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Results for “Laser-Doppler Flowmetry”

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At least 721 records · Page 40Linked to original sources
PubMed1994

Intraplaque hemorrhage of the carotid arteries: diagnosis by duplex scanning.

Eighty-three patients with intraplaque hemorrhage of the carotid arteries, explored by Duplex scanning, are reported; 36 among them were also studied by digital angiography and 28 were operated on. The echographic aspect suggesting the presence of an intraplaque hemorrhage is that of a hypo-anechogenic stria separating the intimal plaque from the media-adventitia complex. On the contrary, the angiographic findings are aspecific and unrelated to the presence of intramural blood clots. We think that duplex scanning is the investigation of choice in detecting intraplaque hemorrhage of the carotid arteries. The role of other radiological techniques, such as computed tomography of the neck and magnetic resonance, is also discussed.

Aged↗
PubMed1994

Changes in muscle and liver lactate concentrations after endotoxin infusion in rats.

The interstitial lactate concentration in rat skeletal muscle and liver was measured using a microdialysis method during the early stage of endotoxemia and during lactic acid infusion. The lactate concentration in the muscle and liver interstitium never exceeded the blood lactate concentration throughout the 180 min period after endotoxin administration. The present findings also showed that the muscle and liver interstitial lactate concentration gradually increased in endotoxin-infused animals compared to that in lactic-acid infused animals, although the blood lactate concentration in lactic acid-infused animals was the same as that in endotoxin-infused animals. These findings suggest that the skeletal muscle and liver may consume lactate in an endotoxemic condition. However, the capacity of lactate consumption in the skeletal muscle might gradually decrease after endotoxin administration, although that in liver might be well preserved.

Animals↗
PubMed1995

[Changes in blood flow and skin reaction following radiation therapy].

Skin blood flow (SBF) during radiation therapy was measured and compared with skin reaction to examine the relationship between skin reaction and blood flow. The SBF of 50 patients including 16 with head and neck (H&N) cancer, 13 with breast cancer and eight with lung cancer were analyzed. In the H&N patients, SBF was increased according to the treated dose, while in the breast cancer patients SBF was slightly increased at 10 Gy, and did not change up to 40 Gy. In the lung cancer patients SBF was not increased until 20 Gy, and thereafter increased moderately at 30 Gy. Among H&N, breast and lung cancer patients, the most severe skin reaction was observed at the earliest time in breast cancer patients, while blood flow was only slightly increased. This must have resulted in a relatively higher skin dose than the reference point dose in breast cancer patients. Therefore, differences in the relationship between SBF and skin reaction were observed among different types of cancer patients. However, in H&N cancer patients, SBF was increased as skin dose increased. Skin blood flow could be a good indicator by which to estimate skin reaction quantitatively when the daily skin dose is around 1.6 Gy.

Aged↗
PubMed1994

Ischaemia of the small intestine in patients with systemic sclerosis: Raynaud's phenomenon or chronic vasculopathy?

We investigated duodenal and gastric mucosal blood flow by endoscopic laser Doppler flowmetry (LDF) in ten patients with systemic sclerosis (SSc) and in ten healthy volunteers. In addition, we tested for the presence of small bowel bacterial overgrowth by jejunal aspiration. Jejunal aspiration and LDF were done consecutively, via a gastroscope, using a flexible catheter and laser Doppler probe. Following these procedures, two duodenal biopsies were obtained for light and electron microscopy. Mean duodenal and gastric blood flow were significantly lower in patients with SSc than in normal subjects (516 flux units vs. 240, 521 vs. 202, both p < 0.001). There was no correlation between age and blood flow in patients or volunteers. Four of the ten patients had evidence of significant bacterial overgrowth on jejunal aspiration (> 10(5) colony-forming units/ml). These findings support the hypothesis that within the small intestine of patients with SSc, factors independent of bacterial overgrowth may be responsible for malabsorption. The observed reduction in small-intestine mucosal blood flow may play an important contributory role. Further studies are required to determine whether this represents reversible or chronic progressive ischaemia, and its effect on nutrient absorption.

