Skin Microcirculatory Perfusion Research Articles

Effect of mild moxibustion with moxa stick and infrared mild moxibustion on skin blood perfusion at Waiguan (TE 5).

To observe the changes of skin blood flow perfusion at Waiguan (TE 5) caused by mild moxibustion with moxa stick and infrared mild moxibustion using laser speckle contrast imaging technology, and to compare the microcirculatory effect during and after both moxibustion methods and explore the dose-response relationship of moxibustion. Twenty-four healthy participants were treated with mild moxibustion with moxa stick and infrared mild moxibustion at left Waiguan (TE 5). The record started when the skin temperature reached (44±1) °C, and both moxibustion methods were provided within this temperature range. The 20-minute moxibustion process was divided into four stages (5, 10, 15, and 20 min) using interpolation method, and each participant completed eight interventions with a minimum 24-hour interval between different interventions. The skin surface temperature of the left Waiguan (TE 5) was monitored when both moxibustion interventions were given for 10 min using a TES1306 thermocouple thermometer. The skin microcirculatory blood perfusion units (MBPU) of left Waiguan (TE 5) was measured using a PSIN-01087 laser speckle blood flow imager 1 min before moxibustion, at 5, 10, 15, 20 min during moxibustion and continuously for 20 min after moxibustion in each intervention. The skin surface temperature of the left Waiguan (TE 5) remained within the range of (44±1) °C during both moxibustion methods, with no statistically significant difference (P>0.05). Compared with that before moxibustion, the MBPU of the left Waiguan (TE 5) was increased significantly at 5, 10, 15, and 20 min of both moxibustion methods (P<0.05, P<0.01). Compared with moxibustion for 10, 15 and 20 min, the MBPU of the left Waiguan (TE 5) of moxibustion for 5 min was lower in both moxibustion methods (P<0.01). For both moxibustion methods with the same moxibustion course, the MBPU of the left Waiguan (TE 5) 20 min after intervention was significantly higher than that at 1 min before moxibustion (P<0.001), and there was no significant difference in MBPU between 1 min before moxibustion and 20 min after moxibustion among different groups (P>0.05). Within the same moxibustion method, the MBPU of the left Waiguan (TE 5) 20 min after moxibustion with the intervention of 5 min was lower compared to that of 10, 15, and 20 min of moxibustion (P<0.001), with no significant differences between 10, 15, and 20 min of moxibustion (P>0.05). When controlling the skin temperature at Waiguan (TE 5) within (44±1) °C, infrared mild moxibustion has similar effects on skin microcirculatory blood perfusion as traditional mild moxibustion with moxa sticks. From a dose-response perspective, microcirculation reached a stable state after 10 min of moxibustion, and moxibustion interventions lasting for more than 10 min shows better therapeutic effects.

The acute adaptation of skin microcirculatory perfusion in vivo does not involve a local response but rather a centrally mediated adaptive reflex.

Introduction: Cardiovascular homeostasis involves the interaction of multiple players to ensure a permanent adaptation to each organ's needs. Our previous research suggested that changes in skin microcirculation-even if slight and distal-always evoke an immediate global rather than "local" response affecting hemodynamic homeostasis. These observations question our understanding of known reflexes used to explore vascular physiology, such as reactive hyperemia and the venoarteriolar reflex (VAR). Thus, our study was designed to further explore these responses in older healthy adults of both sexes and to potentially provide objective evidence of a centrally mediated mechanism governing each of these adaptive processes. Methods: Participants (n = 22, 52.5 ± 6.2 years old) of both sexes were previously selected. Perfusion was recorded in both feet by laser Doppler flowmetry (LDF) and photoplethysmography (PPG). Two different maneuvers with opposite impacts on perfusion were applied as challengers to single limb reactive hyperemia evoked by massage and a single leg pending to generate a VAR. Measurements were taken at baseline (Phase I), during challenge (Phase II), and recovery (Phase III). A 95% confidence level was adopted. As proof of concept, six additional young healthy women were selected to provide video imaging by using optoacoustic tomography (OAT) of suprasystolic post-occlusive reactive hyperemia (PORH) in the upper limb. Results: Modified perfusion was detected by LDF and PPG in both limbs with both hyperemia and VAR, with clear systemic hemodynamic changes in all participants. Comparison with data obtained under the same conditions in a younger cohort, previously published by our group, revealed that results were not statistically different between the groups. Discussion: The OAT documentary and analysis showed that the suprasystolic pressure in the arm changed vasomotion in the forearm, displacing blood from the superficial to the deeper plexus vessels. Deflation allowed the blood to return and to be distributed in both plexuses. These responses were present in all individuals independent of their age. They appeared to be determined by the need to re-establish hemodynamics acutely modified by the challenger, which means that they were centrally mediated. Therefore, a new mechanistic interpretation of these exploratory maneuvers is required to better characterize in vivo cardiovascular physiology in humans.

