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Background and Aims Peripheral arterial disease (PAD) occurs at a high frequency in hemodialysis (HD) patients and is known to be associated with poor outcomes. Measurement of the ankle-brachial blood pressure index (ABI) or toe brachial index (TBI) has been used for screening, diagnosis and severity determination of PAD. However, the procedures for measurement of these indices are complicated and the measurements cannot be performed during dialysis sessions. The purpose of the present study was to clarify the ability of the toe blood flow and pulse amplitude measured with a portable laser Doppler flow meter (LDF) to detect PAD in dialysis patients, in comparison with the diagnostic abilities of ABI and TBI. Methods Fourteen patients on maintenance HD participated in this study. The mean age was 65.2 years old and the mean duration of HD was 9.1 years. We measured the ABI and TBI before HD, and the blood flow and pulse amplitude on the ventral side of the first toe with a portable LDF (pocket LDF®, JMS Co., Ltd., Tokyo, Japan) during the HD session on the same day. The correlations between the blood flow / pulse amplitude in the toe and the ABI / TBI were investigated. The sensitivity and specificity of the blood flow and pulse amplitude in the toe for PAD detection were determined by a receiver operating characteristic curve analysis. Statistical analysis was performed using the Fisher’s exact test. A p value of Results and Discussion No significant correlation was found between the blood flow and the pulse amplitude in the toe (p = 0.454). The blood flow was not correlated with either the ABI or the TBI (p = 0.286, p = 0.115, respectively). However, the pulse amplitude showed significant correlations with both the ABI and TBI (p < 0.001, p < 0.05). When we used the general reference cutoff values for ABI and TBI of 0.9 and 0.6, respectively, the sensitivity and specificity of ABI for the detection of PAD were 0.75 and 0.75, respectively, and those of TBI were 1.0 and 0.75, respectively. On the other hand, the sensitivity and specificity of blood flow in the toe were 0.50 and 1.0, respectively, when the cutoff value was set at 23.8 mL/min. The sensitivity and specificity of the pulse amplitude were 0.75 and 1.0, respectively, when the cutoff value was set at 7.6 mL/min. These results indicate that the pulse amplitude in the toe showed a high diagnostic ability, like ABI and TBI, for the detection of PAD. Although our results in this study were obtained from a small sample size and further investigation is warranted, the pulse amplitude measured with the portable LDF was correlated well with both the ABI and TBI, and its sensitivity and specificity for the detection of PAD were also high, indicating the high diagnostic ability of the pulse amplitude for PAD. As compared to the measurement of ABI or TBI, the pulse amplitude in the toe can be easily measured with a portable LDF, even during a dialysis session. Thus, we believe that the use of a portable LDF might be of great benefit as a screening tool for PAD. Conclusion The pulse amplitude in the toe measured with a portable LDF may have the potential to become a novel easily measurable index in the screening of dialysis patients for PAD.

Objective To determine the percentage of the blood flow signal that is derived from dental pulp when recording from exposed dentine in a human premolar. Design Recordings were made from 7 healthy teeth in 5 subjects (aged 22–33 yr.) with a laser Doppler flow meter (Periflux 4001) using either a red (635 nm) or an infrared (780 nm) laser. After exposing dentine above the buccal pulpal horn (cavity diam. 1.6 mm, depth 3 mm) and isolating the crown with opaque rubber dam, blood flow was recorded alternately with infrared or red light from the exposed dentine under four conditions: before and after injecting local anaesthetic (3% Mepivacaine without vasoconstrictor) (LA) over the apex of the root of the tooth; after exposing the pulp by cutting a buccal, class V cavity in the tooth; and after sectioning the coronal pulp transversely through the exposure. Results There was no significant change in mean blood flow recorded with either light source when the tooth was anaesthetized or when the pulp was exposed. After the pulp had been sectioned, the blood flow recorded with infrared light fell by 67.8% and with red light, by 68.4%. The difference between these effects was not significant. Conclusions When recording blood flow from exposed coronal dentine with either infrared or red light in a tooth isolated with opaque rubber dam, about 68% to the signal was contributed by the pulp. The signal:noise ratio was better with infrared than red light, and when recording from dentine than enamel.

