis, bronchiectasis associated or not associated to cystic fibrosis
• Pregnancy or breastfeeding
• Suspected bacterial or fungine pulmonary superinfection during hospital stay

Patients with respiratory failure (P/F < 300) due to SARS-CoV-2 pneumonia