What is pulmonary edema?
Leakage of excessive interstitial fluid, which accumulates in alveolar spaces
What can cause pulmonary edema?
- Hemodynamic or cardiogenic pulmonary edema (due to increased hydrostatic pressure)
- Direct increase in capillary permeability (result of microvascular injury)
Morphology of pulmonary edema
Gross:
- Lungs are heavy, firm, fluid-filled
- Typically begins basally
Microscopic:
- Engorged capillaries in interstitium
- Granular pink material in alveolar spaces
- Over time:
- hemosiderin-laden macrophages
- fibrosis
Acute lung injury
Characterized by abrupt onset of significant hypoxemia and bilateral pulmonary infiltrates in the absence of cardiac failure (noncardiogenic pulmonary edema)
Conditions associated with development of ARDS
Sepsis
Diffuse pulmonary infections
Gastric aspiration
Mechanical trauma
ALI pathology
-Initiated by injury of pneumocytes and endothelium
-sets in motion a cycle of increasing inflammation and pulmonary damage
components:
-endothelial activation
-adhesion and extravasation of neutrophils (degranulation)
-accumulation of intraalveolar fluid and formation of hyaline membranes (from sloughing of pneumocytes) - damage of type II pneumocytes leads to surfactant abnormalities
-resolution (can lead to fibrosis)
