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Results for “Laser-Doppler Flowmetry”

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At least 1,261 records · Page 70Linked to original sources
PubMed1993

[The effect of prostaglandin E1 and prostaglandin F2 alpha in the ischemic small intestine of dogs].

The effect of PGE1 and PGF2 alpha in the ischemic intestinal tract were examined. In 40 mongrel dogs, we studied ischemic models of small intestine. PGE1 or PGF2 alpha was injected into the anterior mesenteric artery after reperfusion according to each occlusion time, and the tissue blood flow was measured on both mucosal and serous sides of small intestinal loop by laser flowmeter to examine the relation to the extent of tissue damage. Tissue blood flow of the ischemic intestine after the injection of PGE1 increased by 148-208% in the 3-5 hr occlusion group and by 86-110% in the 7-10 hr occlusion group. Tissue blood flow after the injection of PGF2 alpha decreased by 39-59% in the 3-5 hr occlusion group and by 1-15% in the 7-10 hr occlusion group. These results indicate that the effect of PGE1 and PGF2 alpha in the ischemic intestine would be available up to 3-5 hr of ischemia. Histological examination revealed that viability of the remaining crypt was high in the PGE1 injection group but low in the PGF2 alpha injection group. These findings suggest that PGE1, if try at the early stage, would be effective for the treatment of ischemic lesion.

Alprostadil↗
PubMed1993

Biological zero in laser Doppler measurements in normal, ischaemic and inflamed human skin.

The Biological Zero (BZ) signal in laser Doppler flowmetry was recorded during temporary occlusion of the arterial circulation to the limb by a blood pressure cuff inflated suprasystolically for 2 min. The non-thermoregulatory skin at the ankle was compared with the thermoregulatory skin over the toe pad in patients with lower limb arterial obstructive disease, elderly controls without arterial disease and young healthy adults under cool (15-17 degrees C) and warm (25-27 degrees C) ambient conditions. The absolute BZ values did not differ significantly within the three groups at the two room temperatures. However the resting laser Doppler flowmetry signal (LDflux) was consistently higher under warm than cold room temperatures: these differences were much greater at the toe than at the ankle. Accordingly, the relative size of BZ, expressed as a percentage of the resting LDflux, was least over the toe in a warm room (5-10%) and greatest over the malleolus (59-83%) in the cold room. The changes during the evolution of a positive tuberculin skin reaction were followed as a model of chronic inflammation in man. The resting LDflux rose 10 fold (from 0.3 to 3.4V) while the change in the BZ was minor (0.16-0.2V). Thus the rise in LDflux in a fully developed tuberculin reaction was approximately 30X greater than that for the corresponding BZ. Concurrent measurements of the alternative output from the laser Doppler flowmeter (CMBC) showed in a similar pattern. Since the BZ signal can be a substantial proportion of the resting LDflux measurement, we support the recommendation that the BZ should be measured wherever possible and practicable, for subtraction from the observed LDflux to assess the true flow: 'raw' LDflux measurements should be interpreted with extreme caution, particularly at relatively low resting LDflux levels.

Adolescent↗
PubMed1993

Evidence for skin microvascular compartmentalization by laser-Doppler and photoplethysmographic techniques.

Indices of perfusion were obtained using commercial laser-Doppler instruments with differing wavelengths on metatarsal skin of sheep (which is abundant with AVAs) and compared with quantitative measurements of AVA and capillary blood flow using microspheres; an infra-red photoplethysmograph was also compared. The data provide physiological evidence that laser-Doppler instruments of longer wavelength sense to a greater depth, and our photoplethysmograph behaves similarly to a "near-infra-red" laser. Thus, we suggest that near-infra-red light, either laser-Doppler or photoplethysmograph, should be used to measure a parameter most representative of total local blood flow, and light of a very much shorter wavelength, probably green light, would allow more confidence in estimates of true capillary perfusion. Because the commonly used visible red light can, but does not necessarily detect deep AVA perfusion, the influence depending upon the magnitude of the AVA perfusion, measurements by an instrument based on such red light is difficult to define.

Animals↗
PubMed1993

[Experimental study of acute spinal cord injury: a study of spinal blood flow].

