Sauna effects on hemorheology and other variables.

Blood viscosity at 10 shear rates, plasma viscosity, packed cell volume, plasma fibrinogen, serum alpha 2-macroglobulin, and serum proteins were measured in 83 patients with low-tension glaucoma (LTG) and 23 patients with 'high-tension glaucoma' (HTG: at least one IOP reading above 40 mmHg) and compared with those in 50 controls. Blood and plasma viscosity values and packed cell volume were significantly higher in the LTG group than those in controls. The HTG and the LTG groups differed only in plasma viscosity, but smoking and drinking habits in the HTG patients were greatly different from those in LTG patients and controls, thus preventing interpretation of data in the HTG group. Within the LTG group viscosity values were highest in a subgroup designated earlier by us as focal ischaemic LTG, whereas another subgroup, senile sclerotic LTG, did not show significant differences compared with controls. These findings may indicate a factor in the pathogenesis of visual field defects and disc cupping in some patients with LTG.

Some studies indicate that obesity is associated with rheological disturbances. Because there are usually sex differences in the type of obesity we decided to evaluate rheological differences between male and female obese patients. We studied 18 morbidly obese men, mean age 43.66 +/- 11.32 years, mean body mass index (BMI) 49.82 +/- 6.03 kg/m2 and 20 obese females, mean age 40.6 +/- 11.86 years, mean BMI 47.41 +/- 8.81 kg/m2. Blood and plasma viscosity measurements were performed using a cone-plate viscometer (Brookfield DV-II). Erythrocyte elongation and red blood cell (RBC) aggregation were measured using the Laser-assisted Optical Rotational Cell Analyser (LORCA). Whole blood viscosity and RBC deformability expressed by the elongation index were significantly higher in obese men. We did not observe differences in plasma viscosity, corrected blood viscosity and aggregation parameters among the obese population. Blood viscosity correlated with selected RBC aggregation indices. We conclude that morbidly obese patients presented sex-dependent differences in some rheological properties. This study indicates a relation between erythrocyte aggregation indices and blood viscosity in obese populations.

A direct relationship between blood pressure and viscosity has frequently been reported, although clear data are not available. To better understand the relationship between these two variables, we evaluated blood viscosity and blood pressure in a group of healthy subjects without cardiovascular risk factors. Healthy subjects were selected from participants in a campaign of prevention of cardiovascular disease (n = 103). They underwent blood sampling for measurement of plasma and blood viscosity, haematocrit, blood lipids and glucose. The quantity and distribution of body fat was assessed by body mass index and waist/hip ratio, respectively. Systolic blood pressure (SBP) correlated significantly with age (r = 0.222) and waist/hip ratio (r = 0.374). Diastolic blood pressure (DBP) correlated significantly with waist/hip ratio (r = 0.216), haematocrit (r = 0.333) and blood viscosity (r = 0.258). Multiple linear regression analyses demonstrated that the only variable significantly associated with SBP was age, while haematocrit was the only variable significantly associated with DBP. Blood viscosity was closely related to waist/hip ratio. These findings show that SBP, in healthy subjects, is not influenced by haematocrit and blood viscosity. In contrast, DBP is related to the values of haematocrit. Among classical cardiovascular risk factors, waist/hip ratio is closely related to blood viscosity.

Hemorheologic variables in critical limb ischemia before and after infrainguinal reconstruction.

Twelve patients with Type II diabetes mellitus, insufficiently controlled with oral hypoglycemic agents, were studied before, after 2 months, and after 4 months on insulin therapy. For comparison the same variables were also studied in 10 healthy subjects. From the start, in the diabetic group, the authors found alterations in the hemorheologic parameters indicated by increased values for whole blood viscosity, plasma viscosity, red cell transit time (RCTT), and decreased values for white cell initial relative filtration rate (IrFR). In hematologic parameters they found increased values for mean corpuscular volume (MCV), leukocyte count, counts of neutrophils and monocytes, and a decreased count of lymphocytes. They also found increased values in the lipid parameters P-triglycerides and Apo B/Apo A-I ratio, risk factors of coronary atherosclerosis. After 4 months of insulin treatment whole blood and plasma viscosity were still increased, but there was a partial improvement of lipoprotein abnormalities. Red and white cell filterability, however, tended to normalize. These results indicate that changes in blood cell filterability do not necessarily influence in vitro measurements of blood viscosity. The change in RCTT during the insulin treatment was associated with a decreased MCV and the change in white cell IrFR with a decrease in the number of monocytes. This change of white cell filterability during insulin therapy, probably due to a reduced number of monocytes, may be of interest in the study of atherosclerosis and circulatory disease in diabetics.

