Changes In Whole Blood Viscosity Research Articles

Sex-differential downregulation of methotrexate on plasma viscosity and whole blood viscosity in psoriasis.

Psoriasis is associated with an increased risk for cardiovascular disease (CVD). Methotrexate (MTX) is often used as a first-line system therapy and there is a need to determine its effect on whole blood viscosity (WBV) and plasma viscosity (PV) in psoriasis.METHODSA prospective, single-center, interventional study with a total of 111 psoriatic patients who received MTX therapy from October 22, 2018, to December 28, 2019, and 111 age- and sex-matched healthy controls. Changes in WBV, PV, blood counts, liver and renal function were evaluated.RESULTSPsoriatic patients had significantly higher levels of WBV and relative viscosity (RV) at low shear rate (LSR), erythrocyte aggregation index (EAI), and PV than sex and age-matched healthy controls. PV was positively correlated with erythrocyte sedimentation rate (ESR), ESR was positively correlated with high sensitive C-reactive protein (hCRP). But only hCRP was positively associated with psoriasis area severity index (PASI) score. MTX significantly decreased the levels of PV, ESR, hCRP, and blood pressure (BP) in male patients, and the level of WBV in female patients. Sex-specific downregulation of MTX on WBV, PV, hCRP, and BP, indicating that the effect of MTX on the risk of cardiovascular disease was related with sex.

Intraoperative changes in whole-blood viscosity in patients undergoing robot-assisted laparoscopic prostatectomy in the steep Trendelenburg position with pneumoperitoneum: a prospective nonrandomized observational cohort study

BackgroundThe aim of this study was to investigate the effect of the steep Trendelenburg position (STP) with pneumoperitoneum on whole-blood viscosity (WBV) in patients undergoing robot-assisted laparoscopic prostatectomy (RALP). The study also analyzed the associations of clinical patient-specific and time-dependent variables with WBV and recorded postoperative outcomes.MethodsFifty-eight adult male patients (ASA physical status of I or II) undergoing elective RALP were prospectively analyzed in this study. WBV was intraoperatively measured three times: at the beginning of surgery in the supine position without pneumoperitoneum; after 30 min in the STP with pneumoperitoneum; and at the end of surgery in the supine position without pneumoperitoneum. The WBV at a high shear rate (300 s− 1) was recorded as systolic blood viscosity (SBV) and that at a low shear rate (5 s− 1) was recorded as diastolic blood viscosity (DBV). Systolic blood hyperviscosity was defined as > 13.0 cP at 300 s− 1 and diastolic blood hyperviscosity was defined as > 4.1 cP at 5 s− 1.ResultsThe WBV and incidences of systolic and diastolic blood hyperviscosity significantly increased from the supine position without pneumoperitoneum to the STP with pneumoperitoneum. When RALP was performed in the STP with pneumoperitoneum, 12 patients (27.3%) who had normal SBV at the beginning of surgery and 11 patients (26.8%) who had normal DBV at the beginning of surgery developed new systolic and diastolic blood hyperviscosity, respectively. The degree of increase in WBV after positioning with the STP and pneumoperitoneum was higher in the patients with hyperviscosity than in those without hyperviscosity at the beginning of surgery. Higher preoperative body mass index (BMI) and hematocrit level were associated with the development of both systolic and diastolic blood hyperviscosity in the STP with pneumoperitoneum. All patients were postoperatively discharged without fatal complications.ConclusionsChanges in surgical position may influence WBV, and higher preoperative BMI and hematocrit level are independent factors associated with the risk of hyperviscosity during RALP in the STP with pneumoperitoneum.Trial registrationClinical Research Information Service, Republic of Korea, approval number: KCT0003295 on October 25, 2018.

Patient-Specific Computational Fluid Dynamics in Ruptured Posterior Communicating Aneurysms Using Measured Non-Newtonian Viscosity : A Preliminary Study.

