SEARCH · PubMed Health

Results for “Microcirculation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources

PubMedDate not supplied

[The physiology of microcirculation].

Since the work of Harvey and Malpighi, there have been more questions than answers in the physiology of the microcirculation. The microvessels and the interstitial connective tissue form a true functional and structural unit in which the capillary is only a passive feature. It is subject to the constraint of the connective tissue that surrounds it, is only a reflection of the hydraulic conditions above and below it and is a luxury metabolic pathway compared with the importance of the derivative or shortcircuit arteriovenous pathway in which the metarteriole is of major importance. Continual renewal, apparent vasomotor character, and extreme permeability sum up the physiology of the microcirculation. The cybernetics is dominated by the arteriolo-venular functioning and by chain rections. Stasis, the opening of arterio-venous anastomoses, and sludge are the main pathological features. Investigation of capillary function remains difficult under clinical conditions, since different methods give a global picture, that of the vascular-tissue unit.

Capillaries↗

PubMed1998

[Microcirculation in gastrointestinal cancer and some possibilities of its correction].

Microcirculation and blood rheology were studied in 348 patients with tumors of the gastrointestinal tract. Such disorders as increased blood and plasma viscosity, aggregates of erythrocytes and their increased stability of shape were recorded in conjunction with hypo- and dysproteinemia, endogenous intoxication syndrome and microvascular disturbances. Microcirculation significantly improved and endoxemia was alleviated following photomodification of the blood by use of helium-neon laser radiation and application of an original procedure of infusion.

Blood Viscosity↗

PubMed1999

[Assessment of tissue microcirculation in patients with aseptic necrosis of femur heads in systemic lupus erythematosus (SLE)].

AIM: To study microcirculation in the tissues above the hip joints with and without aceptic necrosis of the femur head for diagnosis of necrosis stages. MATERIALS AND METHODS: 22 SLE patients were examined for blood flow above the region of affected and intact (control) hip joints using clearance of Xe-133 from the intratissue deposit. Basal circulation and factors of its regulation were investigated with laser dopplerflowmetry. RESULTS: Effective skin blood flow above the hip joints with necrosis stage I significantly differed from that of the control. Basal skin blood flow above the hip joints in suspected stage I of aceptic necrosis differed significantly from the control and that in stage II osteonecrosis. CONCLUSION: The study of tissue microcirculation above the hip joints in SLE patients with aceptic necrosis of the femur heads allows making diagnosis both at early and late stage of osteonecrosis.

Blood Flow Velocity↗

PubMed1976

[Role of microcirculation in the development of pulmonary hypertension in chronic non-specific lung diseases].

A comparison of the results of morphological studies of pulmonary and pleural microcirculation with the indices of haemodynamics in the system of the pulmonary artery in patients with chronic non-specific lesions of the lungs accompanied by suppurative processes indicates the participation of microcirculation in the development of pulmonary hypertension. A lasting course of the disease with frequent exacerbations results in profound changes in the system of micricirculation. The pathological developments in the vascular terminals, the disorders in the rheological properties of the blood, in vascular permeability- the hampered lymph drainage that are the causes of irreversible metabolic shifts not only become additional factors in the development of the underlying pathology, in the formation of bronchiectases in particular, but also provide for a further development of pulmonary hypertension.

Adult↗

PubMed1999

[Examination of skin microcirculation with laser-Doppler flowmetry in patients with essential hypertension].

The estimation of microcirculatory parameters in patients with essential hypertension and in normotensic control group was the aim of this study. The study group consisted of 14 patients with essential hypertension confirmed by 24-hours ABP. 10 healthy patients served as control group. The flow in the skin microcirculation was measured by laser-Doppler flowmeter (PF-3, PERIMED) on dorsal part of the palm. Microcirculatory indices were registered in resting conditions, during one-minute occlusion reaction and during reactive hyperemia. The following indices were calculated: resting flow, biological zero, maximal flow, time to maximal flow, ratio of maximal to resting flow, ratio of resting flow to biological zero and ratio of maximal flow to biological zero. Skin microcirculation was highly disturbed in patients with essential hypertension. It was expressed by significantly higher biological zero and longer time to maximal flow.

