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Results for “BLOOD VISCOSITY”

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PubMed2006

Sodium modeling attenuates rises in whole-blood viscosity during chronic hemodialysis in children with large inter-dialytic weight gain.

Elevated whole-blood viscosity (WBV) is a risk factor for atherosclerosis and thrombosis. We analyzed WBV during hemodialysis (HD) in children and tested the hypothesis that sodium modeling (NaM) attenuates an increase in WBV. Each of six children underwent two control (C) and two NaM HD sessions, B and E. Rapid decline in sodium (Na) concentration occurred at the beginning of HD in B and at the end in E. We measured WBV at different shear rates (SRs) and documented the amount of fluid removed (FR), change in blood volume (BV), and hematocrit (Hct) before, during, and after HD. The percent increase of WBV in control sessions was significantly different at 2 h and 3 h during and after HD from baseline values. The mean percent change in WBV from baseline increased linearly over time during HD (R2>0.90). Hct, FR, and BV correlated with WBV (P<0.05). The effects of NaM on attenuation of WBV were statistically significant in three subjects with >5% inter-dialytic weight gain (IDWG) (P<0.05). WBV increased during HD in children. NaM appears to attenuate the rise in WBV in children with large IDWG.

Adolescent↗
PubMed1993

Effects of mannitol on cerebral blood flow, blood pressure, blood viscosity, hematocrit, sodium, and potassium.

In our miniature swine model of brain retraction ischemia under conditions simulating the neurosurgical operating room, we studied the effects of bolus mannitol (2 g/kg) administration on cerebral blood flow, blood pressure, blood viscosity, hematocrit, sodium, and potassium serially for 4 hours following administration, at which time a second bolus was administered. Both viscosity and hematocrit were significantly decreased transiently following both the first and second boluses. Sodium was decreased for 30 minutes following the first bolus, 15 minutes following the second bolus, and increased at 150 minutes and later following the second bolus. There was a mild decrease in blood pressure and a mild increase in cerebral blood flow following mannitol, but little difference between the first hour following a bolus (when the viscosity and hematocrit were decreased) and hours 2-4 (when they were near baseline). Mannitol's effects on blood pressure and cerebral blood flow probably depend on factors in addition to its effects on blood viscosity and hematocrit. The results are discussed in light of previous findings that bolus mannitol administration may improve cerebral blood flow in ischemia, but does not appear to benefit the preservation of brain electrical activity.

Animals↗
PubMed1988

Maternal whole blood viscosity in pregnancy hypertension.

Hemoconcentration is prominent in preeclampsia. Concomitant changes in the flow properties of maternal blood, i.e. in whole blood viscosity (WBV), might be related to the occurrence of fetal or maternal complications. To test this hypothesis, WBV was estimated in 228 pregnancies. Patients were assigned to one of four groups according to maximum diastolic blood pressure. Significantly higher WBV values were found in the more hypertensive groups throughout pregnancy. WBV data, obtained between 26 and 36 weeks of amenorrhea, contributed significantly, independently of hypertension, to the prediction of fetal outcome. With regard to maternal complications, no significant contribution of WBV data could be established independently of blood pressure. The results support the hypothesis that WBV is a determining factor in the efficacy of placental perfusion.

Blood Viscosity↗
PubMed1994

Resting whole blood viscosity of elite rowers is related to performance.

This study investigated the relationships between resting whole blood viscosity (WBV), haemoglobin concentration (HGB), haematocrit (HCT), and performance in 25 highly-trained national squad rowers (11 women and 14 men). The WBV and HGB were measured at rest prior to a 2500 m simulated race on a Concept rowing ergometer when performance (P) was measured by average velocity. A group of 12 rowers were measured on just one occasion, another 11 were measured twice with an intervening 5 weeks of continued training and 2 were measured three times, the third test after another 4 weeks. Regression analyses making simultaneous use of both intra- and interindividual data indicated a significant inverse relationship between P and WBV (at both high and low shear rates), a relationship which was strengthened after statistically controlling for the effects of HGB, this effect being slightly more significant than HCT. A significant positive regression also emerged between P and HGB, but only after statistically controlling for the influence of WBV at high shear rate. Overall, stronger relationships were demonstrated in the male rowers compared with the female. These data, in the light of previous evidence that fitter people tend to have lower WBV, would indicate that blood rheology unrelated to HGB (or HCT) is related to performance in relatively homogeneous and already highly-trained athletes.

