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At least 1,747 records · Page 97Linked to original sources
PubMed2000

[Role of microcirculation in multiorgan failure of infectious origin].

The normal host response to infection is a complex process which serves to localize and control bacterial invasion and to initiate repair of injured tissue. This inflammatory process is accompanied by activation of circulating and fixed phagocytic cells and generation of pro-inflammatory and anti-inflammatory mediators. Sepsis results when the prerequisite inflammatory response to infection becomes generalized, and thereby extends to involve otherwise normal tissue which is remote from the initial site of injury or infection. Sepsis is typically associated to cardiovascular alterations that have been characterized by increases in oxygen delivery to the tissues. Paradoxically, the host's systemic inflammatory response syndrome may simultaneously disturb the ability to adequately match tissue oxygen needs and availability at a time when tissue oxygen needs are typically increased. Depressed tissue oxygen availability relative to augmented needs may result from dysfunction at all of the central, regional, and microregional levels of the circulation. Significant dysregulation in the process by which oxygen availability is usually matched to changing tissue oxygen needs is typical associated with changes the microvascular blood flow behavior, vascular reactivity and endothelial and leukocyte activation. Specific tools developed to explore the microcirculation have been applied in the setting of both human and animal models sepsis. Abnormalities observed in the septic microvasculature are characterized by reductions in cutaneous and skeletal muscle blood flow and in mucosal intestinal ischemia and hypoxia. Regarding the skeletal muscle organ system, microvascular abnormalities were further characterized by an impairment of blood flow to increase in response to oxygen need increase. Also, microvascular abnormalities in the intestine were associated with evidence of endothelial and leukocyte activation leading to epithelial dysfunction. Thus, sepsis appears to be associated with early onset microvascular dysfunction. The relationship between microvascular dysfunction and endothelial and leukocyte activation leading to organ failure has been suggested by numerous studies.

Blood Flow Velocity↗
PubMed1995

Forehead skin microcirculation during tilt table testing and lower body negative pressure.

Noninvasive skin microcirculation measurements based on a new Near Infrared sensor technique (NIR/Fa. Silicon Sensor GmbH; Berlin) were embeded in a tilt table experiment for simulation of acute effects of weightlessness (HDT -6 degrees) and active standing with the Russian Tschibis-LBNP device. The phenomenon of orthostatic intolerance depends on complex interactions among functional characteristics of central and peripheral cardiovascular control. The purpose of this study was to assess the blood volume and flow motion changes as well as pulsatile spectral pattern during orthostatic and antiorthostatic stress.

Adult↗
PubMed1997

[Comparison of evaluation methods on changes of facial microcirculation during induction of motion sickness].

In order to increase the accuracy of motion sickness grading criteria, infrared thermography and Laser Doppler microcirculation blood-flow detector were used in 60 healthy male individuals: before, immediately, and 20 min after paralleled-swing stimulation. Facial skin temperature and microvessel blood-flow were recorded. The results showed that facial skin temperature and blood flow in facial microvessels fell together with the appearance of pallor. However, the degree of pallor observed with naked eye was inconsistent with that found by thermography or facial blood flow. It suggests that the accuracy of grading might be improved with the use of thermography or measurement of facial microvessel blood flow.

Face↗
PubMed1975

Effects of vasodilating agents on the microcirculation in marginal parts of the skeletal muscle.

The present investigation was performed to gain information on the changes in the microcirculation of the skeletal muscle during the application of vasodilating agents. The flow velocity in various microvessels was measured cinematographically in isolated and non-isolated muscles of the hindlimb in cats and rats. During the intra-arterial infusion of acetylcholine (1 mug/kg times min), bradykinin (2 mug/kg times min) and isoprenaline (1 mug/kg times min) a decrease in the flow velocity up to a complete stasis was found in most of the microvessels in the marginal parts of the muscles examined. These reactions set in when the femoral flow increased and disappeared when the femoral blood flow returned to the baseline level. The experiments demonstrate that the increase in total blood flow induced by the intra-arterial infusion of vasodilating agents may be associated with a reduced perfusion of certain parts of the striated muscles.

Animals↗
PubMed1975

Metabolic and myogenic factors in local regulation of the microcirculation.

