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At least 127 records · Page 7Linked to original sources
PubMed1993

The effect of Leboyer delivery on blood viscosity and other hemorheologic parameters in term neonates.

OBJECTIVE: This study was done to compare postnatal alterations in blood viscosity, hematocrit value, plasma viscosity, red blood cell aggregation, and red blood cell deformability in term neonates undergoing both early umbilical cord clamping and delivery according to the Leboyer method. STUDY DESIGN: The umbilical cords of 15 healthy, term infants were clamped within 10 seconds of birth (early cord clamping), and 15 infants delivered according to the Leboyer method were placed on the mother's abdomen, and the umbilical cords were clamped 3 minutes after birth. Hemorheologic parameters were studied in umbilical cord blood at 2 hours, 24 hours, and 5 days from the time of delivery. RESULTS: The residual fetal placental blood volume decreased from 45 +/- 8 ml/kg (x +/- SD) after early cord clamping to 25 +/- 5 ml/kg after delivery by the Leboyer method. After Leboyer-method delivery, the hematocrit value rose from 48% +/- 5% at birth to 58% +/- 6% 2 hours after delivery, 56% +/- 7% at 24 hours, and 54% +/- 8% after 5 days. Blood viscosity in the Leboyer-method group increased by 32% within the first 2 hours but did not change significantly during the following 5 days. Plasma viscosity, red blood cell aggregation, and red blood cell deformability were not affected by the mode of cord clamping. CONCLUSIONS: Delivery by the Leboyer method leads to a significant increase in blood viscosity as a result of increasing hematocrit value, whereas other hemorheologic parameters are similar to those of infants with early cord clamping.

Blood Viscosity↗
PubMed1989

Effects of clinostatism and orthostatism on blood viscosity.

The present study was planned to study the magnitude of the effects of body position upon blood viscosity. We compared blood rheological properties in nine healthy subjects after 1 h in a horizontal position and after 1 h in a vertical position. After orthostatism, blood viscosity was 38%, 41%, and 22% higher at 0.05, 1, and 20 s-1 shear rates, respectively. This result was the consequence of the increase of hematocrit (41.2% +/- 2.3% vs 44.2% +/- 2.7) and plasma viscosity (1.55 +/- 0.09 mPa.s vs 1.67 +/- 0.08 mPa.s) induced by orthostatism in all the subjects. The rise of the different plasma proteins and fibrinogen was the cause of the plasma viscosity increase. Blood viscosity at standard hematocrit (45%) was not significantly altered by orthostatism. Rheological studies at standard hematocrit showed that body position did not modify red cell deformability and aggregability. As suggested by the increase in hematocrit and plasma proteins and by the absence of alteration of blood rheological properties at standard hematocrit, the large effect of body position upon blood viscosity is the consequence of the hemoconcentration without alteration of erythrocyte deformability and aggregability.

Blood Viscosity↗
PubMed1980

Increased blood viscosity in young women using oral contraceptives.

Blood viscosity and its major determinants (hematocrit, plasma fibrinogen, and plasma viscosity) were measured in 25 men, 25 women who were not using oral contraceptives, and 25 women who had been using oral contraceptives for at least 3 months. Mean blood viscosity and hematocrit were significantly higher in women using oral contraceptives than in women who were not (p < 0.001), and use of oral contraceptives abolished the normal sex difference in blood viscosity and hematocrit. After correction to a standard hematocrit of 45%, blood viscosity was still higher in users or oral contraceptives, as was plasma fibrinogen (p < 0.05). Plasma viscosity was not significantly increased in users of oral contraceptives.

Adolescent↗
PubMed2000

[Estimation of blood viscosity in woman at puerperium].

Marks of blood viscosity in different states of physiology and of pathology of man are well-supplied documentary evidence. One recognized also influence of blood viscosity on disclosure of some disease processes. Period pregnancy and labour joins with changes of volume and of composition of blood circulation. Authors decided to price blood viscosity in period puerperal and to compare these given to universally coming to light anaemia's woman in puerperium. Investigations one passed in groups pregnant and woman in puerperium from different degree exacerbations of anaemia. Obtained results of stickiness one achieved to morphological parameters of blood. One ascertained, that blood viscosity is less at woman in puerperium than at women pregnant and grows less together from degree anaemia's.