Adult↗

PubMedDate not supplied

[Endothelial function and the microcirculation in diabetes mellitus].

The role of endothelial dysfunction in the pathogenesis of diabetic microangiopathy is reviewed. Reversible alterations in microcirculation, consisting of increased capillary pressure, blood flow and endothelial permeability, can be detected at an early stage in diabetes mellitus. Irreversible structural modifications of the vascular wall, such as thickening of the basal membrane due to the extracellular accumulation of proteins, take place at later stages. Atherosclerosis further affects microcirculation in diabetes mellitus by decreasing autoregulatory capacity and blood flow reserve. Endothelial dysfunction has been observed to precede the onset of microvascular lesions, as demonstrated by reduction in the vasodilatory response to vasoactive agents and by alterations in the antithrombotic properties of the endothelium. Experimental data available so far suggest that endothelial dysfunction may be directly related to hyperglycemia. Abnormalities in lipoprotein metabolism, generation of glycation end products, and increased oxidative stress may also be responsible for the endothelial dysfunction in diabetes mellitus. Insulin resistance appears to be related to endothelial dysfunction in non-insulin-dependent diabetes mellitus through a reduction in the biological activity of endothelial-derived nitric oxide.

Animals↗

PubMedDate not supplied

[Methods for vascular exploration in man: microcirculation and veins].

The pharmacodynamic evaluation of venotropic compounds deals mainly with vascular reactivity and fluid exchanges. At the microvascular level, three kinds of approaches can be used: (1) clinimetric measurements of cutaneous temperature (thermometry), skin colour (chromametry) and leg volume; (2) indirect physical parameters evaluating the haemodynamic or nutritional efficacy of the microcirculation (TcPO2 and laser doppler); (3) capillaroscopy with digital image analysis, which allows a quantification of the microvascular bed, of some kinds of transcapillary exchanges and of lymphatic microcirculation. At the venous level, they are also several usable techniques: (1) US duplex, which allows measurements of venous diameter variations; (2) plethysmography, which evaluates the compliance of the venous system from pressure/volume curves.

Capillaries↗

PubMed1999

[Evaluation of functional potentials of microcirculation in patients with obliterating diseases of lower limb vessels].

An analysis of the data of laser doppler fluorometry in 136 patients has shown that different obliterating diseases have different typical fluorometric features of changes in microcirculation. Results of the postischemic test are of greater informative value in the noninvasive assessment of the functional state of microcirculation. The significance of the functional tests was particularly increasing in critical ischemia of the lower extremities. The intraoperative determination of the muscle blood flow allowed performing the control of the lower extremity revascularization and determining the optimum level of amputation.

Adult↗

PubMed2000

[Long-term effect of topically applied isopropyl unoprostone on microcirculation in the choroid-retina].

PURPOSE: To study the long-term effect of topically applied 0.12% isopropyl unoprostone (unoprostone, Rescula) on microcirculation in the ocular fundus. MATERIALS AND METHODS: Using a laser speckle tissue circulation analyzer, normalized blur (NB), a quantitative index of blood flow velocity and tissue blood flow, was measured in the optic nerve head (ONH) and choroid-retina before and 4.5 hours after an instillation of placebo into both eyes in 11 normal human volunteers. Intraocular pressure (IOP), blood pressure, and pulse rate were also measured. A drop of unoprostone or the placebo was instilled into each eye in a double-blind manner twice a day for 21 days (the treated or untreated eye). RESULTS: Twenty-one days later, NB values in the ONH and the choroid-retina increased significantly and the IOP decreased significantly only in the treated eyes. Ocular perfusion pressure showed no significant changes. CONCLUSIONS: These results suggest that the increase of the blood flow in the microcirculation in the human ocular fundus following the relatively long-term topical application of unoprostone may be due to reduction in vascular resistance.

Administration, Topical↗

PubMed1997

[The effect of anisodaminum and dexamethasone on microcirculation, TNF, LPO and pathology in MODS].

