摘要:

Periodic fluctuations, regular slow-wave flowmotion, were induced in the skeletal muscle of six mature anesthetized New Zealand White rabbits by acute femoral artery pressure reduction from a median control value of 78 to 36 mm Hg. This phenomenon was monitored simultaneously with four laser Doppler flowmetry (LDF) probes placed over the gastrocnemius muscle in a linear array with a spacing of 5 mm. The median relative peak-to-trough amplitude of the oscillatory flow patterns was 47%, white a frequency of approximately 2.5 cycles per minute (cpm), which remained relatively stable over an observation period of 1 h ( ± 15-20%). Application of two frequency analysis methods, Welch’s FFT method and Prony Spectral Line Estimation yielded similar results and showed a correlation coefficient of r = + 0.84. Spectral coherence between pairs of regular slow-wave flowmotion records decreased with increasing probe separation (0.28 at 5 mm; 0.01 at 15 mm). However, patterns of frequency fluctuation over time were significantly correlated between concurrent record pairs regardless of probe separation. These results suggest that the regular slow-wave flowmotion signal originates in regions that are independently regulated by local vasoactive sites, which may be called pacemakers. These sites may also be influenced by an additional common control mechanism, which may be myogenic/metabolic or central in natu

ISSN:0167-6865    

DOI:10.1159/000178946

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Many methods are available today for clinical evaluation of the blood supply to an extremity or part of an extremity, some of which are excellent for determining the presence and severity of arterial and venous disorders. These methods, however, do not give any information on the microvascular status of the diseased areas. This is particularly true for the skin circulation, which has a rather complex vascular network with nutritional and thermoregulatory vessels, arteriovenous shunts, etc. The most useful method for clinical evaluation of the skin capillary circulation is vital capillary microscopy. The skin capillaries in an area with a reduced microcîrculation change in structure, and it is possible to evaluate the viability of the skin by microscopic studies of these capillary changes. Both morphology and blood flow can be investigated. By using different intravital fluorescent dyes, e.g. sodium fluorescein and indocyanine green, the microvascular dynamics, flow distribution and microvascular permeability can also be studied. The total skin microcirculation can be evaluated by Laser Doppler fluxmetry, which measures primarily the blood flow in the thermoregulatory vascular bed, i.e. the subpapillary arterial and venous plexa. It is easy to use in clinical practice, but interpretation of the results can sometimes be difficult. Measuring transcutaneous oxygen tension has for many years been used in clinical routine to evaluate the viability of skin in patients with vascular disorders. It has recently been shown that inhalation of oxygen may induce vasoconstriction in healthy subjects and in patients with moderate arterial insufficiency, but an increase of the skin microcirculation in areas of severe ischaemia. By using different combinations of the above mentioned microcirculatory techniques, valuable information can be gained regarding pathophysiological phenomena of the microcirculation in many diseases, e.g. vascular disorders, collagenosis. Raynaud’s phenomenon, diabetes and hypertension. Using techniques for both macro- and microcirculation is also of great importance for evaluating the effect of therapeutic procedures in several of these disorde

ISSN:0167-6865    

DOI:10.1159/000179093

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Laser Doppler fluxmetry may improve the monitoring of cortical blood flow in neurosurgical patients. So far, however, the variability of laser Doppler readings found in the cerebral cortex has prevented a consequent usage of the technique in clinical practice. The current report analyzes the regional variability of laser Doppler readings from experimental animals. Typical frequency histograms of observed flow values display non-Gaussian distributions. A simulation technique is used to assess the number of measuring sites required for valid estimates of regional cortical flow. From a total of 990 local flow measurements from 45 rabbits random samples of sizes between 5 and 100 were repeatedly drawn to estimate the variability of median flow thus determined. The study underlines that small sample sizes below n = 20 are associated with a large variability (95th percentile: +38%) which decreases in a biphasic manner. Sample sizes above n = 25 are necessary to obtain more reliable information on regional cerebral blood flow: the 95th percentiles remain between 24 and 28% up to n = 45, and are still at 15% with n = 99.