ObjectiveThe objective of this study was to analyze patient-specific blood flow in ruptured aneurysms using obtained non-Newtonian viscosity and to observe associated hemodynamic features and morphological effects. MethodsFive patients with acute subarachnoid hemorrhage caused by ruptured posterior communicating artery aneurysms were included in the study. Patients’ blood samples were measured immediately after enrollment. Computational fluid dynamics (CFD) was conducted to evaluate viscosity distributions and wall shear stress (WSS) distributions using a patient-specific geometric model and shear-thinning viscosity properties. ResultsSubstantial viscosity change was found at the dome of the aneurysms studied when applying non-Newtonian blood viscosity measured at peak-systole and end-diastole. The maximal WSS of the non-Newtonian model on an aneurysm at peaksystole was approximately 16% lower compared to Newtonian fluid, and most of the hemodynamic features of Newtonian flow at the aneurysms were higher, except for minimal WSS value. However, the differences between the Newtonian and non-Newtonian flow were not statistically significant. Rupture point of an aneurysm showed low WSS regardless of Newtonian or non-Newtonian CFD analyses. ConclusionBy using measured non-Newtonian viscosity and geometry on patient-specific CFD analysis, morphologic differences in hemodynamic features, such as changes in whole blood viscosity and WSS, were observed. Therefore, measured non-Newtonian viscosity might be possibly useful to obtain patient-specific hemodynamic and morphologic result.

Changes in whole blood viscosity during hemodialysis and mortality in patients with end-stage renal disease.

Whole blood viscosity (WBV) plays a role in hemorheology and is determined by many factors such as red blood cell factors, plasma protein and blood volume. As WBV changes during hemodialysis, mortality may be due to changes in WBV in patients on hemodialysis. However, there are few prospective data on the relationship between changes in WBV and overall mortality in dialysis patients. We tried to investigate the correlations between values of WBV at variable shear rates before and after hemodialysis and overall or atherosclerosis-related mortality in patients with end-stage kidney disease.Forty-three patients receiving hemodialysis were enrolled in this study. In this 5.8-year prospective observational study, analyses of the effects of WBV at shear rates of 300 s-1 (systolic WBV; SBV), 5 s-1 (diastolic WBV5; DBV5), and 1 s-1 (diastolic WBV1; DBV1) during dialysis on all-cause and atherosclerotic mortality was performed.Among a total of 43 patients, 27 (62.7%) died over the course of the study. Thirteen deaths were caused by atherosclerotic events. A high degree of change in WBV at shear rates of 300 s-1 and 5 s-1 during hemodialysis (ΔSBV, ΔDBV5) was positively correlated with overall mortality (HR = 4.688, 95% confidence interval [CI], 1.269-17.319, p = 0.020; HR = 3.941, 95% CI, 1.057-14.701, p = 0.041, respectively). A high degree of change in diastolic blood pressure (ΔDBP) during hemodialysis was also positively correlated with overall mortality (HR = 3.035, 95% CI, 1.039-8.867, p = 0.042). However, comparative analysis between WBV at shear rates of 300 s-1, 5 s-1, and 1 s-1 and overall mortality did not reveal any significant relationships. Kaplan-Meier analysis revealed that the all-cause mortality was significantly higher in patients from a high degree of change of WBV at shear rates of 300 s-1, compared to those from the moderate or low degree of changes of WBV at shear rates of 300 s-1 (p = 0.020, log-rank test). Survival rate in high ΔDBP was lower than that of moderate or low ΔDBP group in Kaplan-Meier survival analysis (p = 0.004, log-rank test).Our data showed that a high degree of change in WBV at variable shear rates during hemodialysis might impact overall survival in patients with end-stage kidney disease. However, large-scale studies to evaluate the relationship of WBV with overall mortality and atherosclerotic mortality will be needed.

Absence of association between whole blood viscosity and delirium after cardiac surgery: a case-controlled study.

