Clinical investigation of skin microcirculation

Microangiopathy in Rheumatic Diseases

Capillaries are part of the microcirculation, which consists of arterioles, capillaries, and venules and are the connecting link between the arterial and venous blood circulation [...].

Exoscope-based videocapillaroscopy system for in vivo skin microcirculation imaging of various body areas

The capillary system immediately responds to many pathologies and environmental conditions. Accurate monitoring of its functioning often enables early detection of various diseases related to disorders in skin microcirculation. To expand the scope of capillaroscopy application, it is reasonable to visualize and assess blood microcirculation exactly in the areas of inflamed skin. Body vibrations, breathing, non-flat skin surface and other factors hamper the application of conventional capillaroscopes outside the nailfold area. In this paper, we propose an exoscope-based optical system for high-quality non-invasive computational imaging of capillary network in various areas of the body. Accurate image matching and tracking temporal intensity variations allow detecting the presence of blood pulsations, precise mapping of capillaries and photoplethysmogram acquisition. We have demonstrated the efficiency of the proposed approach experimentally by in vivo mapping and analysis of microvessels in wrist, forearm, upper-arm, breast and hip areas. We believe that the developed system will increase the diagnostic value of video capillaroscopy in clinical practice.

How to measure retinal microperfusion in patients with arterial hypertension

PURPOSE

Assessment and monitoring of changes in microcirculatory perfusion, perfusion dynamic, vessel structure and oxygenation is crucial in management of arterial hypertension. Constant search for non-invasive methods has led the clinical focus towards the vasculature of the retina, which offers a large opportunity to detect the early phase of the functional and structural changes in the arterial hypertension and can reflect changes in brain vasculature. We review all the available methods of retinal microcirculation measurements including angiography, oximetry, retinal vasculature assessment software, Optical Coherence Tomography Angiography, Adaptive Optics and Scanning Laser Doppler Flowmetry and their application in clinical research.

MATERIALS AND METHODS

To further analyse the applicability of described methods in hypertension research we performed a systematic search of the PubMed electronic database (April 2020). In our analysis, we included 111 articles in which at least one of described methods was used for assessment of microcirculation of the retina in hypertensive individuals.

RESULTS

Up to this point, the methods most commonly published in studies of retinal microcirculation in arterial hypertension were Scanning Laser Doppler Flowmetry followed shortly by Optical Coherence Tomography Angiography and retinal vasculature assessment software.

CONCLUSIONS

While none of described methods enables the simultaneous measurement of all microcirculatory parameters, certain techniques are widely used in arterial hypertension research, while others gain popularity in screening.

Acute skin trauma induces hyperemia, but superficial papillary nutritive perfusion remains unchanged

OBJECTIVES

Superficial skin papillary capillaries with blood supply from a superficial vascular plexus and regulated by local metabolic needs supply oxygen and nutrients for epithelial cell proliferation. A deep vascular plexus regulated by autonomous nerves serves body thermoregulation. In healthy volunteers, we assessed circulatory effects of a standardized skin trauma by CAVM, DRS, and LDPM to assess the measuring depth of the three techniques and to describe the acute trauma effects on nutritive and thermoregulatory perfusion.

METHODS

Volunteers (n=12) were examined at baseline and after induction of a 5.0 mm×1.0 mm incision on the forearm; 30 minutes after the trauma induction, data were collected at 0-1, 2-3 and 30 mm distances.

RESULTS

LDPM showed hyperemia at 2-3 mm distance (35.8±15.2 a.u.), but not at 30 mm distance (7.4±2.5 a.u.) compared to baseline (8.8±1.8 a.u.). The DRS saturation increased at 2-3 mm (71.2±4.8%), but not at 30 mm (49.8±7.9%) compared to baseline (45.8±7.4%). Capillary density and flow velocities were unaffected at all distances.

CONCLUSIONS

The results indicate that skin nutritive papillary capillary function can be assessed by CAVM and DRS, but not with LDPM because of its dependence of the deep plexus perfusion.

Nailfold Capillaroscopy in Rheumatic Diseases: Which Parameters Should Be Evaluated?

Video nailfold capillaroscopy (NFC), considered as an extension of the widefield technique, allows a more accurate measuring and storing of capillary data and a better defining, analyzing, and quantifying of capillary abnormalities. Capillaroscopic study is often performed on the patients suspected of having microcirculation problems such as Raynaud's phenomenon as the main indication for nailfold capillaroscopy. Capillaroscopic findings based on microcirculation studies can provide useful information in the fields of pathophysiology, differential diagnosis, and monitoring therapy. Nailfold capillaroscopy provides a vital assessment in clinical practices and research; for example, its reputation in the early diagnosis of systemic sclerosis is well established and it is also used as a classification criterion in this regard. This review focuses on the manner of performing video nailfold capillaroscopy and on a common approach for measuring capillary dimensions in fingers and toes.

CALCIUM CHANNEL BLOCKADE AND FUNCTIONAL MICROCIRCULATION CHANGES IN HYPERTENSIVE PATIENTS WITH DIFFERENT INDIVIDUAL AND TYPOLOGICAL CHARACTERISTICS

Aim. To identify individual and typological functional features of peripheral blood flow and assess microcirculation (MC) dynamics after a single-dose administration of nifedipine in patients with arterial hypertension (AH).

Material and methods. Laser Doppler flowmetry (LDF) was used for the MC assessment in 39 patients with Stage II–III AH.

