[The effect of low fibrinogen concentrations on human blood viscosity]

Simultaneous studies of viscosity, red cell aggregation and deformation were carried out on human blood with different fibrinogen concentrations using a Brookfield viscometer fitted with a reflection photometer. Fibrinogen progressively increased rouleaux formation, while decreasing viscosity at low and increasing it at higher concentrations. This antagonism is explained by the specific hemodynamic effects of the rouleaux formed under either condition.