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PubMed2006

Blood viscosity and its relationship to iron deficiency, symptoms, and exercise capacity in adults with cyanotic congenital heart disease.

OBJECTIVES: This study sought to determine the relationship between blood viscosity and iron deficiency and their impact on symptoms and exercise function in adults with cyanotic congenital heart disease. BACKGROUND: Iron deficiency is believed to raise whole blood viscosity in cyanotic congenital heart disease, although available data are inconsistent. METHODS: Thirty-nine cyanotic adults were prospectively assessed for iron deficiency (transferrin saturation < or =5%), hyperviscosity symptoms, and exercise capacity. Same-day measurement of whole blood viscosity and hematocrit (Hct) adjusted viscosity (cells resuspended in autologous plasma to Hct of 45%) was performed at shear rates ranging from 0.277 s(-1) to 128.5 s(-1). RESULTS: Viscosity did not differ between patients with iron deficiency (n = 14) and those without (n = 25). Whole blood viscosity correlated with Hct (r = 0.63, p < 0.001 at low shear and r = 0.84, p < 0.001 at high shear) but not with red blood cell size or iron indices. Hyperviscosity symptoms were independent of iron indices but directly correlated with increased Hct-adjusted viscosity (r = 0.41, p = 0.01). Exercise capacity did not differ in iron-deficient patients. However, peak oxygen consumption was higher in those with Hct > or = 65% (12.6 +/- 3.4 ml/kg/m2 vs. 9.8 +/- 2.6 ml/kg/m2, mean +/- SD, p = 0.036) despite higher whole blood viscosity in these same individuals (p < 0.01 for all shear rates). CONCLUSIONS: Iron deficiency is common in cyanotic adults but does not alter viscosity. Hyperviscosity symptoms are associated with a higher Hct-adjusted viscosity independent of cell size or iron stores. Higher Hct is associated with better exercise capacity. Further work to understand the origin of hyperviscosity symptoms is warranted.

Adult↗
PubMed1977

Blood viscosity in modern medicine.

The understanding and measurement of blood viscosity play an important part in mordern medicine. The basic principles and relevances of fluid viscosity are discussed. Factors which alter viscosity include shear rate, haematocrit, erythrocyte deformability, internal fluidity, pH, plasma proteins, temperature, osmolality, lipids and leucocytes. In vivo changes in vascular architecture are thought to influence blood viscosity. Some of the clinical conditions in which viscosity is important are described. Hyperviscosity should be treated before complications arise.

Blood Flow Velocity↗
PubMed1983

Blood viscosity and erythrocyte filterability: their evaluation in diabetes mellitus.

Blood viscosity and erythrocyte filterability were assessed in forty-five diabetics subdivided for type and vascular complications. From the obtained data, it is evident that blood viscosity at high shear rates does not distinguish diabetics from normals nor diabetics from one another, whereas at low shear rates it is able to differentiate normals from diabetics and diabetics with and without vascular complications. As for the erythrocyte filterability, it is evident that the Vrbc, obtained by filtering whole-blood, distinguishes diabetics from normals, whereas this does not happen with the DI, obtained by filtering red blood suspended (5%) in prefiltered autologous plasma.

Adolescent↗
PubMed1977

Blood viscosity factors in evaluation of submaximal work output and cardiac activity in men.

Sixty-two male subjects, including patients with postmyocardial infarction, angina, other disorders, and normals, were studied by exercise testing on the bicycle ergometer, including exercise ECG, and by in vitro determination of blood viscosity, plasma viscosity, aggregation of red cells, and other factors. Significant correlations were found between the blood viscosity factors on the one hand, and different terms describing physical fitness and cardiac functions on the other. In all correlations an elevation of blood viscosity factors led to lower fitness or lower cardiac efficiency; and a decrease of blood viscosity (or plasma viscosity, or compound viscosity product) was associated with better fitness and higher cardiac efficiency. Similarly, ECG ST-segment depression was proportional to increase of blood viscosity factors. All these highly significant correlations were found within a very narrow range of hematocrits, while the hematocrit value itself was not significant in this study.

Adult↗
PubMed1975

Elevation of blood viscosity, aggregation of red cells, haematocrit values and fibrinogen levels with cigarette smokers.

