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Results for “Laser-Doppler Flowmetry”

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PubMed1994

[Study of cutaneous microcirculation using the laser-Doppler method in syndrome X].

Aim of the study was to verify the relationship between syndrome X and generalized microangiopathy. Three groups of patients were selected: Group A, 11 patients with typical syndrome X; Group B, 8 patients with atypical chest pain; Group C, 12 control normal subjects. Microvascular circulation was investigated with a laser Doppler Periflux PF3 at rest (15 min); during ischemia (3 min); during post-ischemic hyperemia on the plantar side of the big toe (where arterovenous anastomoses are particularly abundant) and on the dorsum of the foot (where these anastomoses are very scanty). During each recording we calculated: the mean flux value (FV); the mean concentration of moving blood cells (CMBC); the FV/CMBC ratio (which is related to the flow velocity); the mean percent increase of the three parameters during hyperemia. Patients with syndrome X as compared to the other subjects showed: 1) a significantly higher FV/CMBC ratio at rest and during hyperemia both on the plantar side of the big toe (respectively p = 0.01 and 0.015) and on the dorsum of the foot (respectively p = 0.011 and 0.006). These findings suggest a higher flow velocity in microvascular circulation; significantly lower percent increase of FV and CMBC during hyperemia in the plantar side of the big toe (respectively p = 0.04 and 0.014) but not on the dorsum. The increase of flow velocity at rest and low vasodilatatory reserve after ischemia in an area which is rich of arterovenous anastomoses in patients with syndrome X might be explained by the presence of a basal arterovenous hyperstomia.

Adult↗
PubMed1994

Retinal blood flow changes during pregnancy in women with diabetes.

PURPOSE: To study retinal blood flow (RBF) during pregnancy in subjects with and without diabetes and to relate the changes to progression in diabetic retinopathy. METHODS: RBF in a major temporal retinal vein was measured, where possible, during all three trimesters (T1 to T3) and the postpartum period (PP) using laser Doppler velocimetry (measuring velocity [V]) and monochromatic fundus photographs (measuring diameter [D]). RESULTS: In the subjects without diabetes (n = 19), no significant change in RBF was demonstrated. V was significantly greater in T3 than in PP (P = 0.01). D was significantly smaller in T1 to T3 than in PP (P < or = 0.01). RBF in the subjects with diabetes was significantly higher in T2 and T3 than in PP (P < 0.05). V increased from T1 to T2 (P = 0.04) and decreased from T2 to PP (P = 0.001) and from T3 to PP (P = 0.002). The only significant change in D was a smaller value in T1 than in PP (P = 0.003). However, it was only those subjects whose DR progressed (n = 11) who had a significant increase in RBF during pregnancy (P = 0.0001). CONCLUSIONS: These data suggest that the hyperdynamic circulation present in pregnancy led to compensatory retinal vessel constriction (autoregulation) in the group without diabetes; this was largely absent in the patients with diabetes, with resultant increase in retinal blood flow associated with worsening retinopathy. This finding lends further support to the hypothesis that increased retinal blood flow is a pathogenic mechanism for diabetic retinopathy.

Adult↗
PubMed1994

[Comparison of different monitoring techniques for vascular access in chronic hemodialysis].

Aim of the study was to compare different techniques of monitoring for vascular accesses in our chronic hemodialysis patients. Twenty seven patients (14 men, 13 women) were investigated. The accesses studied consisted of 19 arteriovenous fistulas and 8 vascular protheses. Twenty-four were trouble free, venous pressure was high in two, one was difficult to puncture. Three measurements of recirculation percentage were made for each patient, as well as a color Doppler flow imaging, and a digital angiography of the access. Recirculation measurements were normal for all patients including those with functional abnormalities. A stenosis was found 9 times with the Doppler and 10 times by angiography, there being disagreement between the two techniques in one case. The location of the stenosis was the same in the 9 concordant cases. There was a very strong correlation between the degree of stenosis found using the two techniques (p < 0.0001). In conclusion, measurement of recirculation appears to us to be of no interest for verifying a vascular access. On the other hand, the color Doppler seems to be an excellent choice for detecting an abnormality. An arteriographic confirmation seems necessary before correction.