Measuring brain electrical impedance (rheoencephalography) is a potential technique for noninvasive, continuous neuro-monitoring of cerebral blood flow autoregulation in humans. In the present rat study, we compared changes in cerebral blood flow autoregulation during CO2 inhalation measured by rheoencephalography to changes measured by laser Doppler flowmetry, an invasive continuous monitoring modality. Our hypothesis was that both modalities would reflect cerebral blood flow autoregulation. Male Sprague-Dawley rats (n=28; 28 control and 82 CO2 challenges) were measured under anesthesia. The surgical preparation involved implantation of intracerebral REG electrodes and an LDF probe into the brain. Analog waveforms were stored in a computer. CO2 inhalation caused transient, simultaneous increases in the signals of both laser Doppler flow (171.99 ± 46.68 %) and rheoencephalography (329.88 ± 175.50%). These results showed a correlation between the two measured modalities; the area under the receiver operating characteristic curve was 0.8394. The similar results obtained by measurements made with laser Doppler flowmetry and rheoencephalography indicate that rheo-encephalography, like laser Doppler flowmetry, reflects cerebral blood flow autoregulation. Rheoencephalography therefore shows potential for use as a continuous neuro-monitoring technique.

Flow-mediated dilatation (FMD) is an established, but investigator-demanding method, used to non-invasively determine nitric oxide (NO)-dependent endothelial function in humans. Local thermal hyperemia (LTH) or post-occlusive reactive hyperemia (PORH) of the skin measured with a laser Doppler flow imager may be a less demanding alternative of FMD. We investigated the reproducibility of the different measures of vascular function, their interrelationship and the NO-dependency of LTH. Measurements were performed twice in 27 healthy men (8 smokers), one week apart. Local application of NG-monomethyl-l-arginine (L-NMMA) by means of iontophoresis was used to determine the NO-dependency of LTH. Using L-NMMA, the peak and plateau responses of LTH were reduced by 31% (p .001) and 65% (0.001), respectively. For all measurements the coefficient of variation (CV) was higher in smokers than in non-smokers. For non-smokers the CV of FMD was 12%, of LTH peak response 17%, of LTH plateau response 12%, of PORH peak response 14% and of PORH area under the curve response 11%. FMD correlated weakly with the PORH peak and area under the curve response (r = 0.39 and 0.43, p .05), whereas the LTH-plateau response correlated with the PORH peak response (r = 0.68, p .01) in non-smokers, but FMD and LTH peak or plateau responses were unrelated. In conclusion, the LTH plateau response is for two-third NO-dependent, but unrelated to FMD. Furthermore, despite easy to perform the LTH responses are not more reproducible than FMD. Given the weak associations, the different methods of vascular function assessment are not interchangeable.

The aim of the present study was to investigate the effect of quantitatively measured cold perception (CP) thresholds on microcirculatory response to local cooling as measured by direct and indirect response of laser-Doppler (LD) flux during local cooling at different temperatures. The CP thresholds were measured in 18 healthy males using the Marstock method (thermode placed on the thenar). The direct (at the cooling site) and indirect (on contralateral hand) LD flux responses were recorded during immersion of the hand in a water bath at 20°C, 15°C, and 10°C. The cold perception threshold correlated (linear regression analysis, Pearson correlation) with the indirect LD flux response at cooling temperatures 20°C (r=0.782, p0.01) and 15°C (r=0.605, p0.01). In contrast, there was no correlation between the CP threshold and the indirect LD flux response during cooling in water at 10°C. The results demonstrate that during local cooling, depending on the cooling temperature used, cold perception threshold influences indirect LD flux response.

Phalen's test has been one of the most significant of clinical signs when making a clinical diagnosis of idiopathic carpal tunnel syndrome (CTS). However, it is unknown whether intraneural blood flow changes during Phalen's test in patients with CTS. In this study, an intraoperative Phalen's test was conducted in patients with CTS to observe the changes in intraneural blood flow using a laser Doppler flow meter. During Phalen's test, intraneural blood flow showed a sharp decrease, which lasted for 1 min. Intraneural blood flow decreased by 56.7%-100% (average, 78.0%) in the median nerve relative to the blood flow before the test. At 1 min after completing the test, intraneural blood flow returned to the baseline value. After carpal tunnel release, there was no marked decrease in intraneural blood flow. This study demonstrated that the blood flow in the median nerve is reduced when Phalen's test is performed in vivo.