Hemorheological abnormalities are independent cardiovascular risk indicators and adversely affect the outcome of cardiovascular disease. Single LDL apheresis treatment was shown to improve blood and plasma viscosity, red cell aggregation and deformability. However, the long-term effects of LDL apheresis on hemorheology are still unknown. Therefore, we investigated hemorheological parameters in 23 patients (11 women, 12 men) with angiographically established coronary heart disease and drug-resistant hypercholesterolemia regularly treated with LDL apheresis for 7.6+/-3.1 years. Hemorheological measurements (whole blood viscosity, plasma viscosity, red blood cell aggregation at stasis and low shear rate) were analyzed in all patients before and after the initial LDL apheresis as well as before a current LDL apheresis. Single LDL apheresis resulted in significantly reduced plasma viscosity, whole blood viscosity and erythrocyte aggregation index. However, long-term apheresis had no sustained effect on plasma and whole blood viscosity. Our data indicate that in contrast to its beneficial short-term effects, long-term LDL apheresis does not stably improve hemorheology.

The haemorheological disturbances observed in primary hypertension arise mainly from haemoconcentration, which leads to an elevation of blood and plasma viscosity and increased aggregation of red blood cells (RBCs). We evaluated the rheological properties of blood and central haemodynamic indices in 13 men with untreated primary hypertension (WHO stage I and II), during a baseline period and after intravenous infusion of 1000 ml of 0.9% NaCl (within 12-15 min). The rheological properties studied were: whole blood viscosity (WBV), plasma viscosity (PV), haematocrit (HCT) and plasma fibrinogen concentration (PF). The central haemodynamic indices were: mean intra-arterial blood pressure (MAP), central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), total peripheral resistance index (TPRI) and the vascular hindrance index (VHI). Plasma renin activity (PRA) and plasma noradrenaline concentration (P-NA) were also measured. Volume expansion with saline caused haemodilution as expressed by a fall in HCT (P less than 0.001), WBV (P less than 0.001) and PV (P less than 0.01). At the same time, CVP, MAP and VHI increased (P less than 0.05) while PRA decreased (P less than 0.05) and P-NA remained unchanged. Mean values of the cardiac index (CI) and stroke volume index (SVI) did not change significantly. We did not observe any significant relationship between haemodynamic and haemorheological parameters, during baseline or between their respective changes after the infusion. The results indicate that although hypervolaemic haemodilution produced by saline infusion in hypertensive patients may improve blood flow properties (HCT, WBV, PV), blood pressure (BP) is not reduced; rather the converse is true. The reduction in HCT and hence the improved blood rheology, did not affect calculated vascular resistance. Thus, correction of WBV does not acutely normalize BP in primary hypertension.

Objective To study the effect of Naotongliting capsule (NLC) on hemorheology and platelet aggregation in blood stasis rats. Method The rat model of blood stasis was established with adrenaline subcutaneous injection in combination with ice-water socking. Aspirin and Yangjiao capsule were selected as contrast medicine to observe the effect of NLC on whole blood viscosity, plasma viscosity, haematocrit, fibrin and platelet aggregation in blood stasis rats. Result NLC could reduce hemorheology and platelet aggregation in blood stasis rats. Conclusion NLC is helpful to adjust hemorheology and plateiet aggregation in blood stasis rats, indicating its good effect of activating blood circulation to remove blood stasis. Key words: Naotongliting capsule; syndrome of blood stasis rats; Hemorheology

The aim of the present study was to investigate the effects of manipulating hematocrit by different methods (acute exercise, training or isovolumic hemodilution) on blood viscosity in high-level aerobic endurance athletes. We hypothesized than increasing hematocrit does not always cause a rise in blood viscosity.Sixteen endurance athletes underwent maximal exercise before and after 4 weeks of training with (LHTL; n = 10) or without (placebo; n = 6) Live High-Train Low modalities. Total hemoglobin mass was measured before and after training by a carbon monoxide rebreathing technique. After training, subjects performed two maximal exercise bouts separated by isovolumic hemodilution (phlebotomy and/or plasma volume expander) to readjust red blood cell volume and plasma volume to baseline values. Blood samples were obtained before and after exercise to assess hematocrit and blood and plasma viscosity.Training session (LHTL and placebo) increased hematocrit (Hct) in all subjects but without any significant change in blood viscosity. The decrease in plasma viscosity in all groups may explain this result. Isovolumic hemodilution caused a drop of Hct without any significant change in blood viscosity at rest. Maximal exercise increased Hct, blood and plasma viscosities in both groups, regardless of isovolumic hemodilution. However, peak hemorheological values after exercise were lower after isovolumic hemodilution.In conclusion, while acute increase in Hct during exercise caused an increase of blood viscosity, the chronic increase of Hct induced by training session did not result in a rise in blood viscosity. The lowering of plasma viscosity during training may compensate for the increase of Hct, hence limiting its impact on blood viscosity.