Adolescent↗
PubMed1993

[Evaluation of neonatal prognosis using Doppler velocimeter in cases of a high risk fetus].

The authors describe the main characteristics of the Doppler method in the early diagnosis of chronic fetal distress, and report their personal results in the study of 51 high risk pregnancies. In their study the fetal doppler ultrasound findings were correlated with birth weight related to gestational age, and neonatal morbidity. The parameters established from the doppler ultrasound assessment were the placenta resistance (calculated from the formula of Pourcelot: R = S-D/S applied to the umbilical artery) and the cerebro-placental index, Rp/Rc, Rc being the index of cerebral arterial resistance. The diagnosis performance of the method appeared very good: the Rp index was found to be highly specific for hypotrophy (85,7%) and for neonatal morbidity (90%), the RCP index adding its own good sensitivity (85% for hypotrophy and 83,3% for neonatal morbidity). The authors conclude upon the interest to study simultaneously the fetal umbilical and cerebral arterial circulations. The pathological significance of the two indexes appears different so that they are to be complementary in the evaluation of fetal distress.

Female↗
PubMed1994

The hyperperfusion of the psoriatic plaque correlates histologically with dilatation of vessels.

We examined psoriatic lesions on the upper legs in 20 patients, using a two-dimensional Laser-Doppler-Scanner (Laser Doppler Perfusion Imager LDI, Lisca Development, Linköping/Sweden). The plaques were evaluated weekly during therapy with dithranol. Five plaques were reconstructed three-dimensionally before and after therapy (reconstruction program ANAT 3D, SIS, Münster, Germany). The psoriatic plaque was represented in the Laser Doppler Perfusion image as a sharply demarcated, hyperperfused area. The perfusion of the plaques dropped during therapy with dithranol to just slightly increased values, compared with normal skin (2.04 arbitrary units AU, healthy skin 1.1 AU). Using three-dimensional reconstruction, we investigated the volume of dermal vessels and the density of papillae. When compared, the volume of papillary vessels was twice as large in psoriatic as in healthy skin. The number of the papillae per square millimetre, detected by three-dimensional reconstruction, was not reduced significantly during therapy. We think that the increased perfusion of the psoriatic plaque is due to the combination of morphological (dilatation of vessels), dynamic (increased blood flow) and optical effects (reduced scattering and increased sampling depth of the laser-beam in acanthotic tissue).

Anthralin↗
PubMedDate not supplied

Effects of nonsteroidal anti-inflammatory drugs upon intrarenal blood flow: selective medullary hypoperfusion.

Nonsteroidal anti-inflammatory drugs (NSAIDs) predispose to acute and chronic renal failure, possibly due to intrarenal hemodynamic effects. In anesthetized volume-expanded rats, total renal blood flow (RBF) was measured by an ultrasonic flowmeter placed around the left renal artery, superficial cortical blood flow (sCBF) by a flunt laser-Doppler probe placed over the kidney surface, mid-cortical (mCBF) and outer medullary blood flow (oMBF) by a needle laser-Doppler probe inserted into the renal parenchyma. Indomethacin (5 mg/kg i.v.) caused no significant change in RBF (n = 9) or mCBF (n = 6) and slightly increased sCBF (to 106 +/- 2% of baseline; n = 8, p < 0.05). By contrast, oMBF dropped significantly (to 55 +/- 4% of baseline; n = 8, p < 0.0001) within 30 min of indomethacin administration. Similarly, acetylsalicylate (50 mg/kg i.v.) slightly increased sCBF (to 110 +/- 3% of baseline; n = 5, p < 0.05) but caused a significant drop in oMBF (to 54 +/- 2% of baseline; n = 5, p < 0.0001). These results suggest that NSAIDs cause a profound and selective reduction in oMBF which may predispose to acute or chronic intrarenal damage by aggravating medullary hypoxia.

