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PubMed1991

Effect of hydroxypropylmethylcellulose on gastrointestinal transit and luminal viscosity in dogs.

The effects of hydroxypropylmethylcellulose on upper gastrointestinal transit, viscosity, and water flux were studied in six dogs fistulated at the proximal duodenum and/or mid-jejunum. Combinations of different grades of hydroxypropylmethylcellulose were prepared as 2% or 3.3% solutions to yield input viscosities of low (approximately 5000 cp at 37 degrees C and 1 s-1), medium (15,000 cp), or high (30,000 cp) viscosity. Hydroxypropylmethylcellulose modified intralumenal viscosity, with a linear relationship existing between input and lumenal viscosity. With regard to transit, the lag time before the onset of chyme recovery increased linearly as a function of luminal viscosity. There was also a pronounced decrease in the first-order emptying rate constant as lumenal viscosity increased from water to low-viscosity hydroxypropylmethylcellulose, but as viscosity was further increased there was little additional change. These results indicate that water-soluble fibers can exert a significant influence on both the lumenal viscosity and the transit profile in the upper gastrointestinal tract.

Animals↗
PubMed1988

The effect of hemodialysis on whole blood, plasma and erythrocyte viscosity.

The effect of hemodialysis (HD) on blood viscosity has not been adequately investigated. We studied blood viscosity during HD employing coneplate viscometry. Ten patients with end-stage renal disease were studied before and immediately after HD. To dissect the possible effects of HD on plasma and red blood cell (RBC) determinants, we measured whole blood, plasma, and reconstituted erythrocyte viscosities. The latter consisted of RBC's suspended in a buffered saline solution (pH = 7.4 units). In addition, serum, electrolytes and hematocrit (HCT) were measured. The results revealed a significant rise in whole blood viscosity after dialysis. Likewise, plasma viscosity rose considerably with dialysis. However, when the RBC's were reconstituted to a constant HCT, no significant difference was noted before and after HD. As expected, body weight, blood urea nitrogen (BUN) and creatinine concentrations fell while HCT and protein concentration rose with HD. A significant correlation was found between the observed rise in HCT, and dialysis-induced rise in whole blood viscosity. Likewise, the observed rises in plasma viscosity after dialysis significantly correlated with the rise in protein concentration. In addition, the change in whole blood and plasma viscosity values correlated with the degree of ultrafiltration (weight loss). In conclusion, whole blood and plasma viscosity rises with hemodialysis. The observed rise in viscosity is primarily due to hemoconcentration.

Acid-Base Equilibrium↗
PubMed1977

Blood viscosity in Waldenström macroglobulinemia.

Patients with Waldenström macroglobulinemia were studied for the presence or absence of the hyperviscosity syndrome, the relative serum viscosity value, and the calculated whole blood viscosity to identify a level at which symptoms occurred. The majority of symptomatic patients had whole blood viscosity values above 8.0 centipoises. There was a direct correlation between whole blood viscosity and relative serum viscosity, r = 0.75. One patient with central nervous system abnormalities was identified as having a high whole blood viscosity but a low serum viscosity. It was concluded that the vast majority of patients with the hyperviscosity syndrome will be identified by measuring the relative serum viscosity. In patients with central nervous system findings and a low serum viscosity, the whole blood viscosity should be determined either by direct measurement or by calculation.

Blood Viscosity↗
PubMed1996

Apparent viscosity of the synovial fluid from mid-carpal, tibiotarsal, and distal interphalangeal joints of horses.

