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Microcirculatory Response to Photobiomodulationa??Why Some Respond and Others Do Not: A Randomized Controlled Study
摘要： Photobiomodulation (PBM), a non‐ionizing, non‐thermal irradiation, used clinically to accelerate wound healing and inhibit pain, was previously shown to increase blood flow. However, some individuals respond to PBM, but others do not. The purpose of this study was to investigate factors affecting this patient‐specific response using advanced, noninvasive methods for monitoring microcirculatory activity. In this prospective, randomized controlled trial (NCT03357523), 20 healthy non‐smoking volunteers (10:10 males:females, 30 ± 8 years old) were randomized to receive either red‐ (633 nm and 70 W/cm2) or near‐infrared light (830 nm and 55 mW/cm2) over the wrist for 5 minutes. Photoplethysmography, laser Doppler flowmetry, and thermal imaging were used to monitor palm microcirculatory blood volume, blood flow, and skin temperature, respectively, before, during, and 20 minutes after irradiation. Participants with skin temperature change ≥0.5°C from baseline were considered “responders”. Near‐infrared PBM was found to induce a 27% increase in microcirculatory flow that increased to 54% during the 20‐minute follow‐up period (P = 0.049 and P = 0.004, respectively), but red light PBM did not increase the median flow. Only 10 of 20 participants were responders by thermal imaging (i.e., ≥0.5°C from baseline), and their initial skin temperature was between 33 and 37.5°C. The non‐responders had either “hot” hands (≥37.5°C) or “cold” hands (≤33°C). In responders, the meantime to 20% increase in microcirculatory blood volume and blood flow was less than 2.5 minutes after initiation of PBM irradiation. We demonstrated that PBM induces arteriolar vasodilatation that results in both immediate and long‐lasting increased capillary flow and tissue perfusion in healthy individuals. This response was wavelength‐dependent and modified by skin temperature. These findings regarding physiological parameters associated with sensitivity or resistance to PBM provide information of direct relevance for patient‐specific therapy.
关键词： body temperature regulation,laser‐Doppler flowmetry,microcirculation,low‐level laser therapy,vasodilation,thermal imaging,photoplethysmography
更新于2025-09-23 15:19:57
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The preliminary validation of laser Doppler flowmetry in systemic sclerosis in accordance with the OMERACT filter: A systematic review
摘要： Objectives: To investigate the validation status of laser Doppler flowmetry (LDF) in systemic sclerosis (SSc) according to the ‘Outcome Measures in Rheumatologic Clinical Trials’ (OMERACT) filter. Methods: The literature was systematically reviewed to identify all reports assessing the microcirculatory flow in SSc patients. The OMERACT filter (cid:1)including the domains of truth, discrimination and feasibility(cid:1) was applied and a quality assessment was done by the ‘Good Methods Checklist’. To ease the comparison between studies the results were grouped per dynamic test situation: basal, cold/heat challenge and occlusion. Results: The literature search resulted in 4332 hits. Based on title and abstract screening 243 hits were retained and of these, 52 full texts described an assessment by LDF in SSc patients. Finally, 18 studies passed the quality assessment and form the object of this review. The review reveals that expert consensus is lacking on the face and content validity of LDF in SSc. The construct validity of LDF, on the other hand is partially validated. Conflicting results exist on the discriminant capacity of LDF in distinguishing healthy from diseased patients, primary from secondary Raynaud’s phenomenon and in differentiating between disease subsets. Yet, complementing an LDF-measurement with a heat challenge, as well as the evaluation of the post-occlusive hyperaemic response, has the potential to elicit a difference between healthy and diseased patients. Lastly, data on the feasibility of LDF in SSc is lacking in the identified literature. Conclusion: This systematic review emphasizes the very preliminary validation status of LDF in the assessment of the microcirculatory flow in SSc.
关键词： OMERACT,Validity (epidemiology),Microcirculation,Outcome measure,Systemic scleroderma,Laser Doppler flowmetry
更新于2025-09-19 17:13:59
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Laser Doppler blood flowmeter as a useful instrument for the early detection of lower extremity peripheral arterial disease in hemodialysis patients: an observational study
摘要： Background: A simpler method for detecting atherosclerosis obliterans is required in the clinical setting. Laser Doppler flowmetry (LDF) is easy to perform and can accurately detect deterioration in skin perfusion. We performed LDF for hemodialysis patients to determine the correlations between blood flow in the lower limbs and peripheral arterial disease (PAD). Methods: This retrospective study included 128 hemodialysis patients. Patients were categorized into the non-PAD group (n = 106) and PAD group (n = 22), 14 early stage PAD patients were included in the PAD group. We conducted LDF for the plantar area and dorsal area of the foot and examined skin perfusion pressure (SPP) during dialysis. Results: SPP-Dorsal Area values were 82.1 ± 22.0 mmHg in the non-PAD, and 59.1 ± 20.3 mmHg in PAD group, respectively (p < 0.05). The LDF-Plantar blood flow (Qb) values were 32.7 ± 15.5 mL/min in non-PAD group and 21.5 ± 11.3 mL/min in PAD group (p < 0.001). A total of 21 non-PAD patients underwent LDF before and during dialysis. The LDF-Plantar-Qb values were 36.5 ± 17.6 mL/min before dialysis and 29.6 ± 17.7 mL/min after dialysis (p < 0.05). We adjusted SPP and LDF for PAD using logistic regression, SPP-Dorsal-Area and LDF-P were significantly correlated with PAD (p < 0.05). The receiver-operating characteristic curve analysis indicated cut-off values of 20.0 mL/min for LDF-Plantar-Qb during dialysis. Conclusion: LDF is a simple technique for sensitive detection of early-stage PAD. This assessment will help physicians identify early-stage PAD, including Fontaine stage II in clinical practice, thereby allowing prompt treatment.
