Plasma, viscosity

Serum proteins, serum protein electrophoresis, plasma viscosity... 

When there is evidence of carditis (cardiac enlargement or pericarditis), complete bed rest is advised and a corticosteroid should be used instead of aspirin since the latter may precipitate cardiac failure. Prednisolone should be given in a dose sufficient to suppress clinical and laboratory (ESR, plasma viscosity, C-reactive protein) signs of inflammation 10-15 mg/d is usually adequate in adults, and specific therapy for cardiac failure may also be necessary. 

Blood and plasma viscosity fall by 5-10% during the administration of coumarins in healthy volunteers and in patients with coronary artery disease (36). This may also explain, at least partly, the antianginal effect of coumarins. The mechanism might be related to changes in the protein composition of the plasma. 

Intravenous immunoglobulin expands the plasma volume and increases blood viscosity, which can lead to volume overload in patients with cardiac insufficiency (41). Stroke, thromboembolic events, and myocardial infarction have been reported after high-dose treatment with intravenous immunoglobulin, which increases plasma viscosity (41 3). 

Thrombosis in elderly patients with an increased risk of thrombosis, such as those with hypertension or previous episodes of infarction, has been described (44). A few cases of thrombosis subsequent to intravenous immunoglobulin have been reported, including myocardial infarction in five patients, stroke in four cases, and spinal cord ischemia in one (45). It has been postulated that these events are induced by platelet activation and increased plasma viscosity (12). 

Several cases of intravenous immunoglobulin-related thrombosis have been reported (78,79). It can be either venous or arterial (80). It has been suggested that thrombosis can be caused by platelet activation and increased plasma viscosity (79). In patients with vascular risk factors, such as old age, hypertension, and a history of stroke or coronary artery disease, complications, such as myocardial infarction, pulmonary embolism, stroke, and acute spinal cord events, have been described (80). Intravenous immunoglobulin enhances platelet aggregation and the release of adenosine triphosphate in human platelets in vitro. In addition, there is a dose-related increase in plasma viscosity with increasing plasma immunoglobulin concentration (79,80). 

Injection into the left ventricle or the proximal aorta is likely to produce more marked effects. Cardiac rate, stroke volume, and cardiac output increase. There is a rise in right and left atrial pressures and left ventricular end-diastolic pressure. The pulmonary arterial pressure is also increased. The blood volume expands and peripheral blood flow increases and then decreases as systemic resistance falls. The hematocrit falls and venous pressure gradually rises. As the systemic arterial pressure falls, the heart rate increases. These responses are largely due to the injection of strongly hypertonic solutions, which promote a rapid expansion of the plasma volume water shifts from the extravascular fluid spaces to the blood and moves out of the erythrocytes, which shrink and become crenated. Blood viscosity rises, but plasma viscosity does not increase significantly. The erythrocytes give up potassium to the plasma and this might contribute to the observed reduction in peripheral vascular resistance. 

Naftidrofuryl is a complex acid ester of diethylaminoetha-nol, with direct vasodilatory properties and antagonistic effects on 5-HT (via 5-HT2 receptors) and bradykinin. It also causes an intracellular increase in ATP concentrations, improves cellular oxidative metabolism (by activating succinate dehydrogenase), and reduces blood and plasma viscosity and fibrinogen concentrations. 

In human medicine, starches with smaller average molecular weights have less profound effects on hemostasis (Treib et al 1999). This may also be the case in horses, although only one dose has been tested. In healthy horses, a 8ml/kg dose of a 10% pentastarch solution resulted in a slight decrease in the thrombin time 12 h after administration, which returned to normal after 24 h. No effect on prothrombin time or partial thromboplastin time was documented (Meister et al 1992). In healthy horses, the initial phase half-life of pentastarch is 5.6 h and the terminal phase half-life is 122 h. However, the effects on PCV, plasma total solids and plasma viscosity appear to last only 12-24 h (Meister et al 1992). In equine clinical cases, the half-life may be as short as 2h (Hermann et al 1990). Pentastarch, although available in the USA, is only approved for leukapheresis in human medicine. 