Acute adaptation of skin microcirculatory perfusion does not involve local responses

Effective cardio-circulatory adaptation is central to managing acute physiological challenges (e.g., posture change) as in chronic pathological processes (e.g., hypertension or heart failure) to continuously harmonize hemodynamics with cell needs. Acute responses such as sudden venous and capillary flow and pressure changes are believed to be linked to tissue-related intervenients (neuro-humoral, metabolic, endocrine) converging to a “local reflex” thought to protect capillary integrity in the absence of disease (the veno-arteriolar reflex VAR). Similar observations were produced in healthy individuals with increasing pressure using an inflated cuff applied in one limb – the post-occlusive reactive hyperemia (POHR). Our group has been involved in the quest to identify players and mechanisms in acute adaptive circulatory responses to in vivo perfusion changes. Recently we studied microcirculatory responses to hyperemia (produced by massage and by occlusion) and to a standard VAR maneuver. Protocols were independently applied to each participant to ensure full hemodynamicalrecovery. Sixty-six healthy participants of both sexes (mean age 31,3 + 3,6 years old) were selected. Distal perfusion was measured in both feet by laser Doppler flowmetry following massage and VAR (n=56). The PORH in one (randomly chosen) brachial artery was followed by optoacoustic tomography (OAT) in the ventral forearm (n=10).Reactive hyperaemia has been referred to be governed by local endothelial vasodilators sensory nerves and myogenic activities, while VAR is regarded as a regional reflex resulting from local interactions between myogenic fibers and non-adrenergic vasoconstrictive neurons. Massage and PORH are very different stressors (in intensity, duration, and extension) but both produced a significant perfusion increase in both limbs detected by LDF. VAR consistently evoked an opposite perfusion decrease in both limbs. Our results clearly indicate that these responses are not local. With the cuff applied to the arm, OAT functional imaging analysis of the PORH response in the ventral forearm revealed a sequential movement of blood from the skin superficial plexus to the deeper vascular structures with occlusion and returning with cuff deflation that confirms a centrally mediated response. An equivalent circuit is present with VAR with reverse effect. This response, which we named the Prompt Adaptive Hemodynamical Response (PAHR), appears to be independent of sex or age. No matter the involved receptors, different intensity spinal-supraspinal inflow produce proportional somatic and autonomous outflow, which also suggests that PAHR might be used as an endpoint with clinical relevance to characterize in vivo vascular function. This research is funded by Fundação Ciência Tecnologia (FCT) by grant UIDB/04567/2020. J Gregório is supported by FCT by the SES contract CEEC/CBIOS/EPH/2018. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Flowmotion imaging analysis of spatiotemporal variations in skin microcirculatory perfusion.

