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.

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.