A study of blood viscosity factors was carried out on male smokers and non-smokers (125 volunteers) in the age group 45 to 55 years. The smoker's group exhibited elevated haematocrit values, fibrinogen levels and blood viscosity (P less than 0-025), and increased aggregation of red cells and plasma viscosity (P less than 0-005). Especially in the dependence of aggregation of red cells on the level of fibrinogen, the smokers of blood group O showed higher values than smokers of blood group A (P less than 0-01). Elevation of blood viscosity factors and functions in smokers suggests that pathways to ischaemia and thrombosis, to which smokers are more prone than non-smokers, may move through the blood high-viscosity syndromes.

Blood Sedimentation↗
PubMed2000

Effect of long-term exercise training on blood viscosity during endurance exercise at an anaerobic threshold intensity.

Blood viscosity (etaB) is low in athletes, but the effect of exercise training on etaB during endurance exercise at an anaerobic threshold (AT) intensity in non-athletes is not well known, although it is known that exercise training sometimes induces the hyperviscosity syndrome. Fourteen subjects were recruited and divided into 2 groups: those who trained at an AT intensity for 30 min/day, 3 times weekly for 1 year (Group T, n=8), and sedentary subjects (Group C, n=6). The test protocol consisted of a single 30-min treadmill exercise at each individual's AT intensity, which was determined in advance. The etaB, plasma viscosity (etaP), and hematocrit were measured just before and at the end of the treadmill exercise. The subjects were not allowed to drink any water before exercise. In the Group C subjects, the hematocrit and etaP increased significantly and the etaB tended to increase. However, in the Group T subjects, the hematocrit and etaP did not increase and the etaB decreased significantly. These data indicate that long-term exercise training attenuates the increase in blood viscosity during exercise.

Adult↗
PubMed1987

Effect of temperature dependent changes in mechanical stability of red cell aggregates on relative apparent whole blood viscosity.

As the temperature dependence of relative apparent whole blood viscosity eta rel is still controversial, the relation between the temperature dependence of red cell aggregation (RCA) and that of eta rel was examined in normal donors and in patients with venous ulcers of the leg. Apparent whole blood viscosity was measured in the DEER-rheometer (0.01 Pa less than tau less than 2.9 Pa) at 10 degrees C, 20 degrees C, 30 degrees C and 37 degrees C. The instrument was calibrated for each temperature to correct for changes in viscometer geometry. Simultaneously the minimal shear stress tau Tmin to keep RCA dispersed was determined by photometric aggregometry. eta rel was found to increase with decreasing temperature. By basing the relative cold induced increase in eta rel on the state of RCA as defined by the ratio of tau/tau Tmin the relation between both features is verified: With increasing RCA the cold induced increase in eta rel is progressively enhanced.

Blood Viscosity↗
PubMedDate not supplied

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.

Analysis of Variance↗
PubMed1990

[The anti-hemorrhagic shock of acupuncture on neiguan and its effect on the cardial pump function and the blood viscosity].

The purpose of this paper is to study and analyse the effects of the cardial pump function and the blood viscosity on rabbits with hemorrhagic shock by puncturing Neiguan. In the experiment 30 rabbits were divided into the electroacupuncture (EA) group and the control group, each group was 15 rabbits. The cardial pump function, the blood pressure and the blood viscosity were recorded during normalize, shock, and EA. The results were as following. 1. The blood pressure of the rabbits which were in hemorrhagic shock was raised by needling Neiguan. MAP was raised from 43 +/- 8 to 87 +/- 15 mmHg (p less than 0.001). 2. The cardial pump function were reinforced by needling Neiguan. SV was increased from 0.41 +/- 0.46 (before EA) to 0.73 +/- 0.12 ml (p less than 0.0001). CO, SI, CI. and WL were improved in a certain degree with difference significant. In the EA group the each index of the cardial pump function was higher than that of the control group. There was statistical significant between the two groups. 3. Needling Neiguan, the blood viscosity was tending to normality. The blood plasma viscosity was increased. There was significant difference (p less than 0.05). These results suggest that needling Neiguan may protect the cardial pump function, raise the blood pressure, play a positive role during anti hemorrhagic shock.

Acupuncture Points↗
PubMed1998

Effects of food and water withdrawal and high temperature exposure on diurnal variation in blood viscosity of broiler chickens.