Flowmotion is the rhythmical variations in measured skin blood flow that arise due to global and local regulation of the vessels and can be studied using frequency analysis of time-resolved blood flow signals. It has the potential to reveal clinically useful information about microvascular diseases, but the spatial heterogeneous nature of the microvasculature makes interpretation difficult. However, recent technological advances in multi-exposure laser speckle contrast imaging (MELSCI) enable new possibilities for simultaneously studying spatial and temporal variations in flowmotion. To develop a method for flowmotion analysis of MELSCI perfusion images. Furthermore, to investigate the spatial and temporal variations in flowmotion in forearm baseline skin perfusion. In four healthy subjects, forearm skin perfusion was imaged at 15.6 fps for 10 min in baseline. The time-trace signal in each pixel was analyzed using the wavelet transform and summarized in five physiologically relevant frequency intervals, resulting in images of flowmotion. Furthermore, a method for reducing the effect of motion artifacts in the flowmotion analysis was developed. The flowmotion images displayed patterns of high spatial heterogeneity that differed between the frequency intervals. The spatial variations in flowmotion, quantified as the coefficient of variation, was between 11 % and 31 % in four subjects. Furthermore, significant temporal variations in flowmotion were also observed, indicating the importance of a spatiotemporal analysis. The new imaging technique reveals significant spatial differences in flowmotion that cannot be obtained with single-point measurements. The results indicate that global statistics of flowmotion, such as the mean value in a large region of interest, is more representative of the microcirculation than data measured only in a single point. Therefore, imaging techniques have potential to increase the clinical usefulness of flowmotion analysis. • Flowmotion imaging displays significant spatiotemporal variations in forearm skin blood flow. • Flowmotion imaging has potential to be more accurate than single-point techniques. • A simple and effective method for motion artifact removal is presented.

Spatiotemporal processing in photoplethysmography for skin microcirculatory perfusion imaging.

Technological advances in the real-time visualization of cutaneous microcirculation aim to realize benefits including high-resolution imaging, suppressed noise, and robust temporal coherence. Photoplethysmography (PPG), a noninvasive technique that measures single or multiple points of relative blood volume changes in blood vessels under the skin, shows potential as a signal candidate for visualizing blood vessels and tracking blood flow. However, challenges still remain, such as extracting/image reconstruction of the blood vessel/flow signal in a precise frequency window (<0.2 Hz) from a noisy image that is caused by the loss of spatial coherence of the light source in a turbid biological tissue. We attempted to overcome this challenge by adopting a combination of direct-contact-type, lens-less, conformable imagers and singular value decomposition (SVD) in this study. We focused on the numerical analysis of SVD for discriminating the tissue and vein blood flow in PPG for reconstructing blood fluidic images, followed by a complete demonstration of skin microcirculation blood tracking in the vessel visualization process when applying our lens-less, conformable, wearable imagers.

Relationship of mottling score, skin microcirculatory perfusion indices and biomarkers of endothelial dysfunction in patients with septic shock: an observational study

BackgroundIn patients with septic shock, the skin is often chosen for the evaluation of peripheral perfusion and oxygenation. Changes in skin microcirculatory vessel oxygen saturation and relative hemoglobin concentration can be described using a mottling score or captured with hyperspectral imaging. However, the effectiveness of the mottling score in assessing microcirculation remains to be shown. We hypothesize that the mottling score in patients with septic shock is related to skin microcirculatory perfusion indices quantified by hyperspectral imaging, biomarkers that reflect endothelium activation and damage, and clinical outcome.MethodsHyperspectral imaging of the knee area was performed in 95 intensive care patients with septic shock enrolled in a single-center observational study to obtain relative oxy/deoxyhemoglobin concentration values and construct anatomical maps of skin microcirculatory saturation. The blood was sampled to obtain concentrations of thrombomodulin, plasminogen activator inhibitor-1 (PAI-1), soluble intercellular adhesion molecule-1 (ICAM-1), soluble vascular cell adhesion molecule-1 (VCAM-1), angiopoietin-2, and syndecan-1. The spectrophotometrically obtained skin microvascular perfusion indices were compared to the mottling score and biomarker concentration. The association between mottling score, skin microcirculatory perfusion indices, and 28-day mortality was also analyzed.ResultsMicrocirculatory oxygen saturation was significantly lower and total hemoglobin concentration was significantly higher in patients with a mottling score of 2 compared to those with a score of 0 (p = 0.02), with no difference between other scores. We found an association between microcirculatory oxygen saturation and PAI-1 levels (rho = − 0.3; p = 0.007). Increased mottling score and decreased microcirculatory oxygen saturation were predictive of 28-day mortality (mottling score 2 vs 0: OR 15.31, 95% CI 4.12–68.11; microcirculatory oxygen saturation: OR 0.90, 95% CI 0.85–0.95). Endothelial biomarkers did not increase the predictive value of skin microcirculatory perfusion indices.ConclusionsHigher mottling scores are associated with lower microcirculatory oxygen saturation but with significant overlap between scores. Microcirculatory oxygen saturation is a quantitative measure of peripheral oxygenation and is more specific than the mottling score in predicting 28-day mortality.