It is well known that the worsening of neurological findings after spinal cord injury is due to the secondary progression of pathological changes which may be caused by spinal cord blood flow disturbance. We measured spinal blood flow of 5mm rostrally and caudally distant portions from the injured point, using the laser Doppler flowmeter experimentally. Forty rats were used. Ten of these were used as a control group. And thirty animals were injured at the level of the tenth thoracic cord with a 50g epidural one minute compression method and measured continuously from 30 minutes before the injury to 6 hours after the injury. Twenty two surviving animals were evaluated. In the control group, spinal blood flow was stable. But in the injured group, spinal blood flow dropped by 30.6 + 9.8% on the rostral side and 37.3 + 17.6% on the caudal side in comparison with the resting value soon after the injury. Although the flow improved to 89.3 + 11.1 and 71.3 + 17.8% respectively 15 minutes later, it dropped again gradually and reached 42.8 + 14.1 and 66.2 + 16.4% respectively 6 hours after the injury had been inflicted. Lastly, in the animals, carbon perfusion was performed through the left ventricle. The normal figured vasculature in the preparation of the injured and measured portion was calculated with a microcomputer imaging analyzer and compared with control groups. The number of the normal vessels was significantly more abundant on the caudal side than on the rostral side (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Perfusion in the anterior tibial muscle measured by laser Doppler flowmetry after graded periods of hindlimb ischemia in rats.

In the present study laser Doppler flowmetry was used to evaluate skeletal muscle perfusion before and after acute hindlimb ischemia in rats. Three laser Doppler microprobes were placed in the anterior tibial muscles of both legs. Six animals were used as non-ischemic controls and 22 animals were subjected to complete ischemia in the left hindlimb for 0.5 to 4.5 hr. By calculating a perfusion index based on recordings from the left and the right leg, a continuous measurement of relative perfusion could be performed. Reactive hyperemia was demonstrated after ischemia of shorter than 2 hr duration. After longer occlusion periods, the reperfusion decreased with increasing duration of ischemia. It is concluded that the use of laser Doppler microprobes offers possibility for continuous evaluation of relative microvascular blood flow in normal and postischemic skeletal muscle, and that the technique would be useful in experimental studies concerning ischemia-reperfusion injury of skeletal muscles.

Animals↗
PubMed1993

Laser Doppler flowmetry, transcutaneous oxygen pressure and thermal clearance in patients with vascular intermittent claudication.

In the present study, heat thermal clearance (HTC) was compared to laser Doppler flowmetry (LDF) and transcutaneous oxygen pressure (tcPO2), measured on the forefoot of 17 patients with vascular intermittent claudication and 10 controls in various positions at rest and after a treadmill exercise test. The mean ankle brachial systolic pressure ratio (ABSP) of the patients, measured using ultrasonic Doppler velocimetry, was 0.53 +/- 0.05. Their walking distance was 480 +/- 100 meters, the treadmill exercise being stopped as soon as pain sensation. No statistically significant difference was found between patients and controls for HTC, LDF, tc P02, forefoot and ankle skin temperatures. Statistically significant differences between patients and controls occurred in the sitting position for tcPO2, in standing position for HTC and after treadmill exercise for tcPO2 and LDF. When assuming the sitting position HTC did not vary significantly in patients and decreased in controls, LDF decreased and tcPO2 increased in both groups. After treadmill exercise, HTC in patients did not vary compared to supine values and HTC decreased in controls, tcPO2 remained unchanged in controls and decreased in patients, LDF increased in controls and decreased in patients. No significant correlations were found between the different techniques measured at rest in patients and controls. However in patients, after the treadmill test, LDF correlated with the walking distance (r = 0.667) and with ABSP (r = 0.641), HTC inversely correlated with the walking distance (r = -0.680) and ABSP (r = -0.577). Laser Doppler, tcPO2 and HTC are useful as tools to understand the alterations of cutaneous microcirculation of the lower limbs in patients with V.I.C.. However their results need to be interpreted with caution because these methods do not measure directly blood flow.

Adult↗
PubMed1993

A clinical comparison of two laser Doppler instruments. Fiber-optic probe versus integrated probe.