Adolescent↗
PubMed1983

[Blood viscosity and erythrocyte deformability in diabetic retinopathy].

The whole blood and plasma viscosity, hematocrit and plasma fibrinogen were studied in 26 diabetic patients (11 with and 15 without retinopathy) and in 25 non-diabetic control subjects. Blood viscosity, plasma viscosity and plasma fibrinogen were significantly higher in diabetics than in controls, but no significant differences were found when diabetics with retinopathy were compared to diabetics without retinopathy. The red cell deformability was significantly reduced in diabetics if compared with that of controls; the statistical significance of this reduction was confirmed only in the group of diabetics with retinopathy, but failed when the group of diabetics without retinopathy was considered.

Adult↗
PubMed1989

[Analysis of whole blood viscosity in patients with acute myocardial infarction using a rotation viscosimeter].

Rheologic characteristics of arterial and venous blood have been examined by Rotovisco RV-100 (Haake, FRG), a present-day rotation viscosimeter. Sixty-three acute myocardial infarction cases with intravenous infusion of sodium nitroprusside are analyzed. The detected time course of the reduction of arterial and venous blood viscosity during sodium nitroprusside infusion helps specify the pattern of this drug action in patients during the acute period of myocardial infarction.

Adult↗
PubMed1988

Change of hematocrit and blood viscosity in cholesterol-fed rabbits.

In the cholesterol-fed rabbits, we observed that the whole blood viscosity was maintained at the normal level in spite of the decrease in hematocrit. This phenomenon suggests that there exists some visco-regulatory mechanism, and we could simulate it by a simple integration type model.

Animals↗
PubMed1979

[Variations in blood viscosity of insulin-dependent diabetic subjects controlled by artificial pancreas (author's transl)].

A study of blood viscosity at 3 rates of determination (0.232-0.348 and 1.16 sec-1) in insulin-dependent diabetic subjects controlled by artificial pancreas, shows a reduction in this parameter after 30 hours of feed back control. The relationship between these variations, the mechanical cohesion of the agglutinated red cells, and the deformability of these structures are discussed.

Artificial Organs↗
PubMed1998

The non-ionic surfactant Poloxamer 188 (RheothRx) increases plasma and whole blood viscosity.

RheothRx injection is an intravenous formulation of Poloxamer 188, a non-ionic block copolymer surfactant which is actually used in clinical studies, e.g., during thrombolysis in acute myocardial infarction. We have analysed the influence of RheothRx on plasma and whole blood viscosity of healthy individuals in vitro. For that purpose plasma was incubated with 0, 0.75, 3.75 and 18.75 mg/ml RheothRx and whole blood with a constant hematocrit of 41.4% with 0, 0.4, 2 and 10 mg/ml RheothRx at 37 degrees C. Viscosity was measured with a Couette viscometer at shear rates of 94, 11, 0.9 and 0.1 s-1 as well as with a newly developed oscillating viscometer. In contrast to other studies, we found no favourable effect of RheothRx on plasma and whole blood viscosity. At the highest RheothRx concentration an increase in high and low shear viscosity was observed. Erythrocyte morphology remained unchanged. These data, although on normal blood in vitro, suggest that the positive effects of RheothRx in vivo may not be caused by improved flow properties of blood, but could rely on other mechanisms.

Adult↗
PubMedDate not supplied

[Blood viscosity in ischemic heart disease].

Through a capillary viscometer we measured venous and arterial blood viscosity (BV) in 25 patients with the diagnosis of ischemic heart disease (IHD); 10 of them with unstable angor pectoris (UA) and 15 with acute myocardial infarction (MI). The control group consisted of 100 normal individuals in whom the normal values were 2.70 +/- 0.10 centipoises, where as in patients with AU the values were 4.03 +/- 1.40 centipoises and in the group with MI was 3.65 +/- 1.20 centipoises. Statistically, we correlated the BV obtained in both groups with the following parameters: coronary risk factors, cell blood count; serum glucose, cholesterol and triglycerides as well as the number of coronary arteries involved. The levels of venous and arterial BV were elevated in both groups of patients in comparison with the control group. We concluded that arterial and venous BV is elevated in patients with IHD independently of the hematocrit. This suggest the probability of some other factors such as plasmatic viscosity and platelets aggregation could play a role in the BV elevation of this group of patients.