In order to evaluate the effect of anisodaminum and dexamethasone to the microcurculation, TNF, LPO and pathology in MODS, we first established MODS model using cecem ligature and perfuration of rabbit then divided it into four groups: anisodaminum, dexamethasone, combined anisodaminum and dexamethasone and control. After used the corresponding drugs we observed the change of microcirculation, TNF, LPO and organ pathology. The result showed that microcirculation improved, the serum level of TNF and LPO decreased, and the pathomorphological changes lessensed. It is suggested that the combined use of anisodaminum and dexamethasone may be a new way for treating MODS.

Animals↗

PubMed1999

Endothelin, microcirculation and hemorheology.

Although a large amount of data concerning microcirculation and cardiovascular disease exists, little is known about microcirculation and hypertension. This is largely due to the difficulty in selectively examining capillaries and metarterioles, independently from small arteries or large vessels. The physiological role of capillaries and metarterioles, the two elements that make up the microcycle, is peculiar and closely related to metabolic exchange. During the hypertensive state, several factors can alter these mechanisms. These include elevated plasma viscosity, abnormal membrane properties of red blood cells, and an increase in fibrinogen, LTL and hematocrit levels. The question of whether an abnormal release of endothelium derived vasoactive factors from capillaries, or an abnormal production of chemical factors by blood cells running through the vasculature area is present in hypertensives is fascinating, but unfortunately neither experimental nor clinical data has yet been able to answer it. Recently, evidence of the formation of endothelin by red blood cells from endogenous precursors was given, suggesting that red blood cells may modulate the vascular tone both directly, through the release of ATP or endothelin-1, and indirectly, when hemolysis occurs and hemoglobin is released. The pathological significance of these findings has not been clearly demonstrated in hypertension thus far, although it is reasonable to hypothesise that there are clinical implications for the pathogenesis and the progression of vascular damage during the hypertensive state.

Animals↗

PubMed1999

Influence of radiographic contrast media (Iomeprol 350 versus Iopentol 350) on cutaneous microcirculation: single-center prospective randomized double-blind phase iv study in parallel-group design.

OBJECTIVE: This single-center, prospective, randomized, double-blind phase IV study in parallel-group design was carried out to investigate whether either of two different x-ray contrast media (iomeprol 350 or iopentol 350) injected into the axillary artery has any influence on cutaneous microcirculation. METHODS AND RESULTS: The investigation was carried out on two groups of patients (n = 10 in each group) who had to undergo a diagnostic heart catheter angiography. The confirmatory response variable for the study was the mean capillary erythrocyte velocity (mm/sec). Blood flow through the ipsilateral nail-fold capillaries was recorded continuously for 3 minutes before and 6 minutes after the injection of the randomly assigned x-ray contrast medium, and was evaluated off-line. A contrast medium-induced, rheologically determined disturbance of the microcirculation was found, which was due to two different effects. First, the high intrinsic viscosity (iopentol = 12.3 mPa.sec) led to an immediate reduction in capillary blood flow. This did not occur in the case of iomeprol (intrinsic viscosity = 7.5 mPa.sec). Second, the contrast medium molecules cause a morphological change in the erythrocyte membrane; echinocytes are formed and are further desiccated depending on osmolality of the contrast medium. CONCLUSION: The time course of the conversion of erythrocytes into echinocytes leads to a maximum reduction in capillary erythrocyte velocity of 30 seconds after the bolus of contrast medium. For the more viscous contrast medium of higher osmolarity (iopentol), this led to a significant overall reduction of up to 48.6% in capillary blood flow (p < 0.0001) that lasted for up to 150 seconds, while iomeprol did not significantly affect capillary blood flow (p = 0.2759).

Arteriosclerosis↗

PubMed2000

[Characteristics of microcirculation and vascular responsiveness in elderly patients with hypertension and ischemic heart disease].

Microcirculation and vascular responsiveness were studied in 52 patients with arterial hypertension and ischemic heart disease versus 48 healthy elderly persons. The patients were found to have defects of the end blood flow in all links of microcirculation, longer and more severe vasoconstriction of conjunctival and skin vessels in response to norepinephrine and cold stimulation tests.