1. Three experiments were conducted to investigate the diurnal variation of blood viscosity in broilers. In experiment 1 food and water were supplied freely at 20 degrees C (20-FW). In experiment 2 food and water were withdrawn at 20 degrees C (20-NFW), while in experiment 3 food and water were withdrawn at 30 degrees C (30-NFW). 2. Blood sampling time points were 09.00 h, 15.00 h, 21.00 h, 03.00 h and 09.00 h the next day in each experiment. 3. In all experiments, whole blood viscosity (WBV), red blood cell count (RBC) and haematocrit (HCT) were greater during the dark (21.00 h and 03.00 h) than during the light period. During the dark period, there were no differences in WBV, RBC and HCT between 20-FW and 20-NFW, or between 20-NFW and 30-NFW. At 09.00 h, WBV and HCT were higher in 20-FW than in 20-NFW. At 15.00 h and 09.00 h (day 2), WBV and HCT were greater in 20-NFW than in 30-NFW. 4. There were no light-dark differences in plasma viscosity (PV), plasma protein concentration (PPC) or mean corpuscular volume (MCV) in any experiment. However, 20-NFW birds had a lower PPC and higher MCV compared with 20-FW, and a higher PPC and lower MCV compared with 30-NFW, while no difference was found in PV. 5. WBV increased linearly with RBC and HCT. PV increased with PPC, while MCV decreased. 6. These results indicate that there is diurnal variation in whole blood viscosity, which is greater during the dark than during the light period. During the light period it is strongly influenced by high environmental temperature and food and water withdrawal.

Acclimatization↗
PubMed1990

Branch retinal vein occlusion: the pathogenetic role of blood viscosity.

The pathogenesis of branch retinal vein occlusion has not been completely clarified. The role of abnormal blood viscosity in the appearance and evolution of the disease has recently been advocated. We studied 54 patients with long-standing branch retinal vein occlusion from a hemorrheologic point of view. Depending on the extension of retinal ischemia, two subgroups were identified. Hematocrit, blood and plasma viscosity, whole blood filterability, cell deformability, and fibrinogen levels were investigated. Thirty-five subjects of similar age, sex, and risk factors of diabetes and hypertension served as controls. Our results showed that blood viscosity is higher in patients with occlusion and particularly in those with severe retinal ischemia. Statistical analysis showed a direct correlation between blood viscosity and hematocrit.

Adult↗
PubMed1993

Blood viscosity during long-term treatment with ticlopidine in patients with intermittent claudication. A double-blind study.

The aim was to test within a randomized, double-blind trial whether the antiaggregant drug ticlopidine might reduce blood viscosity as has been claimed. Sixteen patients with intermittent claudication were studied before and after three years of treatment with ticlopidine, 500 mg/day, or placebo. At baseline, the viscosity values were significantly higher as compared with a reference group of healthy subjects. Whole-blood viscosity, measured at four different shear rates at hematocrit adjusted to a standard 40%, decreased significantly at follow-up, with no difference between ticlopidine treatment and placebo. Hematocrit showed a slight increase in the placebo group. The viscosity parameters were unrelated to lower limb blood flow variables, ankle/brachial index, and walking distances. The mechanism behind the overall decrease in whole-blood viscosity is obscure but could possibly be explained by lifestyle changes. Smoking habits were, however, unaltered. Since plasma viscosity remained increased, it might indicate that some erythrocyte factor, notably red cell aggregability and deformability, had improved. It is concluded that ticlopidine had no long-term effect on blood viscosity.

Aged↗
PubMed2000

Preventive magnesium supplement reduces ischemia-induced hearing loss and blood viscosity in the guinea pig.

The effect of magnesium (Mg) on ischemia-induced hearing loss was investigated in two groups of adult pigmented guinea pigs of either an optimal or suboptimal (physiologically high or low) Mg status maintained by different diets. Total Mg concentrations of the perilymph, cerebrospinal fluid, blood plasma and red blood cells were found to differ significantly between the two groups, as tested in a previous study. Local vascular impairment was produced by unilateral ferromagnetic thrombosis of cochlear blood vessels. Cochlear blood flow (CBF) and hearing function were measured using laser Doppler flowmetry and auditory brain-stem response audiometry, respectively. Ferromagnetic thrombosis resulted in significant reductions of the mean apical CBF in both experimental groups and of the mean basal CBF in the low Mg group compared to the contralateral ears. In the high Mg group, the basal CBF was not decreased. However, the laser Doppler signals revealed considerable interindividual variations and the differences found between the two experimental groups were not significant. In contrast, the hearing loss in the low Mg group was significantly higher than that in the high Mg group. A correlation was found to exist between the vascular impairment and the hearing threshold shift. In a separate series, we also tested the effect of Mg on hemorheology and found both the blood viscosity and blood viscoelasticity to be significantly lower in the high Mg group than in the low Mg group, depending on the shear rates tested. The present findings show that a preventive oral Mg supplement can significantly reduce the rate of ischemia-induced hearing loss and improve blood viscosity in the guinea pig.

