Postural Hypotension Flashcards
How can standing up from a lying or sitting position cause an increase in pressure of the blood of the feet and legs?
In the horizontal position the weight of the blood produces negligible pressure
However when a person is standing the intravascular pressure everywhere becomes equal to the pressure generated by the cardiac contraction plus an additional pressure of gravity acting on that point
Explain how postural hypotension arises
When going from a lying to standing position, blood pressure in the lower limbs increases resulting in s pooling of blood in the veins and an expansion of the veins rather than the return of blood to the heart. The increased pressure in the capillaries in This area causes increased filtration of fluid into the interstitial space
The combined effects of venous pooling and increased capillary filtration result in the effective loss of circulating blood volume which decreases mean arterial blood pressure
