Acute respiratory failure is a common entity in intensive care units nowadays and is associated with significant morbidity and mortality, thus representing a major health problem. Most of the published epidemiological studies on this condition were performed when modern ventilatory strategies and non-invasive ventilation were not available. Therefore, an actual evaluation on the incidence and outcomes of this syndrome is mandatory. We will perform an observational prospective study of patients admitted with acute respiratory insufficiency in several ICUs in Brazil.

Inclusion Criteria:

• Need for non-invasive or invasive mechanical ventilation for more than 24 hours in the first 48 hours of admission to the intensive care unit.

Exclusion Criteria:

• Tracheostomized patients
• Patients admitted to ICUs for monitoring or in post-operatory of non-complicated surgeries.
• Patients with cancer on terminal stage.

Patients admitted to intensive care units in Brazil with acute respiratory failure