MECHANICAL INVESTIGATIONS ON ARTIFICIAL HEMODIALYSIS

The studies on cardiovascular system introduced by Max Anliker and coll have been very important because have opened a new method to look to determine the mechanical properties of the wall of the large vessels. The data have given the constant phase velocities for the pressure, axial and torsion waves, also the laws of attenuation of these waves were egual with exponential law with a negative constant multiplied by proportion of distance and wavelength. The law of attenuation has open a great problem of discussion, because the biological tissues have viscous-elastic properties but not linear as everybody who knows such materials knows. Now if a biological soft tissue has a deformation to return to the original condition is not given by a curve of presenting an egual shape but the presence of Coulomb resistance to deformation gives the particular low damping of the return to original dimension. The Knopoff theory has been used to arrive to a solution and explication of the experimental results by Anliker. We do not discuss now the mathematical problems and the equations connected to this theoretical biomechanical analysis, but if somebody is interested to discuss we have no problems of fit, because wee must see the interest of this medical people present now. When a transplant of organ is made we have the arteries of two different persons are connected and we are in presence of two similar but not egual wall are sutured, if the second is more soft then the previous part, will generate to a short period of time a stenosis due to a turbulent movement of the blood in the initial part of the new artery, with the process of sedimentation of the blood cells and obviously the sutured part is closed, the blood has at first difficulty to enter in the donor organs and day by day the blood stops and the donor organ is out owing to a necrosis. We have seen how this process can arrive to interest tilt 10% of patient, when the different age between patient and donor is of 15 years and the donor is younger in kidney transplantation. The definition of this effect was called Bononiensis Control Parameter (BCP). In conclusion, the importance of the determination of the viscous-elastic properties of the great vessels of cardiovascular system of a patient is very important to define and know when a transplant is necessary, looking for and selecting the more similar condition of the donor vessels or prosthesis.