[Critique of using the Staverman sigma reflection coefficient in the theory of microcirculation]

The usage of the reflection coefficient sigma defined by Staverman within the theory of microcirculation in tissues requires free perfusion through semipermeable membranes, which does not exist in the reality of tissue blood supply. In accordance to the principle of continuation of the hydraulics the reflection of colloidosmotic particles at semipermeable membranes in tissues does not comply with the condition of steady state regimes. Considering this fact the relevance of sigma in theoretical and practical investigations is challenged.