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PubMed1994

Alterations in blood viscosity in horses competing in cross country jumping.

Packed cell volume and plasma total protein (TP), serum albumin (Alb) and globulin (Glb), and plasma ionized calcium (PCa) concentrations, blood viscosity (BV), and plasma viscosity (PV) were measured in 42 horses at rest and after the cross country jumping phase of a horse trial competition. The BV and PV were determined at 6 shear rates (230, 115, 46, 23, 11.5, 5.75 s-1), using a digital rotational cone and plate microviscometer. A paired t-test was used to determine differences between PCV, TP, Alb, Glb and PCa values at rest and after exercise. The PCV, TP, Alb, and Glb values increased (P < 0.05) in horses after exercise. The PCa concentration decreased (P < 0.05) in horses after exercise. Mean BV and PV in the 42 horses at rest and after exercise were fitted to an asymptotic function. Significant (P < 0.05) correlation at all shear rates was seen between BV at rest and PCV, TP, Alb, Glb, and PCa values at rest; and between BV after exercise and PCV, TP, Alb, Glb, and PCa values after exercise. Significant correlation was not seen between PV at rest and TP, Alb, Glb, and PCa at rest, or between PV after exercise and TP, Alb, Glb, and PCa concentrations after exercise at any shear rate.

Animals↗

PubMedDate not supplied

The effect of long-term treatment with hypotensive drugs on blood viscosity and erythrocyte deformability in patients with essential arterial hypertension.

This study examined ninety-six patients with essential arterial hypertension (WHO grade I-II) who had been under treatment for a period of at least one year before participating in the study. When the study began the patients received no drug treatment for one month. At the end of this washout period their basal situation was evaluated and drug treatment was begun (26 patients on calcium antagonists, 39 on beta-blockers and 31 on angiotensin converting enzyme inhibitors). The patients were evaluated again after one and two years of uninterrupted treatment with the chosen medication. The results obtained indicate that in a basal situation hypertensive patients have higher blood viscosity and erythrocyte rigidity values than the control group. Regardless of the drug treatment used, the patients experienced during the study a progressive deterioration of their hemorheological situation consisting of an increase in red blood cell rigidity and increased blood viscosity. These results indicate the importance of evaluating the hemorheological parameters of hypertensive patients and suggest that it may be advisable to include in their treatment some kind of medication that prevents progressive rheological deterioration.

Adrenergic beta-Antagonists↗

PubMed1987

The influence of maternal whole blood viscosity on fetal growth.

To explore the relevance of the rheological properties of maternal blood in pregnancy to fetal growth a study of whole blood viscosity (WBV) was conducted in the early third trimester of 138 pregnancies. A significant negative correlation was found between WBV at low shear rate and birthweight centile. As the rheological parameters were found to be negatively correlated with the placenta coefficient, an independent role for maternal WBV seems likely. When WBV, placental weight and degree of infarction accounted for significant contributions in a logistic regression model, diastolic blood pressure data did not assist in the correct prediction of occurrence of a low birthweight centile (less than 10th). A simplified model is proposed, to explain the mechanisms by which some clinical variables may express their influence on fetal growth. In conclusion, it is suggested that WBV might be considered one of the factors which determine the efficacy of placental perfusion on the maternal side. However, as this variation in efficacy of placental perfusion is only weakly reflected in variations in birthweight, the influence of WBV on fetal growth cannot be very important.

Adolescent↗

PubMed1989

[Dynamics of blood viscosity indices in patients with alcoholic myocardiodystrophy].

According to I. V. Strel'chuk's classification, 120 patients with alcoholic myocardiodystrophy induced by stage I-III chronic alcoholism were examined. The control group included 25 normal men. The rheological blood parameters (fluidity limit, apparent viscosity, red blood cell aggregation ratio, and hematocrit) were examined over time: before treatment, after its discontinuance, and one month after discharge from hospital. It was shown that blood viscosity increased with the disease gravity, whereas the results of the treatment correlated well with the initial patient's status. In stages I and II chronic alcoholism, the study parameters could return to normal, while in stage III, blood viscosity remained significantly higher than normal both towards the end of the treatment at hospital and on control examination one month after discharge. The control over blood rheology performed over time may be recommended as an additional method for assessing the disease gravity and efficacy of the treatment of alcohol-induced abnormalities.

Alcoholism↗

PubMed1992

[Changes of blood viscosity in patients undergoing cardiac surgery during cardiopulmonary bypass].

The patient undergoing open-heart surgery depends on hypothermia and cardiopulmonary bypass (CPB) to maintain organ perfusion during cardiac arrest. Increased blood viscosity during hypothermic CPB might be life-threatening, so hemodilution is imperative. Fourteen open-heart patients of ASA class II-III were included in this study. Pre- and intra-CPB viscosity changes were observed. Before CPB, 6 ml blood sample was drawn out from open-heart patients after systemic heparinization and another 6 ml blood sample was drawn out from the oxygenator after CPB was established. The hematocrit and relative viscosity of each sample in different temperatures were measured. The result revealed that as the temperature decreases, the viscosity of each sample increases apparently. As compared to the pre-CPB blood sample, the hematocrit of blood obtained intra-CPB decreases from 36.81 to 27.04, (p < 0.001), and the viscosity also decreases at all different temperatures (p < 0.001). Blood viscosity obtained at 37 degrees C pre-bypass is not statistically different from the sample at 25 degrees C during bypass. Obviously, increased viscosity due to hypothermia is buffered by hemodilution after using large amount of fluid as priming solution during CPB. Therefore, the hematocrit and viscosity remain within physiologic ranges.

Adult↗

PubMed1984

Blood viscosity, finger systolic pressure and effect of dazoxiben treatment in primary vasospastic disease.

