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PubMed2001

[Coping with stress and blood viscosity in stroke prevention patients].

INTRODUCTION: Hematocrit, fibrinogen and blood viscosity influence blood fluidity and are well known stroke risk factors. Studies have shown relationships between these factors and psychological stress. AIM: The aim of this study was to investigate how stroke risk patients with increased hematocrit, increased fibrinogen, or increased plasma viscosity differ from patients free of these risk factors in their ways of stress coping. METHOD: 6503 persons participated in the following stroke risk investigations: biographical and risk factor orientated anamnesis, neurological status investigation, laboratory investigation, sonographic investigation and psychological investigation. After assessment of several risk factors, differences in stress coping between risk factor and non-risk factor groups were investigated by means of the t-test and the Wilcoxon-test. RESULTS: Men with pathological hematocrit showed significantly higher scores in the coping strategy resignation and a tendency to less positive self instruction and response control attempts. Women with higher values of hematocrit demonstrated higher values in resignation and drug intake. Men with higher fibrinogen showed significantly higher scores in distraction, vicarious satisfaction, minimising by comparison and tendency to flee as well as a tendency towards drug intake. Women with increased fibrinogen showed no differences. Men with normal plasma viscosity had significantly higher values in tendency to flee and tendencially in desire for social support and lower values in minimising by comparison. Women with increased plasma viscosity demonstrated higher scores in resignation and aggression. CONCLUSIONS: The presence of elevated values in parameters of blood viscosity coincides with increased passive and defensive coping mechanisms, whereas non-risk factor persons show raised values in active coping styles.

Adaptation, Psychological↗
PubMedDate not supplied

[Frequency and gradient dispersion of viscosity of dna solutions].

Gradual and frequential dispersion of the viscosity of DNA solution in cattle splin was studied. Zimm--Crothers rotational viscosimeter was used for determining gradient relationship of viscosity eta (g). To determine frequential dispersion of viscosity a magnetelecttric vibrational viscosimeter with the working range of 16-100 Hz was produced. It was found that gradient relationship of specific viscosity coincides within the measuring error with the frequential relationship of actual component of specific viscosity at dynamic measurements. The influence of the alternating force with the frequency f is equivalent to the effect of stationary applied force producing the gradient g=k with f, where k=3,2 plus or minus 0,4.

Animals↗
PubMed1975

[Clinical and statistical considerations on the relation between hematocrit value and blood viscosity].

Blood viscosity at various speed gradients was determined in 186 patients, a range of 245 haematocrit readings varying between 12 and 72 being examined. Statistical analysis of the results revealed a direct proportionality relationship between the two parameters, with viscosity expressed in logarithms. The regression lines accentuate their slope as the speed gradient falls. When determined at high speed gradients, blood viscosity can quintuplicate its value by varying the haematocrit from 10 to 70, while it can increase fully ten times at low speed gradients with the same haematocrit reading variations. Using blood from the same subject, resuspended at different haematocrits, viscosity values were obtained along the lines of regression up to haematocrits of about 70; for higher readings, viscosity data lie above these lines to a greater extent the higher is the speed gradient. Emphasis is laid on the great importance of the haematocrit reading from the rheological viewpoint and the significant clinical deductions that can be made.

Adult↗
PubMed2002

Plasma viscosity in female patients with hypothyroidism: effects of oxidative stress and cholesterol.

Hypothyroidism is associated with atherosclerotic events, however, the mechanism is unclear. We investigated the effects of oxidative stress and cholesterol on plasma viscosity in female patients with hypothyroidism (n = 20; mean age: 45.5 +/- 5.5 years) at baseline and after L-thyroxine replacement therapy (average daily dose being 0.1 to 0.15 mg). Two blood samples were taken after 2.3 +/- 1.2 months. In hypothyroid state plasma viscosity and thiobarbituric acid reactive substance (TBARS; marker of oxidative stress were significantly higher (p < 0.001 and p < 0.001), and plasma protein thiol (antioxidants) levels were significantly lower (p < 0.001) than in the healthy state (female; n = 15). After L-thyroxine replacement therapy, patients reached to euthyroid state. In this state, the levels of plasma viscosity and TBARS were decreased (p < 0.001 and p < 0.001), and protein thiol levels were significantly elevated (p < 0.001). There was a significant correlation between plasma cholesterol and viscosity (r = 0.64, p < 0.001), as well as plasma protein thiol (r = -0.59, p < 0.001) in the patients. The correlation between viscosity and TBARS was weak (r = 0.29, p < 0.01). Therefore hypothyroidism may be associated with atherosclerotic process by different mechanisms.

Adult↗
PubMed2002

Blood viscosity and platelet function in patients with obstructive sleep apnea syndrome treated with nasal continuous positive airway pressure.