OBJECTIVE: To compare the apparent viscosity of normal synovial fluid of the mid-carpal, tibiotarsal, and interphalangeal joints of horses. DESIGN: Viscosity evaluation over a range of shear rates was used to characterize the apparent viscosity of synovial fluids from the 3 joints. ANIMALS: 60 clinically normal adult horses. PROCEDURE: Viscosity data for synovial fluid samples were obtained over a shear rate range of 10 to 250/s and apparent viscosity was calculated at 50, 100, 150, 200, and 250/s. Effect of shear rate on apparent viscosity was determined, using a two-way ANOVA, with significant differences tested, using a Tukey's test at a significance level of P < 0.05. RESULTS: Synovial fluid from all these joints indicated shear thinning behavior: decreased apparent viscosity with increased shear rate. Apparent viscosity of synovial fluid from the 3 joints was not significantly different over the shear rate range of 50 to 250/s. CONCLUSION: Results of this study indicate that the apparent viscosity of the distal interphalangeal joint is not less than that of other joints, as has been reported. CLINICAL RELEVANCE: The observation of decreased synovial fluid viscosity of distal interphalangeal joint fluid should be considered as suggestive of joint disease.

Analysis of Variance↗
PubMed1998

Opposite effects of low-density and high-density lipoprotein on blood viscosity in fasting subjects.

Given the enlarging body of evidence implicating increased blood viscosity in atherogenesis, the authors hypothesize that lipoproteins modulate the atherogenic process by affecting blood viscosity. In order to define the magnitude of the effect of lipoproteins on blood viscosity, capillary viscometry was performed on blood from 16 healthy, fasting subjects, and results were correlated with lipoprotein-cholesterol levels. Low-density lipoprotein-cholesterol was positively associated with blood viscosity (r = 0.610, p = 0.01). High-density lipoprotein-cholesterol was negatively associated with blood viscosity (r = -0.479, p = 0.06). A multiple regression model was developed with these data, revealing that 54% of variation in blood viscosity was attributable to these lipoproteins. This model was validated on a second dataset, in which these lipoproteins accounted for 28% of variation in blood viscosity. A second model, including hematocrit, serum viscosity, and high-density lipoprotein-cholesterol levels, explained 73% of variation in blood viscosity. By modulating blood viscosity and flow, lipoproteins may affect the residence time of atherogenic particles and atherogenesis.

Adult↗
PubMed2005

Effects of Viscoseal, a synovial fluid substitute, on recovery after arthroscopic partial meniscectomy and joint lavage.

This was a pilot, single blind, randomised, controlled study in patients requiring partial meniscectomy. The aim was to assess whether replacing the synovial fluid lost during arthroscopy with a hyaluronic acid-containing synovial fluid substitute (Viscoseal) would reduce the severity and duration of post-operative symptoms during the 4 weeks post-surgery, in comparison to the standard arthroscopy procedure alone. Fifty patients were randomly assigned to either undergo arthroscopic partial meniscectomy alone (control group: n=25) or to receive 10 ml Viscoseal into the joint at the end of the procedure (Viscoseal group: n=25). Forty patients (20 per group) completed the study. Despite the small patient population in this pilot study, some interesting results were obtained. On Day 1 after surgery, the mean values for pain at rest (VAS) increased in both groups but this increase was lower in the Viscoseal group (8.9+/-23.1 mm) than in the standard therapy group (20.0+/-25.9 mm) (Mann-Whitney statistic MW-S: P=0.0525) and remained in favour of Viscoseal for the first 3 days after surgery. Joint swelling decreased to a greater extent in the Viscoseal group with an observed superiority at Day 7 (MW-S: P=0.1187) and a proven superiority at Days 12 (MW-S: P=0.015) and 28 (MW-S: P=0.0072). Diclofenac intake was lower in the Viscoseal group from Day 3 to Day 28 with a proven superiority (LB-CI > 0.5) in favour of Viscoseal on Days 3 (MW-S: P = 0.0093), 4 (MW-S: P= 0.0075), and 7 (MW-S: P = 0.0195) indicating that the product had an NSAID-sparing effect. Viscoseal was safe and well-tolerated and no adverse reactions occurred during the study. These findings indicate that Viscoseal may be useful as a synovial fluid substitute after arthroscopy.

Activities of Daily Living↗
PubMed2005

Pressure dependence of viscosity.

