Overall conclusions

Abstract

P.G. This meeting has once more demonstrated that the ‘simple’ test of red cell filtration is indeed anything but simple. Much of its complexity results from the following three problems:

• the difficulty of providing the appropriate hydrodynamic test conditions which, on one hand, must be chosen so as to provide a ‘mechanical challenge’ to the cell without inducing ‘mechanical damage’.

• the difficulty of defining those cellular properties which are actually being detected by the test. The discussion at this meeting has shown increasing agreement that the ‘ease of entrance’ into the pore rather than the cell passage through it influences the measurement. This certainly includes several aspects of red cell rheology such as elastic and viscous membrane properties or the viscosity of the intracellular hemoglobin; but it also includes morphological features of the cell such as surface area, volume, and shape.

• the difficulty of selecting appropriate conditions of the chemical environment (pH, anticoagulant, etc). Here, one faces the dilemma that conditions must to some extent be standardized if cellular properties only are to be measured, but in a standardized chemical environment alterations of these properties due to factors in the patient’s own plasma may be masked.