Table 1.
Risk factors for ARDS required for study inclusion and exclusion criteria considered
| Risk Factor | Definition |
|---|---|
| Sepsis | Known or suspected source of systemic infection plus at least two of the following: a) temperature >38°C or <36°C; b) heart rate >90 beats/min; c) respiratory rate >20 breaths/min or PaCOC <32 mm Hg; d) WBC count >12,000/mm3, <4,000/mm3, or >10% bandemia. |
| Septic shock | Fulfill requirements for sepsis plus one of the following: a) SBP <90 mm Hg or a reduction of ≥40 mm Hg from baseline for ≥30 mins, unresponsive to 500 mL of fluid resuscitation; b) need for vasopressors to maintain systolic blood pressure SBP ≥90 mm Hg or within 40 mm Hg of baseline. |
| Pneumonia | Fulfill two or more of the following: a) new airspace opacity on chest radiograph; b) temperature >38.3°C or <36.0°C, white blood cell > 12,000/mm3 or <4,000/mm3 or >10% bandemia; c) positive microbiological culture. |
| Aspiration | Defined as witnessed or documented aspiration event or the retrieval of gastric contents from the oropharynx, endotracheal tube, or bronchial tree. |
| Trauma | Defined as multiple fractures and/or pulmonary contusions. Multiple fractures are defined as a fracture of two long bones, an unstable pelvic fracture, or one long bone and a pelvic fracture. Pulmonary contusion is defined as airspace opacity on chest radiograph within 8 hrs of admission to the emergency room and evidence of blunt trauma to the chest, for example, fractured ribs or ecchymosis overlying airspace opacity. |
| Multiple transfusion | Defined as receiving ≥8 units of packed red blood cells within 24 hrs |
| Exclusion criteria | |
| 1. Age < 18 yrs | |
| 2. Diffuse alveolar hemorrhage | |
| 3. Chronic lung diseases other than chronic obstructive pulmonary disease or asthma that may preclude diagnosis of ARDS | |
| 4. Directive to withhold intubation or decision to withdraw aggressive ICU care | |
| 5. Immunosuppression not secondary to corticosteroid | |
| 6. Treatment with immunomodulation agents such as granulocyte colony-stimulating factor or inhibitors of tumor necrosis factor | |
PaCO2, arterial carbon dioxide tension; WBC, white blood cell; SBP, systolic blood pressure; ARDS, acute respiratory distress syndrome; ICU, intensive care unit.