Scanning Capillary Tube Viscometer Research Articles

Association of Cerebral Artery Stenosis with Blood Viscosity in Patients with Transient Ischemic Attack

Background: Blood viscosity (BV) reflects blood thickness and stickiness, crucial for vascular health. Elevated BV is linked to stroke risk factors, suggesting a role in transient ischemic attacks (TIA).Methods: This retrospective observational study investigated BV levels in TIA patients with and without cerebral artery stenosis. Patients admitted within 24 hours of symptom onset between March 2017 and December 2021 were included. Baseline characteristics, including demographics and vascular risk factors, were assessed. BV measurements were obtained within 24 hours of symptom onset using a scanning capillary-tube viscometer. Patients were categorized into TIA groups based on the presence or absence of cerebral artery stenosis.Results: Of the 153 TIA patients screened, 86 were included for analysis. The mean age was 62.6 years, with a predominance of hypertension (59%) and dyslipidemia (45%). Patients with cerebral artery stenosis (TIA-AT group, n=56) exhibited significantly higher BV levels within 24 hours of symptom onset compared to those without stenosis (TIA-E group, n=30). This finding suggests a potential link between underlying pathophysiological mechanisms of TIA and BV levels.Conclusion: Despite the limitations of a single-center, retrospective study, this research suggests that there is evidence of increased blood viscosity in patients with TIA who have cerebral artery stenosis, implying that blood viscosity may play a role in the pathophysiology of TIA. Further research involving larger cohorts is warranted to elucidate the precise mechanisms linking BV to TIA and to validate its utility as a prognostic marker and therapeutic target in TIA management.

Association between blood viscosity and early neurological deterioration in lacunar infarction.

BackgroundUnderstanding the factors related to early neurologic deterioration (END) is crucial in the management of patients with lacunar infarction. Blood viscosity is a significant factor for microvascular perfusion. We investigated the association between blood viscosity and occurrence of END in lacunar infarction.MethodsWe included consecutive patients admitted for lacunar infarction within 72 h from symptoms onset. END was defined as an increase in the National Institute of Health Stroke Scale (NIHSS) score ≥2 within 24 h of admission. Viscosity was measured within 24 h of hospitalization with a scanning capillary tube viscometer. Viscosity measured at a shear rate of 300 s−1 was defined as systolic blood viscosity (SBV), whereas that measured at a shear rate of 5 s−1 as diastolic blood viscosity (DBV).ResultsOf the 178 patients included (median age, 65.5; interquartile range [IQR], 56.0, 76.0], END occurred in 33 (18.5%). DBV was significantly higher in patients with END than those without END (13.3 mPa·s [IQR 11.8, 16.0] vs. 12.3 mPa·s [IQR11.0, 13.5]; P = 0.023). In the multivariate analysis, DBV was independently associated with the occurrence of END (odds ratio 1.17; 95% confidence interval 1.01–1.36; P = 0.043). Subgroup analysis showed no heterogeneity in the effect of viscosity on the occurrence of END.ConclusionsBlood viscosity at a low shear rate (DBV) was associated with the occurrence of END in patients with lacunar infarction. Blood rheology may be important in pathophysiology of END in patients with lacunar infarction.

Whole blood viscosity is associated with extrahepatic metastases and survival in patients with hepatocellular carcinoma.

Whole blood viscosity (WBV) is increased in cancer patients and associated with the advanced stage with systemic metastases. However, relevance of WBV in hepatocellular carcinoma (HCC) remains unclear. This pilot study included a discovery cohort of 148 treatment-naïve HCC patients with preserved liver function, and a validation cohort of 33 treatment-experienced HCC patients with nivolumab. Systolic and diastolic WBV was measured using an automated scanning capillary tube viscometer at diagnosis or before the nivolumab treatment. Extrahepatic metastases were observed in 15 treatment-naïve patients (11.3%) at diagnosis. Portal vein tumor thrombosis (PVTT), tumor size, number of tumors, and systolic/diastolic WBV were factors associated with extrahepatic metastases. Systolic WBV and diastolic WBV were significantly increased in patients with metastases compared with patients without metastases. Multivariate logistic regression showed that high diastolic WBV > 16 cP was an independent factor associated with metastases. Notably, patients who developed extrahepatic metastases during the observation period among patients without metastases at diagnosis had higher diastolic WBV initially. Patients with high diastolic WBV had poor survival, and multivariate Cox regression analyses showed high diastolic WBV was an independent risk factor for poor survival with the Child-Pugh B7 and PVTT. High diastolic WBV also predicted poor survival in patients with low alpha-fetoprotein (AFP) and proteins induced by vitamin K antagonist-II (PIVKA-II) levels. In 33 nivolumab-treated patients, high diastolic WBV before the treatment was also tended to be associated with overall and progression-free survival. Our study is the first in which high WBV is associated with the distant metastases and survival in patients with HCC, but future prospective, large cohort studies are necessary to validate the results.