Adult↗
PubMed1987

Correlation between shear dependent blood viscosity, electrical resistance and calculated width of the marginal layer in blood perfused capillary tubes.

Viscosity and shear dependent changes in electrical resistance (delta R) were measured simultaneously in blood perfused capillaries (I.D. = 0.58 mm, 1 = 300 mm, TW = 0.04 to 0.5 Pa). It appears that delta R is primarily caused by the development of a low resistant cell free marginal layer. Red cell aggregation strongly supports the development of delta R, while in non-aggregating blood the shear induced change in conductivity is rather small. Theoretical and experimental data become closely correlated if the calculated width of the marginal layer, being 1 to 5% of the capillary radius, is inserted into a modified form of Poiseuille's law. It is concluded that under the conditions of plug flow the non-Newtonian flow behavior of EDTA blood almost exclusively depends upon the width of the marginal layer, being a function of shear stress and hematocrit.

Biomechanical Phenomena↗
PubMed1989

[Effect of fenofibrate on fibrinogen concentration and blood viscosity. Consequences for myocardial microcirculation in coronary heart disease?].

The effect of fenofibrate (a clofibrate derivative) on fibrinogen concentration, blood viscosity and myocardial microcirculation was examined in 35 patients with coronary heart disease (n = 27) or hypertension (n = 8). After eight weeks' administration of 250 mg fenofibrate daily cholesterol and triglycerides levels decreased significantly, as did the fibrinogen concentration, from a mean of 300.7 +/- 75.1 mg/dl to 252.3 +/- 61.2 mg/dl (P less than 0.01). Plasma viscosity and erythrocyte aggregation were also significantly lowered (from 1.43 +/- 0.09 to 1.37 +/- 0.07 mPas and 15.0 +/- 3.1 to 13.5 +/- 2.2, respectively; P less than 0.01). In eight of twelve subjects selected from the whole group thallium myocardial scintigraphy demonstrated, after eight weeks of treatment with fenofibrate, a global (in two) or regional (in six) increase in blood flow. Reduction of fibrinogen concentration may in coronary heart disease achieve an improvement in myocardial microcirculation with decreased myocardial ischaemia.

Blood Viscosity↗
PubMedDate not supplied

[The effect of Cardil (diltiazem) in chronic hypoxia on the cationic balance in the cardiovascular system and on blood viscosity in rats].

Experiments on albino rats showed that injection of cardil (diltiazem) (10.5 mg/kg) daily for 7 days in chronic pressure-chamber hypoxia promoted the correction of hypoxia-induced changes in blood viscosity and cation balance in the erythrocytes, blood plasma, tissues of the abdominal aorta and heart (except for the myocardial Ca2+ content) in decrease of the passive and active Na+ and K+ transport through the erythrocyte membrane, increase of free energy (dFi > 0) of the erythrocyte--plasma--vascular wall system which was reduced in rats kept for 14 days under conditions of hypoxia in a pressure chamber. Chronic hypoxia reduced the anticalcium effect of of cardil (diltiazem) in the myocardial cells and its influence on the increase of the transparietal potential difference in the abdominal aorta.

Animals↗
PubMedDate not supplied

A newly designed oscillating viscometer for blood viscosity measurements.

A newly designed type of oscillating viscometer is described. The viscometer consists of either a tube or a rod oscillating at a resonance frequency with amplitudes in the micro- and nanometer range. A fluid flowing through the tube or surrounding the rod damps the torsional oscillations. The increase in the damping depends on the viscosity of the fluid and is used to determine viscosity. It was found that viscosity measurements are feasible during blood flow. This new type of viscometer may be useful to the study of biophysical properties of blood at the wall surface during flow and give new insights into blood flow. The device allows direct viscosity measurement on blood directly as it is drawn from the vein through the tube without any anticoagulant.

