Red blood cell deformability in patients with human immunodeficiency virus infection.

Red blood cell (RBC) deformability is a major determinant of the ability of the RBC to pass repeatedly through the microcirculation. A decrease in RBC deformability leads to tissue perfusion and organ dysfunction. The purpose of this study was to measure the rigidity of RBCs from human immunodeficiency virus (HIV) seropositive individuals and investigate its relation to immune status and viral load. A filtration method based on the initial flow rate principle was used to determine the index of rigidity (IR) of 53 samples from HIV patients and 53 healthy individuals. The mean IR was significantly increased in patients with HIV compared to healthy individuals (P < 0.01). IR was inversely correlated with current CD4+ T-lymphocyte counts (P < 0.0001). High CD4 cell counts (>200 cells/microl) are related to low IR values, independently of the viral load (VL). No differences in rigidity were noted between the VL groups, although there was a trend towards an increased IR in patients with high VL within the group of CD4<200. RBC deformability is decreased in HIV disease, in a degree mainly related to CD4 depletion. Further studies are needed to elucidate the underlying mechanisms and the role of VL in highly immunocompromised HIV patients.

Influence of contrast media on red blood cell deformability.

Iodinated contrast media (CM) are widely used in diagnostic imaging and therapeutic interventional procedures of everyday clinical practice and are associated with multiple hemodynamic and hemorheological effects. The purpose of our work was to investigate the red blood cell (RBC) rheological properties after in vivo administration of low-osmolar or iso-osmolar CM by measuring their membrane deformability (Index of Rigidity, IR) using a filtration method. Blood samples were taken from patients who underwent digital subtraction angiography of the peripheral arteries at various times before and after intravenous administration of CM. CM included iso-osmolar Iodixanol, low-osmolar Iopromide and low-osmolar Iopentol. In the whole patient group an IR increase of 59% was calculated 5 minutes after administration of CM followed by a normalization of elevated IR values within the following hour. The 5-min IR increase was strongest in the group treated with Iopromide, whereas administration of Iodixanol was associated with a more modest transient IR increase. Intravenous injection of CM in humans may be associated with a transient but considerable decrease of RBC membrane deformability and particularly for the iso-osmolar CM the induced changes in membrane deformability seem to be more moderate.

Severe sepsis and diabetes mellitus have additive effects on red blood cell deformability.

OBJECTIVES: Diabetes mellitus is accompanied by microvascular complications leading to organ dysfunction, while sepsis is a major cause of morbidity and mortality in diabetics. We addressed the hypothesis that red blood cell (RBC) deformability may be additively compromised in septic diabetic patients, leading to a further impairment of microcirculation. METHODS: Forty patients suffering from severe sepsis, 12 patients suffering from diabetes and 24 diabetic patients with severe sepsis were enrolled. A filtration method and a hemorheometer were used to measure the RBCs' index of rigidity (IR). RESULTS: We observed no differences in severity, organ dysfunction and outcome between diabetic and non-diabetic septic patients. Mean SAPS II score was 23.5% vs 26.8% in non-diabetic and diabetic septic patients, respectively. The mortality in non-diabetic septic patients was 22.5% and in septic diabetics was 34.3%, while septic shock occurred in 15.0% and 20.8%, respectively. We detected higher IR (17.72+/-6.31) in septic diabetics than in patients with diabetes and no sepsis (12.26+/-2.28, p< or =0.001) and in patients with sepsis and no diabetes (13.9+/-2.86, p< or =0.01). CONCLUSION: The presence of diabetes mellitus seems to affect the already compromised RBC deformability of septic patients, probably leading to serious microcirculatory functional impairments in septic diabetic patients.

Effect of hydroxyurea on the deformability of the red blood cell membrane in patients with sickle cell anemia.

Sickle cell disease is characterized by vaso-occlusive episodes, mainly in the small vessels, resulting in tissue ischemia, multi-organ failure, and, occasionally, death. Hydroxyurea (HU) is an agent with important and effective role in the treatment of patients suffering from this disease. The purpose of this study was to estimate the effect of HU on the deformability of the red blood cell's membrane (RBCM) in an effort to possibly improve the rheological properties of the RBCs of patients with sickle cell anemia (SCA), as well as to investigate the mechanical and rheological properties of these cells using micropipette and filtration techniques. The rigidity index, IR, which is a measure of cell rigidity and the elastic shear modulus, mu, which is a measure of cell's membrane deformability (CMd), of the RBCs from normal subjects, used as normal controls, were found significantly lower as compared to those of patients with SCA, regardless the treatment with HU. Patients under treatment with HU exhibited values better than those of untreated patients, in both, IR as well as mu, although still worse than the values of normal controls.