Animals↗
PubMed1994

Transcutaneous Po2 and Pco2 measurement in dermatology.

Although transcutaneous Po2 (tcPo2) and Pco2 (tcPco2) measurement was originally developed for the non-invasive Pao2 and Paco2 monitoring, its utilization in dermatology is discussed in this article. Our experimental and clinical studies have revealed that tcPo2 is easily influenced and reduced by various skin changes, such as hyperkeratosis, acanthosis, cellular infiltrate and fibrosis as well as the circulatory disturbance in the skin, and that tcPco2 is kept stable except in ischemic or bullous lesions. Although tcPo2 could be a marker reflecting the severity of some lesions, simultaneous measurement of tcPco2 and cutaneous blood flow would offer more precise information about the circulation and respiration in the skin.

Animals↗
PubMed1994

Bioengineering and the skin: from standard error to standard operating procedure.

Bioengineering techniques for examination of the skin, measuring principles and sources of error relative to technique, study design, measuring conditions and variability related to test subjects and preconditioning are reviewed. Principles of validation and standard operating procedures (SOP) are discussed, including guidelines for measurement of transepidermal water loss (TEWL) and laser Doppler cutaneous blood flow. Today typical errors are not related to a measuring device but to the way it is used.

Biomedical Engineering↗
PubMed1993

Laser Doppler flux and tissue oxygen tension as indicators of colonic perfusion in pigs.

OBJECTIVE: To evaluate laser Doppler flowmetry (LDF) and tissue oximetry (TpO2) for intraoperative assessment of colonic perfusion in pigs. MATERIAL: Eight pigs weighing from 19-22 kg. INTERVENTIONS: Relationships of laser Doppler flux and TpO2 to mean arterial pressure (MAP) were measured in porcine sigmoid colon. The influence of different fractional inspired oxygen concentrations (FiO2) and the variability of the laser Doppler flux were evaluated. RESULTS: Highly significant reproducible non-linear perfusion compared with pressure relations were found with both methods (r > or = 0.9, p < 0.0001). There was a rapid decrease when MAP fell below 90 mmHg. The dependency of TpO2 on FiO2 was omitted by using the ratio TpO2:PaO2. The coefficient of variation of repeated LDF recordings of 30 second duration with the hand held probe was 0.11 (0.07-0.16) (median and 95% confidence interval). Three recordings gave a reproducible mean flux with an estimated precision of 10% either way. Simultaneous recordings with sutured and hand-held probes correlated well (r > or = 0.9, p < or = 0.01). CONCLUSION: Both methods yielded quantitative and reproducible intraoperative assessments of colonic perfusion, and are applicable for clinical use.

Animals↗
PubMed1994

Laser Doppler skin perfusion pressure in normal and vascular subjects with rest pain: an universal measurement?

Laser-Doppler (LDF) skin perfusion pressure was measured and compared with Doppler ankle pressure measurements in 40 normal subjects and 20 patients with rest pain and ankle/foot Doppler pressure lower than 70 mmHg. Six different, commercially available LDF instruments were used. To obtain perfusion pressure a standard blood pressure cuff was used measuring the pressure at which the skin flux reading reached the biological zero level when inflating the cuff (P1) and the pressure at which the LDF tracing reappeared after deflating the cuff from sovrasistolic pressure level (P2). Perfusion pressure (PP) was considered to be the average [P1 + P2]/2. No differences in PP amongst the 6 instruments both in normal and vascular subjects were observed. These results indicate that PP is an universal LDF measurement which can be easily obtained with different LDF instruments.

Ankle↗
PubMed1993

[Cutaneous microcirculation in systemic sclerosis. Morpho-functional research using capillaroscopy and laser-Doppler].

