Indirect and direct ARDS—distinguishing features
| Indirect ARDS | Direct ARDS | |
|---|---|---|
| Causes | Severe sepsis Trauma Blood product transfusion (TRALI) Pancreatitis Cardiopulmonary bypass Burns | Pneumonia Aspiration Smoke inhalation Pulmonary contusion Reperfusion injury |
| Clinicopathological hallmarks | Neutrophilic alveolitis Hyaline membranes Microthrombi Probable predominance of endothelial injury Imaging and plasma evidence of (non-pulmonary) pathology, for example, pancreatitis | Neutrophilic alveolitis Hyaline membranes Microthrombi Probable predominance of alveolar epithelial injury Chest imaging evidence (CT) of initiating process, for example, lung contusion |
| Proposed biomarkers | Angiopoetin-2 von Willebrand factor Soluble thrombomodulin Interleukin 8 Soluble ICAM-1 | Surfactant protein-D Receptor for advanced glycation end products Krebs von den Lungen-6 Club cell 16 |
ARDS, acute respiratory distress syndrome; ICAM-1, intracellular adhesion molecule 1; TRALI, transfusion associated lung injury.