Association of blood viscosity with first-pass reperfusion in mechanical thrombectomy for acute ischemic stroke.

Elevated blood viscosity has been reported as a risk factor for cerebrovascular disease. The relationship between blood viscosity and outcomes of mechanical thrombectomy (MT) for large artery occlusion (LAO) were investigated in the present study. A total of 238 patients were enrolled and systolic blood viscosity (SBV) and diastolic blood viscosity (DBV) were measured using the scanning capillary tube viscometer. Receiver operating characteristic (ROC) analysis was performed to specify the association of viscosity with the first-pass reperfusion (FPR). Multivariable and regression analyses were performed to evaluate the relationship of viscosity with FPR and various variables. Based on ROC analysis, the best DBV cutoff value was 10.55 (cP). In multivariable analysis, high DBV was associated with FPR failure (odds ratio 2.82, 95% confidence interval 1.64-4.22; p = 0.001). Increased DVB could be associated with elevated SBV, hematocrit level, and blood urea nitrogen/creatinine ratio (p = <0.001, 0.004, and 0.002, respectively). Elevated DBV was associated with FPR failure. Patients with high DBV had longer thrombus length and required more stent passages than patients with low DBV.

Prior antithrombotic use is significantly associated with decreased blood viscosity within 24 hours of symptom onset in patients with acute ischemic stroke

Background Blood viscosity (BV) is the intrinsic resistance of blood to flow and is a measure of blood stickiness. Several clinical and epidemiologic studies have demonstrated an association between BV and the occurrence of major thromboembolic events. Although BV is significantly higher in cases of lacunar or cardioembolic strokes, its relationship with demographic and laboratory parameters during the acute stage of ischemic stroke is unknown. We investigated the relationship between baseline characteristics of acute ischemic stroke and BV within 24 hours of symptom onset in patients with acute ischemic stroke. Methods We enrolled patients aged 40 years or older with documented histories of ischemic stroke or transient ischemic attack within 24 hours of symptom onset. A scanning capillary-tube viscometer was used to assess whole BV. Results The mean age was 69.6±12.03 years and 44.4% of the patients were female. Of 189 patients, 68.3% had a history of hypertension; 27%, diabetes; 42.9%, hypercholesterolemia; 3.7%, coronary artery disease; and 18%, stroke. Additionally, 40.7% were current smokers. Sixty-one patients (32.3%) were regularly taking antithrombotics. Multiple linear regression analysis revealed that hematocrit was positively corelated with increased BV and prior antithrombotic use was corelated with decreased BV. Hematocrit-adjusted partial correlation demonstrated that prior antithrombotic use was significantly associated with decreased BV. Conclusion Prior antithrombotic use is significantly associated with decreased BV within 24 hours of symptom onset in patients with acute ischemic stroke. Our findings indicate that antithrombotic medications may change the hemorheological profile in these patients. Key Words: Aspirin; Blood viscosity; Hematocrit; Blood platelets; Stroke

Elevated blood viscosity is associated with cerebral small vessel disease in patients with acute ischemic stroke

BackgroundIncreased level of blood viscosity, which is one of the major factors that determine blood rheology, has been reported as a risk factor or predictor for cerebrovascular events. We investigated how blood viscosity is associated with acute stroke and chronic radiological manifestations of cerebral small vessel disease, and how blood viscosity changes after stroke.MethodsWe prospectively enrolled consecutive patients with acute ischemic stroke. Whole blood viscosities at a low or high shear rate were measured using a scanning capillary tube viscometer, and were referred to as diastolic blood viscosity (DBV) and systolic blood viscosity (SBV), respectively. Correlations between blood viscosity and acute stroke etiology or chronic radiological manifestations of cerebral small vessel disease were investigated. The temporal profiles of blood viscosity at the onset of stroke and follow-up at 1 and 5 weeks were investigated.ResultsOf the 127 patients admitted with acute ischemic stroke, 63 patients were included in the final analyses. DBV at the onset of stroke was significantly higher in small artery occlusion (SAO) stroke than in other stroke subtypes (p = 0.037). DBV showed a significant positive correlation with the number of chronic lacunes (r = 0.274, p = 0.030). The temporal profiles of DBV in SAO stroke showed a transient decrease due to the hydration therapy after 1 week and recurrent elevation at 5 week follow-up (p = 0.009).ConclusionsOur study suggests that elevated DBV may play a role in the development of acute and chronic manifestations of cerebral small vessel disease. The recurring elevation of DBV in SAO stroke indicates that sufficient hydration and additional therapeutic interventions targeting blood viscosity may be needed in patients with SAO stroke.

