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Results for “Laser-Doppler Flowmetry”

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At least 37 records · Page 2Linked to original sources
PubMed1992

Cold fingers in leprosy.

Under conditions of maximal thermoregulatory peripheral dilatation, most healthy subjects (both Indian and European) showed raised blood flow in the fingertips (measured by laser Doppler flowmetry) where the skin temperature is only slightly lower than the core body temperature. Most borderline lepromatous (BL) leprosy patients had much colder fingers and the blood flow was slow: borderline tuberculoid (BT) patients had skin temperatures similar to those seen in healthy subjects, but their fingertip blood flow was reduced relative to that in control subjects. The occurrence of cold fingers and slow blood flow was clearly associated with evidence of sensory impairment to light touch, pressure and temperature. Slower fingertip blood flow was strongly associated with impairment of vasomotor control in this anatomical region, suggesting that both may be a consequence of leprosy peripheral neuropathy, at least in patients with early leprosy, but it is likely that leprosy arteriopathy may contribute to the lowered peripheral perfusion in advanced cases. It is suggested that the simple clinical sign of cold fingers may be of value in the preliminary assessment of patients presenting at any leprosy control clinic in the tropics.

Adult↗
PubMed1992

Ultraviolet B dose-dependent inflammation in humans: a reflectance spectroscopic and laser Doppler flowmetric study using topical pharmacologic antagonists on irradiated skin.

Normal skin responds acutely to ultraviolet (UV) light exposure with complex inflammatory mechanisms. In the present study UVB irradiation ranging from subclinical erythema doses to twice the minimal erythema dose (24 mJ/cm2 to 96 mJ/cm2) was delivered to the skin of 8 volunteers. Pre-irradiated sites were immediately afterwards exposed to a 24-h occlusive patch containing 1 of 4 anti-inflammatory agents or vehicle control. The resultant change in erythema (vascular reaction) was measured objectively using laser Doppler flowmetry (LDF) and reflectance spectroscopy (RS). The 4 anti-inflammatory compounds reduced the UVB-induced vascular reactions in different and dose-dependent ways. Betamethasone-17-valerate and diphenhydramine were most effective at the 24 mJ/cm2 dose site and indomethacin and acetylsalicylic acid were more effective at sites > or = 48 mJ/cm2. Ranking the reduction in oxygenized hemoglobin (OH) content was as follows: betamethasone-17-valerate (OH reduction = 37.4%) > indomethacin (OH reduction = 21.5%) > acetylsalicylic acid (ASA) (OH decrease = 21.0%) > diphenhydramine (OH reduction = 18.4%). Using LDF, the total ranking of the cutaneous blood flow (BF) reduction was: indomethacin (BF reduction = 39.7%) > betamethasone-17-valerate (BF reduction = 32.7%) > acetylsalicylic acid (BF decrease = 17.5%) > diphenhydramine (BF reduction = 12.3%). Diphenhydramine significantly reduced erythema only at the lowest irradiation dose (24 mJ/cm2) and the decrease in OH was associated with an increased amount of deoxygenized hemoglobin (DOH). A similar slight venous dilatation was present at acetylsalicylic acid-exposed sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMedDate not supplied

Skin blood flow after intradermal injection of ropivacaine in various concentrations with and without epinephrine evaluated by laser Doppler flowmetry.

BACKGROUND AND OBJECTIVES: Skin blood flow changes after intradermal injection of ropivacaine in various concentrations with or without epinephrine were investigated using laser Doppler flowmetry. METHODS: Twenty-three non-smoking, healthy, young male volunteers participated. Four test sites were used on each forearm (volar surface) in a randomized, double-blind study. Recordings were made at 20, 40, 60, and 90 minutes after intradermal injection (0.1 ml, 30-gauge needle). Injections of saline and 1% lidocaine and an untreated area served as controls. In Series 1, various concentrations of ropivacaine (1%, 0.5%, 0.375%, 0.125%, and 0.063%) were injected. RESULTS: The data from this series showed a dose-response relationship: 1% ropivacaine provoked an increase in skin blood flow similar to saline; 0.5% and weaker concentrations of ropivacaine showed a reduction in flow compared to saline, this being more pronounced with the weakest solutions (0.125% and 0.063%). In Series 2, injection of 1:200,000 (5 micrograms/ml) epinephrine alone and injections of ropivacaine in various concentrations (1%, 0.5%, and 0.25%) with addition of epinephrine were carried out. Injection of epinephrine alone showed a flow almost as low as at the untreated control sites. Ropivacaine epinephrine injections were followed by a lower skin blood flow compared to saline, but the flow was significantly larger compared to the effect of epinephrine itself at the 20-minute recording. CONCLUSION: The combination of ropivacaine and adrenaline did not accentuate but instead diminished the vasoconstrictive effect of epinephrine.