The present study examined the effects of local heat, global heat, and the interaction between these two endothelial stressors on the blood flow of the skin of the foot in people who are older and who have diabetes.Subjects who were older (mean age 64.2 +/- 5.9 years) and were younger (mean age 25.7 +/- 2.9 years) and subjects who had diabetes (mean age 62 +/- 5.9 years, mean duration 13.2 +/- 9.1 years) participated. Subjects were exposed to three global temperatures (16 degrees C, 24 degrees C, and 32 degrees C), and the blood flow response was recorded on the foot with a laser Doppler flow meter for 30 s following applications of local heat (30 degrees C, 33.5 degrees C, and 37 degrees C) using a Peltier junction to clamp the skin for 2 min.All three groups significantly increased blood flow from the 16-24 degrees C environments for the 37 degrees C application of local heat (P(Younger) = 0.02, P(Older) = 0.02, P(Diabetes) = 0.01). Those with diabetes and those who were older only increased blood flow 5% and 6% from the 24-32 degrees C environment, which was not statistically significant (P(Older) = 0.12, P(Diabetes) = 0.14).There appears to be considerable blood flow reserve in younger subjects to tolerate heat stress. In contrast, older subjects and those with diabetes reach a critical level after which additional heat does not cause in increase in blood flow.

This investigation aimed to: 1) develop a method to obtain reproducible laser Doppler flow readings (LDFRs) at the gingiva of the maxillary front teeth; 2) evaluate regional gingival blood flow (GBF) in healthy gingiva by laser Doppler flowmetry; 3) compare hand-held LDFR (H-LDFR) with splint LDFR (S-LDFR); and 4) monitor changes in GBF in experimental gingivitis (EG) and chronic gingivitis (CG).The LDFR, gingival index (GI), and plaque index (PI) were measured at 13 gingival sites (teeth #6 to #11) in 10 healthy volunteers (five males and five females), 23 to 34 years of age, over a period of 12.5 +/- 3.27 days employing a partial-mouth EG model and in 11 patients (three males and eight females), 20 to 63 years or age, with CG. LDFRs were obtained by S-LDFR or H-LDFR.H-LDFRs were significantly higher than S-LDFRs (P0.05). All EG subjects developed gingivitis (PI: 2.77 +/- 0.23; GI: 1.5 +/- 0.53). EG-LDFRs at diseased sites increased slightly but not significantly over the study period. All CG-patients had high plaque and inflammation scores (PI: 2.8 +/- 0.2; GI: 1.63 +/- 0.78). CG-LDFRs at sites with GI1 were significantly higher than LDFRs at healthy sites (P0.05). CG-LDFRs were significantly higher than EG-LDFRs at sites with a comparable GI (P0.05).LDFRs are positively correlated with the degree of gingival inflammation. GBF demonstrated significant differences in EG and CG. Modifications of the probe are needed to enhance its clinical applicability in clinical research of periodontal diseases.

Stagnation of peripheral blood flow is the cause of various diseases. Changes in peripheral blood flow after oral administration of Kampo medicines in mice with betamethasone-induced oketsu syndrome and normal mice were examined using a laser Doppler blood flow meter. The Kampo medicines used were: Toki-shakuyaku-san; Kami-shoyo-san; Keishi-bukuryo-gan; Daio-botanpi-to; Tokaku-joki-to; Goshuyu-to; and Hange-koboku-to. In the oketsu mice, blood flow was improved by single-dose administration of Toki-shakuyaku-san, Kami-shoyo-san, Keishi-bukuryo-gan, Daio-botanpi-to, Tokaku-joki-to, and Goshuyu-to, but only Toki-shakuyaku-san increased blood flow significantly in normal mice. In addition, blood flow decreased after single-dose administration of Keishi-bukuryo-gan, Daio-botanpi-to, and Tokaku-joki-to in normal mice.

summary Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental injury has been associated with losses of pulpal sensibility. The purpose of this study was to assess the outcome of splint therapy on tooth fracture type-related PBF values. In 15 trauma patients, a single maxillary incisor treated by repositioning and splinting was investigated by LDF to assess local PBF values. Perfusion units were taken in four sessions, on the day of splint removel, and 12, 24 and 36 weeks after splint removal. Analysis of the tooth fracture type-related PBF measurements revealed root fractures to be associated with a significant decrease (P 0·05). The main findings of this study suggest splint therapy of root fractures of the central maxillary incisor to be associated with a short- and long-term decrease in PBF values. The LDF may become useful in the detection of transient ischaemic episodes and the identification of teeth at risk for adverse sequelae such as avascular necrosis and tissue loss.