Patterns of flow were recorded from individual capillaries of mesentery and muscle during autoregulation and reactive hyperemia. In cat mesentery at normal arterial pressure capillary blood flow was often periodic in nature. When arterial pressure was reduced periodicity was abolished and in certain cases mean flow increased. Elevation of venous pressure at this time caused restoration of flow periodicity and simultaneously a large fall in mean flow. Vasomotion and autoregulation in mesentery appear to be dependent on intravascular pressure per se. In cat sartorius muscle substantial increase in flow was seen in most capillaries during reactive hyperemia. In certain capillaries the pattern resembled the gross flow pattern while others showed a brief hyperemia and then a period of flow arrest that is presumably due to a strong precapillary vasoconstriction. The latter response is suggestive of a myogenic control while the former may be due to accumulation of metabolites. In frog pectoralis muscle reactive hyperemia was very prolonged in comparison to cat sartorius muscle. The general pattern of flow was consistent with the notion of a strong metabolic control mechanism. The three tissues studied provide examples of strong myogenic, strong metabolic, and combined metabolic and myogenic control of the microcirculation.

Animals↗
PubMed1975

Pressure regulation in the microcirculation.

The results of direct pressure measurements are described which demonstrate that pressures in a certain fraction of mesenteric capillaries remain remarkably constant during large changes in systemic pressure. The results of isogravimetric studies, reported in the literature, are also described which indicate that this phenomenon may also occur in the intestine. The question is raised whether capillary pressures may therefore be regulated. Pressures recorded from mesenteric arterioles and capillaries are shown which indicate that maintenance of a constant capillary pressure is primarily the consequence of the vascular architecture peculiar to this tissue, and is merely a secondary reflection of mechanisms associated with flow regulation. The results of direct pressure measurements recorded in the microcirculation of intestinal muscle are also shown. These data indicate that capillary pressures in innervated, denervated, and xylocaine-treated intestinal muscle change in direct proportion to variations in arterial pressure. It is concluded that capillary pressures in the intestinal muscle layers are therefore not regulated, so that the observation that capillary pressures may be maintained is probably a phenomenon unique to the mesentery. Pressures recorded from capillaries in the mucosal villi are also shown and compared to capillary pressures measured in the microvasculature of mesentery and intestinal muscle. When systemic pressure was normal (107 +/- 10 mm Hg), capillary pressure in the mesentery averaged 30 to 33 mm Hg; capillary pressures in the intestinal muscle averaged 22 to 24 mm Hg; and capillary pressures in the mucosal villi averaged 13 to 15 mm Hg. These data suggest that mesenteric capillaries are primarily a filtering network; intestinal muscle capillaries are normally in fluid balance; whereas at rest mucosal capillaries are primarily absorptive. These pressures, recorded from the three major regions of the rat intestine, were used to calculate a weighted average for the whole organ. The calculated value, based on assumed values for relative capillary densities, was 17 mm Hg. This result compares favorably with data from whole organ, isogravimetric studies, and may clarify some of the apparent discrepancies between previous isogravimetric and servopressure studies.

Animals↗
PubMedDate not supplied

[principal characteristics of tumor microcirculation revealed by experimental techniques in vivo].

In this brief review, we show that intravital microscopy has permitted characterization of the specific aspects of tumour microcirculation. Microvascular networks in tumour are largely different from those in non-tumoural tissue or in non-tumoural neoangiogenesis. Both from the anatomical and the hemodynamical aspects, the tumour microvascular network appears highly chaotic. In vivo measurements have shown the large heterogeneity of oxygen and metabolic status associated with tumour growth. Effects of antiangiogenic drugs can also be tested using intravital microscopy. These techniques have also allowed demonstration of the specific vasomotor response of vessels irrigating tumours, thus allowing specific modulation of tumour blood flow.

Animals↗
PubMed2002

[Can adenosine triphosphate induce maximal hyperemic response in patients with impaired coronary microcirculation?: comparison of hyperemic response to adenosine triphosphate administered by intravenous and by intracoronary injection using Doppler guide wire].

