Study-required risk factors for acute respiratory distress syndrome on admission to an intensive care unit
| Sepsis | As defined by Bone et al. 24 to be a known or suspected source of systemic infection and at least two of the following: 1) temperature >38°C or <36°C; 2) heart rate >90 bpm; 3) respiratory rate >20 bpm or Pa,CO2 <32 mmHg; 4) WBC >12000·mm−3, <4000·mm−3 or >10% bands. |
| Septic shock | Fulfil requirements for sepsis and one of the following: 1) SBP <90 mmHg or reduction of ≥40 mmHg from baseline for at least 30 min unresponsive to 500 cc fluid resuscitation. 2) The need for vasopressors to maintain SBP≥90 mmHg or within 40 mmHg of baseline. |
| Pneumonia | Fulfil two or more of the following: 1) new infiltrate on CXR; 2) temperature >38.3°C or <36.0°C, WBC >12000 or <4000·mm−3 or >10% bandaemia; 3) positive microbiological culture. |
| 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 infiltrates on CXRs within 8 h of admission to the emergency room and evidence of blunt trauma to the chest, e.g. fractured ribs or ecchymosis overlying the infiltrate. |
| Multiple transfusions | Defined as receiving ≥8 units of packed RBC within 24 h. |
| Aspiration | Defined as witnessed or documented aspiration event or the retrieval of gastric contents from the oropharynx, endotracheal tube or bronchial tree. |
Pa,CO2: carbon dioxide arterial tension; WBC: white blood cells; SBP: systolic blood pressure; CXR: chest radiograph; RBC: red blood cells.