To detect the unintentional generation of subarachnoid hemorrhage (SAH) during thread occlusion of the middle cerebral artery (MCA) in rats, a single laser-Doppler flowmetry (LDF) probe was positioned over the ipsilateral cortex. Occlusion of the MCA resulted in an immediate drop of the LDF signal to 21.4+/-8.0% which was followed by a partial recovery to 31+/-11% in animals without SAH. In contrast, a sustained decrease to 7.4+/-5% (P

Aims. The introduction of laser Doppler (LD) techniques to assess burn depth has revolutionized the treatment of burns of indeterminate depth. This paper will systematically review studies related to these two techniques and trace their evolution. At the same time we hope to highlight current controversies and areas where further research is necessary with regard to LD imaging (LDI) techniques. Methods. A systematic search for relevant literature was carried out on PubMed, Medline, EMBASE, and Google Scholar. Key search terms included the following: “Laser Doppler imaging,” “laser Doppler flow,” and “burn depth.” Results. A total of 53 studies were identified. Twenty-six studies which met the inclusion/exclusion criteria were included in the review. Conclusions. The numerous advantages of LDI over those of LD flowmetry have resulted in the former technique superseding the latter one. Despite the presence of alternative burn depth assessment techniques, LDI remains the most favoured. Various newer LDI machines with increasingly sophisticated methods of assessing burn depth have been introduced throughout the years. However, factors such as cost effectiveness, scanning of topographically inconsistent areas of the body, and skewing of results due to tattoos, peripheral vascular disease, and anaemia continue to be sighted as obstacles to LDI which require further research.

Introduction: We compared pancreatic blood flow (PBF) measured by perfusion CT with deconvolution method and Laser Doppler Flow (LDF) to determine whether uncollected contrast material from the pancreas affects measurement of perfusion CT, using porcine pancreatitis model (n = 7). Materials and Methods: The pancreas was divided into head and tail. We arranged that PBF of tail was circulated by single input/output vessel. Ischemic pancreatitis was induced to tail, shutting off input/output vessel for 30 min. PBF was measured both by perfusion CT with deconvolution method and LDF, during the overall course. We calculated uncollected ratio of contrast material, assuming area-under-curve differences between the input and output vessels correspond to uncollected. Results: tail PBF measured by perfusion CT with deconvolution was significantly correlated with LDF, despite of pancreatitis (P < 0.05). The uncollected ratio was 19 %. Discussion: Although the uncollected ratio was not few, result of perfusion CT was significantly related with LDF.

ZusammenfassungBei 12 Patienten mit Erysipelen am Unterschenkel erfolgten Messungen der Mikrozirkulation in Ruhe und bei hämodynamischen Funktionstests. Bestimmt wurden: Hauttemperatur, Erythemstärke (a-Wert der Colorimetrie), transkutaner Sauerstoffpartialdruck (tcPO2 bei 37° C und 44° C Elektrodentemperatur) sowie Laser-Doppler-Flux (LDF). Die Messungen wurden im Zentrum der Erysipele und an den gesunden kontralateralen Beinen zu Beginn, während und eine Woche nach Ende der Antibiotikatherapie durchgeführt. Zum Zeitpunkt der akuten Entzündung zeigten alle Parameter deutliche Veränderungen; diese wiesen Reaktionsmuster auf, wie sie auch bei Dermatosen mit morphologischen Veränderungen des Kapillarsystems gefunden werden. Nach klinischer Abheilung wiesen tcPO2 bei 37° C und Laser-Doppler-Flux sowohl in Ruhe als auch bei den Funktionstests noch deutliche Veränderungen auf.

