Question on hypoxemia and hypotension.

[Singh]

Why does severe hypoxemia cause systemic hypotension?
(Davidsons p. 507 lower right).

Thanks in advance.
Best regards, Singh.

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[babinski bob]

Why does severe hypoxemia cause systemic hypotension?
(Davidsons p. 507 lower right).

Thanks in advance.
Best regards, Singh.

Probably because low pO2 causes arteriolar dilation. If all the arterioles dilate then you'll get systemic hypotension. Sorta the same principle w/ endotoxic shock and iNOS expression which causes systemic hypotension. Induced NO release leads to massive dilation and you get hypotensive. Just remember that hypoxia in the lungs leads actually leads to vasoconstriction to shunt blood away from the most poorly perfused areas.

 

[SaltySqueegee]

Probably because low pO2 causes arteriolar dilation. If all the arterioles dilate then you'll get systemic hypotension. Sorta the same principle w/ endotoxic shock and iNOS expression which causes systemic hypotension. Induced NO release leads to massive dilation and you get hypotensive. Just remember that hypoxia in the lungs leads actually leads to vasoconstriction to shunt blood away from the most poorly perfused areas.

Yes, but I don't believe it is the O2 doing the dilating in the peripheral vasculature. It's probably the CO2.

Increased CO2, as a corollary to Hypoxemia, causes BAND3 Anion exchangers in RBCs and Vasculature Endothelial cells to "let-go" of the cytoskeletal wall, thus resulting in overall dilation. NO is a messenger in the system to cause the relaxation, but it is probably a result of CO2 more than O2.

 

[CaptainZero]

Yes, but I don't believe it is the O2 doing the dilating in the peripheral vasculature. It's probably the CO2.

Increased CO2, as a corollary to Hypoxemia, causes BAND3 Anion exchangers in RBCs and Vasculature Endothelial cells to "let-go" of the cytoskeletal wall, thus resulting in overall dilation. NO is a messenger in the system to cause the relaxation, but it is probably a result of CO2 more than O2.

This is going back to the "chest pain" module (which I'm not about to dig out right now) from december, but I seem to remember that lactic acid and other anaerobic metabolites (Adenosine maybe? - not solely anaerobic I suppose) also contributed to the hypotension inducing vasodilation associated with hypoxemia.
Just a thought...