Classification of ARDS according to the Berlin definition (European Society of Intensive Care Medicine, American Thoracic Society, Society of Critical Care Medicine):
| Start | Within one week of onset of risk factors or new or increasing respiratory symptoms. | |
| Radiological findings | Bilateral diffuse compressions on chest x-ray or chest CT that cannot be explained by pleural effusions (increase in fluid content between the parietal pleura (pleura) and visceral pleura (pleura)), collapsed lung areas (e.g., pneumothorax/collapsed lung), or space occupying lesions. | |
| Cause of pulmonary edema(accumulation of water in the lungs). | Heart failure (cardiac insufficiency) or hypervolemia (increase in volume of circulating blood in the circulation) as a cause is excluded or not entirely explained by it; an objective procedure (e.g., echocardiography; cardiac ultrasound) is required to exclude hydrostatically induced pulmonary edema if no risk factors are present. | |
| Extent of hypoxia/hypoxemia | Mild | paO2/FIO2 = 201-300 mmHg with PEEP or CPAP ≥ 5 cm H2O |
| Moderate | paO2/FIO2 = 101-200 mmHg with PEEP ≥ 5 cm H2O | |
| Severe | paO2/FIO2 < 100 mmHg with PEEP ≥ 5 cm H2O | |
| Risk factors | Directly | Pneumonia (lung inflammation), aspiration (e.g., inhalation of foreign bodies), pulmonary contusion (pulmonary contusion), pulmonary vasculitis (lung involvement in systemic vascular inflammation), inhalation trauma (chest trauma from inhalation of corrosive, toxic, hot, or cryogenic gases or aerosols), near drowning |
| Indirect | Nonpulmonary sepsis (blood poisoning not caused by success), pancreatitis (inflammation of the pancreas, burns, noncardiogenic shock (shocks not caused by pumping failure of the heart), mass transfusion, trauma, intoxications (poisonings) | |
Legend
- CPAP: Continuous Positive Airway Pressure (= form of ventilation that combines the patient’s spontaneous breathing with a permanent positive airway pressure (PEEP) maintained during inspiration and expiration).
- PEEP: positive end-expiratory pressure (invasive ventilation).
Note: The additional cardiogenic-related pulmonary edema (heart-related water accumulation in the lungs) is no longer an exclusion criterion in the definition of ARDS.
