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Results for “Microcirculation”

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At least 1,711 records · Page 95Linked to original sources

PubMed1992

Abnormalities of cutaneous microcirculation in atopic eczematics.

There are signs of abnormal microcirculation in atopics, yet reliable methods for its non-invasive measurement are scarce so far. Since the phenomenon of dermographism (D) elicited by blunt stroking of the skin reflects the functional response of cutaneous vessels to pressure, we studied the haemodynamics of D using laser-Doppler microfluxometry (LDF) and infrared thermography (IR-TH) in patients with atopic eczema (n = 23) and in healthy controls (n = 21) under standardized investigative conditions. Only in-patients not treated with corticoids were selected. LDF values showed a marked reduction in the intensity of hyperaemia in the patients as compared with the controls, according to the visual degree of the dermographic blanching effect (white, delayed white, indifferent; pink). A reduction of the radiating skin temperature vis-à-vis the controls was measured by IR-TH. These results yield evidence that dermographic pallor of atopic skin depends on the strength of local vasoconstriction, possibly including altered blood flow in cutaneous shunt vessels.

Adolescent↗

PubMed1998

[Use of laser-doppler perfusion for evaluation of microcirculation in patients with diabetes type I].

UNLABELLED: The purpose of this study was to investigate the foot skin microcirculation in type 1-diabetic patients. The study group comprised 67 patients divided into four subgroups: 13 women and 11 men healthy and had no family history of diabetes; 19 women and 24 men had type 1-diabetes. The studied measurements included 7 parameters determined during rest and post occlusive hyperaemia. They were performed with laser Doppler fluxmetry using surface probe localised in distal part of the lower limbs. The most significant data localised the probe in thumb. The maximum of hyperaemic response (MAX) was significantly lower in the diabetic patients as compared to the healthy subjects (p < 0.01). The time of peak flow (TM) was higher (p < 0.01) in diabetic patients as compared to the control subjects. The half time of hyperaemia (TH) was significant longer (p < 0.05) for diabetic groups. CONCLUSION: The laser Doppler method is helpful to identify patients with risk development diabetic complications. The most valuable data is MAX, TM and TH, the best localisation of the probe seems to be the most distal point of thumb.

Adult↗

PubMed1976

[Intravascular disorders of microcirculation and microthrombus formation in patients with chronic ischemic disease of the heart].

Most of the 104 patients with ischaemic heart disease had distinct functional and structural microcirculation disorders. The slugging syndrome was revealed in 98% of the cases. In 56% of the patients microthrombus formation was noted in the microcirculatory bed, as well as a reduction of the perfusion capillary blood flow and an increase of the shunting flow, the half-resorption of sodium-131I from the skin and muscle depot being decreased. A clear relationship is noticed between the intravascular microcirculatory disorders, the functional state of the erythrocytes and platelets, the increased coagulation potential of the blood, the appearance of components that indicate the possibility of a diffuse intravascular blood coagulation (fibrinogen B, products of fibrinogen and fibrin decomposition), the changes in lipid metabolism. Stasis of the blood flow with distinct signs of the slugging syndrome, microthrombosis, activation of the kallikrein-kinin system and increasing shunting flow were revealed in patient with a severe course of the disease. Criteria for a quantitative assessment of the noted changes were developed.

Adult↗

PubMed1976

[Disorders of microcirculation and systemic circulation in acute pancreatitis and methods of their correction].

Clinically (in 186 patients) and experimentally the authors studied the peculiarities of variation in microcirculation, organ blood flow and systemic circulation in acute pancreatitis. The authors emphasize the leading role of early arising circulatory disorders in the pathogenesis of acute pancreatitis. The main pathways for correction of hemodynamic disturbances with due account of their causes, character and the sequence of development are described.

Acute Disease↗

PubMed1994

The role of the microcirculation in the multi-organ dysfunction syndrome.

The systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) are significant causes of morbidity and mortality in the intensive care unit. The pathogenesis of MODS is poorly understood; however, endotoxin (LPS) and cytokines (for example interleukins, tumor necrosis factor and platelet activating factor) are thought to play a major role by inducing microvascular injury. A crucial step in the normal functioning of the immune system is the adhesion of cells to each other and, via extravasation, penetration of the extracellular matrix. This is an essential process for normal host defence against injury and infection. In SIRS this process becomes uncontrolled, leading to extravasation of neutrophils causing tissue injury and inflammation. In addition there is increased capillary permeability. It is this disturbance of the microcirculation that is responsible, either wholly or in part, for the development of SIRS and MODS.

Cell Adhesion Molecules↗

PubMed1976

[Characteristics of the terminal segments of the lymphatic system of microcirculation according to the data of scanning electron microscopy].

