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Results for “Laser-Doppler Flowmetry”

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At least 1,711 records · Page 95Linked to original sources
PubMed1996

Postocclusive reactive hyperemia estimating peripheral vascular resistance: a noninvasive method to predict outcome of infrainguinal vascular reconstructions?

OBJECTIVE: The peripheral vascular resistance is an important factor determining the outcome of infrainguinal revascularizations. When measured intraoperatively, it correlates to graft patency, but to select patients to surgery a preoperative, preferably noninvasive, method is necessary. The aim of the present study is to test if parameters recorded during postocclusive reactive hyperemia can be used for that purpose. EXPERIMENTAL DESIGN: This prospective study compares patients with occluded grafts within 30 days postoperatively to patients with patent grafts. SETTING: University Hospital. PATIENTS: Thirty patients with critical ischemia scheduled for infrainguinal bypass surgery. MEASURES: Correlations between intraoperatively measured peripheral resistance and preoperatively recorded parameters of postocclusive reactive hyperemia. The ability of the values to predict outcome. RESULTS: Peripheral resistance correlated significantly to two parameters during postocclusive reactive hyperemia recorded after thigh occlusion, flux reappearance time (r=0.47, p=0.01) and time to peak flux (r=0.41, p=0.03). Intraoperative peripheral resistance predicted graft occlusion at 30 days with a 90% accuracy, while parameters obtained during reactive hyperemia, only tended to predict adverse outcome. CONCLUSIONS: Several parameters during reactive hyperemia show weak correlation to intraoperatively measured peripheral resistance, but none was able to accurately predict graft failure. Further studies are needed to evaluate its capability for patient selection.

Aged↗
PubMedDate not supplied

[Local cerebral ischemia in rats induced by ligation of the middle cerebral artery].

A model of local cerebral ischemia induced by ligation of the middle cerebral artery, which is a modification of the techniques proposed by A. Tamura and others, is suggested. It allows experiments to be conducted on conscious animals with appraisal of the morpho-functional state of the nervous system. Ligation of the middle cerebral artery caused a marked decrease (by 85 +/- 9%) in the blood flow in the temporal area of the cerebral cortex. The use of this method will promote a purposeful search for drugs for the treatment of patients with ischemic disorders of cerebral circulation.

Animals↗
PubMed1996

[The Laser-Doppler microcirculation technique in the study of the orthosympathetic system in obese and non-insulin-dependent diabetic patients].

Parasympathetic as well as cardiovascular sympathetic activity is perturbed in the heart of diabetic and obese subjects. The aim of this work was to assess the effect of sympathetic control on variations in skin blood flow in 14 controls, 42 subjects with non-insulin-dependent diabetes and 57 obese subjects without diabetes. All subjects had normal blood pressure and had no other disease state which might modify skin blood flow. Laser-Doppler measurement of skin blood flow on the palmar aspect of the right first finger was performed at rest and during three tests which activate sympathetic tone: deep respiration (R), active orthostatism (O) and Valsalva's manoeuvre (V). In all 113 subjects, there was a negative correlation between age and the standard deviation of blood skin flow at rest (p = 0.001) and rate of blood skin flow decline during R (p = 0.002), O (p < 0.0001) and V (p = 0.005). The standard deviation and slope of decline in blood skin flow during R was lower than the initial levels in controls in 11 diabetes patients and 6 obese subjects and in 15 diabetic patients and 12 obese subjects respectively. The slope of decline in skin blood flow during O was positively correlated with plasma cholesterol (p = 0.002), red cell aggregation index (p = 0.013) and negatively with hematocrit, glucose control and creatininemia. The respective effects of these factors were analyzed in each of the three groups of subjects. These preliminary results suggest that 1) the variation in skin blood flow at rest is regulated by the sympathetic system and the drop in skin blood flow during the three tests activating the sympathetic system decreases with age, 2) sympathetic control of peripheral vasoconstriction is reduced in many diabetic and obese subjects, 3) red cell aggregability and different metabolic parameters and renal function have an effect.

Diabetes Mellitus, Type 2↗
PubMed1996

Electrophysiological evaluation of peripheral autonomic function in leprosy patients, leprosy contacts and controls.

Since there is immunocytochemical evidence that the initial damage in leprosy is directed at distal, small, unmyelinated nerve fibers, we investigated several electrophysiological methods for their potential value in detecting peripheral autonomic dysfunction in leprosy contacts and leprosy patients. Fingertip blood flow velocity and its control by vasomotor reflexes (VMR) with a laser Doppler flowmeter, fingertip skin temperature, and the sympathetic skin response (SSR) to exosomatic stimuli were studied in 89 leprosy patients, 36 leprosy contacts and 47 normal subjects. Whereas there were no significant differences between the groups in fingertip skin temperature and resting blood flow velocity measurements, there were significant differences in the prevalence of impaired fingertip VMR and absent SSR. The prevalence of absent SSR in leprosy patients was 60.9%, in contacts 13.8%, in controls 6.3%. The prevalence of abnormal VMR in leprosy patients was 61.2%, in contacts 34.7% and in controls 10.6%. VMR testing is a more sensitive test method for autonomic dysfunction compared with the SSR. The implication of impairment in vasomotor and sudomotor function in leprosy contacts needs yet to be determined. However, we propose this to be a response to exposure to Mycobacterium leprae, which represents either ongoing nerve damage or nonprogressive residual autonomic nerve damage. We suggest that VMR testing and SSR are valuable methods to evaluate early leprous neuropathy.