BackgroundDelirium after cardiothoracic surgery is common and associated with impaired outcomes. Although several mechanisms have been proposed (including changes in cerebral perfusion), the pathophysiology of postoperative delirium remains unclear. Blood viscosity is related to cerebral perfusion and thereby might contribute to the development of delirium after cardiothoracic surgery. The aim of this study was to investigate whether whole blood viscosity differs between cardiothoracic surgery patients with and without delirium.MethodsIn this observational study postoperative whole blood viscosity of patients that developed delirium (cases) were compared with non-delirious cardiothoracic surgery patients (controls). Cases were matched with the controls, yielding a 1:4 case–control study. Serial hematocrit, fibrinogen, and whole blood viscosity were determined pre-operatively and at each postoperative day. Delirium was assessed using the validated Confusion Assessment Method for the Intensive Care Unit or Delirium Screening Observation scale.ResultsIn total 80 cardiothoracic surgery patients were screened of whom 12 delirious and 48 matched non-delirious patients were included. No significant difference was found between both groups in fibrinogen (p = 0.36), hematocrit (p = 0.23) and the area under curve of the whole blood viscosity between shear rates 0.02 and 50 s-1 (p = 0.80) or between shear rates 0.02 and 5 s-1 (p = 0.78).ConclusionIn this case control study in cardiothoracic surgery patients changes in whole blood viscosity were not associated with the development of delirium.

Effects of hematocrit and red blood cell–independent viscosity on canine thromboelastographic tracings

It is well established that hematocrit (Hct) influences whole blood thromboelastography (TEG) tracings. Previous studies showed hypercoagulable TEG tracings in anemic patients despite clinical expectations that anemia often prolongs bleeding. TEG is a viscoelastic assessment of clot kinetics, and Hct is the main determinant of whole blood viscosity. TEG changes in anemia may be an in vitro artifact due to Hct effect on blood viscosity rather than true in vivo changes in hemostasis. The effect of changes in whole blood viscosity on TEG independent of Hct is not well understood. Twenty-one blood samples from seven dogs were manipulated to produce one of three Hct conditions (45, 20, and 10%). Each was tested in two situations: viscosity adjusted to normal by adding alginate (ALG) or dilution with equal volume of saline (SAL). Both samples were analyzed with TEG simultaneously. Twenty percent Hct plus ALG and 10% Hct plus ALG were significantly more viscous than their SAL counterparts (p=0.0156). Ten percent Hct plus SAL, 20% Hct plus SAL, and 45% Hct plus SAL all had different viscosities (p=0.006). Twenty percent Hct plus SAL and 10% Hct plus SAL had significantly shorter K and higher angle, MA, and G compared to their ALG counterparts as well as 45% Hct plus SAL (p<0.05). ALG samples with low Hct, normal viscosity showed hypocoagulable tracings, whereas SAL samples with low Hct, low viscosity showed hypercoagulable tracings. TEG variables are influenced by whole blood viscosity altered with ALG, independently of Hct.

Effects of the coadministration of Huatuo Zaizao pills and aspirin on hemorrheology and blood coagulation in rabbits

Huatuo Zaizao pills (HT) is a compound used in Chinese medicine for the treatment of cerebrovascular diseases. The present study aimed to investigate the effects of the coadministration of HT and aspirin on hemorrheology and blood coagulation in rabbits. Rabbits were randomly divided into the control, HT, aspirin and HT plus aspirin groups (n=5 animals per group). The rabbits were treated with HT at a dose of 1 g/kg, aspirin at a dose of 5 mg/kg or HT (1 g/kg) plus aspirin (5 mg/kg) administered by gavage. Blood samples were collected prior to treatment and at 2 or 4 h after treatment. Compared to the control group, there were no significant changes in whole blood viscosity (WBV), plasma viscosity (PV), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and fibrinogen content (FIB) in the HT or the aspirin group. Coadministration of HT and aspirin prolonged APTT, PT and TT and decreased WBV and PV. The findings indicated that coadministration of HT and aspirin exerted a more potent effect on hemorrheology and blood coagulation, compared to each agent administered alone, and may be a novel approach to the prevention and treatment of hemorrheological disorders.