Adolescent↗
PubMed1995

[Influence of acupuncture on blood pressure, contents of NE, DA and 5-HT of SHR and the interrelation between blood pressure and whole blood viscosity].

Twenty spontaneous hypertensive rats (SHR) with systolic blood pressure (SBP) >or= 20 kPa were chosen and divided randomly into two groups (acupuncture group and control group). The former was acupunctured on bilateral Quchi (L1 11), Zusanli (ST 36). Another 46 immature SHRs which were about 7-week-old with SBP ranged from 16 kPa to 20 kPa were given 10% high molecular weight dextran (HMWD) or normal saline by intervention respectively. The results showed: 1. After three course of acupuncture, SHRs' SBP dropped remarkably from 25.493 +/- 0.73 kPa to 19.547 +/- 0.555 kPa (P < 0.01); 2. After three courses of acupuncture, NE and 5-HT contents in plasma were lowered (P < 0.05, < 0.01) and DA content in plasma was increased (P < 0.05) compared with that in the control group. 3. After three course of acupuncture, NE content in brainstem, hypothalamus, cerebral cortex increased (P < 0.005-0.01) and DA content in brainstem, cerebral cortex increased remarkably (P < 0.005-0.01) compared with that in the control group. 5-HT content in brainstem, hypothalamus, and cerebral cortex increased obviously compared with that in the control group. 4. After 1 or 2 hours of intervention of 10% HMWD to immature SHR, the whole blood viscosity and blood pressure rise remarkably compared with normal saline group. The experiment implies that the mechanism of lowering the blood pressure of SHR by acupuncture lies in that it can adjust NE, DA and 5-HT contents in plasma and central nervous system to adjust the activity of sympathetic, reduce whole blood viscosity etc.

Animals↗
PubMed1998

Docosahexaenoic acid inhibits blood viscosity in stroke-prone spontaneously hypertensive rats.

Increased blood viscosity facilitates the formation of thrombosis. This is an important risk factor in the occurrence of cerebral infarctions. The present study was undertaken to elucidate whether docosahexaenoic acid (DHA) inhibits blood viscosity, hematocrit and fibrinogen in the disease animal model, stroke-prone spontaneously hypertensive rats (SHRSP). An attempt was also made to clarify the effect of DHA on blood pressure in SHRSP. Blood viscosity, hematocrit and fibrinogen in non-treated SHRSP increased significantly when compared with levels in age-matched non-treated Wistar Kyoto rats (WKY). SHRSP rats which were administered DHA for 5 weeks displayed significant decreases in blood viscosity, hematocrit and fibrinogen when compared with the values in non-treated SHRSP. The blood pressure of DHA-treated SHRSP was significantly lower than that of non-treated SHRSP. A positive correlation existed between blood pressure and blood viscosity. These findings suggest that decreased blood viscosity induced by DHA appears to be associated with the reduction of thrombosis formation and hypotensive action in SHRSP.

Aging↗
PubMed1986

Correlation between umbilical vein blood flow and umbilical blood viscosity in normal and complicated pregnancies.

Umbilical vein blood flow (UVBF) was studied during the last 24 h before delivery using a combination of real-time and Doppler ultrasonic equipment in 64 normal and pathological pregnancies and the results were correlated with the values of whole blood viscosity taken from the umbilical vein after delivery. UVBF was reduced in the subgroup with chronic fetal distress (n = 14) (P less than 0.001) and the hypertensive pregnancies (n = 17) (P less than 0.05), whereas umbilical blood viscosity was increased only in the subgroup with chronic fetal distress (P less than 0.01) as compared with the normal pregnancies (n = 24). A significant positive correlation was observed between the umbilical blood viscosity and haematocrit values in all the groups of patients. UVBF and blood viscosity had a significant negative correlation in chronic fetal distress (P less than 0.001) and in hypertensive pregnancies (P less than 0.05), but not in normal or diabetic pregnancies (n = 9). Thus haemoconcentration leading to increased fetal blood viscosity may act as an aetiological factor in the reduction of UVBF in developing fetal distress.

Blood Viscosity↗
PubMed2005

Pentoxifylline attenuates the increase in whole blood viscosity after transfusion.