We reanalyze the pressure dependence of viscosity of liquids of constant composition under isothermal conditions. Based exclusively on very general considerations concerning the relationship between viscosity and "free volume," we show that, at moderate values of pressure, viscosity increases, as a rule, with increasing pressure, provided the liquid is in stable or metastable (undercooled) equilibrium states. However, even if the behavior of the viscosity is governed by free volume effects, deviations from a positive pressure dependence are possible, when the liquid's thermal expansion coefficient is negative. We derive an equation that allows one to quantitatively determine the pressure dependence of viscosity, which requires, in the simplest case, only the knowledge of the temperature dependence of viscosity at constant pressure, the thermal expansion coefficient, and the isothermal compressibility of the liquid. As an example, the negative pressure dependence of water in the range of temperatures 0-4 degrees C and of several silicate liquids, such as albite, jadeite, dacite, basalts, etc., could be explained in such a way. Other glass-forming liquids initially (for moderate pressures) show a positive pressure dependence of viscosity that changes to a negative one when subjected to high (approximately GPa) isostatic pressure. A detailed analysis of water and already mentioned silicate melts at GPa pressures shows that, in addition to free volume effects, other pressure induced structural transformations may have to be accounted for in a variety of cases. By this reason, the theoretical analysis is extended (i) in order to describe the pressure dependence of viscosity for systems that are in frozen-in thermodynamic nonequilibrium states (glasses, i.e., undercooled liquids below the glass transition temperature Tg) and (ii) to systems which undergo, in addition to variations of the free volume, pressure induced changes of other structural parameters. In such cases a decrease of viscosity with increasing pressure may occur, in principle, even if the thermal expansion coefficient is positive. In this way, the present analysis grants a general tool to estimate the pressure dependence of viscosity and supposedly settles the controversy in the current literature.

Journal Article↗
PubMed2000

In vitro and in vivo determination of the UV protection factor for lightweight cotton and viscose summer fabrics: a preliminary study.

BACKGROUND: One of the most important elements in the prevention of skin cancer is the use of comfortable UV-protective clothing. Owing to their low weight, cotton fabrics, and especially viscose fabrics made from filament yarns, are ideal for summer clothing and in fact enjoy a high degree of acceptance among consumers. Two methods are available for determining the UV protection factor (UPF) of textiles: the in vitro method is based on the spectrophotometric determination of the transmission of UV radiation through these fabrics; the in vivo method is based on the determination of the minimal erythema dose for a test subject with and without textiles. OBJECTIVE: This study was performed to assess the UPF of lightweight cotton and viscose fabrics and whether the use of these two methods to determine the UPF of viscose fabrics and cotton fabrics produces congruent results. METHODS: We tested 7 different viscose fabrics and 7 different cotton fabrics. Three of the viscose fabrics (ENKA SUN) had been specially treated, by depositing pigments in the fibers, to confer UV-protective properties. The determination of the in vitro and in vivo UPF was performed with a spectrophotometer and sun simulator, respectively. RESULTS: The in vivo measurements on the untreated viscose fabrics produced UPF values lower than those obtained from the in vitro measurements. For one of these untreated viscose fabrics, the difference between the in vivo UPF and the in vitro UPF was statistically significant (P <.05). In contrast, the in vivo measurements on the specially treated viscose textiles and on the cotton fabrics resulted in UPF values higher than the in vitro UPF values. For one specially treated viscose fabric and 4 cotton fabrics, this difference was statistically significant (P < .05). CONCLUSION: Our results suggest, however, that-depending on the type of fabric-determination of the UPF by the in vitro method is not in agreement with the in vivo method. In vivo measurements made with lightweight specially treated UV-protective clothing showed in contrast to the untreated viscose fabrics that these garments offer very good protection against UV radiation. These results underscore the importance of developing and refining such UV-protective materials.

Adult↗
PubMed2003

Evaluation of a new high-viscosity octylcyanoacrylate tissue adhesive for laceration repair: a randomized, clinical trial.

