critical care medicine
Acute Hypoxemic Respiratory Failure (AHRF, ARDS)
Introduction
Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 < 60 mmHg) without hypercapnia. It is caused by intrapulmonary shunting of blood with resulting in ventilation-perfusion (V/Q) mismatch due to airspace filling or collapse (eg, cardiogenic or non-cardiogenic pulmonary edema, pneumonia, pulmonary hemorrhage) or possibly airway disease (eg, sometimes asthma, COPD); or by intracardiac shunting of blood from the right- to the left-sided circulation. Findings include dyspnea and tachypnea. Diagnosis is by arterial blood gas measurement and chest x-ray. Treatment usually requires mechanical ventilation. (See also Overview of Mechanical Ventilation .) 