Adult↗
PubMed1992

The oligemic phase of cortical spreading depression is not blocked by tirilazad mesylate (U-74006F).

Cortical spreading depression is characterised by a wave of depolarization that moves across the cortex leaving in its wake a state of hyperpolarization. Characteristic changes in cerebral blood flow are also seen and these consist of a wave of hyperemia followed by an oligemia, the latter lasting some hours in some experimental animals including the cat. In this study cerebral blood flow was measured using laser Doppler flowmetry in the anesthetised ventilated cat. Spreading depression was initiated with a pin-prick injury prior to or following administration of U74006F (tirilizad mesylate; 3 mg/kg, ivi) or an identical volume of vehicle. Laser Doppler probes were placed bilaterally and in each case studied both the hyperemic and oligemic phases of spreading depression were preserved after administration of either U74006F or its vehicle. These data suggest that free radical mechanisms have no significant role in mediating the blood flow changes of spreading depression and are consistent with data in the literature of a quantitative using single-point measurements that again U74006F does not affect spreading depression.

Animals↗
PubMed1992

Intrathecal somatostatin in the guinea pig: effects on spinal cord blood flow, histopathology and motor function.

In the present investigation, the vasoconstrictive, motor and neurodegenerative effects of intrathecal somatostatin (SST) were assessed in guinea pigs implanted with lumbar intrathecal catheters. Five consecutive dose increments of SST (5, 10, 15, 30 and 60 micrograms) to a total of 120 micrograms during the period of 16 +/- 3 min, resulted in a moderate (< 20%), gradual decrease of the spinal blood flow monitored with the laser-doppler method. A subsequent injection of clonidine (50 micrograms) or norepinephrine (10 micrograms) resulted in a more pronounced decrease of spinal blood flow (35% and 79%, respectively). Three consecutive, daily intrathecal injections of 30 or 60 micrograms SST did not cause any loss of weight support or paralysis of the hind limbs. There were no histopathological changes in the white or gray matter of the thoracic and lumbar sections of the spinal cords. It is concluded that SST, in the doses studied, is not neurodegenerative in guinea pigs. These findings are in contrast to those previously seen in rats. The implication of this study may be the necessity to use several alternate animal species in order to evaluate the antinociceptive and neurodegenerative properties of the peptides administered by the intrathecal route and the choice of dose to be compared across species.

Animals↗
PubMed1992

Intraoperative prediction of ischaemic injury of the bowel: a comparison of laser Doppler flowmetry and tissue oximetry to histological analysis.

Intraoperative diagnosis of inadequate colonic perfusion would contribute to prevention of ischaemic colitis after abdominal aortic reconstructions. The aim of this study was to evaluate laser Doppler flowmetry (LDF) and tissue oximetry (TpO2) as predictors of the development of bowel necrosis. Devascularised loops of colon and ileum in anaesthetised pigs were divided into 10-20 mm segments and measurements of laser Doppler flux and TpO2 were performed in each segment. After 7 h of ischaemia the segments were resected for histological and biochemical analysis. In 65 colonic and 58 ileal segments a significantly lower flux was found in segments with necrosis of greater than or equal to 30% of the mucosal thickness compared to segments with necrosis of less than or equal to 10% (p less than 0.01). The discriminant flux value was 50 perfusion units, confirming a previous clinical study. The specificity was 0.96 and the sensitivity 0.94. Flux was inversely correlated to tissue lactate concentration. Significantly lower TpO2 was found in 19 colonic segments with necrosis of greater than or equal to 30% of mucosa compared to 19 colonic segments with necrosis of less than or equal to 10% (p less than 0.01). Using a discriminant value of 5kPa, a specificity of 0.79, and a sensitivity of 0.95 were calculated. In 27 ileum segments no significant difference in TpO2 between different histological groups was found (p greater than 0.30). The results show that LDF and TpO2 can predict ischaemic injury of the colon, and LDF also of the small bowel.