BACKGROUND AND OBJECTIVE Hyperthermia was induced in tumor-bearing C3H mice using a Nd:YAG laser emitting near-infrared radiation at 1,064 nm. The efficacy of multiple implanted fiberoptics in the control of the RIF-1 tumor was investigated. STUDY DESIGN/MATERIALS AND METHODS RIF-1 tumors in the right hind leg were heated interstitially at 42, 44, or 46 degrees C for 30 or 60 minutes. Two, three, or four 400-microns quartz fibers terminating in a 1.0-cm cylindrical diffusor were inserted into each tumor, as were five microthermocouples to monitor temperature during treatment. Laser Doppler Flow (LDF) was also recorded pre- and post-treatment to determine changes in red blood cell flux in overlying skin (42, 44, or 46 degrees C) and the center of the tumor (46 degrees C). RESULTS These experiments indicated that interstitial heating at 42, 44, and 46 degrees C resulted in tumor growth delay, although long-term control of tumors was not achieved. Treatment using four fibers resulted in the greatest tumor growth delay at 42 and 44 degrees C, increasing tumor doubling time by 50% or greater compared to control tumors; tumor growth delay following 46 degrees C treatments was seven times greater than that in control tumors. Significant changes (decreases) in LDF (P < .05) were seen in four treatment groups, using two fibers at 42 degrees C for 30 minutes, four fibers at 44 and 46 degrees C for 60 minutes on the overlying skin, and 46 degrees C for 60 minutes in the center of the tumor. CONCLUSIONS Initial data indicate that interstitial heating with multiple fibers increases tumor growth delay compared to previous single fiber treatments, with tumor growth delay increasing with increasing treatment temperature; however, long-term tumor control was not achieved under the conditions investigated. Follow-up studies will explore the use of higher temperatures and/or longer treatment times in order to optimize tumor response.

Changes in finger tissue blood volume (TBV) measured by light transmission and in laser Doppler flow (LDF) were obtained during long breathing (of 12 s period) and associated with the respiratory phases, inspiration and expiration. For fifteen out of sixteen subjects TBV and LDF started to decrease 0–2 s after the start of expiration and increased during inspiration but the start of increase occurred before the start of inspiration, showing that the respiratory-induced changes in TBV and LDF are mainly associated with the expiration. Decrease of TBV and LDF after expiration was also found during the inspiratory gasps (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Flowmotion within skeletal muscle in vivo is difficult to determine and has depended upon invasive studies with implanted Laser Doppler flow (LDF) probes. This study reports the novel use of RT-CEU...

Arterial pulsatility was measured using an optical interferometer. As opposed to laser Doppler flow meters, the prototype system the authors evaluated can detect pulsation profiles of major arteries with potentially useful information including pulse wave velocity, profile of pulse pressure, etc. >

Low-frequency fluctuations in the laser Doppler flow signal (LDFS) from the skin are related to microvascular mechanisms of flow control. Wavelet spectral analysis has been used to correlate fluctuations in the LDFS with the endothelial, neurogenic and myogenic mechanisms of control in the frequency intervals 0.005-0.02 Hz, 0.02-0.06 Hz and 0.06-0.16 Hz, respectively. Generally the signal power, in each frequency interval, derived from the respective wavelet coefficients, is used as a measure of the activity of the related mechanism of microvascular control. However, the time-domain characteristics of the fluctuations in the LDFS in each frequency interval are poorly known. As a consequence, there is a lack of objective criteria to properly measure, in each frequency interval, the related hemodynamic parameters. Here a time-domain method is proposed to analyze and quantify fluctuations in the LDFS in each frequency band. Baseline (32 degrees Celsius) and thermally stimulated (42 degrees Celsius) LDFS of forearms from 15 healthy volunteers were collected and analyzed. The data obtained indicate that inappropriate time windows, frequently used for measurements, increase the variability of the measured signal power, diminishing the capability of the method when assessing microvascular dynamics and dysfunctions. To overcome this limitation, an objective method to measure the LDFS power in each frequency band is proposed.