The relationship between forearm skin speed-resolved perfusion and oxygen saturation, and finger arterial pulsation amplitudes, as indirect measures of endothelial function.

Endothelial function is important for regulating peripheral blood flow to meet varying metabolic demands and can be measured indirectly during vascular provocations. In this study, we compared the PAT finger response (EndoPAT) after a 5-minutes arterial occlusion to that from forearm skin comprehensive microcirculation analysis (EPOS). Measurements in 16 subjects with varying cardiovascular risk factors were carried out concurrently with both methods during arterial occlusion, while forearm skin was also evaluated during local heating. Peak values for EPOS skin Perfconv and speed-resolved total perfusion after the release of the occlusion were significantly correlated to the EndoPAT RHI (ρ=.68, P=.007 and ρ=.60, P=.025, respectively), mainly due to high-speed blood flow. During local heating, EPOS skin oxygen saturation, SO2, was significantly correlated to RHI (ρ=.62, P=.043). This indicates that SO2 may have diagnostic value regarding endothelial function. We have demonstrated for the first time a significant relationship between forearm skin microcirculatory perfusion and oxygen saturation and finger PAT. Both local heating and reactive hyperemia are useful skin provocations. Further studies are needed to understand the precise regulation mechanisms of blood flow and oxygenation during these tests.

Assessment of various traditional Chinese medicine formulas on skin micro-circulatory perfusion.

Laser Doppler imagery is a contemporary form biomedical science specializing in non-evasive micro-circulation investigation. This paper outlines the process and results of applying twelve different test samples to mouse skin to collect data variation of micro-circulation, then judge the effects of different formulas in skin health improvement. More specifically, it is said [15] that micro-circulation is associated with anti-aging (otherwise known as micro-circulation acceleration) by the way of improvement of nutrition supply and hazard substance elimination, has some effects of skin anti-aging. In this paper, compared with Group 0 (the blank group), Group 1, and Group 2 formulas have statistically significant differences in skin micro-circulation perfusion, which implies that those two groups are provided with better anti-aging formulas. So, Group 1's formula and Group 2's formula have the most significant positive effect on the skin health.

Effect of fluid therapy on skin microcirculatory perfusion during induction of general anesthesia in patients undergoing major abdominal surgery

Objective To investigate the changes in skin microcirculatory perfusion during induction of general anesthesia and the effects oftwo fluid therapy regimens in patients undergoing abdominal surgery.Methods Thirty-six ASA Ⅰ or Ⅱ patients aged 18-64 yr scheduled for elective major abdominal surgery were randomized to receive either 6% hydroxyetlayl starch(130/0.4)7 ml/kg(HES group,n=18)or lactated Ringer's solution 7 ml/kg(RL group,n=18)for compensatory intravascular volultne expansion(CVE)before tracheal intubation.Meanwhile both groups received continuous intravenous infusion of RL at a of 8 ml·kg~(-1)·h~(-1).Tracheal intubation was performed at 40 min after the onset of infusion.Anesthesia was maintained with with sevoflurane,remifentanil and rocuronium.Operation was started at 20 min after tracheal intubation.The microcirculatory perfusion was measured on forehead skin by using Doppler perfusion imaging system(LDPI)PI)at the onset of fluid infusion(T_0,baseline),the end of endotracheal intubation(T_1)and the onset of skin incision(T_2).Rwsults The MAP,HR,blood gases and body temperature were within the normal during the experiment and there was no significant difference between the 2 groups.The skin microcirculatory perfusion and CVP at T_1 were significantly higher in group HES than in group RL(P 0.05),the skin microcirculatory perfusion at T_2 was singificantly decreased in both groups(P<0.01),and CVP and PaO_2/FiO_2 at T_(1.2) were significantly increased,while Hb at T_(1.2) was significantly decreased in both groups(P<0.05).The skin microcirculatory perfusion in both groups was significantly lower at T_2 than at T_1(P<0.01).Conclusion The infusion of 6% HES 130/0.4 can improve the skin microcirculatory perfusion and the effect is better than that of RL during induction of general anesthesia in patients seheduled for abdominal surgery. Key words: Microcirculation; Skin; Fluid therapy