关键词： Skin perfusion pressure,Peripheral arterial disease,Laser doppler flowmetry
更新于2025-09-16 10:30:52
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Minimally invasive laser Doppler flowmetry is suitable for serial bone perfusion measurements in mice
摘要： In vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and determined that it can be used serially in the same mouse without causing signs of inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique is suitable for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.
关键词： Laser Doppler flowmetry,Vascular supply,Serial measurement,In vivo,Bone blood perfusion,Minimally invasive
更新于2025-09-16 10:30:52
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[IEEE 2019 3rd School on Dynamics of Complex Networks and their Application in Intellectual Robotics (DCNAIR) - Innopolis, Russia (2019.9.9-2019.9.11)] 2019 3rd School on Dynamics of Complex Networks and their Application in Intellectual Robotics (DCNAIR) - Synchronization of the process of autonomous regulation of blood circulation with low-frequency components of the laser Doppler flowmetry signal
摘要： The features of the individual dynamics and interaction of the elements of the autonomous regulation of blood circulation and blood flow fluctuations in the microvasculature of the skin were investigated. Phase synchronization of the laser Doppler flowmetry signal with processes of autonomic regulation is revealed. This may indicate the effect of vegetative regulation on the myogenic range of laser Doppler flowmetry.
关键词： Laser Doppler flowmetry,heart rate variability,blood pressure variability,photoplethysmogram,cardiointervalogram,0.1 Hz,statistical significance,phase capture
更新于2025-09-12 10:27:22
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Characterization of Microvascular Post Occlusive Hyperemia Using Laser Doppler Flowmetry Technique in Subjects With Cardiometabolic Disorders
摘要： Introduction: Laser Doppler flowmetry (LDF) provides a noninvasive real-time quantification of relative changes in cutaneous perfusion. Assessment of the microvascular function can provide information on the development of various cardiometabolic disorders. In recent years, non-invasive measurements have gain attention, due to the potential complications associated to invasive procedures. Objective: To differentiate the microvascular function between subjects with cardiometabolic disorders and healthy controls. Methods: Evaluation through LDF during post-occlusive reactive hyperemia (PORH) in patients with or without history of cardiometabolic disorders. Results: Peak values of microvascular flow during post-occlusive reactive hyperemia and both upload and recovery slopes were lesser in the pathological group. Conclusion: A novel approach to characterize LDF during PORH was useful to differentiate patients with cardiometabolic disorders from healthy subjects.
关键词： Laser Doppler flowmetry,cardiometabolic disorders,microvascular function,post-occlusive reactive hyperemia
更新于2025-09-12 10:27:22
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Gastroscopy assisted laser Doppler flowmetry and visible light spectroscopy in patients with chronic mesenteric ischemia
摘要： Mucosal pathology due to chronic mesenteric ischemia (CMI) is rarely seen during upper endoscopy. Combining Laser Doppler Flowmetry (LDF) and Visible Light Spectroscopy (VLS) may aid in detection of CMI at an early stage. We aimed to investigate the utility of LDF and VLS in detecting microcirculatory changes in patients with CMI during upper endoscopy. In a single center, prospective study, 104 patients were evaluated for mesenteric ischemia during a 24 months period. Patients with a consensus diagnosis of CMI (n ? 40) were examined with LDF and VLS. Thirty-two were successfully treated and had a definitive diagnosis of CMI. Results were compared with controls (n ? 38) with normal intestinal circulation evaluated with duplex ultrasonography (DUS). Treatment response was evaluated clinically and with DUS at 1 month and with VLS and LDF at 3 months. A significant reduction in mucosal capillary hemoglobin oxygen saturation (SO2) was found in CMI patients compared to controls before treatment: mean ± SD: 67 ± 9%, 81 ± 4%, respectively (p < .001). A significant reduction was also seen for the relative hemoglobin (rHb) amount, flow and velocity (p < .001). The sensitivity of SO2 measured by VLS for diagnosing CMI was 94% and the specificity 72% (cut-off 78%), calculated with ROC curve analysis. A combination of SO2 and rHb increased the test sensitivity and specificity to 97% and 79%, respectively. Conclusion: CMI patients have significantly reduced microcirculation in the stomach and duodenum compared to controls. The results suggest that VLS should be included when performing an upper endoscopy in patients with suspected CMI.
