Mean Whole Blood Viscosity Research Articles

Blood hyperviscosity in acute and recent COVID-19 infection.

Elevated estimated blood viscosity (EBV), derived from hematocrit and globulins, is associated with thrombotic complications, organ failure, and higher mortality in COVID-19 patients. Although informative, EBV does not account for cellular interactions or fibrinogen. Investigate whether patients with acute and recent COVID-19 have altered whole blood viscosity (WBV) when measured at both high and low shear rates using in vitro blood samples from patients. Cross-sectional study of 58 patients: 15 in the intensive care unit with acute COVID-19, 32 convalescent (9 < 8weeks [W] from acute infection, 23 > 8 W), and 11 controls without COVID-19. WBV was measured at high (300 s-1) and low (5 s-1) shear rates (HSR, LSR) using a scanning capillary viscometer.RESULTSAcute and convalescent patients < 8 W had mean WBV at LSR (16.0 centipoise [cP] and 15.1 cP) and HSR (5.1 cP and 4.7 cP). Mean WBV of convalescent > 8 W and control patients were 12.3 cP and 13.0 cP at LSR, and 4.1 cP and 4.2 cP at HSR. Acute and < 8 W patients had significantly higher WBV at both HSR and LSR compared to patients > 8 W (all p≤0.01). No significant differences in WBV were observed between acute and < 8 W patients, or between patients > 8 W and controls. Hyperviscosity provides a possible explanation for thrombotic risk in acute and convalescent (< 8 W) patients. These findings have important implications for thromboprophylaxis.

Whole blood viscosity and red blood cell adhesion: Potential biomarkers for targeted and curative therapies in sickle cell disease.

Sickle cell disease (SCD) is a recessive genetic blood disorder exhibiting abnormal blood rheology. Polymerization of sickle hemoglobin, due to a point mutation in the β‐globin gene of hemoglobin, results in aberrantly adhesive and stiff red blood cells (RBCs). Hemolysis, abnormal RBC adhesion, and abnormal blood rheology together impair endothelial health in people with SCD, which leads to cumulative systemic complications. Here, we describe a microfluidic assay combined with a micro particle image velocimetry technique for the integrated in vitro assessment of whole blood viscosity (WBV) and RBC adhesion. We examined WBV and RBC adhesion to laminin (LN) in microscale flow in whole blood samples from 53 individuals with no hemoglobinopathies (HbAA, N = 10), hemoglobin SC disease (HbSC, N = 14), or homozygous SCD (HbSS, N = 29) with mean WBV of 4.50 cP, 4.08 cP, and 3.73 cP, respectively. We found that WBV correlated with RBC count and hematocrit in subjects with HbSC or HbSS. There was a significant inverse association between WBV and RBC adhesion under both normoxic and physiologically hypoxic (SpO2 of 83%) tests, in which lower WBV associated with higher RBC adhesion to LN in subjects with HbSS. Low WBV has been found by others to associate with endothelial activation. Altered WBV and abnormal RBC adhesion may synergistically contribute to the endothelial damage and cumulative pathophysiology of SCD. These findings suggest that WBV and RBC adhesion may serve as clinically relevant biomarkers and endpoints in assessing emerging targeted and curative therapies in SCD.

Relationship between apical thrombus formation and blood viscosity in acute anterior myocardial infarction patients.

Aim: This study sought to investigate the predictive value of whole blood viscosity (WBV) to identify high-risk patients who will develop an apical thrombus during the acute phase of anterior transmural infarction. Materials & methods: Consecutive 1726 patients with first acute anterior myocardial infarction were evaluated. WBV was calculated according to the Simone's formula. Results: Patients with an apical thrombus had prolonged pain to balloon time, higher rate of post-PCI thrombolysis in myocardial infarction flow ≤1 and significantly higher mean WBV values at both shear rates than those without an apical thrombus. Conclusion: WBV values at both shear rates were found to be significant and independent predictors for early LV apical thrombus formation complicating a first-ever anterior wall myocardial infarction.

Serum nitric oxide level correlates with serum brain natriuretic peptide and whole blood viscosity in hemodialysis patients

BackgroundNitric oxide (NO) is tonically synthesized by the vascular endothelium and known as a marker of vasodilatation and blood flow. As NO has a critical role in hemodynamics, NO may be associated with other hemodynamics-related factors including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and whole blood viscosity (WBV). It has been reported that serum NO level increased in patients undergoing hemodialysis. However, there are few reports about the relationship between NO and hemodynamic parameters in hemodialysis patients. ObjectiveWe investigated the associations between serum levels of NO and other hemodynamics-related factors such as ANP, BNP and WBV in patients with hemodialysis. MethodsNO, ANP, and BNP levels before hemodialysis were measured using ELISA method. We measured WBV in pre- and post-dialysis. ResultsMean serum levels of NO, ANP, and BNP were 13.97 ± 10.34 μg/mL, 198.85 ± 61.56 pg/mL, and 1233.32 ± 280.81 pg/mL, respectively in patients with hemodialysis. The mean WBV values at shear rates of 1, 5, and 300 s−1 for pre-dialyses were 168.5 ± 62.5, 76.9 ± 20.6, and 33.3 ± 3.8 mP, respectively. Serum NO level was positively correlated with WBV at shear rates of 1, 5, and 300 s−1 at pre- and post-hemodialysis. There is a correlation between serum nitrite levels and the change of SBV during hemodialysis. Serum nitrite levels correlated with the serum BNP levels. ANP levels have a negative correlation with pre-dialytic WBV. However, BNP levels did not correlate with WBV during hemodialysis. ConclusionsWBV is linked to an imbalance in serum vasoactive substances in hemodialysis patients and can cause significant hemodynamic disturbance.

