Characterization of the non-invasive assessment of the cutaneous microcirculation by laser Doppler perfusion scanner.
ABSTRACT Microcirculatory dysfunction contributes to morbidity and mortality in vascular diseases. Here, we aimed at establishing a sensitive and valid method to measure microvascular reactivity during post-occlusive reactive hyperemia (PORH) using scanning laser Doppler perfusion imaging (LDPI) of the forearm.
In a first series, LDPI was methodologically evaluated on the volar forearm of healthy volunteers (n = 10) before and after one to five minutes of upper arm occlusion. In a second series, readings were performed in 20 healthy subjects and 20 patients with coronary artery disease (CAD).
Three minutes of forearm occlusion were sufficient to induce maximal vasodilation during PORH as indicated by maximal increase in perfusion unit (PU) amplitude that did not further increase after five-minute occlusion. Five-minute occlusion led to a significant prolongation of PORH with greater area under curve (AUC) suggesting longer lasting vasodilation of microvessels. The five-minute occlusion was associated with lower variability as compared with three minutes (intraindividual variability: 9-17% vs. 12-21%; interindividual variability: 13-24% vs. 14-26%). CAD patients exhibited significantly reduced amplitude (105 +/- 49 vs. 164 +/- 35 PU; p < 0.001), ratio (4.7 +/- 1.8 vs. 7.1 +/- 1.8; p < 0.001), and AUC (1656 +/- 1070 vs. 2723 +/- 864 PU x minutes; p = 0.001).
Scanning LDPI is a feasible and reproducible method for non-invasive assessment of the cutaneous microcirculatory response during PORH.
SourceAvailable from: Jean-Luc Cracowski[Show abstract] [Hide abstract]
ABSTRACT: For more than two decades, methods for the non-invasive exploration of cutaneous microcirculation have been mainly based on optical microscopy and laser Doppler techniques. In this review, we discuss the advantages and drawbacks of these techniques. Although optical microscopy-derived techniques, such as nailfold videocapillaroscopy, have found clinical applications, they mainly provide morphological information about the microvessels. Laser Doppler techniques coupled with reactivity tests are widespread in the field of microvascular function research, but many technical issues need to be taken into account when performing these tests. Post-occlusive reactive hyperemia and local thermal hyperemia have been shown to be reliable tests, although their underlying mechanisms are not yet fully understood. Acetylcholine and sodium nitroprusside iontophoresis, despite their wide use as specific tests of endothelium-dependent and -independent function, respectively, show limitations. The influence of the skin site, recording conditions, and the way of expressing data are also reviewed. Finally, we focus on promising tools such as laser speckle contrast imaging.Microcirculation (New York, N.Y.: 1994) 08/2011; 19(1):47-64. DOI:10.1111/j.1549-8719.2011.00129.x · 2.26 Impact Factor
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ABSTRACT: We used real-time LDI to study regional variations in microcirculatory perfusion in healthy candidates to establish a new methodology for global perfusion body mapping that is based on intra-individual perfusion index ratios. Our study included 74 (37 female) healthy volunteers aged between 22 and 30 years (mean 24.49). Imaging was performed using a recent microcirculation-imaging camera (EasyLDI) for different body regions of each volunteer. The perfusion values were reported in Arbitrary Perfusion Units (APU). The relative perfusion indexes for each candidate’s body region were then obtained by normalization with the perfusion value of the forehead. Basic parameters such as weight, height, and blood pressure were also measured and analyzed. The highest mean perfusion value was reported in the forehead area (259.21 APU). Mean perfusion in the measured parts of the body correlated positively with mean forehead value, while there was no significant correlation between forehead blood perfusion values and room temperature, BMI, systolic and diastolic blood pressure (p = 0.420, 0.623, 0.488, 0.099, respectively). Analysis of the data showed that perfusion indexes were not significantly different between male and female volunteers except for ventral upper arm area (p = .001). LDI is non-invasive, fast technique that opens several avenues for clinical applications. The mean perfusion indexes are useful in clinical practice for monitoring patients before and after surgical interventions. Perfusion values can be predicted for different body parts for patients only by taking the forehead perfusion value and using the perfusion index ratios to obtain expected normative perfusion values.Microvascular Research 07/2014; DOI:10.1016/j.mvr.2014.04.007 · 2.43 Impact Factor
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ABSTRACT: To investigate whether a daily intake of a moderate dose of antioxidants modifies the microcirculatory response to smoking, assuming a major influence of oxidative stress on microcirculation. The microvascular response to smoking was assessed in individual capillaries by capillaroscopy before and after two weeks of treatment with oral antioxidants. Smoking prolonged time to peak (TtP) capillary blood flow velocity in all subjects. When the subjects were pre-treated with ascorbate, TtP was comparable to baseline values of untreated subjects. No significant effect of vitamin E was observed either before or after smoking. Capillary blood flow velocity increased after treatment with ascorbate as well as after vitamin E. However, significant reductions in velocity were still observed in response to smoking even after subjects consumed ascorbate and vitamin E (p<0.0004 and p<0.000008 respectively). This study focused on individual capillaries, and confirms that smoking has a very pronounced, direct and reproducible microvascular effect possible to demonstrate in vivo in human capillaries. Moderate intake of the antioxidant ascorbate clearly mitigated the effects induced by smoking. TtP after smoking in subjects treated with ascorbate was similar to that observed in untreated subjects before smoking a cigarette. Thus, oxidative stress could be assumed to play a role in the effects of smoking on microcirculation.Microcirculation (New York, N.Y.: 1994) 08/2011; 19(1):86-93. DOI:10.1111/j.1549-8719.2011.00125.x · 2.26 Impact Factor