关键词： laser doppler flowmetry,acute mesenteric ischemia,Chronic mesenteric ischemia,upper endoscopy,visible light spectroscopy
更新于2025-09-12 10:27:22
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Quantitative Analysis of Heel Skin Microcirculation Using Laser Doppler Flowmetry and Tissue Spectrophotometry
摘要： OBJECTIVE: To examine perfusion changes in the heel skin of individuals with and without diabetes mellitus to understand how skin is pathologically affected by diabetes mellitus. METHODS: This case-control study was conducted at an academic hospital in Tuebingen, Germany. A total of 30 subjects were enrolled in the study: 15 with known type 2 diabetes mellitus and 15 without. Each subject was asked to lie in a supine position on a hard lateral transfer mat for 10 minutes. MAIN OUTCOME MEASURES: Heel perfusion was quantitatively assessed directly after relief of pressure and after 3 and 6 minutes after relief of pressure using laser Doppler flowmetry and tissue spectrophotometry. MAIN RESULTS: Directly after relief of pressure, blood flow increased in the superficial skin layers (2 mm below the surface of the skin) in both groups. However, in deep skin layers (8 mm below the surface of the skin), blood flow increased in patients with diabetes mellitus and decreased in healthy patients. Oxygen saturation (SO2) was higher in healthy subjects directly after pressure relief. CONCLUSIONS: The increase in blood flow in superficial skin layers indicates reactive hyperemia after exposure in both groups. The prolonged hyperemia in deep skin layers in patients with diabetes indicates increased tissue vulnerability. Despite the increase in blood flow in deep skin layers, the SO2 and thus supply of tissue in patients with diabetes were reduced.
关键词： diabetes mellitus,pressure injury,oxygen saturation,blood flow,perfusion,diabetic foot ulcers,laser Doppler flowmetry,pressure ulcer,microcirculation
更新于2025-09-12 10:27:22
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Laser-based Techniques for Microcirculatory Assessment in Orthopedics and Trauma Surgery
摘要： Microcirculatory integrity and proper function are the cornerstones to tissue nourishment and viability. In the clinical environment extended immobility, injuries, and inflammatory reactions demand local microcirculatory adaption to provide adequate supply. Assessment of endothelial adjustment capability and microcirculatory perfusion status, as direct or surrogate markers of disease, are therefore of uttermost interest to the treating physician. Given the simple, noninvasive, nonradiating nature of laser-based techniques for bedside or intraoperative microcirculatory perfusion assessment, this article’s objective is to present a comprehensive overview of available techniques, their technological aspects, and current application. Advantages of individual methods are pointed out and compared with each other. The areas of medical utilization relevant to orthopedics and trauma surgery are exemplified and their available evidence elaborated. A particular focus is put on laser speckle contrast imaging, with its current and future influence on medical practice.
关键词： noninvasive cutaneous microcirculatory perfusion assessment,laser Doppler flowmetry,laser Doppler imaging,Laser speckle contrast imaging
更新于2025-09-11 14:15:04
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Preclinical vascular alterations in obese adolescents detected by Laser-Doppler Flowmetry technique
摘要： Background and aims: Childhood obesity promotes adverse changes in cardiovascular structure and function. This study evaluated whether alterations in skin microcirculation were already present in obese adolescents in a pre-clinical phase of cardiovascular disease. Methods and results: After an overnight fasting 22 obese adolescents and 24 normal-weight controls of similar age and gender distribution underwent clinical and blood examination and assessment of microvascular function by using two non-invasive techniques such as Peripheral Artery Tonometry (PAT) and Laser-Doppler Flowmetry (LDF). As compared to normal weight subjects, obese children had higher blood pressure, were significantly more hyper-insulinemic and insulin resistant, showing significantly higher plasma total cholesterol, LDL cholesterol, triglycerides and alanine aminotransferase (ALT). LDF showed lower pre- and post-occlusion forearm skin perfusion (perfusion units/second (PU/sec); median [IQR]) in obese than in normal weight subjects (pre-occlusion: 1633.8 [1023.5] vs. 2281.1 [1344.2]; p Z 0.015. Post-occlusion: 4811.3 [4068.9] vs. 7072.8 [7298.8]; p Z 0.021), while PAT revealed similar values of reactive hyperemia index (RHI). In entire population, fat mass % (FM%) was an independent determinant of both pre-and post-occlusion skin perfusion. Finally, being obese was associated with a higher risk to have a reduction of both pre- and post-occlusion skin perfusion (OR Z 5,82 and 9,27, respectively). Conclusion: LDF showed very early, pre-clinical, vascular involvement in obese adolescents, characterized by impaired skin microcirculation, possibly reflecting a more diffuse microvascular dysfunction to other body tissues. Whether changing life style and improving weight may reverse such pre-clinical alterations remains to be established.
关键词： Microcirculation,Obesity,Skin,Peripheral artery tonometry,Laser-Doppler flowmetry
更新于2025-09-11 14:15:04