Changes in Whole Blood Viscosity at Low Shear Rates Correlate with Intravascular Volume Changes during Hemodialysis

Elevated blood viscosity has been shown to be independently correlated with cardiovascular risk factors and associated with increased risk of major cardiovascular events, including death and acute myocardial infarction. The aim of the present study was to investigate changes in whole blood viscosity (WBV) at shear rates of 1, 5, and 300 s-1 before and after hemodialysis in patients with end-stage renal disease (ESRD). We also examined the relationship between the changes of WBV and intravascular blood volume. 43 patients with ESRD receiving maintenance hemodialysis were enrolled. WBV was measured using a scanning capillary tube viscometer pre- and post-dialysis to quantify dialytic viscosity surges. Body weight, blood pressure, and hematocrit were also measured before and after hemodialysis, as was the fluid removed during the session. Hemodialysis had a 3 times greater impact on the low-shear WBV at a shear rate of 1 s-1 (i.e., 44.1% change) than on the high-shear WBV at a shear rate of 300 s-1 (i.e., 15.9% change). Changes in the low-shear WBV obtained at shear rates of 1 and 5 s-1 during hemodialysis were significantly correlated with changes in hematocrit. The intravascular blood volume reduction during hemodialysis was positively correlated with the changes in both high-shear and low-shear WBVs. These results suggest that the WBV parameter may hold additional information beyond hemoconcentration. Further research is needed to evaluate the relationship between low-shear WBV surges and increased morbidity in the patient population with ESRD.

The effect of hemodialysis ultrafiltration on changes in whole blood viscosity

Increased whole blood viscosity (WBV) can be injurious to the vascular endothelium and increase the risk of atherothrombotic events. This study examined the effect of hemodialysis ultrafiltration (UF) on WBV, with a focus on high vs. low-volume UF patients. In stable hemodialysis patients, blood was drawn for hematocrit (Hct) and WBV at the start, midpoint, and at the end of dialysis. For analysis, patients were divided into high UF (≥2700 mL) or low UF (<2700 mL) groups. A total of 59 patients completed the study. Mean Hct increased during dialysis in both groups. The intradialytic increase in Hct was significantly greater in the high vs. the low UF group (3.2% vs. 1.28%, P = 0.01), with a significantly higher end-dialysis Hct in the high UF group (40.5% vs. 38%, P = 0.02). At the end of dialysis, both high shear rate WBV (P < 0.01) and low shear rate WBV (P < 0.01) were significantly higher in the high UF compared with the low UF group. There was an approximately two-fold greater increase in high shear rate (P < 0.01) and low shear rate (P = 0.01) WBV during dialysis in high vs. low UF groups. The increase in high shear rate WBV during dialysis was significantly correlated with an increase in Hct (R(2) = 0.63, P < 0.01). We found that hemodialysis UF causes a surge in WBV. The surge was of greater magnitude in high than in low UF patients.

Effect of Huahongjiangxian decoction on hemorheology in patients with hypertension

Objective To observe the effect of Huahongjiangxiantang on hemorheology and plasma fibrinogen (FIB).Methods 100 patients with hypertension were randomly divided into two groups:the treatment group ( n=50) which were treated with Huahongjiangxian-tang,and the control group( n=50)were treated with Aspirin.Hemorheology and plasma fibrin were detected before and after treatment for 8 weeks.Results After 8 weeks treatment,there were significant depressions in whole blood viscosity(low shear rate),RBC deformability index and RBC aggregation index( P＜0.01 ),and better than the control group( P ＜0.05 ).There were significant changes in whole blood viscosity ( high shear rate),plasma viscosity,RBC rigidity index and plasma fibrin ( P ＜ 0.05 ).A number of indicators declined significantly in control group ( P ＜ 0.05 );The rate of platelet aggregation to improve the situation in the control group was better than that of the treatment group,but there was no statistical significance.Conclusion Huahongjiangxiantang can effectively reduce blood viscosity in patients with hypertension and improve the body's red blood cell function and fibrinolysis,benefit to the prevention and treatment of atherosclerosis and reduce the occurrence of thrombotic events. Key words: Hypertension; Huahongjiangxian decoction; Hemorheology

