Evaluation and management of the patient with severe COVID-19

COVID-19 exhibits a broad clinical spectrum, ranging from asymptomatic infection to critical illness associated with high mortality. This manuscript reviews the main risk factors, prognostic tools, and therapeutic strategies in patients with severe and critical disease. Severe illness is characterized by significant hypoxemia and respiratory compromise, whereas critical disease includes acute respiratory distress syndrome, septic shock, and multiorgan dysfunction. Key risk factors include advanced age, male sex, obesity, and smoking, as well as comorbidities such as chronic kidney disease, diabetes mellitus, hypertension, and cardiovascular disease. Several inflammatory (IL-6, C-reactive protein, ferritin), hematologic (lymphopenia, neutrophilia), and biochemical (lactate dehydrogenase, D-dimer, troponin) biomarkers are associated with worse prognosis. Clinical tools such as COVID-GRAM and the 4C Mortality Score enable risk stratification and guide therapeutic decisionmaking. Management involves a stepwise approach to oxygen therapy, starting with conventional devices and progressing to high-flow nasal cannula, noninvasive ventilation, or invasive mechanical ventilation according to clinical evolution. Pharmacologic treatment is based on systemic corticosteroids, particularly dexamethasone, which has demonstrated a mortality benefit. In selected cases, immunomodulatory agents may be added. Supportive measures include lung-protective ventilation strategies, prone positioning, prophylactic anticoagulation, hemodynamic management with vasopressors, and renal replacement therapy when indicated. Early identification and comprehensive multidisciplinary management are essential to improve clinical outcomes.