Adolescent↗
PubMed1997

Superficial blood flow following photodynamic therapy of malignant non-melanoma skin tumours measured by laser Doppler perfusion imaging.

Laser Doppler perfusion imaging offers a new modality for in vivo monitoring of the superficial blood perfusion in biological tissue. In this study, the superficial blood perfusion of malignant non-melanoma skin tumours and the surrounding normal skin was measured in conjunction with photodynamic therapy (PDT) using topical delta-aminolaevulinic acid (ALA)-induced protoporphyrin IX as a photosensitizer. The results clearly show that, in contradiction to PDT with the intravenously administered photosensitizer Photofrin, no direct vascular damage can be seen. With the topical sensitization the blood perfusion is increased immediately after the treatment irradiation. The increased blood flow is seen up to a week after treatment, in a similar way as for an inflammatory reaction. Despite this, all basal cell carcinoma and squamous cell carcinoma in situ lesions in this study healed without any sign of residual tumour after the treatment, suggesting an efficient direct tumour cell destruction induced by PDT.

Adult↗
PubMedDate not supplied

Laser-Doppler imaging assessment of skin hyperemia as an indicator of trauma after adhesive strip removal.

The effect of adhesive tape and dressing removal on skin integrity is particularly important for patients who have increased risk for skin damage or impaired physiological responses to skin trauma. Visual observation of skin erythema does not always provide an adequate assessment of acute injury; detection of trauma is limited by the naturally occurring wide range of skin color and tones. This study had two purposes: (1) to assess the sensitivity and objectivity of laser-Doppler perfusion imaging (LDI) in measuring skin blood perfusion in forearm skin before and after removal of adhesive strips and (2) to determine the relationship between skin perfusion levels after adhesive-strip removal and the peel force required to remove the strips. Variations in peel-force levels were obtained in two ways: first, from naturally occurring skin differences; and second, by using an adhesive remover product (ARP) developed to reduce skin trauma. In 10 subjects, acrylic adhesive strips (13 x 70 mm) were placed in pairs on standardized sites on both volar forearms and peeled off 24 hours later at a constant velocity of 5 mm/sec while the peel force was recorded. During peeling, an ARP was used with one strip; nothing was used on the adjacent paired strip (CONTROL). Skin blood perfusion was measured at 5 and 20 minutes after strip removal by non-contact LDI under the ARP and CONTROL conditions simultaneously. Results show that (1) hyperemia after strip removal is linearly related to peel force (r2 = 0.55, p < .01): (2) use of an ARP, as indexed by the hyperemic response, significantly reduces skin trauma (1.02 [SD = 0.11] versus 1.47 [SD = 0.11], p < .01) with a mean CONTROL/ARP ratio of 1.56; and (3) the peel force required is reduced by using an ARP. These findings indicate that LDI is a useful, sensitive tool for assessment of skin trauma and that reducing peel forces has a positive effect.

Adhesives↗
PubMed1995

Measurement of pulpal blood flow in humans using laser Doppler flowmetry: a technique allowing stability and repeatability of pulpal blood flow measurement during surgical manipulations.

This study was undertaken to validate the repeatability of pulpal blood flow in human teeth with the laser Doppler flowmetry technique using a repeatable method of attachment of the laser Doppler probe. The variation in laser Doppler flowmetry measurements was evaluated over time periods that ranged from hours to days. In a prospective study, the pulpal blood flow was recorded from a maxillary central incisor (randomly selected) at a site directly gingival to the orthodontic bracket of three subjects. Measurements were made eight times over a 2-week period and every 30 minutes over 4 hours for eight recordings. The results indicated that there was only a slight difference between the temporal variability of the laser Doppler measurements over the course of 4 hours (intraday variability) or 2 weeks (interday variability). Furthermore, it appeared that subjects varied in their mean value recordings and may have varied widely in their respective signal-to-noise ratios.

Adult↗
PubMed1997

Intratemporal facial nerve blood flow in guinea pigs.