Common carotid artery hemodynamic factors in patients with cerebral infarctions

The aim of the study was to investigate the changes of the common carotid local hemodynamic factors like wall shear stress and tensile forces in 16 patients with chronic unilateral cerebral infarctions (CUCI), 58 patients with risk factors (RF) for cerebrovascular disease (CVD) and 25 healthy control subjects. The blood flow velocities (BFV), the internal diameters (D) and the vessel wall intima-media thickness (IMT) in the common carotid arteries (CCA) were recorded with color duplex sonography. Systolic (SBP) and diastolic (DBP) blood pressure were measured and mean blood pressure (MBP) was calculated by the formula of Wiggers. Whole blood viscosity (WBV) at the shear rate of 94.5 s-1 was measured on the day of the Doppler ultrasound examination with a rotational viscometer Contraves Low Shear 30. Wall shear stress (WSS), the circumferential wall tension (T) and the tensile stress tau were calculated. The main RF in the patients' groups were hypertension and hyperlipidemia. The SBP, WBV and IMT were significantly increased in the patients with UCI and RF for CVD in comparison to controls. Lower systolic WSS and tau and higher T were established in the patients with UCI. The IMT correlated with WSS and tau. The study confirms the complex influence of the changes in WBV and blood pressure for the development of carotid atherosclerosis.

Effect of Hemodialysis on Whole Blood Viscosity

The purpose of the present study was to examine the effect of hemodialysis procedures on the hemoconcentration status of end-stage renal disease (ESRD) patients. We measured whole blood viscosity (WBV) of 30 ESRD patients using a scanning-capillary-tube viscometer before and after hemodialysis. The blood sample size required for WBV measurements was approximately 3 mL. Pre-dialysis specimens for viscosity measurements were obtained via the fistula needle or Perma catheter prior to initiating hemodialysis, and post-dialysis specimens were drawn from the arterial sample port of the hemodialysis line 3.5 hours after initiation of dialysis treatment. Changes in WBV were measured at high and low shear rates: 80% of patients showed an increased high shear viscosity, whereas 73% of patients demonstrated an increased low shear viscosity. The actual percentage increase in WBV observed after hemodialysis at high and low shear rate ranges varied broadly in the 30 patients. The observed increase in the WBV of ESRD patients over hemodialysis procedures indicates that a segment of patients experience increased flow resistance, particularly at the microcirculatory level. In addition, for the segment of patients experiencing marked increases in WBV during hemodialysis, the vessel wall at the dialysis fistula is exposed to blood with a higher viscosity than at the beginning of the process. The higher blood viscosity at the dialysis fistula is directly related to increased kinetic force and shear stress on the vessel wall, which may be playing a role in increasing the risk of stenosis.

Comparative analysis of chosen hemorheological methods in a group of stroke patients

Blood viscosity is one of the most important factors determining the blood flow. In this report we describe changes in whole blood viscosity in a group of patients after stroke measured as a function of the shear rate (flow curve) and also blood visco-elastic properties measured using oscillatory methods (dynamical mechanical analysis). The principle of the latter method is based on the measurement of the amplitude and phase of the sample oscillations driven by controlled harmonic strain. All measurements were performed by means of a rotary-oscillatory rheometer Contraves LS-40.

Effects of glucose in drinking water on the changes in whole blood viscosity and plasma osmolality of broiler chickens during high temperature exposure

This study was conducted to elucidate the influence of glucose in drinking water on whole blood viscosity and plasma osmolality of broilers during high temperature exposure. Two groups of birds, which had ad libitum access to either a 4% glucose-water solution (Group G) or tap water (Group W), were exposed simultaneously to 30 C from 0300 h for 12 h each day for 3 d. During the experimental period, Group G birds had greater metabolic energy intake and body weight gain than Group W. Hematocrit and whole blood viscosity decreased significantly at 30 C compared to controls at 20 C in Group W, whereas, in Group G, no changes were found for these two variables. Plasma osmolality also decreased at 30 C compared to 20 C in Group W, whereas no change was noted in this variable in Group G. However, at 20 C, plasma osmolality was significantly higher in Group W than in Group G, but no difference was observed between the two groups at 30 C. Plasma protein concentration decreased during exposure to 30 C in both groups, but the decrease tended to be greater in Group W than in Group G. These results suggest that glucose intake may alleviate the influence of heat stress on whole blood viscosity and plasma osmolality.

