Table 8. ISDA/ATS criteria for severe community-acquired pneumonia.
| Main criteria | Invasive mechanical ventilation |
| Septic shock requiring vasopressors | |
| Minor criteria | Breathing rate ≥30 breaths/min |
| PaO2/FiO2 ratio ≤250 | |
| Multilobar invasion | |
| Confusion/disorientation | |
| Uremia (BUN ≥20 mg/dL) | |
| Leukopenia (leukocyte count, <4,000/mm3) | |
| Thrombocytopenia (platelet count, <100,000/mm3) | |
| Hypothermia (core body temperature, <36°C) | |
| Hypertension requiring active fluid resuscitation |
IDSA, Infectious Diseases Society of America; ATS, American Thoracic Society; PaO2, partial pressure of oxygen in arterial blood; FiO2, fraction of inspired oxygen; BUN, blood urea nitrogen.