Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as :

• neuromuscular in origin,
• secondary to acute and chronic obstructive airway diseases,
• alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia,
• and vascular diseases such as acute or chronic pulmonary embolism.

This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.