Two instruments for laser Doppler fluxmetry were compared; a diode laser (Diodopp) with a He-Ne gas laser (Periflux Pf1d). Spatial variability during baseline registration and temporal variability during 3 standardized provocation tests (suprasystolic occlusion, tilting and inspiratory gasp) were evaluated in 20 healthy volunteers. The coefficient of variation (= CV) of the registrations on four adjacent places did not show any significant difference between both instruments. The biological zero obtained during 5 minutes vascular occlusion was always zero with the Diodopp and 4 (3-5) (median, [minimum-maximum]) Perfusion Units with the Periflux. The hyperaemic response measured by both instruments was less pronounced during the Diodopp registration (percentage LDF increase 173% (15-350) vs 354% (86-1100), p < 0.001). Although the CV of the LDF parameters obtained by the Diodopp during the standardized provocation tests was almost always lower then with the Periflux, only occasionally the differences reached statistical significance. We concluded that both laser Doppler instruments are of equal value. The reproducibility of the Diodopp is slightly better, but the hyperaemic response after occlusion is registrated in a different way by both instruments.

Adult↗
PubMedDate not supplied

Umbilical waveform variations in the acutely distressed fetus: an experimental model in the fetal sheep.

In previous experimental studies on the pregnant ewe, umbilical arterial and venous waveform variations, produced by maternal aortic and umbilical cord occlusions of different degrees, were investigated in healthy fetuses (pH > 7.30). In our study, the fetal pH in 10 pregnant ewes was first brought down to below 7.20 with a preliminary series of maternal aortic and umbilical cord occlusions; then the 10 ewes were again submitted to a similar series of maternal aortic and umbilical cord occlusion. There were 24 experimental sessions with series of umbilical occlusions and 27 sessions with maternal aorta occlusions. The differences in waveform responses between these two types of fetuses are characteristic. The acidotic fetus produces more protracted drops in S, D, and venous velocity and, at the end of occlusion, the return to normal is slower with no reactive overflow waveform. In addition, there is a typical venous undulating pattern and no reappearance of blood flow velocity during the umbilical cord occlusion (always observed in healthy fetuses). Another important observation is that the fetal heart rate responses (bradycardia or tachycardia or no fetal heart rate variations) are more erratic in the acidotic fetus and do not relate to the intensity of the occlusion or to the fetal pH. The possible clinical implications of these experimental findings are discussed.

Acidosis↗
PubMed1996

Staphylococcal enterotoxin B applied on intact normal and intact atopic skin induces dermatitis.

BACKGROUND AND DESIGN: Colonization of inflammatory skin diseases with Staphylococcus aureus is a frequent phenomenon and may cause exacerbation of the skin disease. Staphylococcus aureus strains present on atopic dermatitis are capable of releasing staphylococcal enterotoxins, a group of superantigens that are very potent T-cell activators. To determine whether the superantigen staphylococcal enterotoxin B can induce inflammation when applied on the skin, staphylococcal enterotoxin B was applied with and without occlusion on the volar aspect of the skin on the forearm of 10 subjects without skin disease and six subjects with atopic dermatitis of minimal activity and no eczema on the volar aspect of the skin on their forearm. The main outcome measures were clinical rating; determination of the increase of the thickness of the skin-fold; and determination of skin blood flow. RESULTS: Clinically, staphylococcal enterotoxin B induced skin changes of erythema and induration in 10 of 10 healthy volunteer subjects and six of six subjects suffering from atopic dermatitis, while the vehicle induced clinically evident skin changes in only one of 10 healthy subjects and none of six subjects with atopic dermatitis. On day 3 after the application of an occluded patch containing 10 micrograms/cm2 of staphylococcal enterotoxin B in the healthy subjects, the thickness of the skinfold increased 0.47 +/- 0.49 mm (mean +/- SD) (n = 9; P < .02) relative to the increase in the thickness of the skinfold following application of the vehicle. The Doppler laser-measured skin blood flow index had increased from 1.0 +/- 0.4 to 5.3 +/- 3.7 (mean +/- SD) (n = 10; P < .002). On day 3 after the application of occluded patchs containing 10 micrograms/cm2 of staphylococcal enterotoxin B in the subjects suffering from atopic dermatitis, the increase in the thickness of the skinfold increased 0.20 +/- 0.24 mm (n = 6; P, not significant) relative to the increased thickness in the skinfold following application of the vehicle. The Doppler laser-measured skin blood flow index had increased from 1.1 +/- 0.4 to 3.7 +/- 2.2 (n = 6, P, not significant). Three of six subjects suffering from atopic dermatitis experienced a flare of their disease in the elbow flexure ipsilaterally to where the staphylococcal enterotoxin B patch was applied. CONCLUSIONS: The superantigen staphylococcal enterotoxin B applied on intact skin from both normal subjects and patients with atopic dermatitis induces an inflammatory reaction. This finding suggests that superantigens released from S aureus present on the skin in inflammatory skin diseases may exacerbate and sustain the inflammation.

