Acute respiratory failure is a life-threatening impairment of oxygenation, carbon dioxide elimination, or both. Respiratory failure may occur because of impaired gas exchange, decreased ventilation, or both. Common manifestations include dyspnea, use of accessory muscles of respiration, tachypnea, tachycardia, diaphoresis, cyanosis, altered consciousness, and, without treatment, eventually obtundation, respiratory arrest, and death. Diagnosis is clinical, supplemented by measurements of arterial blood gases (ABGs) and chest x-ray. Treatment is usually in an intensive care unit and involves correction of the underlying cause, supplemental oxygen, and ventilatory assistance if needed.