Lymphatic capillaries and postcapillaries in the system of the connective tissue were studied by the method of scanning (raster) electron microscopy. It was shown that these capillaries consisted of chains of ballon-shaped structures-sinuses. Lymphatic capillaries represent an open system which is communicated with the intercellular matter of the connective tissue by means of openings ensuring filtration of the tissue liquid. Impairment of the absorbing function in the fibrous process in the lungs led to deposition in connective tissue cells of cellular detritus and foreign particles with formation around the walls of lymphatic capillaries and postcapillaries of residue-collector zones. Overgrowth of a rough fibrous tissue around these zones brought about atrophy and obliteration of vessels, gradual attenuation of the drenage function in the given region of microcirculation.

Animals↗

PubMed1976

[Comparative analysis of blood coagulation and various indicators of microcirculation in patients with coronary arteriosclerosis and hypertension in the age aspect].

In patients with hypertensive disease and coronary atherosclerosis the blood-clotting potential increases on account of a rise in the level of procoagulants and inhibition of fibrinolysis. Age-specific differences in the characteristics of the coagulation and fibrinolytic system of the blood are levelled out parallel with the development of atherosclerosis and progressive evolution of hypertensive disease. In patients of advanced age a tendency toward a compensatory increased activity of erythrocytic anticoagulation factors is noted, finding its expression in a drop of the procoagulants level, and increase of anticoagulants and in a rising fibrinolytic activity. Changes in the state of the conjunctival microcirculation and the retinal hemodynamics correlate with the intensity of the pathological process and shifts in the blood coagulation system.

Adaptation, Physiological↗

PubMed1976

[Control of intensive care through the measurement of microcirculation and 02 consumption].

The pO2-multiwire electrode measures the intercapillary oxygen tension. The pO2 histogram, which results from such measurements gives precise information about the question as to whether microcirculation is disturbed or not. Thus, pathological changes in respiration and volume can be recognized earlier than with classical methods. The latter registers the mainly central variables which are compensated for a longer period of time. The local pO2 measurement allows individual regulation of respiratory therapy and monitors the response of oxygen therapy. Using this method oxygen deficiency as well as overdosage of oxygen supply can be averted. Thus, important diagnostic and therapeutic indications can be identified.

Central Venous Pressure↗

PubMedDate not supplied

[Myocardial bridging. The role of microcirculation, coronary reserve and systolic endothelial injury].

BACKGROUND: The relationship between myocardial bridging (MB) and ischemic heart disease is still controversial. However, a recent new evidence suggests that this relation is not by chance. PURPOSE: The purpose of our study was to review in a critical manner, the evidence for the relationship between MB and myocardial ischemia and its possible consequences. METHODS: We present 2 cases of our series and review the medical literature from January 1966 to January 1998 published and included in Medline and Current Contents. RESULTS AND CONCLUSIONS: The principal findings after this review were: 1) MB is not a normal variant; 2) The clinical impact of MB depends on its anatomical extension and degree of compressive effect; 3) The MB muscle is not similar to myocytes from other cardiac areas; 4) The environment surrounding coronary artery may be a crucial factor in determining whether the MB influences the induction of heart disorders or not; 5) The overshoot due to compressive effect on coronary artery might determine endothelial injury in the microcirculation post-MB; 6) In some cases, the systolic endothelial injury may contribute to release factors that are able to reduce the coronary reserve, resulting in myocardial ischemia; 7) The possible role of PTCA in this disorder still has to be proven. Surgical treatment should be considered when important myocardial ischemia had been demonstrated, even in those asymptomatic cases.

Adult↗

PubMed1999

[Hypertensive vascular disease and cerebral microcirculation].

Cerebral microcirculation has a series of complex relationships with arterial hypertension determined, on one hand, by the size and the location of the vessels involved, and on the other hand, by the chronic or acute nature of the hypertension. The small arterial vessels of the cerebral parenchyma react to the effects of chronic hypertension with irreversible structural changes, whose pathologic and radiological correlation is chronic ischemia of the white substance, shown by paleness of the white substance, together with small lacunar infarctions, with a clinical association of dementia, motor disorders and pseudo-bulbar syndrome. With the appearance of an acute rise in arterial pressure, these vessels react with generally reversible changes which lead to an increase in the permeability of the hematoencephalic barrier with formation of cerebral edema and a clinical association generally demonstrating the focal nature of the vascular abnormality (such as in hypertensive encephalopathy with changes in posterior hemispheric predominance) or its unilateral location in cases in which the process occurs in one of the carotid territories (post-endarterectomy).

Brain↗

PubMed1998

Hepatic microcirculation during transient hepatic venous occlusion--intravital microscopic observation using hepatic vein clamp model in the mouse.

