暂无摘要。

OBJECTIVE: After a traumatic brain injury (TBI), monitoring of both macrovascular and microvascular blood circulation can potentially yield a better understanding of pathophysiology of potential secondary brain lesions. We investigated the changes in phase shift (PS) between cardiac-induced oscillations of cerebral blood flow (CBF) measured at macro (ultrasound Doppler) and microvascular (laser Doppler) level. Further we assessed the impact of intracranial pressure (ICP) on PS in TBI patients. A secondary aim was to compare PS to TCD-derived cerebral arterial time constant (τ), a parameter that reflects the circulatory transit time.
METHODS: TCD blood flow velocities (FV) in the middle cerebral artery, laser Doppler blood microcirculation flux (LDF), arterial blood pressure (ABP), and ICP were monitored in 29 consecutive patients with TBI. Eight patients were excluded because of poor-quality signals. For the remaining 21 patients (median age = 23 (Q1: 20-Q3: 33); men:16,) data were retrospectively analysed. PS between the fundamental harmonics of FV and LDF signals was determined using spectral analysis. τ was estimated as a product of cerebrovascular resistance and compliance, based on the mathematical transformation of FV and ABP, ICP pulse waveforms.
RESULTS: PS was negative (median: -26 (Q1: -38-Q3: -15) degrees) indicating that pulse LDF at a heart rate frequency lagged behind TCD pulse. With rising mean ICP, PS became more negative (R = -0.51, p < 0.019) indicating that delay of LDF pulse increases. There was a significant correlation between PS and cerebrovascular time constant (R = -0.47, p = 0.03).
CONCLUSIONS: Pulse divergence between FV and LDF became greater with elevated ICP, likely reflecting prolonged circulatory travel time.

OBJECTIVE: To assess microvascular reactivity during a skin thermal challenge early post-cardiac surgery and its association with outcomes.
METHODS: Noninvasive physiological study.
METHODS: Thirty-five-bed department of intensive care.
METHODS: Patients admitted to the intensive care unit post-cardiac surgery.
METHODS: Thermal challenge.
RESULTS: A total of 46 patients were included; 14 needed vasoactive or ventilatory support for at least 48 hours (slow recovery), and 32 had a more rapid recovery. Skin blood flow (SBF) was measured on the anterior proximal forearm using skin laser Doppler. A thermal challenge was performed by abruptly increasing local skin temperature from 37°C to 43°C while monitoring SBF. The ratio between SBFs at 43°C and 37°C was calculated to measure microvascular reactivity. SBF at 37°C was not significantly different in patients with a slow recovery and those with a rapid recovery, but SBF after 9 minutes at 43°C was lower (48.5 [17.3-69.0] v 85.1 [45.2-125.7], p < 0.01), resulting in a lower SBF ratio (2.8 [1.5-4.7] v 4.8 [3.7-7.8], p < 0.01). Patients with lower SBF ratios were more likely to have dysfunction of at least one organ (assessed using the sequential organ dysfunction score) 48 hours post-cardiac surgery than those with higher ratios: 88% versus 40% versus 27% (p < 0.01), respectively, for the lowest, middle, and highest tertiles of SBF ratio. In multivariable analysis, a lower SBF ratio was an independent risk factor for slow recovery.
CONCLUSIONS: Early alterations in microvascular reactivity, evaluated by a skin thermal challenge, are correlated with organ dysfunction. These observations may help in the development of new, simple, noninvasive monitoring systems in postoperative patients.

