Stage Description
Stage 1 Mild disease Patients with uncomplicated upper respiratory tract viral infection, unspecific symptoms as fever, cough (productive or unproductive), fatigue, anorexia, sore throat, nasal congestion, headache, muscle pain, discomfort; rarely diarrhea, nausea or vomiting.
Stage 2 Pneumonia Patients with pneumonia, no signs of severe pneumonia, no need for oxygen therapy.
Stage 3 Severe Pneumonia Fever or suspected respiratory tract infection associated to at least one of the following:
respiratory rate > 30/min, severe dyspnea, SpO2 < 93% in air.
The diagnosis is clinical; chest imaging can exclude complications.
Stage 4 ARDS Outbreak or worsening of respiratory symptoms within 1 week after first clinical manifestation.
Imaging: bilateral radiopacity not related to effusion, atelectasis or consolidations.
Origin of edema: respiratory failure not related to heart failure or fluid overload.
Oxygenation:
- mild ARDS: 200 mmHg < PaO2 / FiO2 ≤ 300 mmHg
- moderated ARDS: 100 mmHg < PaO2/FiO2 ≤ 200 mmHg
- severe ARDS: PaO2/FiO2 ≤ 100 mmHg
- When PaO2 is not available, SpO2/FiO2 ≤ 315 suggests ARDS
Stage 5 Sepsis Organ failure caused by deregulated host response to infection. Signs of organ failure include altered mental status, difficult or superficial respiration, increased respiratory rate, low O2 peripheral saturation, oliguria/anuria, tachycardia, cold extremities, hypotension, and cutaneous alterations, and laboratory findings including altered coagulation, thrombocytopenia, acidosis, hyperbilirubinemia, and increased lactates.
Stage 6 Septic shock Hypotension not responsive to volume expansion; need for vasopressors to keep MAP ≥ 65 mmHg and lactates ≥ 2 mmol/l