Microcirculatory effect of different skin contacting pressures around the blood pressure

We used laser Doppler flowmetry (LDF) and spectrum analysis to investigate the microcirculatory responses to pressure stimulation (PS) of the skin surface. A control group without PS applied, and four groups with different PS (20, 60, 100 and 160 mmHg in groups PS20, PS60, PS100 and PS160, respectively) were formed from seven volunteers. Each experiment involved recording a 20 min baseline and two effect data recorded at 0–20 and 50–70 min after stopping PS. The relative energy contribution (REC) in five frequency bands revealed by Morlet-wavelet transformation was calculated. At the pressed site, the dc component of the flux signal in the second effect increased significantly only in group PS60 compared with the control values. The REC was significantly increased in a myogenic-related band in groups PS60, PS100 and PS160, and was significantly decreased in a nerve-related band only in group PS160. Different PS magnitudes compress vessels to different extents. The proposed vessel-pressing model—which is supported by the results of spectral analysis of flux signals—might help to elucidate the underlying mechanism. The study results indicate that an improved perfusion was sustained for the longest time when applying 60 mmHg PS. This might aid the development of techniques for improving skin microcirculatory perfusion.

Effects of vacuum compression therapy on skin microcirculation in patients suffering from lower limb ischaemia.

We investigated the short-term effect of vacuum compression (VC) treatment on skin microcirculatory perfusion in the foot of patients with lower limb ischaemia and healthy controls. Ten patients with intermittent claudication or rest pain and 5 healthy controls underwent vacuum-compression treatment for half an hour. The leg was positioned in an air-tight plexiglass cylinder in which hypobaric (-115 mm Hg) and hyperbaric (75 mm Hg) pressure could be generated alternately, in order to improve peripheral circulation. The effect on skin microcirculation was investigated using nailfold capillary microscopy (measuring nutritive perfusion), laser Doppler fluxmetry (LDF) (total skin perfusion) and transcutaneous oxygen tension measurements (TcpO2). A few patients experienced ischaemic symptoms during VC, probably because the leg was pinched off through inflation of the cuff. In both patients and controls capillary microscopic parameters did not change significantly. In some cases, microcirculatory perfusion decreased because the leg had cooled during the treatment. Application of a heating matrass annihilated this effect. Only in the patient group a few LDF- and TcpO2 parameters improved slightly, but significantly. Vacuum-compression therapy only slightly improves total skin perfusion and oxygenation, but not the nutritive microcirculation, being an essential factor in the occurrence of ischaemic symptoms. We therefore conclude that this instrument in its present form is not an aid in the treatment of lower limb ischaemia.

Skin microcirculation in diabetic and non-diabetic patients at different stages of lower limb ischaemia

