Diagnostic criteria for severe pneumonia include major and minor criteria: two major criteria: 1, the need for invasive mechanical ventilation (ventilator-assisted therapy); 2, infectious shock requiring vasoconstrictor therapy. Secondary criteria: 1, respiratory rate greater than or equal to 30 times; 2, oxygenation index (PaO2/F02) greater than or equal to 250; 3, x-ray film suggests: multi-lung lobar infiltration; 4, body temperature less than 36 ℃; 5, leukopenia less than 4.0 × 10^9/L.
6, thrombocytopenia less than 10.O×10/L; 7, hypotension, requiring strong fluid resuscitation; 8, impaired consciousness/ disorientation; 9, azotemia, urea nitrogen greater than or equal to 20 mg/dL. Those who meet one major criterion or more than three minor criteria can be diagnosed with severe pneumonia.