Adult↗
PubMed1994

[Effect of pirenzepine on gastric mucosal blood flow in patients after cardiac surgery].

Effect of pirenzepine on gastric mucosal blood flow (GMBF) in adult patients after coronary artery bypass grafting and mitral and aortic valve replacement was evaluated by using endoscopic laser-Doppler velocimetry. Heart rate, blood pressure and cardiac output increased temporarily after intravenous administration of pirenzepine 20 mg. GMBF also increased with these hemodynamic changes. However, GMBF remained significantly higher even after the decrease of cardiac output. Therefore, the increase in GMBF, which might be due in part to increase in cardiac output, could be explained by pirenzepine's own effect on gastric mucosa. Since the GMBF is one of the most important gastric mucosal defensive factors, pirenzepine may be useful in preventing acute gastric mucosal lesions in patients with low cardiac output.

Aged↗
PubMed1994

[Physiological diagnostic techniques of patients with vasculitis].

This article discusses physiological diagnostic methods in the intractable vasculitis, including Buerger's, Takayasu's and vasculo-Behçet disease. Clinical manifestations of these diseases depend on the lesions of the diseased arteries or veins such as obstruction of the extremities often occurring in Buerger's disease, the obstruction of aortic arch branches in Takayasu's disease and the deep vein thrombosis in vasculo-Behçet disease. Measurements of segmental blood pressure and flow allows a detection of peripheral vascular disease and non-invasive diagnostic techniques, such as the doppler ultrasonic techniques and strain-gauze plethysmography, permit accurate evaluation of arterial occlusive disease and estimation of its physiological significance. Noninvasive diagnostic techniques, together with clinical symptoms and physical examinations, make possible correct diagnosis and subsequently appropriate treatment.

Blood Pressure Determination↗
PubMed1994

[NPT: nocturnal penile tumescence test].

The recording of the variations of penile tumescence and rigidity during nocturnal unconscious erections that usually occur with the REM phases of sleep, has been considered the diagnostic tool of choice in the workup of erectile disturbances for a number of years. Such a success is partly due to its absence of invasiveness. Moreover this test was believed to allow to differentiate between the psychogenic and organic origin of impotence. As some authors have recently reported, anxiety state (common among patients who undergo invasive andrological procedure in the office) can at times influence the content of the dream state, thus negatively affecting the spontaneous nocturnal erections. Besides, sleep disturbances such as apnea and motor agitation can also induce erroneous interpretations of NPT graphs. Further, dysfunctions at the level of the cortex and the spine still allow the occurrence of nocturnal tumescence but determine an erectile deficit in the awake state. Clinically, all this poses new questions about the effectiveness of the NPT test in the study of the origin of impotence. The diagnostic methods, despite its world-wide diffusion, remains, under certain aspects, obscure: the operative details and, above all, its interpretative criteria. All this impedes the achievement of uniformity in the evaluation of the results obtained thanks to this test (e.g. the number and duration of erectile episodes, the interpretation of tumescence on its own, of the basal-apical dissociation, of the erectile episodes occurring immediately before waking, and of those of short duration).

Aged↗
PubMed1994

[Doppler velocimetry].

After a brief historical introduction, the Authors describe the methodology of the continuous wave basic and dynamic Doppler examination of the penile arteries as well as the main normal and pathologic patterns. Some special tensiometric tests are reported. Advantages and limits of the afore mentioned examinations are discussed.

Humans↗
PubMed1994

[Tissue blood flow of the sigmoid colon for safe anastomosis following ligation of the inferior mesenteric artery].

