Hypoxic Pulmonary Oedema

[AirConditioner123]

Hi all. I was reading about the causes of pulmonary oedemas when the lungs are under hypoxic conditions, and I just want to check my understanding.

From what I gather, hypoxic pulmonary vasoconstriction occurs in regions of the lung that are not receiving much oxygen (though I'm not sure whether the blood pressure in these pulmonary capillaries increases or decreases). When the entire lung is oxygen deficient, all of the pulmonary capillaries constrict and this leads to pressure build up in the pulmonary artery because blood doesn't move so easily through the capillaries and it takes longer to drain from the artery. However, I also read that pre-capillary sphincters controlling blood flow to capillaries actually decrease intravascular hydrostatic pressure when they contract, so how would an increased pulmonary artery pressure lead to an increase in fluid loss from capillaries?

Edited September 27, 2014 by AirConditioner123

[mackyy20]

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[Joshua201]

An increase in the hydrostatic pressure over that opposed by intravascular oncotic pressure would normally cause fluid loss from the vessels