While higher frequency oscillations (0.021-0.6 Hz) in cutaneous blood flow measured by laser Doppler flowmetry (LDF) relate to oscillations in blood pressure and sympathetic nerve activity, very low-frequency oscillations (VLF, 0.0095-0.021 Hz) do not. The authors investigated whether VLF LDF power is nitric oxide (NO) specific.LDF combined with intradermal microdialysis was used in the calves of 22 healthy volunteers aged 19-27 years. LDF power spectral analysis was performed by windowed fast Fourier transform. The authors tested whether the NO synthesis inhibitor nitro-l-arginine (NLA) produced selective decreases in VLF power before and after stimulation with acetylcholine.NLA alone did not alter total power but selectively reduced VLF power by approximately 50%. LDF and spectral power increased markedly across all spectra with acetylcholine. This increase was blunted by NLA, which selectively reduced VLF power by approximately 50%.The data suggest that VLF oscillations in the laser Doppler signal are NO dependent, increase with cholinergic stimulation, and have potential as a noninvasive marker for NO-dependent microvascular reactivity.

A simple mount capable of securely holding a variety of intracranial probes to the skull was constructed from commonly available clinical consumables. Using this device the cerebral cortical blood flow of preterm lambs was measured using a laser Doppler flow probe, and cerebral pH and cortical electrical impedance were measured in newborn piglets using pH electrodes and Ag/AgCl wire electrodes. In both studies, the mount held the various probes for periods up to 6 h with no dislodgement or probe failure. The simple mount presented here can be adapted to a wide variety of intracranial probes and will hold them securely to the skull.

In this study, the changes in skin blood flow and skin temperature for healthy subjects and the difference in the distribution of the rhythms of skin temperature between healthy subjects and patients with Raynaud's syndrome were analyzed using laser Doppler flow meters, thermocouples and a thermographic system (thermal rhythmography) which is capable of displaying topograms of the power spectra of an arbitrary frequency range with respect to changes in skin temperature. The results showed that the periodic fluctuations of skin temperature may provide a useful index for autonomic nervous conditions, and thermal rhythmography could become a useful tool for the evaluation of autonomic dysfunction or for the preventive diagnosis of neuro-vascular diseases such as Raynaud's syndrome.

It has been known since the nineteenth century that oxygen is taken up by the human skin. With a newly developed sensor it became possible to examine the influence of the vascular supply on the oxygen flux into the skin, tcJ(O2). tcJ(O2) was measured optically by determining the oxygen partial pressure difference, DeltapO2 across a diffusion test membrane, which itself was brought into close contact to the skin surface. Under these conditions DeltapO2 is proportional to the tcJ(O2). The skin perfusion was varied by the application of a hyperemizing ointment on the abdomen of 12 volunteers and by suprasystolic occlusion at the thigh of 20 volunteers. The tcJ(O2) was measured at a temperature of 33 degrees C of the humid skin. It was compared with the skin perfusion monitored by laser Doppler flow, and the capillary oxygen supply measured by transcutaneous partial pressure of oxygen, tcpO2, at an electrode temperature of 37 degrees C. The transcutaneous O2 flux produced a distinct DeltapO2 of 81.8 +/- 8.2 Torr (abdomen) and 72.8 +/- 12.3 Torr (ankle). In hyperemic skin on the abdomen the O2 flux was reduced (DeltapO2 = 57.7 +/- 10.6 Torr). The tcpO2 increased from 8.7 +/- 10.7 to 35.1 +/- 16.9 Torr. During suprasystolic occlusion, DeltapO2 increased by 6.4 +/- 2.3 Torr, whereas laser Doppler flow and tcpO2 decreased significantly. These results indicate that the total oxygen supply of the epidermis and the upper dermis is guaranteed even if the perfusion varies.

The aim of the study was to test the irritancy of 6 antiseptics in an open exposure model. The following agents were tested in their normal use concentrations using open exposures, 2x daily for 4 days in 20 subjects: chlorhexidine 4% (CH), chlorhexidine 0.5% in ethanol 70% (CE), ethanol 70% (ET), iodine 1% in ethanol 70% (IE), povidone-iodine 10% (PI) and sodium hypochlorite 0.25% (SH). Responses were evaluated by visual scoring, subjective irritancy scoring, stratum corneum hydration (Corneometer), transepidermal water loss and laser Doppler flowmetry. Exposure to SH had to be discontinued after 4 applications because of severe subjective irritation. The same held true for IE (7 applications), whereas the other agents were exposed 8x. All evaluation methods showed SH to be significantly more irritating than IE, which was in turn more irritating than CH, CE, ET and PI. Thus, it can be concluded that CH, CE, ET and PI were nonirritating in this open exposure model.