Hemorheological Alteration in Patients Clinically Diagnosed with Chronic Liver Diseases.

Since liver function is changed by chronic liver diseases, chronic liver disease can lead to different hemorheological alterations during the course of the progression. This study aims to compare alterations in whole blood viscosity in patients with chronic liver disease, focusing on the gender effect. Chronic liver diseases were classified into three categories by patient’s history, serologic markers, and radiologic findings: nonalcoholic fatty liver disease (NAFLD) (n = 63), chronic viral hepatitis B and C (n = 50), and liver cirrhosis (LC) (n = 35). Whole blood viscosity was measured by automated scanning capillary tube viscometer, while liver stiffness was measured by transient elastography using FibroScan®. Both systolic and diastolic whole blood viscosities were significantly lower in patients with LC than NAFLD and chronic viral hepatitis (P < 0.001) in male patients, but not in female patients. In correlation analysis, there were inverse relationships between both systolic and diastolic whole blood viscosity and liver stiffness (systolic: r = −0.25, diastolic: r = −0.22). Whole blood viscosity was significantly lower in male patients with LC than NAFLD or chronic viral hepatitis. Our data suggest that whole blood viscosity test can become a useful tool for classifying chronic liver disease and determining the prognosis for different types of chronic liver diseases.

Measuring Blood Viscosity in Normal Tension Glaucoma Patients

Purpose: Non-intraocular pressure (IOP) factors such as vascular factors have been identified as contributing to normal tension glaucoma. However, there is not an established range of haemorheological factors considered normal, nor are there standardized tests. In this study, we investigated differences in blood viscosity and haemorheological parameters between patients with normal tension glaucoma (NTG) and normal controls using a new instrument called the BVD-RO1 (BIO-VISCO. Inc., Jeonju, Korea). Methods: Twenty patients with NTG and 20 age-matched normal controls were included in the study. Haemorheological parameters of the venous blood samples, including blood viscosity at the shear rates of 300 (high shear rate) and 1 (low shear rate) s−1 were measured using an automated scanning capillary tube viscometer. Results: More hematocrit concentration was detected in the NTG group than in the control group (p < 0.05). Furthermore, higher blood viscosities at the high (p < 0.01) and low (p < 0.01) shear rates were found in the NTG group. Conclusions: The NTG patients differed in blood viscosity with the control group. This may signify the importance of hemodynamic factors in the pathogenesis of NTG. J Korean Ophthalmol Soc 2015;56(5):753-758

Blood Viscosity in Subcortical Vascular Mild Cognitive Impairment with versus without Cerebral Amyloid Burden

Subcortical vascular dementia (SVaD) is a common form of dementia, attributed to ischemic small-vessel disease. Blood viscosity (BV) may contribute to the pathophysiology of SVaD. However, SVaD patients with coexisting amyloid deposition may not show differences in BV because their small-vessel disease may result from amyloid angiopathy independently of BV. We, therefore, hypothesized that BV might show different changes compared with control subjects in subcortical vascular mild cognitive impairment (svMCI) that refers to the prodromal stage of SVaD according to cerebral amyloid burden detected by the [(11)C] Pittsburgh compound B (PiB) PET (positron emission tomography), and apolipoprotein 4 (ApoE4) genotype (a known risk factor for vascular and parenchymal amyloid). Our subjects consisted of 33 healthy normal controls (NC), 28 patients with PiB(-) svMCI, and 12 with PiB(+) svMCI. They underwent scanning capillary tube viscometer measuring BV during systolic and diastolic phases. Compared with the NC group, the PiB(-) svMCI group showed increased diastolic blood viscosity (DBV) but no difference in systolic blood viscosity (SBV). By contrast, there was no significant difference in SBV and DBV between the NC and PiB(+) svMCI groups. Within the PiB(+) svMCI group, ApoE4(-) subgroup showed increased DBV compared with the ApoE4(+) subgroup. Increased DBV is an important contributor to the development of "pure" svMCI (ie, without cerebral amyloid deposition). The relationship between BV and PiB(+) svMCI differed according to ApoE genotype, suggesting that the pathogenesis of PiB(+) svMCI might also be heterogeneous.