OBJECTIVE: Tissue adhesives have recently been approved for skin closure. Their low viscosity may result in inadvertent migration. The authors compared the tendency of the adhesive to migrate after laceration closure with a high- or low-viscosity octylcyanoacrylate (OCA). METHODS: This was a randomized, clinical trial set in university and community-based emergency departments. Participants included patients with simple traumatic lacerations. Patients were randomized to laceration closure with low- or high-viscosity OCA tissue adhesive. The outcome measured was immediate adhesive migration (interobserver agreement, kappa = 0.90). Data analysis was performed with proportions compared with chi-square and Fisher's exact tests. RESULTS: Eighty-four patients were randomized to low- (n = 42) or high- (n = 42) viscosity OCA tissue adhesive. Groups were similar in baseline patient and wound characteristics. The high-viscosity OCA was less likely to migrate than the lower-viscosity agent (21% vs. 78%, p < 0.001; odds ratio = 0.3, 95% confidence interval = 0.1 to 0.5). The proportion of patients who noted a sensation of heat during OCA application was higher in the high-viscosity groups (44% vs. 26% respectively, p = 0.11); however, all such patients in both groups would use the device again. At 14 days, there were no wound infections in either group. There was one dehiscence in the high-viscosity group. CONCLUSIONS: The high-viscosity OCA tissue adhesive was less likely to migrate than the lower-viscosity device. Wound dehiscence and infection rates were acceptably low in both treatment groups.

Adolescent↗
PubMedDate not supplied

The influence of suspending phase viscosity on the passage of red blood cells through capillary-size micropores.

Much attention has been paid to the study of blood flow in long, narrow tubes. While the influence of tube diameter and driving pressure have been examined in detail, the influence of suspending phase viscosity has generally been assumed only to affect the blood viscosity in a linearly proportional manner, hence the practice of normalizing apparent blood viscosity values by the suspending phase viscosity to give a relative viscosity (e.g., Pries et al., 1992). While this assumption is probably valid for long tubes, it apparently does not hold for blood flow in short tubes (and by extension also for flow in short or branching capillary segments in vivo) in which RBC deformation plays a more significant role. In this paper we present a series of experiments using the Cell Transit Analyzer (CTA) in which the influence of driving pressure and suspending phase viscosity on RBC passage through short, narrow tubes has been systematically evaluated. Over the range studied (1 to 10 cm water), the influence of driving pressure was found to be unremarkable, in that RBC velocity scaled directly and linearly with pressure. This finding is consistent with previous studies. However, a distinct intercept was observed in the linear relationship between RBC pore transit time and suspending phase viscosity, which presumably arises as a consequence of RBC deformation either at the pore entrance or within the pore. Two simple mathematical models for the suspending phase-viscosity/transit-time relationship were considered. The results show that making CTA measurements over a range of suspending medium viscosities is a simple and practical way to obtain additional information about RBC mechanical properties.

Blood Pressure↗
PubMed1998

Effect of viscosity on metachrony in mucus propelling cilia.

In the present work we report that increasing the viscosity of the medium caused not only a decrease in the ciliary beat frequency but also changes in the metachrony and correlation between cilia. The study was performed using double and triple simultaneous photoelectric measurements on cultured ciliary cells from the frog esophagus in the viscosity range of 1-2,000 cp. We observed that increasing the viscosity intensified the fluctuations in all the measured parameters. Ciliary beat frequency decreased moderately. Even at quite high viscosities (circa 2000 cp.), cilia were still active with beating frequencies of 3-5 Hz. In addition, the degree of correlation between cilia parallel to the effective stroke direction (ESD) decreased, while that perpendicular to the ESD at a low range of viscosities remained unchanged and even increased at high viscosities. Medium viscosities in the range of 30-1,500 cp. altered the metachronal wave properties of cultured frog esophagus. The metachronal wavelength increased by up to 50%, and the wave direction changed towards more orthoplectic type of coordination. According to our recently suggested model [Gheber and Priel, 1990: Cell Motil. Cytoskeleton 16:167-181], these effects can be explained by a decrease in the temporal asymmetry of the ciliary beat. Since similar results were observed in water propelling cilia of Paramecium subjected to medium viscosity ranges of up to 40 cp. [Machemer, 1972: J. Exp. Biol. 57:239-259], we conclude that hydrodynamic interactions govern the metachronal wave properties of both mucus and water propelling cilia, though mucus propelling cilia, with their better adaptation to increased load, are affected at much higher viscosities than water propelling cilia.