Periodic fluctuations, regular slow-wave flowmotion, were induced in the skeletal muscle of six mature anesthetized New Zealand White rabbits by acute femoral artery pressure reduction from a median control value of 78 to 36 mm Hg. This phenomenon was monitored simultaneously with four laser Doppler flowmetry (LDF) probes placed over the gastrocnemius muscle in a linear array with a spacing of 5 mm. The median relative peak-to-trough amplitude of the oscillatory flow patterns was 47%, white a frequency of approximately 2.5 cycles per minute (cpm), which remained relatively stable over an observation period of 1 h (+/- 15-20%). Application of two frequency analysis methods, Welch's FFT method and Prony Spectral Line Estimation yielded similar results and showed a correlation coefficient of r = +0.84. Spectral coherence between pairs of regular slow-wave flowmotion records decreased with increasing probe separation (0.28 at 5 mm; 0.01 at 15 mm). However, patterns of frequency fluctuation over time were significantly correlated between concurrent record pairs regardless of probe separation. These results suggest that the regular slow-wave flowmotion signal originates in regions that are independently regulated by local vasoactive sites, which may be called pacemakers. These sites may also be influenced by an additional common control mechanism, which may be myogenic/metabolic or central in nature.

We simultaneously measured pial arteriolar diameter and changes in cortical blood flow during activation of the somatosensory cortex by sciatic nerve stimulation. The pial vasculature was visualized with a closed-cranial window technique in chloralose-anesthetized rats ( n = 13). Local blood flow was monitored with laser-Doppler flowmetry. During stimulation of the sciatic nerve (0.2 V, 5 Hz, 20 s), vascular diameter and laser-Doppler flow consistently displayed similar response profiles. With 0.5-ms stimulation pulses, the responses showed an initial peak followed by a smaller but sustained plateau dilation. In contrast, 5-ms pulses evoked a monotonically rising response. Our results support the concept that pial arteriolar diameter changes reflect cortical blood flow responses during somatosensory stimulation.

The performances of two laser Doppler flow meters (Periflux model PF3 and Moor Blood Flow Monitor model MBF3D) were investigated. Recordings were made while diluted blood was pumped at different rates through the pulp cavities of extracted human or pig teeth. The probe of each instrument was fixed to the enamel surface 2 mm from the original position of the gingival margin. Both instruments performed similarly, although the Moor gave the better signal/noise ratios. Both were capable of detecting flow in the core of the pulp as well as the superficial part closest to the probe tip. With either instrument, and with any one dilution of blood (range 0.5-45% v/v red cells), there was a near-linear relationship between the blood-flow signal and the flow rate of blood through the tooth. However, when data obtained with different red-cell concentrations were compared, a good correlation between the blood-flow signal and red-cell flux (product of concentration and mean velocity) was obtained only with red-cell concentrations up to 1% v/v. Therefore these instruments would give an accurate indication of blood flow changes only under conditions in which either this value was not exceeded or if the red-cell volume fraction remained constant; neither of which can be assumed to apply when recording from teeth in situ. The signals representing the concentration of moving blood cells were unreliable in both instruments. It is concluded that the information provided by these laser Doppler flow meters can be ambiguous and must be interpreted with care.

Gastric mucosal blood flow (GMBF) was measured by a laser doppler flow meter continually during and after transient forebrain ischemia in rats. The value of GMBF obtained after at 15 min of ischemia did not change significantly compared to that of the preischemic period. However, a 26% decrease of GMBF was detected after 30 min of ischemia. When circulation of the brain was restored, the GMBF increased slightly after 15 min. After 30, 45, and 60 min of restored cerebral circulation, the GMBF decreased significantly and the values were 63%, 58% and 51% of the control, respectively.