Reference intervals for whole blood viscosity using the analytical performance-evaluated scanning capillary tube viscometer

ObjectivesThis study was performed to establish the reference intervals for whole blood viscosity (WBV) using the analytical performance-evaluated scanning capillary tube viscometer (SCTV). Design and methodsThe analytical performance of the SCTV was evaluated using three different levels of QC materials and sixty human EDTA-blood samples. To establish the reference intervals for WBV, 297 healthy individuals (123 men and 174 women) were selected from 1083 subjects. ResultsWithin-day precisions with QC materials and human whole blood and between-day precisions with QC materials were below 5.0%, 6.6% and 8.0% in CVs at all shear rates, respectively. Comparison tests between the SCTV and the Brookfield viscometer showed a significant correlation (R2=0.972, p<0.001). The reference intervals for WBV in healthy men were 3.66–5.41cP at 300s−1 and 23.15–36.45cP at 1s−1 while those in women were 3.27–4.32cP at 300s−1 and 18.20–27.36cP at 1s−1, respectively. ConclusionsUsing the analytical performance-evaluated SCTV, the reference intervals for WBV were established in healthy adults, which could be beneficial to the clinical utility of WBV in the aspect of appropriate modalities for the improvement of blood viscosity.

Cardiovascular benefits of phlebotomy: relationship to changes in hemorheological variables

Renewed interest in the age-old concept of "bloodletting", a therapeutic approach practiced until as recently as the 19th century, has been stimulated by the knowledge that blood loss, such as following regular donation, is associated with significant reductions in key hemorheological variables, including whole blood viscosity (WBV), plasma viscosity, hematocrit and fibrinogen. An elevated WBV appears to be both a strong predictor of cardiovascular disease and an important factor in the development of atherosclerosis. Elevated WBV through wall shear stress is the most direct physiological parameter that influences the rupture and erosion of vulnerable plaques. In addition to WBV reduction, phlebotomy may reduce an individual's cardiovascular risk through reductions in excessive iron, oxidative stress and inflammation. Reflecting these findings, blood donation in males has shown significant drops in the incidence of cardiovascular events, as well as in procedures such as percutaneous transluminal coronary angioplasty and coronary artery bypass grafting. Collectively, the available data on the benefits of therapeutic phlebotomy point to the importance of monitoring WBV as part of a cardiovascular risk factor, along with other risk-modifying measures, whenever an increased cardiovascular risk is detected. The development of a scanning capillary tube viscometer allows the measurement of WBV in a clinical setting, which can prove to be valuable in providing an early warning sign of an increased risk of cardiovascular disease.

Elevated coronary whole blood viscosity in acute coronary syndrome patients

As most clinical studies measure whole blood viscosity (WBV) from peripheral samples, potential differences in WBV obtained from the coronary arteries are often ignored. This study investigated differences in WBV measured from coronary artery specimens in patients with and without acute coronary syndrome (ACS). Consecutive patients with chest pain who underwent diagnostic coronary angiography were divided into two groups [non-ACS (n = 16), ACS (n = 22)]. The ACS group consisted of unstable angina (n = 13) and acute myocardial infarction (n = 9) patients. Two blood samples were obtained from each patient at the both coronary artery ostia prior to coronary angiography. Low-shear and high-shear blood viscosities (BVs) were measured at shear rates of 1 and 300 s-1, respectively, by a scanning capillary tube viscometer (Bio-Visco Inc., South Korea). Both low-shear and high-shear BVs obtained from peripheral, left and right coronary arteries were not different in both groups. Mean coronary low-shear WBV values obtained in ACS group were 29.2% higher than those in non-ACS group (295.3 ± 87.2 mP vs. 228.5 ± 69.2 mP, p = 0.016). Mean coronary high-shear WBV values obtained in ACS group were 15.6% higher than those in non-ACS group (42.9 ± 10.0 mP vs. 37.1 ± 4.6 mP, p = 0.036). Direct measurement of WBV from the coronary artery showed no differences with peripheral samples. Future larger studies are needed to clarify our results.