ISSN:0167-6865    

DOI:10.1159/000178947

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Microangiopathy of chronic venous insufficiency is characterized by elongated, dilated and coiled skin capillaries, which are surrounded by an enlarged pericapillary space (halo). Reduction of capillary number and even areas devoid of microvessels (atrophie blanche) are common in severe chronic venous insufficiency associated with focal microvascular ischaemia (decreased transcutaneous oxygen tension). The superficial network of skin lymphatic capillaries is obliterated in part. Oedema formation results from increased permeability of blood capillaries (enhanced transcapillary diffusion of sodium fluorescein) and deficient lymphatic drainage of interstitial fluid.

ISSN:0167-6865    

DOI:10.1159/000179094

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

The aim of this study was to assess early traumatic haemorrhagic shock (THS)-induced changes in myocardial endothelial cells (mECs) both morphologically and morphometrically. The mECs of capillaries of the left ventricular myocardium were investigated by electron microscopy 15, 30, 60, and 120 min after a standardised THS and compared to a control group. With the use of a computer-assisted image analysis system, we measured the following morphometric parameters – height, area, circumference, cytoplasmic processes, and interendothelial junctions – and determined the number and distribution of cytoplasmic vesicles in every mEC. THS induced a significantly increased formation of cytoplasmic processes and a redistribution of cytoplasmic vesicles towards the cell centre, with the changes peaking between 15 and 60 min. There was no evidence of an increase in mEC height or area/circumference ratio used as indicators for early mEC oedema, although the latter dropped significantly after 15 min. No increase in damaged mitochondria was observed and the interendothelial junctions remained close. The THS-induced ultrastructural changes represent early mEC activation. Irreversible damage of mECs does not oc

ISSN:0167-6865    

DOI:10.1159/000178948

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

During chronic venous insufficiency (CVI), microcirculatory changes, e.g. a decrease in transcutaneous oxygen pressure (tcpO2) and an increase in transcutaneous carbon dioxide pressure (tcpCO2), are implicated in the pathophysiology of trophic disorders leading ultimately to venous ulcers. Daflon 500 mg1, a micronized purified flavonoid fraction, has been shown to improve venous tone, capillary permeability and resistance, and lymphagogue activity at a daily dose of tablets. To assess the effects of Daflon 500 mg on microcirculatory parameters by means of laser Doppler fluxmetry and transcutaneous oxymetry, a 3-month, double-blind, randomized, parallel-group study was carried out in 104 patients divided into 3 groups according to the daily dose: 1 tablet (group 1 n = 34), 2 tablets (group 2, n = 33), on 4 tablets (group 3, n = 37). All patients (mean age 43.7 ± 13.1 years; 100 females, 4 males) included in the study were affected by mild CVI. They were followed for 90 days with visits at 1 month (day 28) and months (day 90). At inclusion, there were no significant differences between groups as regards biometric data, mean tcpO2 (group 1, 62.7 ± 4.5 mm Hg; group 2, 64.0 ± 3.3 mm Hg; group 3, 64.1 ± 3.5 mm Hg), mean tcpCO2 (group 1, 40.7 ± 2.5 mm Hg; group 2, 39.3 ± 2.9 mm Hg; group 3, 40.0 ± 2.5 mm Hg) and laser Doppler parameters. Fourteen patients withdrew from the study (group 1, n = 4; group 2, n = 3; group 3, n = 7): 9 for reasons not related to treatment, 3 for adverse events, 2 because they were lost to follow-up. From day 0 to day 90, mean tcpO2 significantly increased (p < 0.001) in each group (group 1, 3.0 ± 2.1 mm Hg; group 2, 2.9 ± 2.1 mm Hg; group 3, 2.5 ± 1.6 mm Hg), mean tcpCO2 significantly decreased (p < 0.001) in each group (group 1, 2.6 ± 2.0 mm Hg; group 2, 1.7 ± 1.9 mm Hg; group 3, 2.2 ± 1.5 mm Hg). No significant differences were observed between groups. Laser Doppler parameters remained unchanged from day 0 to day 90 in the 3 groups. Symptoms (discomfort, pain, heaviness, burning sensation) and signs (oedema) of CVI as well as perimetric measurements of calf and supramalleolar area were significantly improved in the 3 groups. In conclusion, during this 3-month study, Daflon 500 mg improved oxymetric measurements and did not alter laser Doppler parameters. These data suggest that Daflon 500 mg, at the early stages of CVI, acts favourably on the microcirculatory disturbances also involved in the pathophysiology of more severe s