Whole blood viscosity, plasma viscosity, erythrocyte deformability, and finger systolic pressure (FSP) were measured in ten patients with primary vasospastic (Raynaud's) disease before and after a controlled double-blind prospective trial involving dazoxiben (a thromboxane inhibitor, Pfizer). Five of the patients were assigned to dazoxiben and five to placebo. Before treatment, the FSP at 10 degrees C in the patient groups was significantly lower than that in a normal reference group, but all rheologic variables, measured at 37 and 10 degrees C, were normal. There was no significant correlation between FSP and rheology. Dazoxiben did not yield any subjective relief or give any objective effect.

Adult↗

PubMed1994

Are platelet cytosolic free calcium, serotonin concentration and blood viscosity different between hypertensive and normotensive subjects?

In this study, the platelet intracellular calcium and serotonin (5-HT) concentrations as well as the hemorheological properties were compared in 65 hypertensive (HT) and 25 age-matched normotensive (NT) subjects. The result showed that the platelet intracellular calcium concentration in the HT group was significantly higher than in the NT group (165.4 +/- 12.6 vs. 118.9 +/- 12.4 nM, p < 0.05). However, the platelet 5-HT content in the HT group was significantly lower than in the NT group (0.28 +2- 0.03 vs. 0.38 +/- 0.03 nmol/10(8) platelets, p < 0.05). Moreover, red cell flexibility, red cell deformability, hematocrit, fibrinogen concentration and plasma viscosity were all significantly increased in HT subjects. The whole blood viscosity was generally higher in the HT group. In conclusion, the higher platelet intracellular calcium and lower 5-HT level as well as abnormality of hemorheological properties may be important factors in the initiation and perpetuation of hypertension.

Aged↗

PubMed1998

Blood viscosity and elevated carotid intima-media thickness in men and women: the Edinburgh Artery Study.

BACKGROUND: Several hemostatic and rheological factors have been associated with incident cardiovascular events. However, there have been no reports on the relationship of rheological factors with early atherosclerosis and very few on hemostatic factors. We therefore studied the relationship between these factors and carotid intima-media thickness (IMT). METHODS AND RESULTS: The Edinburgh Artery Study measured fibrinogen, tissue plasminogen activator (tPA), fibrin D-dimer, von Willebrand factor (vWF), blood and plasma viscosities, and hematocrit as part of its baseline examination during 1988-1989. At the 5-year follow-up, valid measurements of IMT had been recorded in 1106 men and women 60 to 80 years old. In men, blood viscosity (P< or =.001) and its major determinants, plasma viscosity, fibrinogen (both P< or =.01), and hematocrit (P< or =.05), were all linearly related to IMT. Furthermore, blood viscosity, fibrinogen (both P< or =.01), and plasma viscosity (P< or =.05) remained significantly associated on multivariate analysis. Correcting blood viscosity to a standard hematocrit of 45% had little effect on its association. In men, there was a significantly increased risk of having an IMT above versus below the upper quartile of its distribution (1.05 mm) for SD increases in blood viscosity (P< or =.01), fibrinogen, corrected blood viscosity, and plasma viscosity (all P< or =.05). With the exception of plasma viscosity, these risks were unaffected by adjustment for other common cardiovascular risk factors. No significant associations were found between any of the hemorheological factors and IMT in women or for tPA, fibrin D-dimer, or vWF in either sex. CONCLUSIONS: These findings suggest that in men, blood viscosity and its major determinants are associated not only with incident cardiovascular events but also with the early stages of atherosclerosis. This may be one explanation for the link between rheological factors and events.

Age Factors↗

PubMedDate not supplied

Model-independent relationships between hematocrit, blood viscosity, and yield stress derived from Couette viscometry data.

This paper describes a procedure, based on Tikhonov regularization, for obtaining the shear rate function or equivalently the viscosity function of blood from Couette viscometry data. For data sets that include points where the sample in the annulus is partially sheared the yield stress of blood will also be obtained. For data sets that do not contain partially sheared points, provided the shear stress is sufficiently low, a different method of estimating the yield stress is proposed. Both the shear rate function and yield stress obtained in this investigation are independent of any rheological model of blood. This procedure is applied to a large set of Couette viscometer data taken from the literature. Results in the form of shear rate and viscosity functions and yield stress are presented for a wide range of hematocrits and are compared against those reported by the originators of the data and against independently measured shear properties of blood.

Blood Viscosity↗

PubMed1991

Treatment of azotemic, nonoliguric, anemic patients with human recombinant erythropoietin raises whole-blood viscosity proportional to hematocrit.

It has been reported that patients with azotemia have reduced red blood cell (RBC) deformability. Since this is a major determinant of whole-blood viscosity (WBV) and rigid RBCs increase WBV disproportionately relative to the level of hematocrit, it is conceivable that sustained improvement of hematocrit with recombinant human erythropoietin (rhEPO) therapy in azotemic patients might result in abnormally raised WBV. To address this concern, WBV and plasma viscosity (PV) were measured in 9 adult patients (4 men, 5 women) with anemia (mean hematocrit 29.2 +/- 2.7%) and azotemia [mean serum creatinine concentration 339.85 +/- 102.44 mumol/l (3.8 +/- 1.1 mg/dl)] before and after 6 months of treatment with rhEPO (50-175 U/kg given intravenously thrice weekly). Baseline and post-treatment hematocrit, WBV and PV were compared to values derived in 50 normal adult subjects with normal renal function [25 women, 25 men; mean serum creatinine concentration 79.56 +/- 8.84 mumol/l (0.9 +/- 0.1 mg/dl), mean hematocrit 42.4 +/- 3.7%]. To compare rheologic factors at subnormal hematocrits, blood from subjects with normal renal function was diluted with autologous plasma to achieve a range of hematocrits from 20 to 50%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1981