The effects of propofol compared to high-dose fentanyl anesthesia on rheologic parameters in coronary artery surgery

High blood viscosity is associated with increased peripheral resistance and high blood pressure (BP). Prehypertension refers to a systemic BP of 120-139 mm Hg systolic (SBP) and/or 80-89 mm Hg diastolic (DBP). Subjects with prehypertension have an increased risk of overt hypertension and incident cardiovascular disease compared with subjects who have optimal BP. In the present study, we investigated the hemorheological profiles of subjects with prehypertension. A total of 418 apparently healthy subjects were enrolled. BP, plasma lipids and glucose were measured using routine methods. Blood and plasma viscosity were measured using a cone-plate viscometer. The participants were grouped according to BP into the following categories: 'normotensive' (n=100), 'prehypertensive' (n=172), and 'hypertensive' (n=146). The blood viscosity, plasma viscosity and hematocrit of the prehypertensive subjects were higher than those of the normotensive subjects (P<0.01), but they were comparable to those of the hypertensive subjects. In simple correlation analyses, SBP and DBP were directly and significantly correlated with age, body mass index (BMI), blood glucose, hematocrit, plasma viscosity and blood viscosity. In multiple regression analyses, age, fasting blood glucose and plasma viscosity were independently related with SBP, whereas blood viscosity, fasting blood glucose and BMI significantly predicted DBP. These data demonstrate that BP in the range of so-called prehypertension is accompanied by important hemorheological changes, which are similar to those observed in people with overt hypertension. These results could explain the increased cardiovascular risk observed in these subjects as well as their susceptibility to hypertension.

Patients suffering from post-thromobotic syndrome are compared to controls in terms of ex-vivo measurements to quantify the rheological behavior of blood: blood and plasma viscosity, haematocrit, red cell aggregation, red cell filterability, erythrocyte sedimentation rate (ESR), plasma fibrinogen. The results show that plasma viscosity, red cell filterability, ESR and fibrinogen are significantly changed indicating a lack of blood fluidity in post-thrombotic disease. It is suggested that the rheological deficit and the venous pathology both contribute to a disturbed microcirculation in the affected limb.

This study evaluates the nature and reversibility of the increase in whole blood viscosity known to be induced by hypothermia. Anticoagulated samples were obtained from normal volunteers and were assayed for cellular deformability by 4.7 microns membrane filtration of whole blood (n = 12) and washed RBCs (n = 10). Results were expressed as filtration rate. Specimens were evaluated for plasma (n = 10) and whole blood (n = 12) viscosity by cone plate viscometer. All assays were sequentially performed at 30 degrees, 34 degrees, and 37 degrees C and difference analyzed by paired t test. Hypothermia resulted in significant impairment of cellular deformability, which was reversed by rewarming: [table: see text] Hypothermia also resulted in a significant increase in plasma viscosity (mean difference = 0.5426 centipoise, p less than 0.02), which was likewise reduced on rewarming. The increase in whole blood viscosity associated with hypothermia is secondary to both diminished cellular deformability and increased plasma viscosity. Both of these alterations are reversible with appropriate rewarming.

To investigate haemorheological changes during pregnancy in a Latin American population and compare to previously published data from Caucasian populations. Cross-sectional study. 75 pregnant women at 10-36 wk of gestation and 17 non-pregnant female controls in Lima, Peru. All the women and their ancestors for three generations were born and lived at sea level. Viscosity, haematocrit and plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting. At 10 wk of gestation, total protein concentration and plasma viscosity were above non-pregnant levels by about 15% and subsequently decreased linearly with gestation. Fibrinogen concentration was increased in the first trimester; it then decreased to a nadir at about 20 wk and subsequently increased. Albumin concentration decreased linearly with gestation. Haematocrit decreased from pre-pregnancy levels at 10 wk to a nadir at about 26 wk. Blood viscosity increased in the first trimester and then decreased with gestation to a nadir at about 26 wk. In the first trimester of pregnancy blood and plasma viscosity are increased and they subsequently fall with advancing gestation. Plasma viscosity reflects the changes in total protein concentration, and blood viscosity is dependent on the interplay of changes in plasma viscosity and haematocrit.

Effect of Renal Replacement Therapy on Viscosity in End-Stage Renal Disease Patients