The purpose of this experiment was to evaluate the etiology of hepatic dysfunction in patients difficult to wean from cardiopulmonary bypass. We hypothesized that increased central venous pressure and subsequent hepatic congestion during weaning from cardiopulmonary bypass would lead to hepatic dysfunction. To induce hepatic congestion in mice, we clamped the hepatic vein for fifteen min, and observed the microcirculation of the liver using an intravital microscope during clamping and the following 30 min of reperfusion. During reperfusion, non-reflow phenomenon, leukocytes adhesion to the wall of sinusoids, erythrocytes sludging, acute swelling of hepatic cells and narrowing of sinusoids were observed. These phenomena were indicative of warm ischemia-reperfusion injury of the liver itself. Based on these findings we concluded that, after repeated episodes of warm ischemia and reperfusion of the liver, hepatic cells would be damaged, and finally hepatic dysfunction was induced. To prevent hepatic dysfunction, repeated attempts to wean the patient from cardiopulmonary bypass should be avoided and increases central venous pressure should be prevented by early use of cardiopulmonary support.

Animals↗

PubMed1999

Microcirculation in chronic alcoholic pancreatitis: a laser Doppler flow study.

Experimental chronic pancreatitis is associated with microcirculatory disturbances but can also be induced or aggravated by perfusion changes. Microcirculatory alterations in human chronic pancreatitis are poorly defined. In this clinical study we investigated pancreatic microcirculation in the normal human pancreas and in chronic pancreatitis by laser Doppler flowmetry. Laparotomy was performed on 13 patients with nonpancreatic disease and on nine patients with chronic alcoholic pancreatitis for pancreatic head resection. Blood flow was measured over the pancreatic head, the uncinate process, over the mesenteric vein, the pancreatic corpus, and over the pancreatic tail by laser Doppler flowmetry. Blood flow was highest in the head of a normal pancreas with a mean of 436 +/- 34 perfusion units (PU), 399 +/- 43 PU in the uncinate process, 286 +/- 30 PU in the pancreatic corpus, and 351 +/- 46 PU in the tail of the pancreas. In the normal pancreas, lowest blood flow was measured over the mesenteric vein (228 +/- 23 PU). In chronic pancreatitis, blood flow in the pancreas was significantly decreased across the whole pancreas (p < 0.01). Furthermore flow-wave pattern was altered in chronic pancreatitis as compared with the normal pancreas. The normal human pancreas has a spatial variation in blood flow, correlating with the pancreatic arterial blood supply. In the chronically inflamed human pancreas, blood flow is significantly diminished, with a lower flow toward the pancreatic head.

Blood Flow Velocity↗

PubMed1999

Role of microcirculation in hepatic ischemia/reperfusion injury.

There is a large body of evidence that the liver microcirculation has to be considered as a major target in hepatic ischemia/reperfusion injury. The nature of microvascular injury, which precedes manifestation of hepatic parenchymal tissue damage, includes both hypoxia due to lack of microvascular perfusion (i.e. no-reflow), and a reperfusion-associated inflammatory response, which includes the activation and dysfunction of leukocytes and Kupffer cells (the reflow paradox). No-reflow in sinusoids is thought to be caused by endothelial cell swelling and intravascular hemoconcentration, and involves also a deterioration of the balance between ET and NO. The reflow paradox is associated with: (i) the release and action of proinflammatory cytokines (TNF-alpha, IL-1) and oxygen radicals; (ii) the up-regulation of endothelial and leukocytic adhesion molecules (selectins, beta-integrins, ICAM-1); and (iii) the interaction of leukocytes with the endothelial lining of the hepatic microvasculature.

Animals↗

PubMed1998

Effects of electroacupuncture at neiguan on myocardial microcirculation in rabbits with acute myocardial ischemia.

This paper reports the effects of electroacupuncture (EA) at Neiguan (P 6) on myocardial microcirculation and electrical activity observed in rabbits with acute myocardial ischemia (AMI) by employing the vascular casting method and taking monophasic action potential (MAP) as an index. It was found that in the ischemic border zone of the heart, the electrical excitability was strengthened, the shortening of the phase repolarization inhibited, and the number of the micrangia increased in some degree following EA. This suggests that EA can relieve arteriolospasm, inhibit extreme dilatation of blood capillaries, modulate imbalance of micro-vasomotion of the coronary artery, improve myocardial blood-supply, and promote normalization of electrical activities of the ischemia myocardium. This fact not only elucidates the recovery mechanism of the ischemic myocardium promoted by EA at Neiguan (P 6), but also provides morphological basis for the theory of relationship between Neiguan of the Pericardium Meridian and the heart.