ISSN:0167-6865    

DOI:10.1159/000179095

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Our goal was to examine the effects of endothelin-1 and endothelin-3 on hamster cheek pouch arterioles in vivo in the absence and presence of endothelin receptor antagonists. Endothelin-1 (0.1, 1.0 and 10 pM) and endothelin-3 (0.1 and 1.0 nM) produced dose-related constriction of cheek pouch arterioles which was inhibited by the endothelin ETAB receptor antagonist PD 142893 (Ac-D-Dip-Leu-Asp-Ile-Ile-Trp) and endothelin ETA receptor antagonist PD 147953 [FR 139317: (hexahydro-1H-azepinyl)carbonyl-Leu-(N-Me)-D-Trp-D-2-Pya]. The thromboxane analogue, U-46619 (0.1 and 1.0 nM) also produced dose-related constriction of cheek pouch arterioles, but in contrast to endothelin-1 and endothelin-3 this vasoconstriction was not abolished by endothelin receptor antagonists. These findings suggest that endothelin-1 and endothelin-3 produce marked constriction of cheek pouch arterioles which appears to be mediated by activation of endothelin ETA receptors.

ISSN:0167-6865    

DOI:10.1159/000178949

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

In the more advanced stages of chronic venous insufficiency, stasis in the skin microcirculation is associated with a decreased red blood cell velocity and an increase in packed cell volume related to the red blood cell piling phenomenon. Although the main factor determining blood viscosity is packed cell volume, the direct relationship between this variable, viscosity and velocity is no longer valid at the microcirculatory level (sigma effect). Viscosity is influenced by blood composition and red blood cell deformability. The aim of this open pilot study was to verify the variations in capillary packed cell volume in comparison with the velocity in 24 patients with third-stage chronic venous insufficiency before (day 1) and after (day 28) a 28-day treatment with Daflon 500 mg, a micronized purified flavonoid fraction consisting of diosmin, 450 mg, and hesperidin, 50 mg, per tablet, 1 g/day, and then 14 days (day 42) after cessation of treatment. Ankle skin microcirculation was evaluated by dynamic capillaroscopy. Values of relative capillary packed cell volume were calculated by a densitometric method, and red blood cell velocity was calculated using the cross-correlation simplified method. Relative capillary packed cell volume (mean ± SD) significantly (p = 0.001) increased from day 1 (64.10 ± 9.34%) to day 28 (72.89 ± 5.74%) and then decreased until day 42 (66.84 ± 7.48%). In the same patients, red blood cell velocity (mean ± SD) significantly (p = 0.041) increased from day 1 (0.26 ± 0.14 mm/sec) to day 28 (0.35 ± 0.11 mm/sec) and then remained stable until day 42 (0.33 ± 0.16 mm/sec). Two possible explanations can account for this apparent discrepancy: first, dissociation between viscosity and velocity due to the Fahraeus-Lindqvist effect (sigma effect); and secondly, increased deformability of red blood cells leading to an increased red blood cell velocity despite an increased packed cell volume. It can be concluded that Daflon 500 mg seems to have a beneficial haemorheological effect, resolving the stasis with an increase in red blood cell velocity. A concomitant increase in relative packed cell volume and red blood cell velocity after therapy suggests an improvement of the flexibility of red bloo

ISSN:0167-6865    

DOI:10.1159/000179096

出版商:S. Karger AG    

年代:1995

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000179098

出版商:S. Karger AG    

年代:1995

数据来源: Karger

ISSN:0167-6865    

DOI:10.1159/000179089

出版商:S. Karger AG    

年代:1995

数据来源: Karger