We examined the tissue blood flow (TBF) of the sigmoid colon to determine which level of inferior mesenteric artery. In 13 patients, TBF of the sigmoid colon was measured in the control state and the clamped state, in which the inferior mesenteric artery (IMA), left colic artery and the rectal were wall clamped. In the clamped state, means of TBF at 10 cm and 15 cm distal to the descend-sigmoid junction were 1.87 +/- 0.77 and 1.10 +/- 0.40, respectively. Mean of TBF at 15 cm was significantly lower than that at 10 cm. In conclusion, TBF which is enough for safe anastomosis reaches as far as 10 cm distal from the descend-sigmoid junction after ligation of IMA. Anastomosis at this level in anterior resection of the rectum is safe in concerning with TBF.

Adult↗
PubMed1994

[Experimental research on choroidal circulation. 2. Choroidal blood flow increase elicited by electrical stimulation of parasympathetic nerve behind the eyeball in the cat].

The present studies were performed to examine whether the nerves behind the eye ball contain parasympathetic fibers which dilate the choroidal blood vessels. Choroidal blood flow in the cat (20 animals) was measured trans-sclerally with a laser Doppler flowmeter. Cats were anesthetized with pentobarbital sodium (30 mg/kg, i.v.) and artificially respirated after injection of pancuronium bromide (0.2 mg/kg/hr, i.v.). Electrical stimulation of the short ciliary nerve as well as of the nerve between the ciliary ganglion and accessory ciliary ganglion, where the sensory nerve is absent, elicited an increase choroidal blood flow in an intensity-dependent manner. Application of capsaicin, which is known to desensitize the polymodal nociceptive C-fibers, to these nerves did not abolish the increase in blood flow in response to electrical stimulation of the short ciliary nerve. Atropine, a muscarinic receptor antagonist, and phentolamine, an alpha-adrenoceptor blocking agent, had no effect on these responses. The results suggest that the blood flow increase elicited by stimulation of these nerves is mediated via activation of the atropine-resistant parasympathetic vasodilator fibers supplying the choroid in the cat.

Animals↗
PubMed1994

Effects of antihypertensive drugs on flow disturbances: nifedipine, captopril, and metoprolol evaluated by quantitative spectral analysis of Doppler flow patterns in patients with carotid stenosis.

Hemodynamic theories of atherogenesis suggest that flow disturbances (departures from laminar flow including high and low shear) and increases in heart rate may be important in the initiation, progression, and complications of atherosclerosis such as dissection and embolism. It is therefore desirable to evaluate the effects of antihypertensive drugs on the occurrence of such flow disturbances. Effects of metoprolol, nifedipine, and captopril were studied, by quantitative spectral analysis, in 20 patients with carotid stenosis to evaluate 3 indices of disturbed flow: peak velocity, spectral broadening index and window index (WI). Heart rate (HR), and the product of WI by HR, were improved (reduced) significantly by metoprolol (p < 0.05), and worsened by nifedipine (p < 0.05), but most of the effect was due to effects on heart rate. These findings suggest that most of the benefit of antihypertensive drugs on flow disturbances can be identified by counting heart rate. Further developments will require improved methods for quantitation of flow disturbances.

Aged↗
PubMed1994

[Use of the "color doppler" technique in diagnosing ovulation].

Graafian follicle growth and development and Doppler flow analysis of blood vessels in the wall of the follicle, was analyzed. Twelve patients with primary infertility were observed between days 12 to 15 of the cycle. Analysis of resistance index (RI) and pulsatility index (PI) of the wall vessels was performed. Statistically significant difference in RI and PI indices in preovulatory and post-ovulatory period was observed.

Female↗
PubMed1994

Hepatic microcirculatory perfusion failure is a determinant of liver dysfunction in warm ischemia-reperfusion.