OBJECTIVES: This study compared the hyperemic responses to adenosine triphosphate (ATP) administered by intravenous and by intracoronary injection in patients with impaired coronary microcirculation. METHODS: The hyperemic responses to intravenous and intracoronary administration of ATP in 107 patients (mean age 63 +/- 10 years, 77 males, 30 females) with impaired coronary circulation [including myocardial infarction (n = 68), cardiomyopath (n = 20) and diabetes mellitus (n = 11)] were compared by measurement of coronary flow reserve (CFR) using the Doppler guide wire. Patients with chest pain syndrome were used as the normal controls. The coronary blood flow velocity was measured at rest and during peak hyperemic responses to intravenous infusion (150 micrograms/kg/min) and intracoronary infusion of ATP (50 micrograms in the left coronary artery, 25 micrograms in the right coronary artery). The CFR was calculated as the ratio of averaged peak velocity during hyperemia to baseline averaged peak velocity. RESULTS: The CFR after intravenous administration of ATP (CFRi.v.) was well correlated with CFR by intracoronary administration of ATP(CFRic) (r = 0.77, p < 0.001). However, the CFRi.v. was also inversely correlated with the ratio of CFRic to CFRiv (CFRic/i.v.) (r = -0.36, p < 0.001). There were no relationships between the changes of hemodynamic parameters(blood pressure and heart rate) induced by ATP and CFRic/i.v. A lower CFRi.v. of less than 2.0 provided significantly greater CFRic/i.v. than that of CFRiv greater than 2.0. CONCLUSIONS: The maximal hyperemic response of coronary artery was not always induced by conventional intravenous administration of ATP, especially in patients with lower CFR than 2.0. High dose of intravenous ATP and/or intracoronary ATP should be administered in patients with lower CFR to attain maximum hyperemia in the impaired coronary circulation.

Adenosine Triphosphate↗
PubMed2000

[Acoustic densitometry for quantification of renal allografts microcirculation and microstructure].

OBJECTIVE: To establish a new method for observing renal allografts microcirculation and microstructure with acoustic densitometry (integrated backscatter, contrast, second harmonics). METHODS: 27 patients with renal allografts were investigated by Doppler, IBS, contrast and second harmonics. Renal allografts failed age in 5 patients 20-61 years. Intravenous injection of SHU-508A was given, compared with pre-injection by quantitative assessment of acoustic densitometry (AD) of renal microstructure. RESULTS: There was a significant difference in the peak intensity, the area under the curve and the half-time of wash-out between pre-injection and injection contrast agent. The wish-in and wish-out curve was shown in a peak shape. The renal allografts with acute rejection were significantly lower than the control group in AD (P < 0.05). No contrast opacification of renal microstructure was present in 5 failed renal allografts and the wish-in and wish-out curve appeared in a straight line shape. CONCLUSION: AD is safe, and efficient in assessing renal allografts microstructure. It more sensitive in detecting allograft complication such as rejection than Doppler.

Adult↗
PubMedDate not supplied

["Small volume resuscitation" in hypovolemic rats. Effects on microcirculation].

BACKGROUND: Numerous publications have analysed the hemodynamic effects of "small volume resuscitation" during the initial phases of hemorrhagic shock. Nevertheless nowadays the information about microcirculatory effects are poor. The aim of this study was to estimate the change of tissue perfusion in hypovolemic rats, before and after infusion of Ringer's lactate (RL), hypertonic saline solution (HS) or blood. METHODS: Mesocecal microcirculation was visualized by intravital microscopy during 30 minutes of hemorrhagic hypovolemia (MAP, mean arterial pressure of 40 mmHg) and subsequent reinfusion period. Rats were resuscitated with RL (shed volume), HS (one-seventh of the shed volume), or blood (shed volume). The perfusion was estimated through speed of red blood cells. Moreover MAP, pH and B.E. was measured. RESULTS: Thirty minutes after hemorrhage a very important decrease of capillary flow was noticed and in lesser quantity, of the flow in arterioles and venules. The RL infusion did not cause measureable changes of microcirculatory blood flows. The HS infusion caused an improvement in the flow of arterioles and venules but not in capillaries. The blood infusion caused a progressive improvement in the flow of arterioles, venules and capillaries, however at slightly lower values than previous hemorrhage. CONCLUSIONS: Neither RL nor HS seem as efficient as blood to restore the microcirculatory blood flow in the mesocecum of the rats submitted to hemorrhagic hypovolemia.

Animals↗
PubMed2002

[Serum concentrations of trace elements and microcirculation during laser therapy for pneumonia].

The impact of laser therapy in the multimodality treatment for pneumonia on the serum levels of trace elements and microcirculation was studied. A total of 105 patients with pneumonia were examined. The patients were divided into 2 groups: 1) 68 patients received laser therapy and 2) 37 patients took drug therapy alone. There was a more substantial reduction in the permeability of cellular membranes, a significant increase in the serum levels of iron and chromium, better circulation at the expense of a vascular component. The above changes highly correlated with laboratory data and external respiratory function parameters.

Adolescent↗
PubMed2002

[Microcirculation and hemostasis in influenza and acute viral respiratory infections complicated with pneumonia].

