Fluid exchange between capillaries and the interstitial fluid. takes place between the blood and interstitial fluid across the thin endothelial walls of the capillaries. blood pressure drives fluid out of the capillaries, blood proteins pull fluid back in the capillaries by osmotic pressure. Difference in osmotic pressure and blood pressure drives fluids out of capillaries at the arteriole end and into capillaries at the venule end.
Premarket approval (PMA) is the FDA process of scientific and regulatory review to evaluate the safety and effectiveness of Class III medical devices.remarket approval (PMA) is the FDA process of scientific and regulatory review to evaluate the safety and effectiveness of Class III medical devices.
For moderate and high complexity tests, the FDA evaluates each new commercial test system during the premarket approval process by scoring seven criteria as described in the CLIA regulations. The final score is used to determine whether the test system is classified as moderate or high complexity. See 42 CFR 493.17.