Pleural effusion (aka water on the lung) is excess fluid accumulating between the 2 pleural layers that surround the lungs.
Although normally containing fluid, excessive amounts can impair breathing by limiting the expansion of the lungs during inspiration
5 types of fluid can accumulate in the pleural space, including:
Hydrothorax (serous fluid)
Transudative pleural effusion, involving increased permeability of the capillaries in the lung, due to release of cytokines or inflammatory mediators (e.g. vascular endothelial growth factor) from the platelet-rich blood clots. It is caused by:
Congestive heart failure
ESRD (end stage kidney disease)
Exudative pleural effusion, caused by:
Cancer, including lung cancer, breast cancer, and lymphoma
What's the difference between transudate and exudate? It sounds so similar?
Transudate is fluid pushed through a blood vessel due to high blood pressure. Exudate is fluid that leaks AROUND the blood vessel's cells, caused by inflammation.
CXR, showing as an area of whiteness, as there is abnormal fluid collection