AIM: To study microcirculation (MC), hemostasis and blood viscosity (BV) in influenza and acute respiratory viral infections (ARVI) complicated by pneumonia. MATERIAL AND METHODS: Conjunctival biomicroscopy, hemostasis and BV were studied in 232 patients with influenza and ARVI. In 91 of them the disease complicated with acute pneumonia (AP), in 87--with obstructive bronchitis. RESULTS: Irrespectively of the disease course, patients with influenza and ARVI showed intravascular changes in MC system, hypercoagulation, deterioration of fibrinolysis. In convalescence platelet aggregation increased, fibrinolytic blood activity enhanced. In influenza and ARVI complicated with AP intravascular changes and hypercoagulation were most pronounced. In uncomplicated influenza and ARVI accompanied by bronchitis such changes are less severe. BV was the highest in development of AP. CONCLUSION: MC and hemostatic disorders arising in influenza and ARVI seem to be essential pathogenetic links provoking development of AP. In intravascular aggregation of platelets and red cells, activation of plasmic hemostasis differentiated treatment with desaggregants and anticoagulants are indicated.

Acute Disease↗
PubMedDate not supplied

Effects of pre-soaked retraction cords on the microcirculation of the human gingival margin.

In the direct treatment of cervical lesions and to improve the impression-making procedure prior to fabricating indirect restorations, exposure of the gingival sulcus and control of hemorrhage or gingival fluid seepage are a prerequisite. For gingival displacement, cords impregnated with medicaments are widely used. In this investigation, the authors first studied in vitro the time course of fluid absorption by retraction cords immersed in test solutions. Thereafter, in a clinical trial, they examined the microcirculatory responses of the gingival margin after subgingival insertion and removal of retraction cords pre-soaked in solutions containing saline, AlCl3, Fe2(SO4)3 or epinephrine. Blood flow was recorded using laser Doppler technique. Blood perfusion fell markedly upon inserting the retraction cord, and this response was invariably present with all the compounds tested. After five-minutes, the decrease became less apparent with cords that were impregnated with physiological saline, AlCl3 or Fe2(SO4)3. Removing the cord elicited a prompt, marked and sustained increase in gingival microcirculation. However, removal of the cord impregnated with 0.1% epinephrine failed to reverse the decreased perfusion, and blood flow to the gingival margin remained low over an additional 20-minute observation. The results of this study indicate that with the exception of epinephrine, all retraction substances tested produced gingival hyperemia for operative procedures. Only epinephrine exhibited sustained vasoconstrictor response. It is anticipated that using laser Doppler flowmetry may be a suitable technique to evaluate the appropriate concentration of epinephrine that would elicit topical vasoconstriction.

Absorption↗
PubMedDate not supplied

[Preeclampsia-eclampsia: a change in utero-placental microcirculation. Immunologic, histologic, and biochemical features].

BACKGROUND: To know the alterations in the microcirculation of the placenta, umbilical cord, as well as the immune and hemorrheologic disorders in preeclampsia-eclampsia. MATERIAL AND METHODS: Two groups were conformed, 30 patients each, all of them with pregnancy of more than 24-week gestation. Group A included patients with preeclampsia-eclampsia and group B (control group) included women with normal pregnancy. In all patients determinations of levels of platelets, fibrinogen, antinuclear antibodies, IgG and IgM anticardiolipin, VDRL were made; clotting times were determined, and histopathologic analyses (placenta, umbilical cord and uterus-placenta membranes) were performed. RESULTS: Platelet levels in the group A were normal in 40% and low in 60%. In group B they were normal in 83.3% and low in 16.7%. with p < 0.05. In group A fibrinogen was normal in 10% and high in 90%; in the group B it was normal in 62.1% and high 37.9%, with p < 0.05. In group A prothrombin time (PT) was normal in 40% and high in 60%; in group B it was normal in 76.7% and low in 23.3%, with p < 0.05. in group TPT was normal in 36.7% and high in 62.1%, with p > 0.05. VDRL was negative in the 100% of the women of group A and positive in the 3.3% of the controls with p > 0.05. The antinuclear antibodies were positive in 6.7% in group A, and in 23.3% in group B, p < 0.05. IgG anticardiolipin antibodies were negatives in the 100% in both groups and IgM antibodies were negative in 96.7% in the group B and 3.3% in group A, p > 0.05. Analysis of histopathologic and immune changes did not show statistic significance when comparing both groups. CONCLUSIONS: Statistical and clinical significance was observed only in the hemorrheologic changes (PT, TPT, fibrinogen and platelets) and in the newborn weight.