Hepatic ischemia-reperfusion (I/R) is characterized by circulatory and metabolic derangements, liver dysfunction, and tissue damage. However, little is known about the causative role of I/R-induced microcirculatory disturbance on the manifestation of postischemic reperfusion injury. Therefore, the intention of the study was to assess changes of hepatic microvascular perfusion (intravital fluorescence microscopy) as related to hepatic morphology (light/electron microscopy), hepatocellular integrity (serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities), and excretory function (bile flow). Sprague-Dawley rats were subjected to 20 minutes (group B, n = 9) and 60 minutes (group C, n = 9) of left hepatic lobar ischemia followed by 60 minutes of reperfusion. Sham-operated animals without ischemia served as controls (group A, n = 10). Lobar ischemia for 20 minutes followed by reperfusion resulted in a significant reduction of sinusoidal perfusion rate (93.9 +/- 1.4%; P < 0.05) and a decrease in erythrocyte flux (90.0 +/- 5.6%) when compared with controls (99.4 +/- 0.2 and 97.9 +/- 2.7%). This was accompanied by a significant increase of serum AST and ALT activities (P < 0.05) and a reduction of bile flow (P < 0.05). Prolongation of lobar ischemia (group C, 60 minutes) aggravated postischemic reperfusion injury (sinusoidal perfusion rate: 87.4 +/- 2.9%; erythrocyte flux: 62.1 +/- 8.4%) and was paralleled by severed hepatocellular damage. Electron microscopy of postischemic tissue demonstrated alteration of nonparenchymal cells (swelling of sinusoidal lining cells and widening of Disse's space) and substantial parenchymal cell damage (swelling of mitochondria, disarrangement of rough endoplasmatic reticulum, vacuolization, complete cytoplasmic degeneration). Initial postischemic increase in serum AST and ALT activities and reduction of bile flow directly correlated with the extent of microcirculatory failure (P < 0.01), ie, impairment of sinusoidal perfusion and decrease of erythrocyte flux, indicating the decisive role of microvascular perfusion failure for the manifestation of hepatic tissue damage and liver dysfunction.

Alanine Transaminase↗
PubMed1994

In vitro fluid dynamic evaluation of the Carbomedics bileaflet heart valve prosthesis in the aortic and mitral positions.

Since the introduction of bileaflet heart valve prostheses their clinical use has continued to escalate. The first of this valve type was the Standard St. Jude Medical (SSJM) prosthetic heart valve in 1977. The Carbomedics prosthetic heart valve (CPHV), introduced in the late 1980s, was intended to improve on the design of the SSJM bileaflet valve. The design changes in the CPHV valve, relative to the SSJM valve, may have the potential to affect its flow fields. This study, using flow visualization laser Doppler velocity measurements and color Doppler flow mapping, was intended to evaluate how these changes affect the flow fields in the near vicinity of the CPHV valve. The study was conducted in an in vitro pulse duplicator system. In the flow visualization study, the flow fields observed with the CPHV valve were quantitatively similar to those seen with the SSJM valve. Centralized jet-like flows with flow separation/stagnation were observed in the illuminated planes. The jet-like flows from the two lateral orifices were broader than that observed from the central orifice for both the CPHV and the SSJM valves. This fact implied that the major part of the volumetric flow was through the two lateral orifices, rather than the central orifice. In the laser Doppler velocity measurements, it was found that the flow field downstream of the SSJM valve was slightly more evenly distributed than that with the CPHV valve. In addition, the extent of the flow separation regions with the CPHV valve were slightly larger than with the SSJM valve. The slight differences in velocity profiles between the SSJM and the CPHV valves were due to the differences in leaflet opening angle. However, the levels of flow turbulence with the CPHV and the SSJM valves were found to be of the same order of magnitude. The results of the flow visualization and LDA velocity and turbulence measurements obtained in the study indicate that the differences in flow fields in the immediate vicinity of the CPHV valve relative to the SSJM valve are insignificant.

Aortic Valve↗
PubMed1992

[Microcirculatory changes in mitral prolapse as an expression of a systemic change in the connective tissue].

