AAST Grade |
Description |
Clincal Criteria |
Imaging Criteria |
Operative Criteria |
Pathologic Criteria |
I |
Retained hemothorax or pleural effusion with positive pleural fluid cultures |
Leukocytosis, fever, chest pain |
Pleural fluid consistent with blood or infected fluid no evidence of loculations |
Retained blood, blood clot, or other non-purulent fluid without lung trapping. |
Culture of fluid positive for organisms |
II |
Purulent, free-flowing pleural effusion or hemothorax by imaging |
Respiratory failure, leukocytosis, fever, chest pain |
Pleural fluid consistent with blood or infected fluid; no evidence of loculation |
Retained blood, blood clot, with purulent areas OR completely purulent fluid. |
Culture of fluid positive for organisms |
III |
Fibrinopurulent stage with loculated areas of effusion or hemothorax |
Respiratory failure, leukocytosis, fever, chest pain |
Pleural fluid consistent with blood or infected fluid, with evidence of loculation |
Retained blood, blood clot or other purulent fluid with limited lung trapping |
Culture of fluid positive for organisms with areas of fibrous peel |
IV |
Organizing stage with evidence for restricted lung expansion and pulmonary mechanics |
Severe respiratory failure, leukocytosis, fever, chest pain |
Pleural fluid consistent with blood or infected fluid with evidence of loculation; significantly decreased lung volumes |
Retained blood, blood clot or other purulent fluid with diffuse pleural inflammation and lung trapping |
Culture of fluid positive for organisms with areas of fibrous peel |
V |
Spontaneous external drainage or spreading extra-thoracic necrotizing soft tissue infection |
Severe respiratory failure, leukocytosis, fever, chest pain |
Above, plus severe inflammatory changes of adjacent abdominal, mediastinal or subcutaneous tissue |
Above, with external drainage or necrotizing soft tissue infection of mediastinum, diaphragm or subcutaneous tissues |
Above, with necrotic soft tissue from mediastinum, or subcutaneous space |