Comparison tests for plasma viscosity measurements

The present study measured plasma viscosity using three different viscometers: Ostwald capillary-tube viscometer, Brookfield rotating viscometer, and scanning capillary-tube viscometer (SCTV). The plasma viscosity data obtained using Ostwald viscometer at 37°C with the conversion constant provided by its manufacturer were in good agreement with those obtained using Brookfield viscometer at 37°C. In addition, the plasma viscosity data obtained using SCTV were in excellent agreement with those from Brookfield viscometer. However, when the Ostwald viscometer is used for plasma viscosity measurements at the room temperature, one should be cautioned because the conversion constant provided by manufacturers may not be applicable to the room temperature as the surface tension of plasma depends on temperature, affecting the accuracy of the plasma viscosity measurement.

Analytical performance evaluation of the scanning capillary tube viscometer for measurement of whole blood viscosity

BackgroundWhole blood viscosity (WBV) is the resistance of blood flow in blood vessels. Increased WBV may be a cardiovascular risk factor. The proper screening of WBV can help the early detection of cardiovascular disease. We investigated the performance of a new scanning capillary tube viscometer (SCTV) for the measurement of WBV. MethodsWe evaluated the total precision of the SCTV for 20days using three control viscosity materials, and the within-day precision with the whole blood samples of three different individuals. For the linearity evaluation, serial dilutions of a high concentration standard material were used. For the method comparison, the results of the SCTV method were compared to those of Brookfield rotating viscometer on 227 subjects. ResultsThe SCTV had good within-run and total-run coefficient of variant (CV)s at low-, medium-, and high-concentration samples, at shear rates of 1 and 300s−1. The within-day CVs with the three human blood samples were 6.3%, 3.7% and 3.8% at a shear rate of 1s−1, and 3.2%, 3.0% and 4.1% at a shear rate of 300s−1. The SCTV method showed an excellent linearity in the range of 84.9 to 558.2 milliPoise (mP) and 28.8 to 71.0 mP at shear rates of 1 and 300s−1, respectively. For the comparison study, the SCTV and the rotating viscometer showed comparable results. ConclusionsThe SCTV showed a stable analytical performance, and was comparable with the rotational viscometer. This new SCTV method can be used in the clinical laboratory for various needs.

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 dye concentration on the viscosity of water in a scanning capillary-tube viscometer

A scanning capillary-tube viscometer (SCTV) determines the viscosity of an opaque liquid by measuring the changes in liquid level in two riser tubes. The current SCTV utilizes an optical sensor (i.e. charge-coupled device (CCD)) to measure the changes in the liquid level, where the liquid blocks the path of the light to the optical sensor. For a transparent liquid, one can use dye to make the liquid opaque. Hence, the present study investigated whether or not the addition of dye altered the viscosity of a transparent liquid such as distilled water. In this study, six different concentrations (0.5, 1, 2, 3, 4, and 7 vol.%) of dye were used. The present results demonstrated that the dye effect on the viscosity of dye–water solution was negligibly small as long as the dye concentration was less than 2 vol.%.

A method of isolating surface tension and yield stress effects in a U-shaped scanning capillary-tube viscometer using a Casson model

The present study introduces a method to consider different surface tensions at two riser tubes for the viscosity measurements of fluids using a U-shaped scanning capillary-tube viscometer (SCTV). The accuracy and repeatability of the SCTV were demonstrated by comparing the viscosity results of distilled water obtained from the SCTV with the well-accepted reference data for water. Non-Newtonian viscosities of bovine blood containing 7.5% ethylenediaminetetraacetic acid (EDTA) and fresh human blood were measured at 25 °C and at a body temperature of 37 °C, respectively. The viscosity results for bovine blood gave excellent agreement with the results obtained from a rotating viscometer. The results demonstrate that whole blood viscosity can be measured over a range of shear-rates in less than 2–3 min without any anticoagulants using disposable U-shaped capillary-tube sets.

A new scanning capillary tube viscometer

The present study introduces a new scanning capillary tube viscometer for measuring fluid viscosity continuously over a range of shear rates including a low shear regime. Using a charge-coupled device sensor array, one could measure the changes in fluid level in a rising tube h(t) from which viscosity and shear rate were mathematically calculated. The concept of the new scanning capillary tube viscometer was validated by measuring viscosities of Newtonian fluids and comparing the results with those obtained with reference data and a rotating viscometer. Furthermore, the present method overcomes one of the major drawbacks of the capillary tube viscometer, the inability to produce viscosity data in a low shear range, by extending the shear rate range as low as 5 s−1 for water and diluted glycerin solutions at room temperature.