Alterations of capillary flow during sepsis

Normal red cells are flexible and can thus negotiate small capillaries with ease. Impaired red cell deformability (RCD) has been found in patients with uremia, peripheral vascular disease, and diabetes. This study was performed in order to determine if impaired RCD is present during sepsis. The RCD of citrated whole blood (WB) and citrated buffy coat-poor whole blood (BCP) from ten septic patients was compared to ten age-, sex-, and race-matched control patients. The samples were passed through polycarbonate 5 micron pore filters at -10 cm H2O pressure according to the technique of Reid. A red cell deformability index was calculated for each patient by multiplying the volume of blood flowing through the apparatus in a 1-minute period by the hematocrit. The results show very highly significant decreases of flow in both the WB and BCP blood in the septic group. Alterations in flow in the WB can be explained on the basis of changes in the buffy coat fraction and/or the red cell deformability. A decrease in flow in the BCP blood can be explained in terms of a diminished deformability of the red cells themselves. This increased rigidity of the red cells could, in part, explain the AV shunting and decreased microcirculatory flow seen in the septic state.