Estradiols are known to prevent cardiovascular diseases, but the underlying mechanisms remain unclear. We assessed the finger skin capillary blood flow in 20 premenopausal women with oral contraception noninvasively by Laser Doppler flowmetry (LDF). Blood flow was registered both under basal conditions and after 2 min of arterial occlusion. Furthermore, the combination with a beat-to-beat online finger blood pressure monitor allowed the calculation of the regional peripheral resistance (RPR). All measurements were performed in the menstrual phase. LDF and RPR were correlated to the estradiol whole blood levels.Both baseline (r(2)=0.826; P0.01) and vasodilation (r(2)=0.747; P0.01) blood flux were significantly correlated to the corresponding estradiol concentrations. A multiple stepwise regression analysis (with age, height, weight, duration of oral contraception, nicotine pack years and estradiol levels in the equation) showed positive correlations between estradiol levels and (a) baseline (P0.05) or (b) vasodilation (P0.05) Laser Doppler flux or (c) time to reach the peak flux (r(2)=0.31; P0.05). Furthermore, the minimal local vascular resistance was negatively correlated to the estradiol levels (r(2)=0.45; P0.05).The study provides evidence that both the baseline and the vasodilation capillary blood flux in women in the menstrual phase depend on the estradiol whole blood levels. Furthermore, the local vascular resistance shows a negative correlation to the hormonal state. Functional or structural alterations of the microvasculature may therefore contribute to the estradiol-associated cardiovascular protection.

Eighteen patients admitted to Duke University Medical Center for upper limb replantation or revascularization were studied. A small laser Doppler flow prism probe and a cutaneous temperature probe were attached to the distal pulp of replanted digits. Measurements were recorded hourly for the first 3 postoperative days. In the successful cases, the mean laser Doppler flow measurement was 1.76 units (lower 97% confidence limit 0.5 units) and the mean temperature was 34.1 degrees C (lower 97% confidence limit 32 degrees C). In 4 patients with vascular compromise, the laser Doppler flow correctly identified the problem. The reduced size of the new laser Doppler probe makes monitoring of distal pulp flow technically easier while maintaining accuracy.

A miniaturized technique to administer vasoactive substances iontophoretically into the human finger skin and to continuously assess the resulting reaction of the vessels is described. Cutaneous blood flow is measured with a laser Doppler flow-meter. The technique has been used in 9 healthy volunteers with norepinephrine as test substance. The described method is a convenient way to evaluate the effects of transdermally applied vasoactive substances in a semiquantitative way without risking central effects of the substance to influence the registered blood flow.

The ability to predict whether burn wounds will heal spontaneously or will require skin grafting is important because of increasing utilization of primary excision and grafting. This study prospectively evaluated the ability of heated laser Doppler flow measurements obtained in the first 48 hours after burn injury to predict whether burn wounds would heal within 3 weeks. Further, the severity of scarring at 3 months was compared with the initial measurements. The measurements predicted healing with 100 percent accuracy and failure to heal with 93 percent accuracy. There was also a significant correlation between initial flow measurements and severity of scarring at 3 months. We conclude that heated laser Doppler flow measurements performed early after burn injury are useful in predicting whether healing is likely to occur, as well as the quality of late scar formation; therefore, the method is useful in selecting patients for primary excision and grafting of burn wounds.

A simple, low cost laser-Doppler flow monitor was developed. The instrument contains a diode laser two photodiodes, all integrated in a probe of small dimensions. The probe can be attached directly on or in tissue for the measurement of blood flow velocities. Out of two different prototypes, one prototype is described, together with test measurements.

Laser Doppler flowmetry has been applied to normal skin and to subepidermal tumours during localized ultrasound hyperthermia in the rat. In normal skin, 40 degrees C hyperthermia only induced a marginal increase in the red blood cell flux. Significant increases occurred after 20 min at 42 degrees C and after 4 min at 44 degrees C. During 44 degrees C hyperthermia maximum fluxes were reached after 24 min. Thereafter, the flow declined and finally approached preheating values. In contrast, in subepidermal tumours 40 degrees C hyperthermia on the average induced a slight decrease of the flux. During 42 degrees C hyperthermia a significant flow decrease was found after 40 min of heating. Following a transient increase in the laser Doppler flow during the heating-up period, 44 degrees C hyperthermia led to a significant impairment of the flux after 24 min. A total shutdown of RBC flux was observed in about 30 per cent of the tumours at 44 degrees C. Upon elevated tissue temperatures, pronounced inter-tumour variabilities in the time- and temperature-dependent changes of RBC flux were observed. Rhythmic oscillations of the RBC flux were found in some subepidermal tumours (0.40 +/- 0.05 cycles/min). Upon heating, these periodic flow variations slowed down significantly (0.20 +/- 0.04 cycles/min), whereas in normal skin the frequency of the flow fluctuations increased.