Introduction Fluid accumulation in air spaces and parenchyma of the lungs leads to impaired gas exchange and may cause respiratory failure Pathophysiology edema arises due to an imbalance in hydrostatic and/or oncotic pressure increased hydrostatic pressure in the pulmonary capillaries (Pc) cardiogenic causes (see below) decreased oncotic pressure in the pulmonary capillaries (πc) kidney or liver dysfunction (e.g. nephrotic syndrome, cirrhosis) movement of fluid is driven by Starling forces Causes changes in pressure are of cardiogenic or non-cardiogenic origin cardiogenic causes include heart failure left heart failure volume overload mitral stenosis in all cases above, an increase in left ventricular end diastolic volume increases hydrostatic pressure in LV, LA, pulmonary vein, and pulmonary capillaries the increase in hydrostatic pressure overwhelms the oncotic pressure in the pulmonary capillaries a transudate leaks into the interstitial space and ultimately into the alveoli non-cardiogenic causes include infection sepsis pneumonia aspiration drowning gastric aspiration drugs heroin high altitude ARDS alveolar-capillary damage Presentation Symptoms dyspnea including orthopnea and paroxysymal nocturnal dyspnea (PND) Physical exam bibasilar inspiratory crackles due to air expanding fluid-filled alveoli rusty-colored sputum due to rupture of pulmonary capillaries from elevated hydrostatic pressure wheezing due to peribronchiolar edema "cardiac asthma" Evaluation CXR congestion in upper lobes perihilar congestion "bat wing configuration" alveolar infiltrates Kerley's lines due to septal edema Biopsy hemosiderin-laden alveolar macrophages ("heart failure cells") macrophages phagocytose blood following rupture of capillaries Treatment Treat underlying condition nitrates and diuretics used for cardiogenic causes Respiratory support Non-invasive positive pressure ventilation supplemental oxygen