UNASSIGNED: An arteriovenous fistula (AVF) is a potential complication of endovascular therapy (EVT). Arteriovenous fistula steal syndrome sometimes leads to severe limb ischaemia; however, assessment of peripheral perfusion in AVF has not yet been established.
UNASSIGNED: A 90 year old woman diagnosed with chronic limb threatening ischaemia underwent EVT. However, subintimal angioplasty of infrapopliteal lesions resulted in AVF formation in the posterior tibial artery (PTA). Revascularisation of the anterior tibial artery and PTA was performed, but severe AVF steal syndrome persisted and wound healing was delayed. An attempt to physiologically assess the effects of AVF closure and perform an AVF closing manoeuvre, if necessary, was performed. The physiological assessment was performed by laser Doppler flowmetry (LDF) and blood flow was temporarily blocked via the AVF at the distal PTA using a 6 F guiding extension catheter. A significant increase in blood flow was observed in the perfused area of the plantar artery. Coil embolisation and covered stent implantation in the PTA completely closed the AVF. During the procedure, peripheral perfusion with LDF gradually increased in the heel and fifth toe. After AVF closure, the skin perfusion pressure values increased significantly, wound healing was accelerated, and complete healing was achieved.
UNASSIGNED: Laser Doppler flowmetry measurements under simulated AVF closure using a guiding extension catheter may be useful for the physiological assessment of peripheral perfusion before percutaneous AVF closure.

Flowmotion analysis of the microcirculatory blood flow is a method to extract information about the vessel regulatory function. It has previously shown promise when applied to measurements during a post-occlusive reactive hyperemia. However, the reperfusion peak and the following monotonic decline introduces false low frequencies that should not be interpreted as rhythmic vasomotion effect.
To develop and validate a robust method for flowmotion analysis of post-occlusive reactive hyperemia signals.
The occlusion-induced reperfusion response contains a typical rapid increase followed by a monotonic decline to baseline. A mathematical model is proposed to detrend this transient part of the signal to enable further flowmotion analysis. The model is validated in 96 measurements on healthy volunteers.
Applying the proposed model corrects the flowmotion signal without adding any substantial new false flowmotion components.
Future studies should use the proposed method or equivalent when analyzing flowmotion during post-occlusive reactive hyperemia to ensure valid results.

BACKGROUND: The effect of kidney transplantation on endothelial dysfunction and autonomic dysfunction in uremia remains controversial, and few studies have evaluated this question. Endothelial dysfunction and autonomic dysfunction, both, be assessed noninvasively using laser Doppler flowmetry (LDF). This study evaluated cutaneous microvascular blood flow and reactivity using LDF in patients undergoing kidney transplantation.
METHODS: This prospective longitudinal cohort study involved 40 patients with chronic kidney disease (CKD) undergoing kidney transplantation, compared with 40 patients without kidney disease. Using LDF, post-occlusive reactive hyperemia (PORH) (resting flow [RF], peak flow, ratio between peak, and RF, hyperemic area, PORH index), and sympathetic constrictor response to inspiratory breath-hold (mean minimum inspiratory values) were evaluated.
RESULTS: RF and sympathetic constrictor response to inspiratory breath-hold (mean minimum inspiratory values), were lower in the CKD group at 1 week and at 3 months after transplantation (p < 0.005). Mean minimum inspiratory values increase in the CKD group, 3 months after transplantation.
CONCLUSIONS: Compared with controls with no CKD, in CKD patients undergoing kidney transplantation, microcirculation by LDF shows improvement after 3 months.

Pulpal modifications taking place during prosthetic tooth preparation using worn-out burs may represent a risk for the vitality of the dental pulp. The aim of this in vivo study was to evaluate whether the wear of diamond burs has an influence on the vascular microdynamics at the level of the dental pulp, during vertical preparation for zirconia crowns. The study was performed with a split-mouth design and included 32 vital permanent monoradicular teeth (20 maxillary and 12 mandibular), from six subjects, aged between 20 and 50 years. The teeth were randomly assigned to two study groups of 16 teeth each. For prosthetic preparation, new burs were used in the first group, and burs at their 5th use were used in the second group. Four consecutive determinations of the pulpal blood flow by Laser Doppler flowmetry (LDF-laser Doppler MoorLab instrument VMS-LDF2, Moor Instruments Ltd., Axminster, UK) were taken for each tooth included in the study: before the preparation (control values), immediately, at 24 h, and at 7 days after the prosthetic preparation. A four-way ANOVA statistical analysis was applied to analyze the effect of four considered factors (bur wear degree, time of measurement, tooth number, and tooth location) on the pulpal blood flow (PBF). A significant increase in pulpal blood flow compared to the baseline was recorded immediately after preparation (p < 0.01), at 24 h (p < 0.01), and at 7 days (p < 0.05) in both groups, but more pronounced in the case of burs at the 5th use. The blood flow was significantly higher in upper jaw teeth, irrespective of the measurement time. In conclusion, the use of worn-out diamond burs produces lasting modifications in the pulpal blood flow of teeth that undergo prosthetic crown preparation. ISRCTN registry: ISRCTN49594720.

