Early Non Invasive Ventilation in Immuno-compromized Patients With Acute Respiratory Failure.

Inclusion Criteria: * Age over 18 years old * ICU admission * Acute respiratory failure defined by (PaO2\<60 mmHg at room air) or (polypnea \>30/min or dyspnea at rest) or respiratory distress. Since less than 72 hours. * Immuno compromized patient defined by solid tumor (treated since less than 5 years) or haematological malignancy (treated since less than 5 years) or Solid organ transplantation or Stem cell transplantation or Immunosuppressive treatment (steroid \> 1mg/kg/d or \>1 month or other immunosuppressive treatment \>1 month) Exclusion Criteria: * Hypercapnia \>50 mmHg or increased of hypercapnia \>10 mmHg under Oxygen treatment * Need of immediate mechanical ventilation * Obvious cardiogenic oedema * Vasopressor use \>0.03 µg/kg/min * Glasgow Score \<13 * End of life decision * Acute myocardial infarction * Patient refusal * Pregnancy * No national health insurance