Patients with obstructive sleep apnea syndrome (OSA) have a high incidence of cardiovascular events. We measured whole blood viscosity at high (94.5 s(-1)) and low (0.1 s(-1)) shear rate, hematocrit, fibrinogen, and platelet hemostatic function (PTA-100) at 7-8 p.m. and 7-8 a.m. in 8 controls and 13 patients, once with the established nasal continuous positive airway pressure (NCPAP) treatment and once without. OSA patients had a higher plasma viscosity (1.37+/-0.11 vs. 1.19+/-0.11 mPa.s in the evening, p<0.05) and fibrinogen (2.61+/-0.49 vs. 2.11+/-0.29 g/l, p<0.05) than controls, without diurnal difference, and similar values with or without NCPAP. Whole blood viscosity and hematocrit were similar in controls and patients before and after a night with or without NCPAP. Platelet activity was significantly higher in the morning than in the evening in controls and patients with or without NCPAP. We conclude that blood viscosity and platelet activity are similar in controls and patients with OSA on a long-term treatment with NCPAP, which is not worsened by a single night without NCPAP. The increase of plasma viscosity and fibrinogen in OSA patients as well as the general increase of platelet aggregation in the morning may contribute to the increased incidence of cardiovascular events.

Aged↗
PubMed1992

Effects of thyroidectomy on the hematocrit and blood viscosity in ovariectomized rats.

The hematocrit and blood viscosity were measured in ovariectomized (Ovx) rats following thyroidectomy or sham operation. Rats were thyroidectomized (Tx) or sham Tx immediately after ovariectomy. Three months later, Ovx, Ovx+Tx, and intact rats at proestrus stage were bled. Blood was collected by heart puncture in rats under ether anesthesia and heparinized. One month after the first bleeding, Ovx and Ovx+Tx rats were bled once again. the viscosity of whole blood and plasma was measured at various shear rates at 37 degrees C by means of a Mooney-Ewart viscometer. The hematocrit was determined by a microhematocrit centrifuge. The plasma osmolality was measured by a computerized micro-osmometer. Concentrations of plasma sodium and potassium were measured by a flame photometer. The concentration of plasma thyroid stimulating hormone (TSH) was measured by a radioimmunoassay. In Ovx+Tx rats, the plasma TSH concentration was higher, but the hematocrit and blood viscosity were lower than those in Ovx and proestrus rats. The levels of plasma sodium, osmolality and viscosity were not altered by ovariectomy and thyroidectomy. These results suggest that the lower blood viscosity in thyroidectomized rats is due to a reduction of hematocrit.

Animals↗
PubMed1992

[Factors that determine the high blood viscosity syndrome in rheumatoid arthritis patients].

High blood viscosity is a syndrome that may be attributed to a group of the most important disorders of microcirculation under different pathological conditions of the body. The given syndrome manifests itself by disorders of red blood cell deformability (RBCD), high plasma and whole blood viscosity. 32 patients with a verified diagnosis of rheumatoid arthritis (RA) were examined, showing varying activity and systemic manifestations. There was a significant decrease of RBCD from 82.0 + 4.5% in patients with grade I activity to 33.0 + 15.0% in patients with grade III activity (p < 0.01). At the same time plasma viscosity remained practically unchanged. Whole blood viscosity rose with RA activity enhancement: in grade I, it was 1.87 + 0.60 relative units, in grade II, it was 2.80 + 0.80 relative units, in grade III, it constituted 5.30 + 3.70 relative units (p < 0.02). It is assumed that RBCD disturbance is one of the most leading signs in the development of high blood viscosity in RA patients.

Adult↗
PubMed2004

[Study on viscosity property of gastrointestinal mucus].

To probe further into the viscosity of gastrointestinal mucus, the samples of gastrointestinal mucus were taken from fifty normal people and were tested with Low-Shear 30 viscometer, and then the viscosity model was obtained. The results indicated that the apparent viscosity of large intestine mucus is greater than that of small intestine and stomach. The gastrointestinal mucus is a kind of non-Newtonian fluid when its apparent viscosity rapidly decreases with the increase of shear rate. When the shear rate increase well enough, the apparent viscosity of gastrointestinal mucus becomes a constant, and the gastrointestinal mucus appears to be a Newtonian fluid.

Adolescent↗
PubMed2004

Measurement of blood viscosity using a pressure-scanning capillary viscometer.

