Pulmonary edema pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Pulmonary edema is due to either failure of the heart to remove fluid from the lung circulation ("cardiogenic pulmonary edema"), or due to a direct injury to the lung parenchyma or increased permeability or leakiness of the capillaries ("noncardiogenic pulmonary edema").
Pathophysiology
It is understood that pulmonary edema is the result of abnormal increase in extravascular lung water (EVLW). Pulmonary edema is caused by either:[1][2][3]
Imbalance of starling force:
- Increase pulmonary capillary pressure
- Left ventricular failure
- Volume overload
- decrease plasma oncotic pressure
- Hypoalbuminemia
- increase negative interstitial pressure
- Negative-pressure pulmonary edema (NPPE) or postobstructive pulmonary edema[4]
Altered alveolar-capillary membrane permeability(acute respiratory distress syndrome)
- In noncardiogenic pulmonary edema, The most common mechanism for a rise in transcapillary filtration is an increase in capillary permeability
- Infectious pneumonia
- Aspiration
- Disseminated intravascular coagulation
- Lymphatic insufficiency
- After lung transplant
- Lymphangitic carcinomatosis
- Fibrosing lymphangitis (e.g., silicosis)
- Unknown or incompletely understood
- High-altitude pulmonary edema
- Neurogenic pulmonary edema
- Narcotic overdose
- Pulmonary embolism
- Cardiopulmonary bypass
The flux of fluid across the capillary level is controlled by a balance between hydrostatic pressure and osmotic pressure gradients between the capillaries and interstitial space that can be calculated via Starling equation:
JV =K.S.([Pmv-Ppmv]-σd[πmv-πpmv])
where:
- JV = volume flow across the capillary bed K = filtration coefficient of the capillary wall S = surface area of the capillary bed Pmv = microvascular hydrostatic pressure Ppmv = perimicrovascular (interstitial) hydrostatic pressure πmv = plasma colloid osmotic pressure πpmv = perimicrovascular (interstitial) colloid osmotic pressure σd = protein reflection coefficient
Gross Pathology
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This is a gross photograph of lungs that are distended and red. The reddish coloration of the tissue is due to congestion. Some normal pink lung tissue is seen at the edges of the lungs (arrows).
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This is a gross photograph of lung demonstrating acute pulmonary congestion and edema. A frothy exudate fills the bronchus (arrow).
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This gross photograph demonstrates the frothy exudate that is being extruded from the lung tissue.
Microscopic Pathology
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This is a low-power photomicrograph of lung from this case. The lung section has a pale-red color indicating proteinaceous material within the lung.
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This is a higher-power photomicrograph of lung. The edema fluid within the alveoli is visible at this higher magnification (arrows). The thickened pleura (1) is on the left.
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This is a higher-power photomicrograph showing edema-filled alveoli in the right portion of this section (arrows).
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This high-power photomicrograph illustrates the edema fluid within the alveoli (1) and the congestion (RBCs) in the alveolar capillaries (arrows).
References
- ↑ Sibbald WJ, Cunningham DR, Chin DN (1983). "Non-cardiac or cardiac pulmonary edema? A practical approach to clinical differentiation in critically ill patients". Chest. 84 (4): 452–61. PMID 6617283.
- ↑ Ware LB, Matthay MA (2005). "Clinical practice. Acute pulmonary edema". N. Engl. J. Med. 353 (26): 2788–96. doi:10.1056/NEJMcp052699. PMID 16382065.
- ↑ Pena-Gil C, Figueras J, Soler-Soler J (2005). "Acute cardiogenic pulmonary edema--relevance of multivessel disease, conduction abnormalities and silent ischemia". Int. J. Cardiol. 103 (1): 59–66. doi:10.1016/j.ijcard.2004.08.029. PMID 16061125.
- ↑ Bhattacharya M, Kallet RH, Ware LB, Matthay MA (2016). "Negative-Pressure Pulmonary Edema". Chest. 150 (4): 927–933. doi:10.1016/j.chest.2016.03.043. PMID 27063348.