Aged↗

PubMed2000

Functional analyses of patient-derived IgG monoclonal anticardiolipin antibodies using in vivo thrombosis and in vivo microcirculation models.

Antiphospholipid antibodies (aPL) have been associated with thrombosis and pregnancy losses in patients diagnosed with antiphospholipid syndrome (APS) and enhance thrombus formation in vivo in mice, but the mechanism of thrombosis by aPL is not completely understood. It has been proposed that aPL may affect endothelial cell (EC) function and/or induce their activation, transforming their anticoagulant surface into procoagulant, thus predisposing to thrombosis. It has been proposed that aPL may affect EC cell function and/or induce their activation, transforming their anticoagulant surface into procoagulant, thus predisposing to thrombosis. This study proposes to test the hypotheses that some IgG anticardiolipins (IgG aCL) with thrombogenic properties in mice, exert their effects through activation of endothelium. We studied seven patient-derived monoclonal aCL for their thrombogenic properties in an in vivo pinch-induced thrombosis model, and their functional activities in activating EC by analyzing in vivo leukocyte adhesion to endothelium in microcirculation in venules in exposed murine cremaster muscle and in vitro adhesion molecule expression in cultured EC. The binding of the monoclonal aCL to EC was also tested. In addition to the previous identified thrombogenic IS2, four of the five new more IgG monoclonal aCL (from two patients) were found to be thrombogenic. Of these five thrombogenic aCL, three caused more in vivo leukocyte adhesion to EC in microcirculation, as compared to that induced by the H2 control human monoclonal IgG, and enhanced expression of adhesion molecules (particularly VCAM-1) on cultured EC. These data show that about 2/3 patient-derived IgG monoclonal aCL are thrombogenic and suggest that some thrombogenic IgG aCL exert their effects through activating EC.

Adult↗

PubMed2000

[Effect of vazaprostan on microcirculation in patients with scleroderma systematic].

AIM: To investigate the effect of vazaprostan (alprostadil) on skin blood flow in patients with sclerodermia systematica (SS). MATERIAL AND METHODS: A total of 51 patients with SS aged 33-70 years were included in the study. 33 of them received a 3-hour infusion of vazaprostan at the standard dose for 20 consecutive days. The rest 18 patients received low molecular dextran solution. Before and at the end of the treatment digital skin microcirculation was measured with a laser Doppler flowmeter. The laser probe was attached to the distal pad of the ring finger on the left hand. Baseline blood flow and vascular reactivity in the tests with sympathetic stimulation, local heating and during orthostasis were evaluated. RESULTS: Baseline blood flow and vascular response to functional tests were significantly reduced in all the patients. At the end of the treatment the flow increased only in patients treated with vazaprostan. Vascular reactivity was not changed after the treatment in both groups of patients. CONCLUSION: Vazaprostan increases baseline blood flow and contributes to the improvement of microcirculation in patients with SS.

Adult↗

PubMed2001

Tumor microcirculation evaluated by dynamic magnetic resonance imaging predicts therapy outcome for primary rectal carcinoma.

Contrast enhanced dynamic studies of malignant tumors performed by computed tomography or magnetic resonance imaging (MRI) are increasingly applied to characterize tumor microcirculation for the prediction of therapy outcome. The aim of our study was to correlate perfusion index (PI) values determined in primary rectal carcinoma before chemoradiation with therapy outcome. In 17 patients with clinically staged T3 primary rectal carcinoma, dynamic MRI was performed before the onset of therapy using an ultrafast T1-mapping sequence. On the basis of the acquired data sets, PI values were calculated on a pixel-by-pixel basis. To characterize the heterogeneity of tumor microcirculation, relative cumulative frequency histograms of PI values within the tumors were computed. Subsequent resection of the tumors allowed correlating PI with histopathological classification. In 12 of 17 patients, T-downstaging as a response to therapy was found, whereas in the remaining 5 patients no therapy response was observed after chemoradiation. A statistically significant difference between both groups was found for the mean PI (P < 0.001; 8.5+/-1.7 ml/min/100 g versus 11.4+/-0.7 ml/min/100 g). Analyzing the cumulative frequency histograms for both groups revealed an optimal discrimination for a P1 value of 12.6 ml/min/100 g. The fraction of pixels in the tumor with PI values larger than 12.6 ml/min/100 g was significantly different (P < 0.001) between therapy-responding (3+/-3.6%) and therapy-nonresponding tumors (21+/-4.3%). The results indicate either a reduced supply of nutrients as well as chemotherapeutic agents attributable to increased shunt flow or highly aggressive tumor cell clusters characterized by increased angiogenic activity. Noninvasive PI measurements by dynamic MRI in rectal carcinoma before therapy seem to be of predictive value for therapy outcome in patients scheduled for preoperative chemoradiation.