Animals↗
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↗
PubMed1992

Viscosity measurements of barium sulfate mixtures for use in motility studies of the pharynx and esophagus.

Detailed viscosity measurements have been made of barium sulfate mixtures over a wide range of viscosities for use in radiography of the esophagus, stomach, and duodenum. A new methodology was developed for more accurate estimation of viscosity in non-Newtonian fluids in conventional cylinder-type viscometers. As base cases, the variation of viscosity with shear rate was measured for standard commercial mixes of e.z.hd (250% w/v) and a diluted mixture of liquid e.z.paque (40% w/v). These suspensions are strongly shear thinning at low shear rates. Above about 3s-1 the viscosity is nearly constant, but relatively low. To increase the viscosity of the barium sulfate mixture, Knott's strawberry syrup was mixed to different proportions with e.z.hd powder. In this way viscosity was systematically increased to values 130,000 times that of water. For these mixtures the variation of viscosity with temperature, and the change in mixture density with powder-syrup ratio are documented. From least-square fits through the data, simple mathematical formulas are derived for approximate calculation of viscosity as a function of mixture ratio and temperature. These empirical formulas should be useful in the design of "test kits" for systematic study for pharyngeal and esophageal motility, and clinical analysis of motility disorders as they relate to bolus consistency.

Barium Sulfate↗
PubMed2001

Blood viscosity and blood pressure: role of temperature and hyperglycemia.

We planned a study to research the relations among blood pressure (BP), viscosity, and temperature in healthy subjects and among BP, viscosity, and glucose in diabetics. With simple random sampling method, 53 healthy and 29 diabetes mellitus (DM) type II subjects were selected. Parameters were determined with capillary viscometer and glucometer at 22 degrees C, 36.5 degrees C, and 39.5 degrees C in healthy subjects, and at 22 degrees C on diabetic patients during OGTT with 75 g of glucose. Statistical evaluations of the data were made with regression analysis, Student t test, Spearman's correlation, and analysis of variance. When temperature decreased from 36.5 degrees C to 22 degrees C, blood viscosity increased 26.13%. This increase resulted in a 20.72% decrease in blood flow rate. According to the Hagen-Poiseuille equation, the required BP increase for compensation of the resulting tissue ischemia was 20.72%. Also, a 34.73% decrease in erythrocyte deformability and 18.71% increase in plasma viscosity were seen. When temperature increased from 36.5 degrees to 39.5 degrees C, blood viscosity decreased 10.38%. This caused 11.15% decrease in blood flow rate, and 11.15% decrease in BP, according to the equation. Erythrocyte deformability increase of 9.92% and plasma viscosity decrease of 4.99% arose from the temperature rise. There is a correlation between total data for temperatures and viscosities (r = -0.84, P < .001). When the mean value of blood glucose increased from 100 to 400 mg/dL, viscosity increased 25% (r= 0.59, P = .002). In this state, blood flow rate decrease was 20% and BP increase for physiological compensation was 25%. Consequently, temperature, glucose and viscosity levels of blood are important factors for BP.

Adult↗
PubMed2001

Studies on rye (Secale cereale L.) lines exhibiting a range of extract viscosities. 2. Rheological and baking characteristics of rye and rye/wheat blends and feeding value for chicks of wholemeals and breads.

