Diffuse Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) is diffuse bleeding from the pulmonary microvasculature into the alveoli. Blood displaces air and disrupts gas exchange, so a patient can progress rapidly from dyspnea and a new oxygen need to hypoxemic respiratory failure. DAH is a syndrome rather than a single disease; identifying its cause determines definitive treatment. Recognize the bedside pattern: otherwise unexplained falling hemoglobin, new bilateral alveolar or ground-glass opacities, dyspnea, cough, hypoxemia, or hemoptysis. Hemoptysis may be absent, so no visible blood does not exclude DAH. Trends in oxygen requirement, work of breathing, mental status, blood pressure, and hemoglobin are more important than any one isolated result. The first priorities occur together: support airway and oxygenation, obtain urgent physician or nurse practitioner assessment, identify and correct a bleeding tendency under orders, and investigate immune, infectious, cardiac, medication-related, and toxic causes. Do not delay stabilization while waiting for serology or bronchoscopy.