One hundred and one non-diabetic and 54 diabetic patients suffering from lower limb ischaemia were divided into (i) asymptomatic subjects, (ii) claudicants, (iii) critically ischaemic patients, i.e. Fontaine III or IV patients with either an ankle pressure < 51 mmHg or a toe pressure < 31 mmHg, and (iv) Fontaine III or IV patients in whom ankle and toe pressures could not be assessed due to vessel wall sclerosis or skin ulceration. Skin microcirculation was investigated to assess (a) the compounding effect of diabetes in leg ischaemia and (b) the additive value of microcirculatory investigation in the appreciation of the severity of the ischaemic disease. The techniques used included capillary microscopy, transcutaneous oximetry and laser Doppler fluxmetry. The severity of ischaemia was readily discernable using microcirculatory techniques. The presence of diabetes appeared to change skin microcirculatory perfusion, but especially in critically ischaemic patients, the microcirculation was no more compromised than non-diabetics. Using skin oxygen tension measurements, a positive predictive value of 77% was obtained in the detection of critical ischaemia, when a cut-off value of 30 mmHg was applied. Seventy per cent of patients, in whom the severity of ischaemia could not be classified using blood pressure measurements, could be classified as critically ischaemic on the basis of microcirculatory investigation. In conclusion, the influence of diabetes on the microcirculation is outweighed by the effects of atherosclerosis when vascular disease becomes severe. Techniques to investigate skin microcirculation are a useful way of assessing the severity of lower limb ischaemia in the presence of diabetes mellitus or if peripheral blood pressures cannot be obtained.

RETRACTED: DOES CORRECTION OF ACIDOSIS INFLUENCE MICROCIRCULATORY BLOOD FLOW DURING CARDIOPULMONARY BYPASS?

We studied 15 patients undergoing cardiopulmonary bypass (CPB) to examine the effect of response to correction of acidosis on microcirculatory blood flow. Acidosis was defined when base excess was less than -10.0 mmol litre-1 while carbon dioxide partial pressure was within the normal range. CPB was carried out at almost normothermic temperature (smallest rectal temperature 35.2 (SD) 0.4 degrees C). Sodium bicarbonate (NaHCO3) was given to correct acidosis during steady state CPB. Skin microcirculatory blood flow was assessed using a double-channel laser Doppler flow (LDF) monitor. LDF was measured on the patient's forehead and forearm before infusion of NaHCO3 (baseline) and 30 s, 1, 3, 5, 7, 10 and 15 min later. Skin, blood, rectal and nasopharyngeal temperatures did not change during the investigation. Plasma viscosity, haemoglobin and carbon dioxide partial pressure also remained unchanged. Mean arterial pressure (MAP) and systemic vascular resistance (SVR) decreased slightly after infusion of NaHCO3 (MAP -29%; SVR -32%). A total of NaHCO3 99.4 (4.4) mmol litre-1 was given for correction of acidosis. pH and HCO3- were within the normal range shortly after the infusion of NaHCO3. LDF measured on both the forehead (+49%) and the forearm (+29%) increased significantly after infusion of NaHCO3. Changes in pH correlated positively with changes in LDF (analyses of co-variance, P < 0.02), but haemodynamic and other laboratory values did not correlate with LDF. We conclude that the microcirculatory response to correction of acidosis with NaHCO3 during CPB can be monitored using skin laser Doppler flowmetry. Infusion of NaHCO3 resulted in a significant improvement in skin microcirculatory perfusion.

The relevance of posturally induced microvascular constriction after revascularisation in patients with chronic leg ischaemia

In patients with severe chronic lower limb ischaemia, postural vasoconstriction is disturbed, resulting in enhanced skin microcirculatory perfusion on leg dependency. After vascular reconstructive surgery, postoperative oedema formation is frequently seen. In 31 patients with leg ischaemia undergoing revascularisation we investigated whether and, if so, for how long after surgery postural vasoconstriction would take to recover, and whether disturbed vasoconstriction correlates with the occurrence of postoperative oedema. Capillary microscopy and laser Doppler fluxmetry were used to assess nutritional and total skin perfusion, respectively. The measurements were performed before and up to 37 days after surgery. After revascularisation, the mean ankle blood pressure index rose from 40 to 82%. All patients, except those with persistently disturbed vasoconstriction showed improved microcirculatory parameters. Postural vasoconstriction was restored in 24 patients, occurring approximately on the eighth postoperative day. All patients who failed to recover vasoconstriction developed postoperative oedema. This study shows that the disturbance in postural vasoconstriction can be reversible, probably due to recovery of arteriolar smooth muscle tone, and that patients with persistently disturbed postural vasoconstriction, are prone to develop postoperative oedema.