Animals↗
PubMed1992

The relevance of posturally induced microvascular constriction after revascularisation in patients with chronic leg ischaemia.

In patients with severe chronic lower limb ischaemia, postural vasoconstriction is disturbed, resulting in enhanced skin microcirculatory perfusion on leg dependency. After vascular reconstructive surgery, postoperative oedema formation is frequently seen. In 31 patients with leg ischaemia undergoing revascularisation we investigated whether and, if so, for how long after surgery postural vasoconstriction would take to recover, and whether disturbed vasoconstriction correlates with the occurrence of postoperative oedema. Capillary microscopy and laser Doppler fluxmetry were used to assess nutritional and total skin perfusion, respectively. The measurements were performed before and up to 37 days after surgery. After revascularisation, the mean ankle blood pressure index rose from 40 to 82%. All patients, except those with persistently disturbed vasoconstriction showed improved microcirculatory parameters. Postural vasoconstriction was restored in 24 patients, occurring approximately on the eighth postoperative day. All patients who failed to recover vasoconstriction developed postoperative oedema. This study shows that the disturbance in postural vasoconstriction can be reversible, probably due to recovery of arteriolar smooth muscle tone, and that patients with persistently disturbed postural vasoconstriction, are prone to develop postoperative oedema.

Adult↗
PubMed1992

Atrial contractility affects phasic blood flow velocity of atrial small vessels in the dog.

OBJECTIVES: The aim was to evaluate the relative contribution of atrial muscle contraction and atrial pressure to the phasic patterns of left atrial arterial and venous flows. METHODS: Using a laser Doppler velocimeter, blood velocities were measured in the atrial small arteries and veins (outer diameter: 150-500 microns) in anaesthetised open chest dogs (n = 21). The velocity sensor was fixed on the vessel surface with a drop of cyanoacrylate glue when good quality Doppler signals were consistently observed. Left atrial pressure and the contractility of the left atrium were changed by premature ventricular contraction and by intracoronary injection of isoprenaline (0.5 microgram), respectively. RESULTS: Premature ventricular contraction increased left atrial pressure significantly during arterial velocity measurements from 8.1(SD 2.7) to 16.4(1.3) mm Hg and during venous measurements from 8.2(1.2) to 14.3(3.7) mm Hg. However, premature ventricular contraction did not change the blood velocity patterns, the maximum deceleration rate of the systolic velocity wave in arteries, or the maximum acceleration rate of the systolic velocity wave in veins. Although isoprenaline did not change the left atrial pressure, it decreased minimum arterial blood velocity during atrial systole, from 3.3(3.4) to -2.5(3.2) cm.s-1, and increased maximum venous blood velocity from 15.9(5.5) to 19.2(7.4) cm.s-1. Isoprenaline also increased both the maximum arterial systolic velocity deceleration rate, from 90(45) to 234(143) cm.s-2, and the maximum venous systolic velocity acceleration rate from 356(230) to 763(366) cm.s-2. CONCLUSIONS: (1) Left atrial pressure is not a major determinant of the blood flow patterns of the atrial arteries and veins, and therefore it may not closely reflect pressure around mural vessels. (2) Atrial contractility affects the blood flow patterns of the atrial arteries and veins.

Animals↗
PubMedDate not supplied

Characteristics of laser Doppler flowmeters with differing optical arrangements.

Recently, various laser Doppler flowmeter (LDF) systems have been used for evaluation of tissue microcirculation. However, indifference has often been shown by doctors and researchers regarding their sampling volume, stability and accuracy, which differ with various optical arrangements. In this study we evaluated the characteristics of three LDF systems with different optical arrangements. The sampling depths in both blood and tissue were found to differ with the different optical arrangements, although the laser power emitted from the probes is nearly equivalent. Each depth significantly changed at haematocrits between 5.0 and 36.5%. The stability and the accuracy of the measurements also differed. In the practical case of tissue microcirculation it is important to measure blood flow with an understanding of the material differences in the characteristics of the LDF systems.

