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Disorders of blood viscosity.

In clinical situations associated with disturbed blood flow, the primary focus is usually on improving cardiovascular performance. However, during recent decades, both basic science and clinical literature reports have presented evidence that the flow properties of blood must also be considered in these situations. Thus, the relatively new fields of haemorheology and clinical haemorheology have evolved; the former deals with the flow and deformation behaviour of blood, plasma and the formed elements of blood, whereas the latter relates to alterations of their behaviour in various pathophysiologic states. This review therefore summarizes some of the salient aspects of clinical haemorheology and of the determinants of blood flow properties (flow rate, haematocrit, plasma viscosity, red cell aggregation, red cell deformability). In addition, it briefly describes several clinical disorders associated with abnormal blood, plasma or cell rheology ('hyperviscosity syndromes' occurring in polycythaemia, leukaemia, sickle cell disease, paraproteinaemias).

Blood Viscosity↗

[The ankle-arm index and whole blood viscosity in patients with type II diabetes mellitus with ischemia of the lower extremities].

The relationship was studied between the ankle-arm index (K/R) and whole blood and plasma viscosity in patients suffering from diabetes mellitus type II with ischemia of lower extremities. The measurements were carried out in 96 patients (80 males and 16 females), of whom 72 were in stage II of Fontaine progression. Immediately after determination of the K/R index blood was taken from vena mediana cubiti adding Na2EDTA for rheological test. Whole blood viscosity was measured with a Low-Shear 100 Contraves viscometer immediately after sampling, and plasma viscosity was measured with a capillary viscometer of Ubbvelohd within 2 hours after sampling. By the method of regression analysis and linear correlation it was found that increased whole blood and plasma viscosity significantly correlated with reduced K/R value in the patients. The obtained results are analysed in biophysical and clinical aspects.

Aged↗

[Gastric mucosal blood flow and blood viscosity in patients with diabetes].

For the study of the microcirculatory disturbance of the digestive tract in patients with diabetes, 41 cases with non-insulin dependent diabetes mellitus (NIDDM) were selected (mean age 53.9 Yrs., 22 male/19 female). Of these patients 9 were without complication, and 32 with complications. Gastric mucosal blood flow (GMBF) was determined at 14 points of laser and greater curvature, anterior and posterior wall of antrum, angle and corpus of stomach, pylorus and anterior wall of duodenum with laser Doppler flowmetry (PF2). Results showed that the mean value of the 14 points of GMBF in 41 patients with NIDDM was 2.81 +/- 0.15(V, mean +/- s mean), which was significantly lower than that of 11 normal subjects (4.77 +/- 0.29V, P < 0.001). The mean GMBF of 8 cases of NIDDM without gastric disease was 2.92 +/- 0.28V, which was also lower than that of normal control (61.2% of normal value, P < 0.001). The GMBF in 27 cases of diagnosed chronic superficial gastritis (CSG 2.79 +/- 0.15V) was lower than the GMBF of 63 CSG patients without NIDDM (3.23 +/- 0.12V, P < 0.05). The viscosity of blood and plasma was determined with NAAKE viscometer in 26 patients with NIDDM. It was found that the blood viscosity was significantly higher than that of the normal control, and the plasma viscosity was also increased but without statistic significance. Results showed that the GMBF of NIDDM was significantly lower than that of the normal subjects or CSG patients without diabetes. It implied that the visceral microcirculatory disturbance also involved the digestive system leading to the GMBF decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Abnormal haemostasis and blood viscosity in malignant hypertension.

We have previously shown abnormalities of haemostasis suggestive of intravascular coagulation in patients with malignant hypertension, a condition associated with retinopathy and renal fibrin deposition. To determine whether such abnormalities are specific to malignant hypertension, we have measured several haemostatic and haemorheological variables in 18 patients with malignant hypertension (Group 1), 18 matched healthy controls (Group 2), and 18 patients with non-malignant hypertension (Group 3) matched for renal pathology, blood pressure and serum creatinine with Group 1. Both Groups 1 and 3 had increased mean levels of fibrinogen, factor VIIIc, beta-thromboglobulin, plasma viscosity and blood viscosity (corrected for haematocrit); and decreased mean levels of haematocrit, antithrombin III and platelet count. Mean levels of fast antiplasmin and alpha2-macroglobulin were elevated in Group 1 but not in Group 3. We conclude that most blood abnormalities are not specific to malignant hypertension; are also present in patients with non-malignant hypertension who have similar levels of blood pressure and renal damage; and might result from renal damage as well as promoting further renal damage by enhancing fibrin deposition. However increased levels of fibrinolytic inhibitors in malignant hypertension merit further investigation in relation to removal of renal fibrin.

Adult↗

Intraoperative changes of transcranial Doppler velocity: relation to arterial oxygen content and whole-blood viscosity.

The association of arterial oxygen content (CaO2) and viscosity with transcranial Doppler (TCD) blood flow velocity in the middle cerebral artery was studied in 20 adults without cerebrovascular disease undergoing abdominal surgery associated with significant fluctuations in hematology. TCD measurements and arterial blood samples were obtained before and directly after surgery but before blood transfusion. There was an inverse association between baseline mean velocity and CaO2 (r = -0.56), hematocrit (r = -0.50), hemoglobin (r = -0.51), and high-shear viscosity (r = -0.46). After intraoperative blood loss, intraindividual fluctuations of TCD measurements, blood oxygenation, and rheologic factors were studied. In multiple regression analysis, changes in CaO2 had the strongest association with changes in TCD values, accounting for 55% of the variation in mean velocity. Addition of hematocrit and viscosity could not account for more variation in mean velocity than CaO2 alone.

Abdomen↗