BACKGROUND: Pentoxifylline improves tissue oxygenation and intestinal blood flow in models of haemorrhagic shock, and it has been used for the treatment of intermittent claudication due to its beneficial effects on haemorheology. We investigated the effects of pentoxifylline on whole blood viscosity during packed red-blood cell transfusion in critically ill adult patients. METHODS: Twenty critically ill patients were randomly assigned to one of two groups (pentoxifylline group: n = 11, placebo group: n = 9) and prospectively studied. Forty-five minutes before and during the packed red-blood cell transfusion (10 ml min(-1)) over a period of 80 min, 1.5 mg kg(-1) . h(-1) pentoxifylline or placebo were administered intravenously. Haematocrit, plasma fibrinogen concentration, total protein concentration, whole blood viscosity (at a shear rate of 10 s(-1), 50 s(-1), and 100 s(-1)) and plasma viscosity were measured. RESULTS: After the packed red-blood cell transfusion, haematocrit levels increased significantly in both groups (pentoxifylline group: from 26.1 +/- 2.8% to 33.0 +/- 3.2; placebo group: from 24.4 +/- 3.3% to 32.6 +/- 2.6%; means +/- standard deviation). Compared to baseline, whole blood viscosity increased in both groups at all shear rates after the transfusion, but the increase was significantly less in the pentoxifylline group (26 +/- 15% vs. 49 +/- 14%, 23 +/- 11% vs. 39 +/- 12%, and 22 +/- 11% vs. 35 +/- 12% for the pentoxifylline vs. placebo groups at shear rates of 10 s(-1), 50 s(-1), and 100 s(-1), respectively). Plasma viscosity, total protein concentration, and fibrinogen concentration remained unchanged and no significant differences among groups were observed. CONCLUSIONS: These results suggest that pentoxifylline is effective in attenuating the increase in whole blood viscosity after a transfusion of packed red-blood cells. Plasma viscosity is not influenced by pentoxifylline.

Adult↗
PubMed1985

Blood viscosity in arctic fishes.

The blood viscosity of arctic char, Salvelinus alpinus, and shorthorn sculpin, Myoxocephalus scorpius, from the arctic (74 degrees 42'N) was measured with a cone-plate viscometer. Blood viscosity of the two arctic species was considerably lower, less shear rate dependent, and less temperature dependent than the blood of winter flounder (Pseudopleuronectes americanus) from more temperate waters. The rheological properties of the arctic fish blood would minimize blood flow resistance and thus be advantageous at the low temperatures (0 degree C) characterizing their environment.

Adaptation, Biological↗
PubMed1991

The estimation of whole blood viscosity by a porous bed method.

A significant impediment in determining the relative contribution of whole blood viscosity to the pathogenesis of cardiovascular and cerebrovascular disease has been the lack of an uncomplicated method to measure whole blood viscosity. To address this problem, a simplified porous bed viscometer has been developed to measure whole blood viscosity. Whole blood is passed through a porous bed of branching channels with a mean pore diameter of 69.6 +/- 20.2 microns and an estimated mean shear rate of 19.6 seconds-1. The effects of sample collection, sample storage, and temperature are described. The mean whole blood viscosity of 242 healthy persons was 22.7 +/- 5.3 seconds, which, when corrected to centipoise using Darcy's equation, corresponds to an apparent viscosity of 5.7 +/- 1.3 cp. There was a significant difference in the whole blood viscosity of normal men and women related to their different packed cell volumes. Platelets and granulocytes influenced whole blood viscosity in proportion to their contribution to the total packed cell volume. Fibrinogen levels did not significantly influence measured whole blood viscosity, which is consistent with the disaggregating conditions and the mean shear rate of the instrument. The porous bed viscometer is a convenient means to measure whole blood viscosity and it should be useful as a screening test for clinical and epidemiologic studies.

Anticoagulants↗
PubMed1984

Blood viscosity studies in native and reconstituted polycythemic blood.