Animals↗
PubMedDate not supplied

Some flow visualization and laser-Doppler-velocity measurements in a true-to-scale elastic model of a human aortic arch--a new model technique.

Flow studies were done in an elastic true-to-scale silicone rubber model of an aortic arch to study further hemodynamic influences on atherosclerosis. The model was prepared from a cast of a young woman. A revised model technique was used. The model had a compliance similar to that of the human aortic arch. Velocity measurements were done in the model with a two component laser-Doppler-anemometer in steady and pulsatile flow using a calcium chloride solution with a viscosity of eta = 3.18 mPas and density of rho = 1.28 kg/m3 at 20 degrees C. The time average Reynolds numbers over a whole cycle in the ascending aorta was Re = 1350. The Womersley parameter for pulsatile flow was a = 20. The pulse wave velocity in the ascending aorta was about c = 5.4 m/sec. The secondary flow behavior was discussed for steady and pulsatile flow. Reverse flows were found, especially along the inner radius of the aortic arch in the descending aorta in steady and pulsatile flow and also in small areas of the ascending aorta and at the branches of the aortic arch. The formation of atherosclerotic plaques at preferred local flow regions is discussed.

Aorta, Thoracic↗
PubMed1992

Alterations of skin microcirculatory rhythmic oscillations in different positions of the lower extremity.

Microcirculatory vasomotion is considered to be an important mechanism promoting and facilitating the transfer of blood cells through skin capillaries. Since skin vulnerability of the leg is closely associated with gravitational factors and skin micro-circulation, we investigated by a laser Doppler apparatus influence of postural changes on skin blood flow oscillations in lower limbs of healthy volunteers. Our data show a marked decrease in microcirculatory oscillation amplitudes at a frequency 7.6 (+/- 0.6) min-1 after lowering the leg. This could be reversed by the application of compressive bandage. Our study points toward a potentially important mechanism of microcirculatory impairment during orthostasis.

Adult↗
PubMedDate not supplied

Comparison of heated-probe laser Doppler and transcutaneous oxygen measurements for predicting outcome of ischemic wounds.

Transcutaneous oxygen (TcPO2) measurement has proven to be an accurate means of predicting healing of ischemic wounds. This study compares the ability of TcPO2 and laser Doppler, modified by the addition of a heated probe (LDHP), to assess wound outcome. TcPO2 and LDHP measurements were made at the same site for 80 wounds, which consisted of 51 amputations (25 above knee, 6 below knee, 20 forefoot) and 29 ulcerations. Healing was defined as complete wound closure. Failure to heal was defined by the necessity for proximal amputation in 22 wounds (6 amputations, 16 ulcers). Outcome criteria were chosen to maximize accuracy and either positive or negative predictive values. Criteria with the greatest accuracy and positive predictive value for wound healing were > or = 11 mmHg for TcPO2 and > or = 50 mv for LDHP range. Criteria with the most appropriate accuracy and negative predictive value for wound failure were < 5 mmHg for TcPO2 and < 35 mv LDHP range. All wounds whose LDHP range was < 35 mv failed to heal, whereas some wounds with a TcPO2 of 0-1 mmHg healed successfully. An absolute prediction of wound healing (100% specificity and negative predictive value) was offered when either LDHP range was > or = 125 mv or TcPO2 was > or = 33 mmHg, although accuracy of either measurement at this criteria was unacceptable for more general application. We conclude that TcPO2 or LDHP will assess wound outcome with similar overall accuracy, although each test may be better for predicting a specific outcome.

Aged↗
PubMedDate not supplied

Cutaneous circulation in Raynaud's phenomenon during emotional stress. A morphological and functional study using capillaroscopy and laser-Doppler.