Whole blood viscosity: Effect of hemodialysis treatment and implications for access patency and vascular disease

Hemodialysis patients have increased mortality from cardiovascular complications. Whole blood viscosity (WBV) and red cell aggregation (RCA) may influence the pathogenesis of vascular complications in this population. The objective of this study was to determine whether the hemodialysis treatment or vascular complications were associated with impaired WBV or RCA. This prospective, cross sectional investigation included 38 patients receiving chronic hemodialysis. Blood samples for WBV, RCA and hematocrit were drawn before and after dialysis. WBV was determined between 10 and 780 s-1 and RCA was measured by calculating aggregate shape parameter. WBV and RCA were subsequently assessed for correlation with a history of vascular disease. The mean WBV, aggregate shape parameter, and hematocrit post-dialysis were significantly higher than pre-dialysis values (p < 0.05). Using a linear model with WBV as the dependent variable, the covariates of aggregate shape parameter, hematocrit, weight, and history of diabetes were not significant. However, pre/post timing of the sample was a significant covariate. WBV correlated with prior access thrombosis or stenosis, especially if the patient had a history of peripheral vascular disease. Higher WBV correlated with an increased incidence of access failure and vascular disease. Repetitive increases in WBV and RCA with each dialysis treatment could contribute to vascular dysfunction in this patient population.

Blood rheological properties are strongly related to the metabolic syndrome in middle-aged Chinese

The current investigation sought to evaluate the relation between hemorheological properties and the metabolic syndrome. 1400 office workers aged 35 to 59 years were enrolled in this study. Waist circumference and blood pressure were determined. Plasma high-density lipoprotein (HDL cholesterol), triglyceride, fasting blood glucose, plasma insulin and whole blood viscosity (WBV) at a high-shear rate of 200 s − 1 were measured at the attendance. Metabolic syndrome was defined according to National Cholesterol Education Program (NCEP)/ATP III guidelines. The metabolic syndrome was identified in 18% of this sedentary population. Mean WBV was 4.71 ± 0.56 mPa s. One-way ANOVA indicated WBV increased across subjects with 0–4 metabolic syndrome components ( F = 3.86, p < 0.01). The highest vs. lowest quartiles of WBV occurred significantly more often among subjects as the number of metabolic syndrome components increased. Across five categories of the metabolic syndrome, the frequencies of the occurrence of the highest vs. lowest quartiles were: 0.40, 0.87, 1.31, 1.92, and 4.80, respectively, showing a significant correlation ( R = 0.817, p < 0.05). Univariate logistic regression analysis showed that the prevalence of hyperviscosity was predicted positively by waist circumference (OR = 1.018, 95% CI: 1.002–1.035, p < 0.05) and negatively by HDL cholesterol (OR = 0.295, 95% CI: 0.133–0.680, p < 0.01), independently of age, sex, and smoking status. In summary, this study has shown that WBV is strongly related to the severity of the metabolic syndrome. We suggest that the hemorheological parameters could potentially be used as an additional indicator of the metabolic syndrome.

Blood Viscosity in Horses With Colic

Whole blood viscosity (WBV) was measured on six healthy horses and ten horses presented for colic surgery. A Wells-Brookfield cone-and-plate microviscometer at 6 rpm was used to determine WBV and WBV was adjusted for packed cell volume (PCV). The ten colic horses were divided into two groups: five horses that died or were euthanatized (group 1) and five horses that were discharged after surgery and medical therapy (group 2). The mean WBV for each group was compared using analysis of variance followed by Duncan multiple-range tests. Mean WBV of group 2 (5.81 +/- 1.48 centipoise [cp]) and normal horses (7.1 +/- 2.3 cp) was significantly (P less than 0.01) lower than group 1 (17.15 +/- 5.71 cp). This preliminary trial shows that horses that died or were euthanatized had a significantly higher WBV than horses surviving. Since viscosity was adjusted for PCV, the differences may represent changes in other factors such as fibrinogen, rouleaux formation, red blood cell deformability, PaO2, or intracellular calcium ion concentration. Thus, increases in WBV in horses with colic may indicate severely compromised regional perfusion that may lead to significant tissue damage. In this preliminary study, it appears that WBV may be a prognostic aid in horses with colic.

Haemorrheological response to plasma exchange in Raynaud's syndrome.

Eight patients with Raynaud's syndrome were treated by weekly plasma exchange for four weeks using a Haemonetics Model 30 Blood Processor. The mean whole-blood viscosity at a shear rate of 0.77/s was significantly lower after treatment, and the mean index of red-cell deformability was significantly improved. In four patients studied serially the mean percentage fall in whole-blood viscosity after a single plasma exchange was 49% at 0.77/s but only 14% at 91/s. All patients noticed symptomatic improvement including healing of ischaemic digital ulcers. In six patients the number of digital arterial segments containing detectable blood flow was measured by directional Doppler; in all six the number increased. It is concluded that plasma exchange is an effective means of haemorrheological treatment and may be beneficial in patients with digital ischaemia.