Examination of the relation between red blood cell aggregation and hematocrit in human and various experimental animals

Heparin-like effect of a dual antiplatelet and anticoagulant (APAC) agent on red blood cell deformability and aggregation in an experimental model

Treatments with different antithrombotic agents can affect micro-rheological variables, such as red blood cell (RBC) deformability and aggregation. Since the effect of dual antiplatelet and anticoagulant (APAC) treatment on micro-rheology is unknown, we aimed to investigate the effect of different intravenous doses of APAC on hematological and micro-rheological variables in a porcine model. Two groups were formed (APAC group, Control group), and blood was collected from the animals at preset intervals. Hematological variables, RBC deformability, and aggregation were measured. We observed an improvement in the RBC deformability measured at a low shear stress range (< 3 Pa). However, after both doses, a decrease in the maximal elongation index of RBC values occurred in the APAC group. RBC aggregation increased after APAC bolus dose, while it gradually and dose-dependently decreased. Supposedly, the improvement in RBC deformability that was observed at a lower shear rate could facilitate aggregation. Administration of APAC and unfractionated heparin (UFH) caused comparable changes in hematological and hemorheological variables. Signs of thrombosis or bleeding did not occur. APAC and UFH had comparable micro-rheological effects.

Albumin effect on hemorheological parameters in patients with liver transplant

BACKGROUND

Liver transplantation is a life-saving treatment in end-stage liver failure. Hemorheological features as blood fluidity and red blood cell aggregation may alter effective tissue perfusion, graft function and hemodynamic variables.

OBJECTIVE

The aim of the study is to investigate effect of albumin infusion on red blood cell deformability and aggregation, blood viscosity and hemodynamics in liver transplant patients.

METHODS

Seventeen live or cadaveric donors were included in this prospective study. Hemorheological and hemodynamic measurements were performed in order to evaluate the effects of albumin infusion in perioperative period.

RESULTS

Erythrocyte aggregation was significantly reduced 90 minutes after albumin infusion (p < 0.01). Mean blood viscosity revealed significant decrease at 20 rpm and 50 rpm after 90 minutes of albumin infusion (p < 0.05). Plasma viscosity decreased significantly compared to the value before albumin infusion at 20 rpm (p < 0.05). Albumin replacement improved hemodynamic variables in patients with low blood pressure and cardiac index measurements (p > 0.05).

CONCLUSIONS

Human albumin infusion led to decrease in whole blood and plasma viscosities, red blood cell aggregation and induced blood pressure and cardiac index elevation in perioperative liver transplant patients. Determination of hemodynamic and hemorheological effects of human albumin replacement in various patient populations may serve beneficial clinical data.

Autologous Blood Doping Induced Changes in Red Blood Cell Rheologic Parameters, RBC Age Distribution, and Performance

Simple Summary

Autologous blood doping (ABD) refers to the artificial increase in circulating red blood cell (RBC) mass by sampling, storage, and transfusion of one’s own blood. It is assumed that some athletes apply this prohibited technique to improve oxygen transport capacity and thus exercise performance. The primary aim of this study was to test whether RBC rheological and associated parameters significantly change due to ABD with the consideration of whether this type of measurement might be suitable for detecting ABD. Further, it was assessed whether those changes are translated into indices of endurance performance. Eight males underwent an ABD protocol combined with several blood parameter measurements and two exercise tests (pre and post transfusion). Results of this investigation suggest a change in the distribution of age-related RBC sub-populations and altered deformability of total RBC as well as of the respective sub-populations. Further, the identified changes in RBC also appear to improve sports performance. In conclusion, these data demonstrate significant changes in hematological and hemorheological parameters, which could be of interest in the context of new methods for ABD detection. However, additional research is needed with larger and more diverse study groups to widen the knowledge gained by this study.

Abstract

Autologous blood doping (ABD) refers to the transfusion of one’s own blood after it has been stored. Although its application is prohibited in sports, it is assumed that ABD is applied by a variety of athletes because of its benefits on exercise performance and the fact that it is not detectable so far. Therefore, this study aims at identifying changes in hematological and hemorheological parameters during the whole course of ABD procedure and to relate those changes to exercise performance. Eight healthy men conducted a 31-week ABD protocol including two blood donations and the transfusion of their own stored RBC volume corresponding to 7.7% of total blood volume. Longitudinal blood and rheological parameter measurements and analyses of RBC membrane proteins and electrolyte levels were performed. Thereby, responses of RBC sub-populations—young to old RBC—were detected. Finally, exercise tests were carried out before and after transfusion. Results indicate a higher percentage of young RBC, altered RBC deformability and electrolyte concentration due to ABD. In contrast, RBC membrane proteins remained unaffected. Running economy improved after blood transfusion. Thus, close analysis of RBC variables related to ABD detection seems feasible but should be verified in further more-detailed studies.

Interspecies Diversity of Osmotic Gradient Deformability of Red Blood Cells in Human and Seven Vertebrate Animal Species

Plasma and blood osmolality values show interspecies differences and are strictly regulated. The effect of these factors also has an influence on microrheological parameters, such as red blood cell (RBC) deformability and aggregation. However, little is known about the interspecies differences in RBC deformability at various blood osmolality levels (osmotic gradient RBC deformability). Our aim was to conduct a descriptive–comparative study on RBC osmotic gradient deformability in several vertebrate species and human blood. Blood samples were taken from healthy volunteers, dogs, cats, pigs, sheep, rabbits, rats, and mice, to measure hematological parameters, as well as conventional and osmotic gradient RBC deformability. Analyzing the elongation index (EI)–osmolality curves, we found the highest maximal EI values (EI max) in human, dog, and rabbit samples. The lowest EI max values were seen in sheep and cat samples, in addition to a characteristic leftward shift of the elongation index–osmolality curves. We found significant differences in the hyperosmolar region. A correlation of mean corpuscular volume and mean corpuscular hemoglobin concentration with osmoscan parameters was found. Osmotic gradient deformability provides further information for better exploration of microrheological diversity between species and may help to better understand the alterations caused by osmolality changes in various disorders.