Blood viscosity measurements are not sensitive enough to detect changes in erythrocyte deformability in cyclosporin-treated patients and its subsequent reversal with fish and corn oil

ABSTRACf Rheological factors might be involved in the adverse effects of cyclosporin therapy. The use of cyclosporin is associated with a lower erythrocyte deformability. In order to investigate whether a decreased erythrocyte deformability was accompanied by changes in whole blood viscosity, measurements were done in patients in which a lower erythrocyte dcformability was found. Twenty nine stable renal transplant recipients, ten receiving cyclosporin, ten cyclosporin-prednisolone and nine azathioprin-prednisolone were supplemented in a double blind cross-over study with fish oil and corn oil for a period of four months each. No difference was found in whole blood viscosity between the patient groups with different immunosuppressive regimens, which means whole blood viscosity measurements did not detect decreased erythrocyte deformability. No decrease in whole blood viscosity was found in renal transplant recipients after supplementation of fish oil and com oil, while erythrocyte deformability increased in the cyclosporin-treated patients. Neither were plasma viscosity and the fibrinogen level influenced by fish or com oil. Whole blood and plasma viscosity are not influenced by the use of cyclosporin. It is concluded that whole blood viscosity measurements are not sufficient to detect changes in erythrocyte deformability and therefore separate measurements of erythrocyte deformability are indicated.

Hematocrit and Cardiovascular Risk Factors among Elderly Men and Women

Changes in whole blood viscosity associated with hematocrit could be one of the pathways along which the cardiovascular disease (CVD) risk factors affect these diseases. Therefore, we studied in a nationwide survey comprising 514 apparently healthy Dutch elderly men and women aged 65-79 the possibility of any association between hematocrit and CVD risk factors (tobacco smoking, serum cholesterol, body mass index and blood pressure). Among men, diastolic blood pressure and total serum cholesterol were positively associated with hematocrit in both bivariate and multivariate regression analysis, whereas positive associations of hematocrit with body mass index and smoking were only significant (p < 0.05) in bivariate analysis. Among women, hematocrit was positively associated with body mass index and smoking. Except for smoking, which was associated with the mean corpuscular volume of the erythrocytes, hematocrit was positively correlated with hemoglobin and the number of erythrocytes. It is concluded that hemorrheological aspects should be considered when studying CVD among elderly people.

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.

Effect of pentoxifylline on microvascular blood flow velocity.

Pentoxifylline (PF), known to increase red blood cell (RBC) deformability, has recently attracted much attention because of its possible effect of reducing capillary resistance. There has been practically no reliable demonstration of an increase in capillary blood flow by this drug. This study was intended to examine the effect of PF and hence deformability changes on microvascular hemodynamics and the rheological mechanisms underlying such an effect. Mesentery microvessels of 15 rats were subjected to intravital microscopic observation under transillumination. Capillary blood flow was measured using a newly developed 2-channel sample-hold scanner incorporated into a video display system. Changes in whole blood viscosity were also measured in order to investigate hemorheological changes. It was found that a significant increase in capillary blood flow (as much as 140%) was brought about by PF administration. The increase in blood flow was particularly remarkable in capillaries of about 13 microns in diameter, while whole blood viscosity measured in vitro showed a reduction of 40% at most. In view of these results and the reported effect of PF on increasing the RBC deformability, increased capillary blood flow can be attributed to the increased RBC deformability.

Influence of blood viscosity on blood flow and the effect of low molecular weight dextran.

Changes in whole blood viscosity are related to changes in the leg blood flow during infusions of low-molecular-weight dextran and Hartmann's solution. A close inverse correlation exists between changes in viscosity and blood flow, the change in blood flow being about three times greater than the change in blood viscosity. The dextran and Hartmann's solution had a similar effect on blood viscosity and blood flow if corrections are made for the difference in haemodilution.