In twelve subjects with Polycythemia vera (P.V.) whole blood, plasma and relative viscosities and the main factors capable of influencing such parameters (Hct, RBCs, WBCs and platelet count, total proteins, gamma-globulins and fibrinogen) were investigated. Ten normal subjects of similar age and sex were studied as control. Whole blood viscosity was determined both in basal conditions and after reconstitution of Hct to normal values by adding some autologous plasma. After the reconstitution of Hct the subjects studied were divided into two groups on the basis of the correlation between Hct and whole blood viscosity. The first group (group A) had a good correlation between Hct and whole blood viscosity; on the other hand the second group (group B) did not show any significant correlation between these two parameters after reconstitution. In basal conditions none of the parameters capable of influencing whole blood viscosity or plasma viscosity permitted any discrimination between the two groups. The relative viscosity, which represents an indirect index of red blood cell deformability, appears to be more elevated in group B. Therefore, the different behaviour of polycythemic blood after reconstitution of Hct might be conceived to be due to a difference in red cell deformability.

Blood Cell Count↗
PubMed1981

Blood viscosity, Raynaud's phenomenon and the effect of fibrinolytic enhancement.

The whole blood and corrected blood viscosity of 17 patients with Raynaud's phenomenon (8 with idiopathic Raynaud's phenomenon and 9 with scleroderma-associated Raynaud's phenomenon) have been compared with 12 normal controls. Viscosity has been measured with a Contraves LSV1 rotating viscometer and the Wells-Brookfield microviscometer at 37 degrees C and 25 degrees C and shear rates ranging from 0.775 s-1 to 230 s-1. Blood viscosity was higher at both the lower temperature and the lower shear rates but this change was the same in the patients as in the normal subjects. There was a significantly higher level of plasma fibrinogen in the patients with scleroderma with a significant increase in the corrected blood viscosity, but not the whole blood viscosity, at both temperatures and all shear rates. The percentage increase of viscosity at low temperatures in the patients was the same as the controls. No evidence was found to substantiate the hypothesis that Raynaud's phenomenon is caused by an excessive increase of blood viscosity at low temperatures. Treatment of 10 patients with stanozolol, a stimulator of fibrinolysis, reduced the plasma fibrinogen and increased the haematocrit did not change the whole blood viscosity. Hand blood flow increased. The improvement of hand blood flow was not therefore caused by change in blood viscosity secondary to the reduction of plasma fibrinogen.

Adult↗
PubMed1983

[Relation of blood viscosity, plasma viscosity and hematocrit].

The results from 398 consecutive measurements of blood viscosity, plasma viscosity and hematocrit were submitted to a statistical analysis. Hematocrit appeared to be the main determinant of blood viscosity, even though its influence was not so strong as illustrated in previous investigations. The correlation between blood viscosity and hematocrit appeared strictly connected with the red cell amount of the blood sample, being higher when the latter exceeded its physiological range; this correlation disappeared when red blood cell amount was strongly reduced, while the correlation between plasma viscosity and blood viscosity had an opposite behaviour. From these results we can conclude that correlations between hematocrit and plasma viscosity with blood viscosity have opposite trends and that a reciprocal interference is often present.

Blood Viscosity↗
PubMed1998

Whole-blood viscosity and the insulin-resistance syndrome.

BACKGROUND: In a previous study we found that elevated blood viscosity was linked to the insulin resistance syndrome, and we proposed that high blood viscosity may increase insulin resistance. That study was based on calculated viscosity. OBJECTIVE: To determine whether directly measured whole-blood viscosity was related to the insulin-resistance syndrome in the same way as calculated viscosity had been found to be. METHODS: Healthy young men were examined with the hyperinsulinemic isoglycemic glucose clamp technique, and we related insulin sensitivity (glucose disposal rate) to other metabolic parameters and to blood viscosity. We established a technique for direct measurement of whole-blood viscosity. RESULTS: There were statistically significant negative correlations between glucose disposal rate and whole-blood viscosity at low and high shear rates (r = -0.41, P = 0.007 for both, n = 42). Whole-blood viscosity was correlated positively (n = 15) to serum triglyceride (r = 0.54, P = 0.04) and total cholesterol (r = 0.52, P = 0.05), and negatively with high-density lipoprotein cholesterol (r = -0.53, P = 0.04) concentrations. Insulin sensitivity index was correlated positively to high-density lipoprotein cholesterol (r = 0.54, P = 0.04) and negatively to serum triglyceride (r = -0.69, P = 0.005) and to total cholesterol (r = -0.81, P = 0.0003) concentrations. CONCLUSIONS: The present results demonstrate for the first time that there is a negative relationship between directly measured whole-blood viscosity and insulin sensitivity as a part of the insulin-resistance syndrome. Whole-blood viscosity contributes to the total peripheral resistance, and these results support the hypothesis that insulin resistance has a hemodynamic basis.