Blood Viscosity↗
PubMed1990

[The effect of combined treatment in chronic congestive heart failure with digoxin, furosemide and pentoxifylline upon blood viscosity].

21 patients with symptoms of chronic congestive heart failure, NYHA classes II-IV, were treated with digoxin and furosemide for at least 14 days. In the next stage of the therapy they additionally received a 200 mg intravenous dosage of pentoxifylline and continued to take pentoxifylline orally for the period of at least 14 days. Before the therapy and after each of its stages echocardiography was performed, rheological and gasometric indices of the blood were determined and the level of physical efficiency was assayed in each patient according to NYHA classification. After the digoxin-furosemide treatment there was a significant increase in viscosity of the blood caused by its condensation. Simultaneously there could be observed a significant increase in physical efficiency in patients and also an improvement in some of indices of the left ventricular functions and in gasometric characteristics of the blood. Due to intravenous administration of pentoxifylline a decrease in blood viscosity occurred. The combined treatment with orally administered digoxin, furosemide and pentoxifylline caused a further decrease of blood viscosity, an improvement in some indices of left ventricular efficiency and gasometric characteristics of blood and also much better physical condition of the patients. The results of the present study show that in chronic congestive heart failure subjects a digoxin-furosemide treatment, besides undoubtedly advantageous haemodynamic effects, also leads to blood viscosity. The addition of pentoxifylline results the reduction of increased blood viscosity and in much better hemodynamic condition of the patients.

Adult↗
PubMed1996

Analytical model for effects of shear rate on rouleau size and blood viscosity.

In this paper, a theoretical model is proposed by using the reversible kinetic equation of colloid coagulation to reveal the effects of erythrocyte aggregation and shear rate on the rouleau size and the blood viscosity. With this model, shear rate gamma dependences of the average size of rouleaux n(e) and the viscosity eta in concentrated red blood cell suspension are derived analytically. In this model, we consider not only the shear rate effect but also the rouleau size effect on the aggregation and degradation mechanism. By comparing with experimental results obtained by Shiga et al., some theoretical parameters have been determined. The variation of rate of rouleau formation with shear rate derived in our model is in fairly good agreement with the experimental results, and the viscosity of the concentrated red cell suspension derived in our model showing shear thinning agrees qualitatively with the experimental results obtained by Chien and Sung.

Animals↗
PubMed1990

[Relation of risk factors for the development of ischemic stroke and indices of blood viscosity].

Sixty-two patients were examined with the purpose of investigating the relationship between atherosclerotic and nonatherosclerotic risk factors and blood viscosity parameters. It was established that particularly large increases of hematocrit, hemoglobin and fibrinogen were observed in association of such risk factors as smoking and alcohol abuse. The importance of these factors for the development of ischemic stroke is discussed.

Adult↗
PubMed2005

Blood viscosity changes in experimentally Trypanosoma cruzi-infected rats.

Microcirculatory alterations would explain focal lesions found in Chagas' cardiomyopathy. Trypanosoma cruzi (T. cruzi) infection induces host blood properties modifications and defensive responses capable of producing blood hyperviscosity, an ischemic risk factor able to affect microvascular blood flow. We studied whole blood viscosity (eta(b)) and plasmatic and cellular factors influencing it in rats, 7 and 14 days after experimental infection with T. cruzi. Increased plasma viscosity (eta(p)) was found in infected versus control rats and it was correlated with high blood parasite levels at 7 days and enhanced gamma-globulin fraction concentration at 14 days. The hematocrit, mean corpuscular volume (MCV) and eta(b) were higher in 14 days infected rats vs. 7 days and control animals. Also, electron microscopy observation showed morphological changes in red blood cells (RBC) at 7 and 14 days post-infection, with increased proportion of echinocyte and stomatocyte shapes transformation. In our rat model of Chagas' disease, BPL, increased plasmatic protein concentration, enhanced MCV and RBC shapes transformation would determine blood hyperviscosity, cause of microvascular blood flow abnormalities.

Animals↗