Adolescent↗
PubMed2000

[Effect of Panax notoginseng saponins combined isovolumic haemodilution on the retinal microcirculation of patients with retinal vein occlusion].

OBJECTIVE: To study the effect of Panax notoginseng saponins (PNS) or isovolumic haemodilution (IHD) and combination of PNS with IHD on retinal microcirculation of patients with retinal vein occlusion (RVO). METHOD: Seventy three patients with RVO were allocated at random to three groups which were treated with PNS, IHD, or PNS + IHD respectively. The retinal circulation time (RCT) and retinal hemorrhage, edema, leakage of capillary, cystoid macular edema (CME), and nonperfusion area of capillary in retina were observed before and after treatment. RESULT: RCT of patients with RVO was shortened by three treating methods. RCT in the patients who treated by PNS + IHD was the shortest, especially in the patients with nonischemic RVO and branch retinal vein occlusion(BRVO). The retinal hemorrhage, edema, leakage of capillary, and CME in the patients treated by PNS + IHD disappeared quicker than those treated by PNS or IHD. At the same time, the incidence of nonperfusion area in patients whose course of disease was shorter than fourteen days was decreased. The perfusion of capillaries was increased at the edge of nonperfusion area which existed before the treatment. But the effect for nonperfusion area which existed before the treatment in the type of ischemic RVO was not obvious. CONCLUSION: The treatment of PNS + IHD can both shorten RCT of patients with RVO, and promote absorption of retinal hemorrhage, edema, leakage of capillary, and CME. It is possible that PNS + IHD treatment also has an effect to decrease the forming of nonperfusion area in patients whose course of disease is at early stage.

Female↗
PubMed1975

Autoperfused multi-organ preparations. II. Microcirculation in the autoperfused organs.

The microcirculation of 46 autoperfused heart-lung-liver-duodenum-pancreas-kidney preparations has been studied and the acid-base conditions were determined. The stability of the autoperfused organ preparation was not ensured by the "multi-organ" arrangement, moreover the combination had a detrimental effect, with reduced tissue perfusion leading to hypoxia and acidosis. This general vasomotor breakdown represented a therapeutic drug resistance, so that the organ preparation failed to solve the problem of temporary organ preservation.

Animals↗
PubMed2002

Effects of pH management during deep hypothermic bypass on cerebral microcirculation: alpha-stat versus pH-stat.

OBJECTIVE: There is controversy regarding the optimal pH strategy during deep hypothermic bypass in children. We directly visualized the effects of the pH-stat and alpha-stat strategy on cerebral microcirculation (including leukocyte/endothelial cell interactions) in a piglet model using intravital fluorescence microscopy. METHODS: Two groups of 5 piglets (mean weight 9.6+/-1.3 kg) with a cranial window over parietal cerebral cortex underwent 10-minute normothermic bypass, 40-minute cooling on cardiopulmonary bypass ([CPB] Hct 30%, 100 mL/kg/min), 60-minute circulatory arrest at 15 degrees C, and 40-minute rewarming with alpha-stat (group alpha) or pH-stat (group pH). Plasma was labeled with fluorescein-ITC-dextran for assessment of microvascular diameter. Circulating leukocytes were labeled and observed in postcapillary venules for adhesion before and up to 120 minutes after CPB. Cerebral tissue oxygenation was evaluated by quantification of NADH autofluorescence, which increases during ischemia. RESULTS: At the end of normothermic bypass diameter of cerebrocortical microvessels increased to 116+/-9% (alpha) versus 119+/-10% (pH) of pre-CPB baseline values. During cooling microvascular diameter decreased in group alpha and significantly increased in group pH (89+/-11% (alpha) versus 132+/-13% (pH) at the end of cooling; P<0.001). During the first 10 minutes of rewarming, the cerebral microvascular diameter was significantly larger when the pH stat strategy was used. Tissue oxygenation at the end of cooling was significantly greater in the pH-stat group (P=0.008). On reperfusion, the pH-stat strategy resulted in significantly more rapid return of tissue oxygenation toward baseline although at the end of rewarming the metabolic recovery was complete in both groups. The whole body lactate during early rewarming was significantly less with the pH stat strategy. There was no significant difference between the groups regarding the number of adherent leukocytes throughout the time course of the experiment. CONCLUSIONS: pH-stat management increases tissue oxygenation during deep hypothermic bypass and after circulatory arrest. Leukocyte/endothelial cell interactions during hypothermic bypass are mild with both alpha-stat and pH-stat.

Animals↗