Sort the clinical manifestation (top) according to whether it is a general findings in all cases of polycythemia or specific to certain causes:
Poiseuille’s law states that flow of a fluid (Q), or cardiac output, correlated directly with the pressure gradient and inversely with the total peripheral resistance:
Cardiac output = ∆P/TPR
Where TPR = πr4/8ηL
- The hematocrit (Hct) is the primary determinant of blood viscosity.
- Blood viscosity is a determinant of the total peripheral resistance.
- As the Hct increases, so too does blood viscosity and total peripheral resistance.
- To maintain cardiac output in the face of an increasing total peripheral resistance:
- ∆P increases, leading to hypertension.
- The diameter (thus the radius) of blood vessels increases, leading to plethora.
Note how you get a big bang for you buck with vasodilation (cardiac output increases to the power of 4)!