Diabetic foot ulcer (DFU) is a severe complication with high mortality. High plantar pressure and poor microcirculation are considered main causes of DFU. The specific aims were to provide a novel technique for real-time measurement of plantar skin blood flow (SBF) under walking-like pressure stimulus and delineate the first plantar metatarsal head dynamic microcirculation characteristics because of life-like loading conditions in healthy individuals.
Twenty young healthy participants (14 male and 6 female) were recruited. The baseline (i.e., unloaded) SBF of soft tissue under the first metatarsal head were measured using laser Doppler flowmetry (LDF). A custom-made machine was utilized to replicate daily walking pressure exertion for 5 min. The exerted plantar force was adjusted from 10 N (127.3 kPa) to 40 N (509.3 kPa) at an increase of 5 N (63.7 kPa). Real-time SBF was acquired using the LDF. After each pressure exertion, postload SBF was measured for comparative purposes. Statistical analysis was performed using the R software.
All levels of immediate-load and postload SBF increased significantly compared with baseline values. As the exerted load increased, the postload and immediate-load SBF tended to increase until the exerted load reached 35 N (445.6 kPa). However, in immediate-load data, the increasing trend tended to level off as the exerted pressure increased from 15 N (191.0 kPa) to 25 N (318.3 kPa). For postload and immediate-load SBF, they both peaked at 35 N (445.6 kPa). However, when the exerted force exceeds 35 N (445.6 kPa), both the immediate-load and postload SBF values started to decrease.
Our study offered a novel real-time plantar soft tissue microcirculation measurement technique under dynamic conditions. For the first metatarsal head of healthy people, 20 N (254.6 kPa)-plantar pressure has a fair microcirculation stimulus compared with higher pressure. There might be a pressure threshold at 35 N (445.6 kPa) for the first metatarsal head, and soft tissue microcirculation may decrease when local pressure exceeds it.

