Table 2 ATS/IDSA criteria for severe CAP

Minor criteria

Respiratory rate ≥ 30 breaths/min

PaO₂/FiO₂ ratio ≤ 250

Multilobar infiltration

Confusion/disorientation

Uremia (BUN ≥ 20 mg/dL)

Leukopenia (white blood cell count < 4 *10⁹/L)

Thrombocytopenia (platelet count < 100*10⁹/L)

Hypothermia (core temperature < 36 °C)

Hypotension requiring aggressive fluid resuscitation

Major criteria

Invasive mechanical ventilation

Septic shock with the need for vasopressors