The effects of red blood cells on coagulation: a thromboelastographic study

ABSTRACT

BACKGROUND: There are reports suggesting the effect of red blood cells (RBCs) on blood coagulation. The effects of red blood cells (RBCs) on coagulation were investigated in vitro while maintaining other coagulation elements constant. METHODS: Twenty-five healthy male volunteers were enrolled. Citrated fresh whole blood was drawn from each subjects and processed into washed RBCs and platelet-rich plasma (PRP). To make six different hematocrit groups with each blood, PRP was mixed with the same volume of serially diluted washed RBCs. Reaction time, coagulation time, clot formation rate, and maximum amplitude were measured using recalcified TEG. RESULTS: The mean +/- SD of six different hematocrit was 38.0 +/- 2.3% (group 1), 28.9 +/- 2.2% (group 2), 21.3 +/- 1.9% (group 3), 13.8% +/- 1.6% (group 4), 7.1 +/- 1.0% (group 5), and 0 +/- 0% (group 6). The platelet count ranged from 141,000 to 292,000/mm3. Maximum amplitude (r = -0.4213, P< 0.001) and alpha angle (r = -0.216, P< 0.05) showed statistically significant negative linear relationship with hematocrit. CONCLUSIONS: A gradual reduction in hematocrit was associated with a shortened coagulation time, no changes in reaction time. This study results suggest that a gradual reduction in the RBC mass in vitro accelerates coagulation and forms stronger fibrin strands.