Five rye lines exhibiting a wide range of extract viscosities were evaluated for the rheological and baking properties of their flours, individually and in blends with hard red spring wheat flour. Commercial cultivars of rye and triticale were included in the study as controls. Extract viscosities of rye flours were higher than those of corresponding wholemeals, indicating shifting of water-extractable arabinoxylan into flour during roller milling. Falling numbers of the rye flours correlated positively with their extract viscosities in the presence (r = 0.73, p < 0.05) or absence (r = 0.65, p < 0.05) of an enzyme inhibitor. Farinograms revealed the weakness of rye and triticale flours compared to wheat flour. Extract viscosities of rye flours were negatively correlated (r = -0.65, p < 0.05) with mixing tolerance index and positively correlated (r = 0.64, p < 0.05) with dough stability, suggesting a positive impact of extract viscosity on dough strength. Extract viscosity was negatively correlated (r = -0.74, p < 0.05) with loaf volume and specific volume (r = -0.73, p < 0.05) and positively correlated (r = 0.73, p < 0.05) with loaf weight of rye/wheat bread. Overall, the results indicated that 30% of flour from high or low extract viscosity rye could be incorporated into rye/wheat breads without seriously compromising bread quality. Inclusion of rye, particularly high extract viscosity rye, in chick diets seriously impeded growth performance and feed efficiency. Part of the arabinoxylan survived bread-making and exerted an effect on chicks, although substantially lower digesta viscosities were observed in chicks fed rye bread diets than in those fed rye wholemeals.

Animal Feed↗
PubMed1982

Plasma and blood viscosities, and aggregation of red cells in racehorses.

Nineteen racehorses have been studied for haemorheologic factors as earlier studies showed a definite correlation between physical fitness and these factors in humans. Results included individual values for all viscosity factors, and the arithmetic means, the latter showing 4.70 +/- 0.49 cP for blood viscosity measured at a shear rate of 180 s-1; 1.100 +/- 0.048 cP for plasma viscosity; 1.045 +/- 0.063 for the rigidity of red cells defined by term 'Tk'; 42.2 +/- 4.1% haematocrit; 290 +/- 39 mg per 100 ml for fibrinogen level; and 278 +/- 75 mm h-1 for aggregation of red cells at 37 degrees C (corrected for plasma viscosity and at constant haematocrit of 30%). Data for subgroups have also been obtained. Linear regressions of apparent blood viscosity against log shear rate were found to be specific to individual racehorses, and differed significantly between some racehorses. Data for blood viscosity, plasma viscosity and haematocrit were near the values reported for human athletes, but rigidity of red cells and aggregation of red cells was found to be much higher in horses. No correlation was found between aggregation of red cells and fibrinogen level. In blood samples from some horses, the erythrocyte sedimentation rates increased with decrease of temperature, while in other samples they increased with increase of temperature. It appears that it is possible to characterise individual horses by blood viscosity factors and viscosity functions.

Animals↗
PubMed1999

Effects of dietary viscosity and energy density on total daily energy consumption by young Peruvian children.

BACKGROUND: Results of prior studies of the effect of viscosity reduction of high-energy-density, starch-containing diets on young children's energy intakes are inconsistent, possibly because of differences in the characteristics of the unmodified diets with which the low-viscosity diets were compared. OBJECTIVE: Our objective was to determine the effects of dietary viscosity and energy density on total daily energy consumption by young, non-breast-fed children. DESIGN: We measured the amount of food consumed and the duration of meals during 3 substudies, in each of which 3 study diets were offered for 4 consecutive days each in random sequence: high energy density, high viscosity (HD-HV); high energy density, low viscosity (HD-LV); and low energy density, low viscosity (LD-LV). The viscosity and energy density of the unmodified starch-containing HD-HV diet were varied across substudies to determine whether the effect of amylase liquefaction was related to the initial characteristics of the HD-HV diet. The viscosity of the HV diets ranged from 79000 to 568000 mPa s; energy density of the HD diets ranged from approximately 4.18 to 4.93 kJ (1.00-1.18 kcal)/g. Viscosity of the LV diets was approximately 3000 mPa s and the energy density of the LD diets was approximately 2.47 kJ (0.6 kcal)/g. RESULTS: In each substudy, children consumed more of the LD-LV diet (g kg body wt(-)(1) d(-)(1)) than of the other diets and more of the HD-LV diet than of the HD-HV diet (P < 0.001). Energy consumption from the HD-LV diet was greater than from the other diets (P < 0.001), but the energy intakes from the latter diets were not significantly different. CONCLUSION: Amylase liquefaction of HD-HV porridges resulted in increased energy consumption by young children.

Anthropometry↗
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↗