Patients with acute respiratory failure (ARF) less than 72 hours after a major cardiac surgery with cardiopulmonary bypass

ARF was defined as one of the following conditions:

• If mechanical ventilation, a partial pressure of oxygen/ inspired oxygen fraction ratio (PaO2/FiO2) < 200, or failure of weaning (failure of spontaneous ventilation test, re-intubation in the first 24 hours), or need for non-invasive ventilation immediately after extubation,
• If spontaneous ventilation: clinical signs of acute respiratory distress (dyspnea at least exertion, cyanosis, polypnea> 25/min, upper or intercostal swallowing, abdominal swing ...), pulse oximetry (SpO2) < 90% or PaO2 <60 mmHg despite oxygen therapy ≥ 3 L/min.

Pneumonia or excluded pneumonia, was determined by consensus of 3 investigators, after an independent post hoc review of the medical records. Pneumonia diagnosis was based on concordance of clinical and radiological criteria (≥ 2 criteria including fever> 38.5 ° C or T <36 ° C, leukocytosis> 10 ^ 9 / L or leukopenia <4.10 ^ 8 / L, purulent tracheal secretions and the appearance or persistence of an infiltrate on the CXR).

It should be confirmed by culture of a respiratory specimen: protected distal sampling with a threshold of significance ≥ 10 ^ 3 colony forming unit/mL or bronchoalveolar lavage with a threshold of significance ≥ 10 ^ 4 CFU/mL.