Many authors hypothesize that mitral valve prolapse (MVP) can be, in most cases, only a clinical sign of a primitive and systemic disorder of the connective tissue, like in Marfan Syndrome (MS). In our previous works we supported the presence of morphological and functional alterations of the microcirculation in patients affected by MS. In order to characterize a possible common denominator between these pathologies we have studied the cutaneous microcirculation in a group of patients affected by MVP, divided into 2 groups: anatomic MVP (MVP) and MVP syndrome (MVPS). The morphologic parameters have been investigated by nailfold capillaroscopy while digital laser-Doppler was used to study skin flowmetry. The results have been compared with a control group. Capillaroscopic remarkers showed an architecturally disorganized microvasculature with aspects related to a reduced compactness of the microvasculature unit with a significatively higher score compared with controls (7.3 +/- 2.9 vs 3.6 +/- 1 p less than 0.0005). Laser-Doppler flowmetry showed a significatively reduced rest flow; ischemic test showed: spike time 48.9 +/- 36.9 vs 15.3 +/- 7.7 s (p less than 0.0005), hyperemic acme 6.6 +/- 2.7 vs 12.5 +/- 8.4 UP (p less than 0.002); % increase 32.1 +/- 20.2 vs 51.5 +/- 15.4 (p less than 0.002). Thermic test showed a significatively higher thermic acme 8.7 +/- 4.2 vs 12.6 +/- 9.11 UP (p less than 0.05). These results appeared to be correlated with stage pathology as it was observed a severe microvasculature disorders in MVPS. Therefore we suppose that a phenotypic continuum may exist between MS and MVP.

Adult↗
PubMed1994

Effects of neural blockade and general anesthesia on the laser-Doppler skin blood flow waves recorded from the finger or toe.

Effects of neural blockade and general anesthesia on the basic wave (BW) and the reflex wave (RW) among the laser-Doppler (L-D) skin blood flow waves recorded on the finger or toe were studied in 2 volunteers and 42 patients. The BW was continuous, rhythmic and independent of respiratory movements. The RW, which was induced by a deep inspiration or a snapping sound, was a transient marked reduction in blood flow. The BW was almost flattened and the RW was no longer induced at the finger under complete wrist block (n = 2), or under cervical or upper thoracic epidural anesthesia extended caudally over T7 (n = 2). On the other hand, the BW was still detected with reducing frequency and the RW could be provoked with one exception at the finger on the side with a sympathetic ganglion block at the C6 vertebral level (n = 14). The BW and RW at the toe were retained under lumbar subdural anesthesia (n = 6) as well. However, under the combination of lumbar subdural anesthesia and lower thoracic epidural anesthesia extending rostrally over T4 (n = 6), both the BW and the RW disappeared at the toe. In the course of deepening nitrous oxide/enflurane anesthesia (n = 10), the BW gradually reduced in frequency until it was almost flattened, and it became difficult to provoke the RW. L-D flowmetry of the finger or toe could be a useful clinical measure for detecting the presence or absence of sympathetic function controlling cutaneous vasomotion.

Adult↗
PubMed1982

Current status of noninvasive tests in the diagnosis of peripheral arterial disease.

In this review of the current status of the vascular laboratory, the major emphasis has been upon those tests that have become well-established and documented, including resting pressure, pulse volume measurements, velocity studies, and three stress measurements--exercise ankle pressure, postocclusive reactive hyperemia, and the toe pulse reappearance time. Additional technology that may have application to peripheral arterial disease includes photoplethysmography, transcutaneous oxygen tension, laser-Doppler velocimetry, fluorescein angiography, infrared thermography, and transcutaneous electromagnetic flowmetry. These techniques, which are currently in development and experimental trial, were not discussed but are likely to provide significant additional information. The future role of the vascular diagnostic laboratory in the area of peripheral arterial occlusive disease appears clear. It has already become a standard resource of the community hospital and tertiary referral center. Its functions will become more and more generally accepted with time as newly graduating physicians who have been exposed to this technology enter the practice of medicine. It should permit obtaining an evaluation of all patients at the expert level, aid in the education of all physicians concerned with peripheral arterial disease, and play an important part in guaranteeing a higher level of patient care than has heretofore been available.

Arterial Occlusive Diseases↗