Animals↗
PubMed1985

[Blood viscosity: an original method for the study of low values of the shear rate].

A method for studying blood viscosity at low shear rates (from 4 x 10(-2) to 7 x 10(1) sec-1), i.e. in the shear range in which higher is the influence of shear rate on viscosity, was developed. Blood viscosity is expressed by the two regression coefficients of a power regression, according to the function: eta = a . Db where eta is viscosity. D is the shear rate, a and b are the two regression coefficients, which are independent of the shear rate. We found that the regression power was highly significant in a wide hematocrit range. Practically, this work deals with the possibility of application to the blood of the Ostwald formula for pseudoplastic flow behavior. We found significant correlations between the two regression coefficients and hematocrit and plasma viscosity, so correcting by calculation the two regression coefficients for standard hematocrit and standard plasma viscosity. This method is simple and can easily be automatically driven by a computer.

Blood Viscosity↗
PubMed1987

[Effect of smoking on blood viscosity and arterial rigidity in normal and hypertensive subjects].

The purpose of the study was to assess whether cigarettes smoking could induce blood hyperviscosity and arterial rigidity in 30 normotensive and 70 hypertensive men aged from 24 to 65 years. Of those, 20 normotensive and 20 hypertensive were cigarettes smokers, while the remaining subjects were non smokers. Age and weight were similar in the 4 groups of subjects. A couette viscometer with coaxial cylinders allowed the measurements of blood viscosity over a wide range of shear rates (0.033 to 241 sec-1) mimicking the flow condition of the circulation, and two strain gauge transducers permitted the measurements of the brachial to radial pulse wave velocity as an index of arterial wall distensibility. In normotensive subjects cigarettes smoking increased pulse wave velocity from 7.1 + 1 to 9.2 + 0.6 m/sec. (P less than 0.05) as well as blood viscosity, which increased both at higher shear rates (+10% from 52 to 241 sec-1, P less than 0.05) and lower shear rates (+20% from 11.2 to 0.2 sec-1, P less than 0.02). In hypertensives, cigarettes smoking increased pulse wave velocity (9.8 + 0.3 to 11.3 + 0.4; P less than 0.05) and blood viscosity (4% at higher shear rate P less than 0.05 and 10% at lower shear rates P less than 0.02). Although hypertensive patients had increased pulse wave velocity and blood viscosity compared to normotensive controls, these variables were not significantly different when hypertensive non smokers were compared to normotensive. The present study demonstrated that cigarettes smoking produced in normotensive and hypertensive men significant rheological disturbances of flow and wall arteries.2

Adult↗
PubMed2000

Blood viscosity and hematological changes during prolonged submergence in normoxic water of northern and southern musk turtles (Sternotherus odoratus).

Musk turtles (Sternotherus odoratus) can survive at least 150 days of submergence in normoxic water at 3 degreesC, during which time there are large increases in packed cell volume (PCV). We investigated the effects of submergence in normoxic water at 3 degreesC on the blood viscosity of musk turtles from northern (Massachusetts) and southern (Alabama) locales. Blood was collected from air-breathing turtles and after 20, 50, 100, and 150 days of submergence in normoxic water at 3 degreesC. Hematological responses to submergence were similar in the two groups, therefore the results were combined. Packed cell volume increased steadily above that of controls after 20, 50, 100, and 150 days of submergence. Hemoglobin concentration also progressively increased above that of controls after 20, 50, and 100 days of submergence but declined to near control values after 150 days. Blood viscosity increased with increasing PCV; however, blood viscosity of musk turtles appears less affected by PCV than is blood viscosity of mammalian species. As such, musk turtles appear to be able to maintain adequate blood flow to tissues while increasing the oxygen carrying capacity of the blood during prolonged submergence. However, after 150 days submergence, oxygen delivery should decrease due to a reduced oxygen carrying capacity of the blood and an increased resistance to blood flow, which may limit the length of time these turtles can remain viable during hibernation.

Alabama↗
PubMed2000

[Rheologic determinants of human blood viscosity during breathing a hypoxic mixture].

Blood samples of healthy male subjects exposed to three-wk hypoxia were analyzed for deformation and aggregation of erythrocytes. Results of the investigation showed that breathing a hypoxic mixture increases blood viscosity by way of raising rigidity of erythrocytes and fastness of their aggregates. A direct correlation between the deformability index and rate of aggregation was established. The physiological effect of this phenomenon is explained by the compensatory reaction of organism in support of the circulation structure and the breathing function of blood in hypoxic conditions.

Adult↗