Adult↗
PubMed1995

[Comparative value of Doppler graphic indices of blood flow rate and pressure in the assessment of the degree of lower limb ischemia].

The authors studied the dependence of Doppler graphic indices of blood flow and pressure at rest on the degree of ischemia of the lower limbs determined by the multistep treadmill test. They examined 50 patients with angiographically detected occluding lesions of the lower-limb arteries. The indices of pressure reflected the degree of the severity of lower-limb ischemia well, but the indices of linear blood flow rate did not correlate with it.

Adult↗
PubMed1995

[Study of anti-tumor effects of hyperthermia combined with hydralazine on experimental tumor].

We analyzed tumor growth delay in experimental tumors after hyperthermia alone, hydralazine (HDZ) injection alone and the combination of these modalities. We also analyzed the energy parameter (ATP/Pi ratio) obtained by 31P-MRS (magnetic resonance spectroscopy). The purpose of this study was to evaluate the usefulness of 31P-MRS as an index of anti-tumor effect. FM3A tumor cells were transplanted subcutaneously in the hind legs of C3H/He mice. We dipped the tumors into a heated circulating water bath. 31P-MRS was performed with a CSI spectrometer. The anti-tumor effect obtained with HDZ alone was insignificant, but combined treatment with hyperthermia and HDZ had a significant synergistic effect. The ATP/Pi ratios for all groups treated separately with HDZ or hyperthermia were not different from the control, but the ATP/Pi ratio decreased after combined use of these agents. There was a significant correlation between the decrease in ATP/Pi ratio and tumor growth delay. We observed a direct relation between the delay in tumor growth and the decline in ATP/Pi ratio after combined treatment with HDZ and hyperthermia. The ATP/Pi ratio 24 hr after treatment may be useful in predicting the efficacy of the combined use of HDZ and hyperthermia.

Adenosine Triphosphate↗
PubMedDate not supplied

[Doppler echographic criteria in determination of the aerobic threshold and ischemia of the lower limbs].

Doppler echographic criteria were developed to define the anaerobic threshold and to detect lower extremity ischemia. Multi-stage treadmill test provided the criteria involving impairments in the time course of recovery of continuous diastolic blood flow in the lower extremity arteries. The criteria allow the anaerobic threshold to be defined in the range of low and high exercises and the severity of ischemia of the saved and amputated limb to be assessed in arterial occlusions. The diagnostic sensitivity of the criteria is 82-87%, its specificity and predictive value are 95-100%.

Adult↗
PubMed1996

Retinal blood flow changes in type I diabetes. A long-term follow-up study.

PURPOSE: The authors previously reported that blood speeds in the retinal arteries were significantly lower in patients with type I diabetes than in controls without diabetes. The purpose of this long-term, follow-up study was to characterize the natural course of changes in blood speed and blood flow in these patients. METHODS: Twenty-four patients were followed up with serial annual measurements of the blood flow in a temporal retinal artery using the bidirectional laser Doppler technique and monochromatic photography. The follow-up period ranged from 2 to 6 years (mean, 3.8 years). Using standardized color fundus photography and fluorescein angiography, a retinopathy score was generated for each eye studied. Linear regression analysis was used to compute the slope of the change in retinal blood flow for each patient during the follow-up period. RESULTS: Retinal blood flow slopes were negative in 15 patients and positive in 9 patients. Multiple linear regression analysis showed that the retinal blood flow slopes were significantly related to the retinal blood flow measured at entry to the study and to the median duration of diabetes during the follow-up period (R2 = 0.56; P = 0.0002). There was a positive correlation between the retinal blood flow slopes and the median retinopathy score during the follow-up period (P = 0.47; P = 0.02). CONCLUSIONS: As duration of diabetes becomes longer and retinopathy becomes more severe, there is a transition from negative to positive retinal blood flow slopes. This bimodal relationship between the change in retinal blood flow and the duration of diabetes reflects the complex pathologic alterations that occur in the diabetic retina.

Adult↗
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↗