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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.