Action Potentials↗

PubMed1999

Effects of intracranial pressure on the pial microcirculation in rats studied by a fiber-optic laser-Doppler anemometer microscope.

The fiber-optic laser-Doppler anemometer microscope (FLDAM) developed in our laboratory was applied to measure red cell velocity in individual pial microvessels in rats to determine the effect of intracranial pressure (ICP) on the pial microcirculation. The red cell velocity and the vessel diameter of pial microvessels were measured through a closed cranial window at controlled values of ICP between 0 and 50 mmHg. As ICP increased from 0 to 50 mmHg, the average relative diameter of venules with respect to the diameter at an ICP of 5 mmHg decreased from 1.18 +/- 0.12 (mean +/- SD) to 0.74 +/- 0.08 and the average relative velocity increased from 0.80 +/- 0.20 to 1.83 +/- 0.42 monotonically. The changes in diameter and velocity of arterioles with ICP were small, and they were not significantly different from those values at an ICP of 5 mmHg except for the diameter at an ICP of 20 mmHg. The mean volume flow rates calculated assuming a circular vessel cross-section did not show any statistically significant change with ICP between 0 and 50 mmHg in both arterioles and venules, which supports the concept of autoregulation.

Animals↗

PubMed1997

[Mechanism of action of neurotensin on microcirculation, metabolism and motility of the small intestine].

The aim of this study was to investigate the influence of neurotensin on total microcirculatory blood flow, oxygen consumption, myoelectric activity and motility of the small bowel. The attempts were made to evaluate the role of L-Arginine, NO-system in the mechanism of action of this peptide on microcirculation, metabolism and motor-activity of the intestine. The experiments were performed in two experimental models--dogs and rats. In Vetbutal anesthetised animals the systemic arterial pressure, superior mesenteric artery blood flow, microcirculatory blood flow and myoelectric activity of the small bowel were continuously monitored. In experiments with dogs effective capillary index, arterio-venous oxygen difference and oxygen consumption were analysed. Neurotensin administered intraarterially caused a dose depended increase in total and microcirculatory blood flow in the small bowel in both groups of animals. The experiment with dogs showed the rise of effective capillary index and intestinal oxygen consumption. Administration of neurotensin changed the profile of myoelectric activity of the small bowel similar to that of postprandial hyperaemia. Inhibition of NO-synthase by the intravenous administration of L-NNA reduced significantly the amplitude of neurotensin hyperaemia. Pretreatment with L-Arginine, the substrate of NO-synthase reversed the hemodynamic, but not motility effects of neurotensin. The results presented proved the role of the L-Arginine-NO in circulatory mechanism, but not motility effects of neurotensin.

Animals↗

PubMed1999

New techniques for clinical assessment of the peripheral microcirculation.

Current methods for clinical investigation of the cutaneous microcirculation in patients are based mainly on laser Doppler and capillary microscopy. The use of laser Doppler gives a semi-quantitative index of superficial tissue perfusion. The most recent devices are capable of analysing both the volumetric and velocimetric components. New instruments use two different frequencies to compare tissue perfusion at different depths beneath the skin surface. The combination of a laser probe and a small automate produces a 2-dimensional image, allowing the evaluation of spatial heterogeneity in tissue perfusion, an important pathophysiological concept in vascular diseases. Capillaroscopy has recently been improved by the emergence of the flexible videomicroscope, allowing easy exploration of not only the classical site of the nail-fold but also of the body skin surface. The use of this method was therefore extended--from peripheral vascular disease and connective tissue diseases to the whole spectrum of trophic changes in the skin of the extremities. Systems for digital image analysis allow quantification of the structure of the microvascular bed (quantitative appraisal of microangiopathies) and function (capillary haemodynamics and exchange). Laser Doppler and capillaroscopy can also be combined for the measurement of red blood cell velocity in single capillaries.

Humans↗

PubMedDate not supplied

[Late radiation effects in the microcirculation system of the mouse brain after chronic low-dose irradiation].

The radiation reaction of the mouse brain microvascular system was investigated 15 months after chronic (dose-rate was 3 cGy/day) and acute (dose-rate 3.2 Gy/min) gamma-irradiation. Late pathological changes in the microvascular system after the acute irradiation (3 Gy) were not found. In the same time, after chronic irradiation with equivalent dose (the accumulated dose was 3 Gy) the depletion of endothelial cell population, and multiple foci of minor pathological changes of endotheliocyte ultrastructure at as many as 50% of the population were revealed. It may be more likely to lead to reduction of tolerance of brain microvascular system to an acute radiation (10 Gy) in the late period after chronic exposure. The mechanism of impairment of brain microcirculation after low chronic irradiation will have to understand.

Animals↗