[The place for using erythrocyte substitutes in hemodilution: XXXX and polymerized pyridoxylated hemoglobin].

@entity61318 @entity871 @entity26 @entity6599 @entity29781 @entity4095 @entity942
In conditions of limited haemodilution (haematocrit 0.25), an improvement in the rheological properties of blood and an increase in cardiac output allow increased perfusion of capillaries and maintenance of tissue oxygenation so long as normal circulating volume is maintained. However, some authors have suggested that blood substitutes enabling @entity26 transport are necessary. The suitability of such substitutes depends on their physicochemical properties and, until now, only the use of haemoglobin solutions and @entity29781 emulsions has been. The use of fluorocarbons requires respiration under @entity871 or pure @entity26 , which is a major limitation. Haemoglobin solutions suffer from inadequate concentration, short vascular persistence and too high an affinity for @entity26 , but these @entity942 disappear with polymerized pyridoxylated haemoglobin. Though both types of preparation can keep animals alive with zero haematocrit for some time, their contribution to oxygenation goes down as the haematocrit goes up. According to Zander and Makowski [40]. the minimum acceptable amount of @entity26 in the blood is reached with a haemoglobin concentration of 4.4 g X 100 ml-1 with a @entity4095 of 90 mmHg (12 kPa), and of 3.3 g X 100 ml-1 with a @entity4095 of 550 mmHg (73 kPa); these values correspond to a haematocrit close to 0.10. At this haematocrit and with a @entity4095 of 90 mmHg, a 70 g X l-1 haemoglobin solution contributes for 28% to the consumption of @entity26 in @entity6599 , while @entity61318 20, used at @entity4095 550 mmHg, takes care of 55% of this consumption. At higher haematocrits, it is not certain that these substitutions have a real advantage over the usual plasma expanders at normovolaemic haemodilution.(ABSTRACT TRUNCATED AT 250 WORDS)