Chronic mixed blepharitis accounts for 51.7% of all ophthalmic diseases. The use of laser Doppler flowmetry (LDF) in the diagnosis of this disease can help establish the initial manifestations of the inflammatory process in the eyelids, which is important for the prevention of possible complications - dry eye disease.
OBJECTIVE: This study was conducted to determine the sensitivity and specificity of the LDF method in the diagnosis of chronic mixed blepharitis based on the study of microcirculatory changes in the eyelid skin.
METHODS: The study included 23 patients with chronic mixed blepharitis (mean age 67±5.8 years) and 18 healthy volunteers (mean age 63±1.1 years). LDF was performed using the LAZMA MC-1 device. ROC analysis was used to determine sensitivity and specificity.
RESULTS: A typical disturbance of the eyelid skin microcirculation was revealed in chronic mixed blepharitis - ischemia - with inhibition of the intensity of the functioning of blood flow regulatory systems and moderate activation of the lymph flow. The sensitivity and specificity of the coefficient of variation (reflecting the vasomotor activity of microvessels) of blood flow was 71.43 and 71.43%, lymph flow - 65.71 and 80.00%; myogenic rhythms of blood flow - 83.33 and 85.71%, lymph flow - 66.67 and 71.43%; neurogenic rhythms of blood flow - 75.00 and 78.57%, lymph flow - 91.67 and 78.57%, respectively.
CONCLUSIONS: Laser Doppler flowmetry of the eyelid skin in combination with clinical, functional and instrumental research methods helped reveal with high sensitivity and specificity the eyelid damage in chronic mixed blepharitis. This method allows assessment of the condition of the eyelids in individuals without diseases of the anterior segment of the eye.
Доля хронического смешанного блефарита в структуре офтальмологических заболеваний составляет 51,7%. Применение лазерной допплеровской флоуметрии (ЛДФ) в диагностике этого заболевания позволяет установить инициальные проявления воспалительного процесса в веках, что важно для профилактики развития возможных осложнений — синдрома сухого глаза.
UNASSIGNED: Определить чувствительность и специфичность метода ЛДФ в диагностике хронического смешанного блефарита на основании изучения микроциркуляторных изменений кожи век.
UNASSIGNED: Обследованы 23 пациента с хроническим смешанным блефаритом (средний возраст 67±5,8 года) и 18 здоровых добровольцев (средний возраст 63±1,1 года). ЛДФ проводили с помощью прибора «ЛАЗМА МЦ-1». Для определения чувствительности и специфичности применяли ROC-анализ.
UNASSIGNED: При хроническом смешанном блефарите выявлено типовое нарушение микроциркуляции кожи век — ишемия — с угнетением напряженности функционирования регуляторных систем кровотока и активацией лимфотока умеренной выраженности. Чувствительность и специфичность коэффициента вариации (отражающего вазомоторную активность микрососудов) кровотока составила — 71,43 и 71,43%, лимфотока — 65,71 и 80,00%; миогенных ритмов кровотока — 83,33 и 85,71%, лимфотока — 66,67 и 71,43%; нейрогенных ритмов кровотока — 75,00 и 78,57%, лимфотока — 91,67 и 78,57% соответственно.
UNASSIGNED: Применение ЛДФ кожи век позволило с высокой чувствительностью и специфичностью выявить поражение век при хроническом смешанном блефарите в сочетании с клинико-функциональными и инструментальными методами исследования. Данный метод позволяет оценить состояние век у лиц без заболеваний переднего отдела глаза.

UNASSIGNED: Type 2 diabetes mellitus (T2DM) is a global health concern with significant implications for vascular health. The current evaluation methods cannot achieve effective, portable, and quantitative evaluation of foot microcirculation.
UNASSIGNED: We aim to use a wearable device laser Doppler flowmetry (LDF) to evaluate the foot microcirculation of T2DM patients at rest.
UNASSIGNED: Eleven T2DM patients and twelve healthy subjects participated in this study. The wearable LDF was used to measure the blood flows (BFs) for regions of the first metatarsal head (M1), fifth metatarsal head (M5), heel, and dorsal foot. Typical wavelet analysis was used to decompose the five individual control mechanisms: endothelial, neurogenic, myogenic, respiratory, and heart components. The mean BF and sample entropy (SE) were calculated, and the differences between diabetic patients and healthy adults and among the four regions were compared.
UNASSIGNED: Diabetic patients showed significantly reduced mean BF in the neurogenic (p=0.044) and heart (p=0.001) components at the M1 and M5 regions (p=0.025) compared with healthy adults. Diabetic patients had significantly lower SE in the neurogenic (p=0.049) and myogenic (p=0.032) components at the M1 region, as well as in the endothelial (p<0.001) component at the M5 region and in the myogenic component at the dorsal foot (p=0.007), compared with healthy adults. The SE in the myogenic component at the dorsal foot was lower than at the M5 region (p=0.050) and heel area (p=0.041). Similarly, the SE in the heart component at the dorsal foot was lower than at the M5 region (p=0.017) and heel area (p=0.028) in diabetic patients.
UNASSIGNED: This study indicated the potential of using the novel wearable LDF device for tracking vascular complications and implementing targeted interventions in T2DM patients.