In order to assess the effects of emotional stress on the cutaneous microcirculation in patients suffering from Raynaud's phenomenon (RP) a group of 18 patients with this pathology and 16 healthy control subjects underwent an "arithmetical test". The microcirculatory response was examined using a laser Doppler apparatus. The results obtained showed a constantly reduced flow during mental stress in normal subjects; in the RP group it was possible to observe: a first subgroup with a reduced flow similar to that seen in normal subjects, and a second subgroup with a paradoxically increased flow. It is likely that the normal vasoconstrictor response is the expression of the functional impairment of the microcirculation alone (primary RP), whereas vasodilatation in response to mental stress is a sign, of the organic development of the disease right from an early stage.

Female↗
PubMedDate not supplied

Evaluation by captopril renal scintigraphy and echo-Doppler flowmetry of hypertensive patients at high risk for renal artery stenosis.

Sixty-three hypertensive patients with probability of obstructive renal artery disease underwent both Captopril renal scintigraphy (CRS) and echo-Doppler flowmetry (EDF) before undergoing renal angiography. Angiography revealed renal artery stenosis (RAS) in 42 patients (unilaterally in 26 and bilaterally in 16). The sensitivity and specificity in the identification of RAS > or = 50% were 90% and 94%, respectively for Captopril renography, and 85% and 78% for echo-Doppler flowmetry. Captopril renography correctly identified stenoses greater than 50%, which is usually held to be the limit of hemodynamic significance. While the Doppler examination was more sensitive than Captopril renography (sensitivity 79% versus 64%) in the detection of all degrees of RAS, less information on the functional significance of RAS was provided. Both CRS and EDF could be usefully employed to assess kidney perfusion, but their appropriate clinical use must take into account inherent differences between the two techniques.

Adolescent↗
PubMed1992

[Effects of biomicrosphere on the cochlear blood flow, blood pressure and heart rate in guinea pigs].

Cochlear blood flow (CBF) in guinea pigs was measured by Laser Doppler flowmeter and biomicrosphere method. The effects of dosages of biomicrospheres and time factor on the CBF, blood pressure and heart rate were observed. The findings suggest that 9 x 10(6). 10.5 x 10(6) biomicrospheres may be most suitable for measuring CBF with biomicrosphere method, and some physiological parameters of the guinea pig must be taken down within 2-10 minutes after microsphere injection.

Animals↗
PubMed1992

Intraoperative and postoperative monitoring of microsurgical free tissue transfers.

Numerous techniques have been described for monitoring the postoperative viability of microsurgical free tissue transfers, and their sensitivity and reliability continue to be evaluated in animal experiments and clinical trials. Relative advantages and disadvantages of these various postoperative monitoring techniques are discussed. The concept of intraoperative monitoring of the microsurgical anastomoses during closure and inset of a free flap is introduced because many free flaps may fail on the operating table, but this only becomes clinically apparent several hours later in the early postoperative period.

Animals↗
PubMed1992

[The effects of intracoronary injection of nitroglycerin on the coronary circulation: evaluation using a Doppler catheter].

To evaluate the effects of intracoronary injection of nitroglycerin (NTG) on the coronary circulation, we measured the flow velocity of the coronary artery using a Doppler catheter. The Doppler catheter was introduced into the region proximal to the left anterior descending artery (LAD) via an 8F guide catheter positioned at the orifice of the left coronary artery. We measured the flow velocity at a point of 3 mm distal to the catheter tip. One mg (2 ml) of NTG was injected via the 8F guide catheter for 10 sec, followed by injection of 3 ml of normal saline. Then the increasing rate of the diastolic coronary flow velocity in the LAD was calculated. Five ml of iopamidol (dye) was also injected for comparison. The subjects consisted of 14 normal persons (G-N), and 12 patients with angina pectoris accompanying critical stenoses of the LAD, who had no ECG changes or no abnormalities by left ventriculography. The subjects with angina pectoris were subclassified as 90% stenoses (G-A: 5 patients), and 99% stenoses (G-B: 7 patients) in the LAD. 1. After intracoronary injection of NTG, the aortic pressure dropped to various degrees in G-N. In 7 of the normal subjects, who had less than a 20% aortic pressure drop, the increased diastolic flow velocity was more rapid than the control diastolic flow velocity 30 sec after the peak velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