Adenocarcinoma↗

PubMed2001

Heparin protects local skin microcirculation in 210 minutes-long intravital microscopy observations under general anaesthesia.

UNLABELLED: Prolonged immobilization of severely ill, bed-ridden patients results in formation of pressure ulcers following inappropriate tissue blood perfusion, and local activation of leukocyte - endothelial cell interactions (L/EC). Various treatment modalities were implemented to improve local microcirculation with controversial results. The aim of our study was to investigate the influence of heparin and buflomedil, drugs improving the microcirculation, on local skin blood perfusion using intravital fluorescent microscopy (IVM) technique. MATERIAL AND METHODS: Experiments were carried out on 24 male hairless mice under inhalatory isofluran anaesthesia. Intravenous injection of FITC-dextran (150 kD, 5%) allowed to visualize capillaries during IVM, after immobilisation of hind limb, in an observation chamber. Observations were performed after i.v. injection of heparin (66 IU/kg b.w., n = 8) or buflomedil (6 mg/kg b.w., n = 8) 30, 120 and 210 minutes after chamber installation. Observations were recorded in 30 sec sequences on S-VHS tapes and evaluated using special software. Functional capillary density (FCD), defined as a total length of red cells perfused capillaries per observation field (expressed in cm/cm(2)), postcapillary venule diameters, and number of sticking leukocytes per 0.2 mm vessel length during 30 sec observation time, served as parameters of skin blood perfusion and activation of L/EC interactions. RESULTS: A statistically significant decrease of FCD from 152.7 +/- 38.5 to 100.7 +/- 36.7 cm/cm (2) (p<0.05) was observed in control animals during 210 min lasting observation. Administration of heparin prevented decrease in FCD occurring in control animals during intravital microscopy, whereas buflomedil was found ineffective. Both drugs induced a nonsignificant reduction in the number of sticking leukocytes, whereas no changes in postcapillary venule diameters could be observed. CONCLUSION: The results suggest a protective effect of heparin in clinical therapeutic doses against impairment of skin perfusion during IVM. This observation may justify a trial on the effects of heparin in prevention of development of pressure ulcers.

Animals↗

PubMed2001

[Comparative evaluation of tissue microcirculation in patients with aseptic necrosis of the femur head in rheumatoid arthritis and systemic lupus erythematosus].

AIM: Comparative investigation of tissue microcirculation above hip joints affected with verified aceptic necrosis of the heads of the femur (ANHF) in patients with rheumatoid arthritis (RA) and SLE. MATERIAL AND METHODS: The microcirculation was compared in 44 RA and 22 SLE patients. Capillary blood flow above the necrotic heads of the femur was studied by 133-Xe clearance from the intratissue depot. Laser doppleroflowmetry examined basal blood flow and factors of its regulation. RESULTS: Effective skin blood flow decreased both in RA and SLE patients at ANHF stage I, remained low at stage II, went up a little at stage III. At stage IV the flow continued to rise in RA patients but fell sharply in SLE. Laser dopplerflowmetry with functional tests reflects ANHF evolution both in RA and SLE. CONCLUSION: Changes in capillary blood flow in SLE above the necrotic heads of the femur are more severe and account for more extensive destruction in the heads of the femur than in patients with RA.

Adult↗