Table 1 Criteria for diagnosis of severe and critical illness
| Severe | Critical |
|---|---|
| ① Shortness of breath, respiratory rate ≥ 30 beats / min | ① Respiratory failure, requiring mechanical ventilation |
| ② Resting state, oxygen saturation ≤ 93% | ② Shock |
| ③Arterial blood oxygen partial pressure (PaO2)/oxygen concentration (FiO2) ≤ 300 mmHg | ③ Combined failure of other organs requiring ICU monitoring and treatment |
| ④Pulmonary imaging of blood showing significant progression of lesions > 50% |