Table 4. Lung injury scoring criteria.
| Lung injury | Score | ||||
|---|---|---|---|---|---|
| Scale | 0 | 1 | 2 | 3 | 4 |
| Extent of lung injury | Absence | <25% | 26 to 50% | 51 to 75% | >75% |
| Alveolar wall thickness | ≤ 1 rbc | > 1 ≤ 2 rbc | 3 to 5 rbc | 6 to 10 rbc | > 10 rbc |
| Hyaline membranes | Absence | Presence | NA | NA | NA |
| Neutrophilic alveolitis | Absence | <10 neutrophils/HPF | 10 to 20/HPF | 21 to 50/HPF | > 50/HPF |
| Suppuration | Absence | Presence | NA | NA | NA |
| Bronchial epithelial degeneration | Absence | Presence | NA | NA | NA |
| Neutrophilic peribronchitis | Absence | <10 neutrophils/HPF | 10 to 20/HPF | 21 to 50/HPF | > 50/HPF |
| Lympho-hiostiocytic peribronchitis | Absence | <10 mononuclear cells/HPF | 10 to 20/HPF | 21 to 50/HPF | > 50/HPF |
| Vasculitis (inflammation) | Absence | Presence | NA | NA | NA |
| Vasculitis (necrosis) | Absence | Presence | NA | NA | NA |
| Emphysema | Absence | < 25% | 25 to 50% | to 75% | > 75% |
| Hemorrhage | Absence | Presence | NA | NA | NA |
rbc: Red blood cells; NA: Not applicable; HPF: High Power Field (magnification x250).