[Hemodilution, defibrinogenation and plasmapheresis in hemorheology]

Blood and plasma viscosity can be influenced by various therapeutic procedures: among these, that of hemodilution stands out. This can be hypovolemic, normovolemic or hypervolemic; it is hypovolemic if blood subtraction is not followed by a liquid reintroduction, it is normovolemic or hypervolemic if there is a liquid reintroduction of the same or higher quantity than the subtracted blood mass. This method has been considered very favorably by surgery in order to save blood for transfusions. Hypervolemic hemodilution can also be carried out without blood subtraction; a report on this method shows good clinical results and positive hematochemical and hemodynamic effects obtained on 93 peripheral vasculopathic patients at stages III and IV of the Fontaine classification. Plasmapheresis, which would be best called plasma-exchange, consists in the removal of that part of the patient's plasma containing abnormal proteins, immune complexes or toxins, and in its substitution by other colloids or crystalloids. Defibrinogenation is not much employed in Italy, as the most effective drugs, such as ancrod and batroxobin are not available in this country. The good results reported were transitory, due to the rapid appearance of antibodies which can inhibit the effects of these drugs. Nevertheless, there also exist minor fibrinogenolytic drugs.