The patient with acute respiratory failure and hemodynamic instability, dyspnea and respiratory distress, respiratory rate ≥28/minute, oxygen saturation <93% despite nasal oxygen support of 5 liters/minute and above, partial oxygen pressure < 60 mmHg despite nasal oxygen support of 5 liters/minute and above, and PaO2/FiO2 < 300 are critically ill with Covid-19 pneumonia and should be treated and followed up in the intensive care unit. After these patients are admitted to the intensive care unit, they should be evaluated in detail in terms of clinical, laboratory and imaging findings. First of all, traditional oxygen support treatments (nasal cannula, face mask, mask with reservoir) should be started, if no results are obtained, high flow nasal cannulation should be applied, and if this method fails, non- invasive mechanical ventilation should be started. If the target oxygen saturation, respiratory rate and optimal respiratory physiology could not be reached despite the oxygen support treatment, intubation and mechanical ventilation support treatment should be started without wasting time. The standard weaning process should also be applied when patients are eligible. Mortality in patients with Covid-19 pneumonia occurs at a rate of 25-50% on the background of developing ARDS and with additional negative prognostic factors.