Adult↗
PubMed1987

Whole blood viscosity during normal pregnancy.

In a serial study the changes in whole blood viscosity at different shear rates and its major determinants were determined in 24 healthy women with normal pregnancies. Whole blood viscosity and plasma viscosity were measured with a rotational viscometer. Red cell aggregation was measured by syllectometry. During normal pregnancy we found a decrease in whole blood viscosity at all shear rates until 29 weeks gestation, followed by a smaller increase between 30 and 37 weeks, which was most pronounced at higher shear rates, especially in nulliparae. The changes in whole blood viscosity were to a great extent determined by the changes in haematocrit and plasma viscosity. Haematocrit was more important for whole blood viscosity at lower shear rates, while plasma viscosity had more influence on high shear blood viscosity. The continuous increase in red cell aggregation had no demonstrable influence on low shear blood viscosity as measured in vitro in a rotational viscometer.

Blood Viscosity↗
PubMed1992

Influence of experimentally elevated blood viscosity on the auditory nerve-brainstem evoked response and threshold.

Blood viscosity, due to its effect on blood flow, is one of the determinants of oxygen delivery. Therefore the influence of elevated blood viscosity on hearing was studied in rats using the auditory brainstem response (ABR) threshold, wave 1 latency, brainstem transmission time (BTT) and wave 1/4 amplitude ratio. Whole blood viscosity (WBV) was elevated by 15-21% in two different ways: elevating the hematocrit (Polycythemia) by acclimation in a hypobaric chamber, or elevating the plasma viscosity by infusing a solution of Polyvinylpyrrolidone-360 (PVP). ABR was recorded before and 24 h after the blood viscosity was elevated, so that each rat served as its own control. Paired t-tests showed that there was no statistically significant difference in the ABR parameters in each of the groups as a consequence of blood viscosity elevation. In conclusion, the elevation of WBV to this degree for this duration, using two different techniques had no effect either on the function of the auditory nerve and the more peripheral sites, or on the central auditory pathway as studied by ABR.

Analysis of Variance↗
PubMed1994

[Significance of perioperative elevation of blood viscosity in patients with esophageal or cardiac carcinoma].

The blood viscosity of 21 patients with esophageal or cardiac carcinoma during preoperative period was measured and compared with that of 25 healthy persons. The results indicate that the blood viscosity in patients is higher than that in the control group (P < 0.001) immediately and one day after operation. Elevation of blood viscosity is not only related to myocardial infarction, but also may be one of the causes for the poor therapeutic effect in patients with carcinomas. It is suggested that proper measures should be taken to control the elevating blood viscosity in patients, especially the elderly ones during the perioperative period. Colloid fluid which is believed to increase blood viscosity should be avoided within the first two days after operation to prevent cardiac complications.

Aged↗
PubMed1975

Blood viscosity and cardiac output in acute experimental anemia.

The significance of blood viscosity alterations during anemia was evaluated in dogs under morphine-chloralose anesthesia. In group I, anemia (mean hematocrit 18.1 +/- 1.3 vol %) was produced by exchange transfusion with clinical dextran (avg mol wt 70,000). In group II, anemia was produced (mean hematocrit 19.9 +/- 0.88 vol %) with 500,000 molecular weight dextran, thus preventing the decrease in blood viscosity in group I. The cardiac output increase in group I (93.4%) with low-viscosity anemia was significantly greater than in group II (43.3%) with unchanged blood viscosity. Group III animals were transfused with a clinical dextran-red cell mixture, and group IV animals received a 500,000 mol wt dextran-red cell mixture. In group III, blood viscosity and cardiac output did not change. In group IV, blood viscosity rose and cardiac output fell significantly. The results suggest that a change in blood viscosity exerts a significant effect upon cardiac output, especially during acute dextran-exchange anemia.

Anemia↗