A newly designed pressure-scanning capillary viscometer is extended to measure the viscosity of whole blood over a range of shear rates without the use of anticoagulants in a clinical setting. In the present study, a single measurement of pressure variation with time replaces the flow rate and pressure drop measurements that are usually required for the operation of a capillary tube viscometer. Using a pressure transducer and capillary, we measured the variation of pressure flowing through capillary tube with respect to time, p(t), from which viscosity and the shear rate were mathematically calculated. For water and anticoagulant-added bloods, there was an excellent agreement found between the results from the pressure scanning capillary viscometer and those from a commercially available rotating viscometer. Also, the pressure-scanning capillary viscometer measured the viscosity of whole blood without heparin or EDTA. This new method overcomes the drawbacks of conventional viscometers in the measurement of whole blood viscosity. First, the pressure-scanning capillary viscometer can accurately and consistently measure the whole blood viscosity over a range of shear rates in less than 2 min without any anticoagulants. Second, this design provides simplicity (i.e., ease of operation, no moving parts, and disposable) and low cost.

Blood Viscosity↗
PubMed2005

Increase plasma viscosity sustains microcirculation after resuscitation from hemorrhagic shock and continuous bleeding.

Resuscitation from hemorrhagic shock (50% of blood volume, BV) followed by continuous bleeding (20% of BV per hour, over the entire observation time, 90 min) was studied in the unanesthetized hamster chamber window model. Blood losses equaled 100% of total BV. A single volume infusion (resuscitation) was performed 60 min after hemorrhage using 25% of the BV with 10% hydroxyethyl starch (HES 200, group HES4), or a mixture of HES 200 with 0.3% or 0.6% (w/v) alginate (groups HES7 and HES10, respectively) leading to solutions with a uniform colloidal oncotic pressure (84-87 mmHg) and viscosities ranging from 3.8 to 9.8 cp. Results showed all solutions to be similar immediately after resuscitation (10-15 min) and diverged after this initial period. The viscosity-enhanced solutions showed improved and longer-lasting effects (90 min) relative to the conventional low viscosity, in terms of sustained arterial blood pressure, microvascular flow, capillary perfusion, and laboratory parameters. All microvascular parameters 90 min after resuscitation with low viscosity fell back to the shock level. Improved recovery obtained with a hyperviscous plasma expander was related to microcirculation shear stress preservation, leading to improve blood flow by lowering peripheral vascular resistance when compared with low viscosity resuscitation. These findings suggest the possibility of using hyperviscous plasma expanders to prolong the period for initial treatment of blood losses and definitive institution therapy.

Alginates↗
PubMed2006

Beneficial effects due to increasing blood and plasma viscosity.

Increased plasma and blood viscosity are usually associated with pathological conditions; however there are several situations in which the elevation of both parameters results in increased perfusion and the lowering of peripheral vascular resistance. In extreme hemodilution blood viscosity is too low and insufficient to maintain functional capillary density, a problem that in experimental studies is shown to be corrected by increasing plasma viscosity up to 2.2 cP. This effect is mediated by Nitric oxide (NO) production via restoration of shear stress at the endothelium as shown by microelectrode perivascular measurements of NO concentration. Moderate elevations of blood viscosity by increasing hematocrit (approximately 10% of baseline) result in reductions of blood pressure by 10 mmHg of baseline. This effect is also NO mediated since it is absent after N-nitro-L-arginine methyl ester (L-NAME) treatment and in endothelial NO synthase deficient mice. These results show that the rheological properties of plasma affect vessel diameter in the microcirculation leading to counterintuitive responses to the increase in viscosity.

Animals↗
PubMed2006

[Investigation of the structure of macromoleculare gels II: analysis of viscosity curves].

Viscosity curves of gels from homo-and copolymers in aqueous medium reviewed in our previous paper were studied. Viscosity vs. rate of shear, and viscosity vs. shearing time were analysed. The viscosity curves can be described with multiplicative functions and the slope of these functions characterizes the orientation ability of polymer molecule-chains under shear. On the base of viscosity vs. shearing time functions the network formed from polymers can be classified into energetic structure, topologic one and/or friction one. It was also established, that the aqueous polymer network structures studied do not thixotropic systems.

Gels↗
PubMed2006

Association of plasma viscosity with cardiovascular risk factors in obesity: an old marker, a new insight.