With increasing temperature all the lipidic methyl and methylene group peaks sharpen and increase in intensity. This is consistent with a general reduction in the plasma viscosity and increased motional freedom of the lipoprotein particles which also significantly increase the 2D HMQC... 

EGb 761 at a dose 200 mg administered to 60 patients intravenously for 4 d improved skin perfusion and decreased blood viscosity without affecting plasma viscosity (Kleijnen and Knipschild, 1992). Another GB extract, LI 1730, increased blood flow in nailfold capillaries and decreased erythrocyte aggregation compared to placebo in 10 volunteers at a dose of 112.5 mg (Jung et al., 1990). Blood pressure, heart rate, packed cell volume, and plasma viscosity were unchanged. 

Wolfe et al. (60) added treatment with pentoxifylline for six months following hemodilution. At one-year follow-up the mean visual acuity improved by 1.5 lines in the 19 treated patients versus a decline of 1.5 lines in the 21 control patients. The mean arteriole-venous transit time normalized more quickly in the treatment group but was equal at one year in both groups. Plasma viscosity decreased with treatment. It is difficult in this study to determine whether the treatment was more beneficial for nonischemic or ischemic CRVO. In this study, CRVOs were considered ischemic when they met two or more of the following conditions two disk areas of nonperfusion, visual acuity less than or equal to 20/200, greater than 10 cotton wool spots. The central vein occlusion study has demonstrated that a better benchmark for ischemic CRVO may be the presence of more than 10 disk areas of non-perfusion. 

In summary, there has been controversy over whether central and branch retinal vein occlusions are associated with increased plasma viscosity or elevated hematocrit and whether the results for nonischemic CRVO are better than the natural history. There have been further contradictory findings regarding the efficacy of this treatment for ischemic CRYO. Although promising results have been demonstrated, the technique requires evaluation with larger randomized controlled clinical trials. 

In patients with stage II peripheral arterial occlusive disease, 800 mg garlic daily for 12 weeks was found to reduce spontaneous thrombocyte aggregation and plasma viscosity (Kiesewetter et al. 1993b). 

The macroscopic rheologic properties of blood are determined by its constituents. At a normal physiological hematocrit of 45 percent, the viscosity of blood is /u, = 4 x 10" dyne s/cm (or poise), which is roughly 4 times that of water. Plasma alone (zero hematocrit) has a viscosity of /u = 1.1 X 10 to 1.6 X 10 poise, depending upon the concentration of plasma proteins. Aftera heavy meal, when the concentration of lipoproteins is hig the plasma viscosity is quite elevated (Whitmore, 1968). In large arteries, the shear stress (t) exerted on blood elements is linear with the rate of shear, and blood behaves as a newtonian fluid, for which. 

In an observational study in London, 20 adults (12 male, mean age 52.6 years) with autoimmune neurological disease were prospectively evaluated while xmdergoing a 1- to 5-day course of high-dose IVIG infusions. There was a rise in plasma viscosity (associated with daily dose and entire course), serum interleukin-6 and erythrocyte sedimentation rate but not corresponding increase in blood pressure, C-reactive protein or fibrinogen. One of twenty patients developed IgG and IgM anticardiolipin antibodies [59 ]. 

Bentley P, Rosso M, Sadnicka A, IsraeH-Korn S, Laffan M, Sharma P. Intravenous immunoglobulin increases plasma viscosity without parallel rise in blood pressure. J Clin Pharm Ther June 2012 37(3) 286-90. 

Figure 10.19(a) Plasma viscosity before and after induction of anaesthesia (11 patients) with intravenous anaesthetic formulations containing Cremophor EL (b) the duration of this effect - a plot showing the viscosity of plasma at a shear rate of 11.5 s " as a function of time in minutes. Taken from Gramstad and Stovner [135] with permission. 

Blood and plasma viscosity are critical since lowered values increase oxygen delivery but decrease shear stress. Consequently, a blood substitute, beyond its effect in maintaining FCD, should be effective in preventing ischemia and apoptosis, which can be accomplished through the maintenance of adequate levels of shear stress. 

Cabrales, R, Tsai, A.G., and IntagUetta, M. Alginate plasma expander maintains perfusion and plasma viscosity during extreme hemodUution. Am Physiol 288 H1708-H1716,2005. 

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