Extracorporeal therapies: should we use plasma instead of blood?

The evolution of extracorporeal therapies has required the parallel evolution of devices designed to extract the blood from the patient and to move it in the extracorporeal circuit. Blood is a peculiar fluid in which viscosity may be strongly affected by the contingent operational conditions of the extracorporeal circuit. Because hematocrit is an important component of blood viscosity, and viscosity may definitely affect the performance of blood purification devices, major problems arise when high hematocrits are present in the patient. All these problems might be avoided if plasma could be used instead of whole blood. Plasma treatment is already performed in various therapies, but the treated plasma is obtained by separation from whole blood in the extracorporeal environment. In this paper we propose a new approach to perform different plasma treatments. Plasma is extracted directly from the patient thanks to a special catheter or plasma extraction device. Utilizing plasmafiltration technology to create a membrane that is placed on the tip of an intravascular catheter, plasma extraction may become easy to perform. The extracted plasma is then available for any type of treatment before being restituted to the patient via a second lumen in the same catheter.