Our previous researches proved that, in patients affected by Raynaud disease, microcirculatory alterations were greater in those cases in which the small vessels showed evocative appearances of a sclerodermatous connectivopathy. In this study we evaluated cutaneous microvasculature in 18 patients suffering from clear systemic sclerosis, compared with a group of 16 subjects affected by primitive Raynaud disease and a group of healthy subjects. We used videocapillaroscopy and laser-Doppler fluxmetry for morphological and functional study respectively. In patients affected by systemic sclerosis the rest flow was clearly reduced and morphological pattern of cutaneous small vessels deranged. The response to ischemic test allowed us to subdivide the skin-bounds in two subgroups: "no responders" 8 subjects (44%), in which reactive hyperaemia was completely absent, "responders" 10 patients (56%) in which the hyperaemia was completely overlapped with that of the two other groups, but with longer reaction times. In skinbounds the capillaroscopic pattern was clearly severe in comparison with other two groups (18.8 +/- 5.7 vs 5.7 +/- 2.3 and 3.6 +/- 1). Thus, in advanced stage of the pathology, is microangiopathy (in its tromboischemic and inflammatory aspects) that plays a very important role in the development of organ damage. Therefore, all those clinical and instrumental tests which may allow a differential early diagnosis between a primitive and a secondary Raynaud phenomenon be done, for its prognostic value in connection with the appearance of systemic sclerosis.

Adult↗
PubMed1994

Cardiovascular and cerebrovascular effects of the applied Valsalva manoeuvre in anaesthetized neurosurgical patients.

We examined the effects of Valsalva's manoeuvre and its four phase on heart rate, central venous pressure (CVP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), and laser Doppler cerebellar cortical blood flow (CBF). Brief Valsalva manoeuvres increased CVP and markedly decreased MAP. Cerebral perfusion pressure significantly (P < or = 0.01, Dunnett's test) decreased during phases 2 and 3 of the Valsalva manoeuvre. Cortical blood flow closely paralleled CPP; CBF decreased to 59% of control during phase 2 and to 57% of control during phase 3 of the Valsalva manoeuvre. The MAP, CPP, and CBF all returned to baseline levels during phase 4 (the overshoot phase) of the Valsalva manoeuvre, and were not significantly greater than control. No autoregulatory change in cerebrovascular resistance occurred throughout the Valsalva manoeuvre. These results suggest that brief Valsalva manoeuvres, as employed during neurosurgical procedures, mainly confirm venous haemostasis, but must be used cautiously due to the marked haemodynamic changes.

Aged↗
PubMed1993

The use of Doppler velocimetry of the umbilical artery before 24 weeks' gestation to screen for high-risk pregnancies.

OBJECTIVE: To describe the prevalence and natural history of absent end-diastolic velocities (AEDV) in the umbilical artery of the fetus between 16 and 24 weeks' gestation, and to evaluate its role as a screening test. DESIGN: Population-based descriptive study. SETTING: Tygerberg Hospital, Tygerberg, South Africa. The hospital serves a population from the lower socio-economic bracket. SUBJECTS: Doppler velocimetry was performed at routine ultrasound examinations for confirmation of gestational age in 496 women. MAIN OUTCOME MEASURES: The occurrence of perinatal death, small-for-gestational-age (SGA) babies and proteinuric hypertension. RESULTS: Forty-four (8.9%) patients had AEDVs at the first examination, but AEDV persisted in only 1. In this case, severe proteinuric hypertension developed unexpectedly at 29 weeks' gestation and the fetus needed delivery because of persistent late decelerations of the fetal heart rate pattern. There was a significant association between the group with AEDV at first examination and the development of proteinuric hypertension (P < 0.05), but no association with SGA babies. The association with proteinuric hypertension was too weak to be of clinical use. CONCLUSION: Doppler velocimetry of the umbilical artery, performed along with routine ultrasound examination to confirm gestational age, is not of use as a screening test for identifying high-risk pregnancies.

Blood Flow Velocity↗