Histologic sections of lung reveal the alveoli to be filled with pale, nongranular pink fluid. Neither leukocytes nor erythrocytes are present within this fluid. Which of the following is the most common cause of this abnormality?
A. Bacterial pneumoniaB. Congestive heart failure
C. lymphatic obstruction by tumor
D. Pulmonary embolus
Ans. B. Congestive heart failure
•Pulmonary
edema refers to excess accumulation of fluid in the extravascular spaces of the
lung. It can be classified based on the etiology into cardio genie pulmonary
edema and noncardiogenic pulmonary edema.
•Cardio
genic pulmonary edema results from abnormalities of hemodynamic Starling. forces, while noncardiogenic pulmonary edema
results from cellular injury.
•Causes
of cardiogenic pulmonary edema include increased hydrostatic forces, as seen
with congestive heart failure the most common cause of pulmonary edema. ;
decreased oncotic pressure, such as resulting from decreased albumin levels;
and lymphatic obstruction.
•Noncardiogenic
edema may be the result of either endothelial injury infections, dis seminated
intravascular coagulopathy, or trauma. or alveolar injury from inhaled toxins,
aspiration, drowning, or near drowning. .
•Microscopically,
pulmonary edema reveals the alveoli to be filled with pale pink fluid.
Cardiogenic edema may lead to alveolar hemorrhages and hemosiderin-laden
macrophages heart failure cells. .
•Where
cardiogenic edema is present, chest x-rays show an increase in the caliber of
the blood vessels in the upper lobes, perivascular and peribronchial fluid
"cuffing". , and Kerley B lines fluid in the interlobular septa. .
Noncardiogenic edema produces a "whiteout" of the
lungs