OBJECTIVE: Although obesity is related with cardiovascular disease, the exact mechanism of the relationship is not fully understood. We aim to examine the relationship between plasma viscosity and obesity as a cardiovascular disease risk factor in obese and non-obese groups. METHODS: We recruited 75 obese subjects (mean age: 40.2+/-8.4 years, Body Mass Index: 33.61+/-2.57 kg/m(2)) who were admitted to the Clinic of Endocrinology and Metabolism of Cerrahpasa Medical Faculty. As a non-obese group (n=70, mean age: 41.78+/-9.7 years, Body Mass Index: 21.84+/-3.42 kg/m(2)) healthy subjects from medical and laboratory staff were selected. Plasma viscosity and lipid profile were measured and atherogenic index was calculated as atherogenic risk factors. RESULTS: Plasma viscosity, total cholesterol and LDL-cholesterol levels and atherogenic index were significantly increased in obese group compared to non-obese group for each p<0.001. We found no significant difference in plasma fibrinogen, insulin, albumin and HDL-cholesterol levels between obese and non-obese groups. Plasma viscosity was correlated with total cholesterol and atherogenic index only in the obese group (p<0.05 and p<0.05 respectively). In the non-obese group regarding PV, we determined a positive correlation with triglycerides (r: 0.470, p<0.05) and negative correlation with HDL-C (r: -0.518, p<0.05). CONCLUSION: Plasma viscosity, an early atherosclerotic risk factor, might be helpful in the assessment of cardiovascular risk in obese subjects along with classical cardiovascular risk factors such as plasma cholesterol and atherogenic index.

Adult↗
PubMed1991

[Hematocrit and hemoglobin, parameters of hematic viscosity, in pregnancy-induced hypertension].

During pregnancy because of physiologic hemodiluition and changes in various plasma protein levels, plasma viscosity is decreased compared to the non pregnant condition. Specifically the whole blood viscosity profile throughout pregnancy follows that of the hematocrit. However some pathological condition like pregnancy induced hypertension and intrauterine growth retardation are characterized by an increase of plasma viscosity. In order to evaluate the effect of plasma viscosity on placental perfusion, in 41 patients affected by pregnancy induced hypertension and with no iron deficiency we compared maternal hemoglobin and hematocrit to the birth weight. High maternal hemoglobin and hematocrit levels were associated to an increased frequency of low weight for date newborns (less than or equal to 10th centile), although the relationship with the hemoglobin levels is stronger (p less than or equal to 0.02) than the one with the hematocrit (p less than or equal to 0.05). In contrast, high weight for date newborns (greater than or equal to 90th centile) were not related to maternal hemoglobin and hematocrit parameters. We found that maternal hemoglobin and hematocrit, indicators of plasma viscosity, are useful in predicting low birth weight, but not high birth weight. We speculate that hypoxia due to the modification of microcirculation is a very important factor in determining the low birth weight; in contrast the oxygen is not the only factor involved in determining the high birth weight.

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↗
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↗
PubMed1989

Blood viscosity in human obesity: relation to glucose tolerance and insulin status.

Obesity is known to be associated with an elevated risk for cardiovascular disease. Rheological disturbances could be factors contributing to these vascular complications. Therefore we have evaluated blood viscosity parameters in 128 obese (BMI greater than 28 kg/m2) adults and in 90 non-obese healthy subjects. Whole blood, plasma and erythrocyte viscosity values were determined with a Contraves LS30 viscosimeter. Plasma and whole blood viscosity were significantly (all P less than 0.001) increased in the obese subjects. The increased low shear erythrocyte viscosity suggested a diminished erythrocyte deformability in obesity. The rheological abnormalities were present even in the absence of impaired glucose tolerance, diabetes, hypertension or hyperlipidaemia. In the obese group the rheological parameters showed significant correlations (at least P less than 0.05) with BMI, insulin or C-peptide area during an oral glucose tolerance test and plasma lipids. Our findings demonstrate that obesity per se may be associated with abnormal blood viscosity properties.

Adult↗
PubMedDate not supplied

Effects of oral and intravenous defibrotide on blood viscosity in patients with peripheral obliterative arterial disease.

Patients with peripheral obliterative arterial disease received 400 mg of defibrotide intravenously (seven patients) or orally (nine patients). Blood and plasma viscosity were measured before therapy, at 30 minutes after and one hour after intravenous administration, and at 1, 2, 3, and 8 hours after oral administration. Thirty minutes after intravenous administration, blood viscosity at a shear rate of 30 sec-1 was reduced from 9.99 to 9.00 and at a shear rate of 180 sec-1 from 6.61 to 6.33 (P less than 0.05). Viscosity returned to baseline after 60 minutes. At 1, 2, and 3 hours after oral administration, blood viscosity at a shear rate of 30 sec-1 was reduced from 8.53 to 7.44, 6.88, and 7.19 (each P less than 0.01) and at a shear rate of 180 sec-1 from 5.88 to 5.51 (P less than 0.05), 5.14 (P less than 0.05), and 5.38 (P less than 0.01); the levels at eight hours were not significantly different from baseline values. Plasma viscosity was not affected by defibrotide. These data confirm previous evidence of a rheologic effect of defibrotide in patients with peripheral obliterative arterial disease and indicate that such an effect can be achieved with oral administration.

Administration, Oral↗