HYPOTHESIS: To investigate the effect of interruption of the stylomastoid artery and the petrosal artery on the facial nerve blood flow with the use of a laser Doppler flowmeter. BACKGROUND: Ischemia of the facial nerve is thought to be one of the most possible causes in idiopathic facial palsy. The blood supply in the facial nerve has been studied morphologically in considerable detail; however, we have little information on its hemodynamics. METHODS: The animals used were 20 guinea pigs. The blood flow in the facial nerve at the geniculate ganglion was measured using a laser Doppler flowmeter, and the change in the facial nerve blood flow between before and after interruption of the stylomastoid artery and the petrosal artery was investigated. The interruption of both arteries was carried out by electrical cauterization with a bipolar coagulator. RESULTS: Interruption of the petrosal artery resulted in almost complete ischemia of the facial nerve at the geniculate ganglion. This decrease in the facial nerve blood flow was significant statistically (p < 0.001). But, interruption of the stylomastoid artery caused no change. CONCLUSIONS: The blood flow in the geniculate ganglion of the facial nerve is thought to come not from the stylomastoid artery but mainly from the petrosal artery. Peripheral facial palsy following ligation of the middle meningeal artery or embolization of the maxillary artery or intra-arterial infusion of anticancer drug into the maxillary artery is likely to be attributed to facial nerve ischemia at the level of the geniculate ganglion.

Animals↗
PubMed1996

Difference between proximal and distal right coronary flow velocity pattern in humans.

The purpose of this study is to clarify the difference between proximal and distal right coronary artery flow velocity pattern in humans. Each portion of the coronary artery in thirteen patients with chest pain syndrome was measured by means of Doppler guide wire. The systolic/diastolic peak velocity ratio and velocity integral ratio at the proximal portion of the right coronary artery were significantly higher than those at distal portion of the right coronary artery (0.97 +/- 0.27, 0.61 +/- 0.20, 0.66 +/- 0.19, 0.44 +/- 0.13, respectively). In the right ventricular branch, coronary flow velocity pattern showed systolic dominancy. Systolic/diastolic peak velocity ratio and integral ratio showed 1.69 +/- 0.62 and 1.00 +/- 0.62 in the right ventricular branch, respectively. It is speculated that the less marked diastolic predominant pattern in the proximal right coronary artery flow velocity may be due to the fact that the proximal right coronary artery supplies both the right and left ventricle but that the distal right coronary artery supplies only the left ventricular inferior wall.

Aged↗
PubMed1997

Utility of Doppler-detectable microbubbles in the diagnosis and treatment of decompression sickness.

BACKGROUND: Doppler-detectable microbubbles (DMB) are frequently used to evaluate altitude decompression stress. However, the role of DMB in the therapy of decompression sickness (DCS) has not been examined. HYPOTHESIS: The ability of Doppler to detect microbubbles during decompression (Doppler test) may be used in the diagnosis of DCS, and to aid clinical decisions about treatment options for DCS. METHODS: We examined the data on DMB and symptoms from NASA Database on DCS (n = 516). The accuracy of Doppler test was obtained from the Receiver Operating Characteristic (ROC) for DMB (grades I through IV), and efficacy was obtained by calculating predictive or post-test probabilities. Threshold analysis was used to obtain the probabilities for testing and/or treatment decisions. RESULTS: The Doppler test was useful for both screening and confirming DCS, when different criteria (grade I for screening; grade IV for confirming) were used for a positive test. Calculation of predictive values and threshold analysis showed that: 1) early recompression was the therapy of choice when post-test probability of disease was > 0.25 in individuals with non-specific pain at altitude, and early recompression with 100% oxygen for 2 h at site level was optimal therapy when this probability was > 0.33; 2) hyperbaric therapy was optimal when post-test probability was > 0.04 in individuals with uncertain symptoms post-flight. CONCLUSIONS: The Doppler test was of greater utility in excluding DCS than confirming its presence, and was useful in making therapeutic decisions on DCS when confronted with non-specific symptoms at altitude.

Aerospace Medicine↗
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↗
PubMed1988

Partitional measurement of capillary and arteriovenous anastomotic blood flow in the human finger by laser-Doppler-flowmeter.

This study was made to see whether changes in blood flow through the capillaries and arteriovenous anastomoses (AVA's) of the human finger can be measured by noninvasive flowmetry. Total finger blood flow (FBF) was measured by venous occlusion plethysmography; blood flow was measured by a laser-Doppler flowmeter (ADVANCE, ALF-2100, Tokyo, Japan) using probes with optic fiber separations of 0.3 mm (LDF-0.3) and 0.7 mm (LDF-0.7). The maximum sensitivities for LDF-0.3 and LDF-0.7 were at depths of 0.8 and 1.2 mm from the tissue surface respectively. Two series of experiments were performed on separate days. In the first series the test hand was immersed in a water bath whose temperature (Tw) was 25 degrees C at an ambient temperature (Ta) of 25 degrees C. Tw was raised to 35 degrees C (local hand warming), which was then followed by an increase in Ta to 35 degrees C (whole body warming). FBF, LDF-0.3, and LDF-0.7 increased during these thermal stimulations. However, the relationship of FBF to LDF-0.3 showed two different regression lines. In contrast, the relationship of FBF to LDF-0.7 showed a single regression line. In the second series, with Ta at 35 degrees C, the test hand was immersed in a water bath at Tw 35 degrees C. Tw was then raised every 10 min by 2 degrees C steps from 35 to 41 degrees C. At Tw 39-41 degrees C, FBF and LDF-0.7 in the test hand were significantly decreased compared with those at Tw 35 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