Results. Marked variability in peripheral blood flow parameters was demonstrated for AH patients. Three main LDF types were identified: aperiodic (ApT), hyperemic, and hypoemic. Single-dose administration of nifedipine (20 mg) resulted in a similar antihypertensive effect across all patient groups. Positive MC dynamics was observed, which manifested in a marked increase in the number of patients with ApT (the most balanced type of peripheral blood flow regulation) and increased input of pulse blood filling into hemoperfusion.

Conclusion. In AH patients, nifedipine-induced changes in peripheral blood flow were associated with an increased number of participants with ApT, as the most balanced type of MC regulation. 

Thermographic assessment of inferior alveolar nerve injury in patients with dentofacial deformity

PURPOSE

The purpose of this study was to evaluate the injury and recovery of the inferior alveolar nerve in orthognathic patients at 1 and 4 weeks after surgery using electronic thermography.

MATERIALS AND METHODS

Twenty subjects with Class III dentofacial deformity were studied. All patients underwent bilateral sagittal split ramus osteotomy. To image the temperature of the face, 1 anteroposterior view and 1 lateral view were taken from both the right and left sides. Similar images were taken at 1 and 4 weeks after surgery. The control was the presurgical temperature of the 20 patients who showed unilateral or bilateral nerve damage after surgery.

RESULTS

In the patients with unilateral nerve damage (n = 14), on the anteroposterior views, the temperatures of the mentum on the 2 sides differed by 0.64 degrees C at 1 week after surgery, and the difference decreased to 0.23 degrees C at 4 weeks after surgery. On the lateral images, the differences in temperature between the mentum areas were 0.10 degrees C at 1 week and 0.27 degrees C at 4 weeks after surgery. In the patients with bilateral nerve injury (n = 6), on the anteroposterior views, the temperatures of the mentum on the 2 sides differed by 0.20 degrees C at 1 week after surgery and 0.13 degrees C after 4 weeks. On the lateral views, the differences were 0.18 degrees C at 1 week and 0.34 degrees C at 4 weeks after surgery. Using the repeated measurement analysis method, the anteroposterior view showed statistically significant results in the patients with unilateral nerve damage.

CONCLUSION

The infrared body temperature method is an objective method that can be applied as a supplemental diagnostic method for inferior alveolar nerve injury.

Non-invasive methods and stimuli for evaluating the skin's microcirculation

Vessels in the skin are arranged into superficial and deep horizontal plexuses and they are involved in thermoregulation, oxygen and nutritional support. The skin has a large number of functions and broad appeal spanning basic mechanistic and clinical research. Indeed, the skin can be used as a marker of normal and impaired vascular control and, owing to its accessibility and frequent involvement, is easy to investigate non-invasively. A large number of non-invasive methods are available for investigating the skin, ranging from those that permit the visualisation of microvessels, to those that monitor blood flow or one of its derivatives (e.g., skin temperature and transcutaneous oxygen). Such methods can be combined with non-invasive, dynamic stimuli (e.g., the use of cold or warm stimuli, activation of the peripheral nervous system or local neuronal systems, and the topical application of vasoactive drugs) and this potentially enables the differentiation of underlying disorders (e.g., primary from secondary Raynaud's phenomenon) and also to quantify changes over time or following intervention. The present article outlines the non-invasive methods and dynamic tests that can be used to investigate the microcirculation of the skin.

Videocapillaroscopic alterations in erythematotelangiectatic rosacea

BACKGROUND

Rosacea is a common chronic dermatosis that involves the cutaneous microvasculature of the face. There are no objective measures for assessing the severity of erythematotelangiectatic rosacea.

OBJECTIVE

Our purpose was to characterize and provide objective measures of vessel changes in erythematotelangiectatic rosacea by videocapillaroscopy.

METHODS

We compared 30 patients with erythematotelangiectatic rosacea with 30 age- and sex-matched patients with facial seborrheic dermatitis and 30 healthy control subjects. Videocapillaroscopy was performed both on the cheeks and on the nailfold region. The analyzed parameters of the face were morphological (background color, vessel irregularities) and quantitative (polygonal net perimeter, telangiectasia, and vessel diameters).

RESULTS

Characteristic alterations of skin vessels were observed in facial rosacea, with a pattern distinct from that of facial seborrheic dermatitis. In particular, rosacea showed neoangiogenesis and significantly larger polygons (13.21 +/- 3 vs 7.8 +/- 3 mm; mean +/- standard deviation, P < .001), more prominent telangiectases (267.8 +/- 108 vs 118.2 +/- 35 microm; P < .001) and larger mean vessel diameter (46.71 +/- 9 vs 24 +/- 10 microm; P < .001) compared with seborrheic dermatitis. Seborrheic dermatitis displayed more polygon irregularities and vessel tortuosity. In contrast, no differences were found in the nailfold region.

LIMITATIONS

Vessel irregularities and overall erythema may be difficult to quantify.

CONCLUSIONS

Videocapillaroscopy may represent a valid adjunctive method in the early diagnosis and measurement of erythematotelangiectatic rosacea.

Capillaroscopy and videocapillaroscopy assessment of skin microcirculation: dermatologic and cosmetic approaches

BACKGROUND

Different noninvasive bioengineering techniques exist to study the microvasculature of the skin and the dynamics of the microcirculation. The goal of these techniques is to visualize the skin capillary circulation easily and directly. Indeed, this information is irreplaceable to study the physiology and physiopathology of the skin capillary circulation efficiently.

AIMS

Capillaroscopy and video-capillaroscopy techniques are presented with different methods to study the capillary structure of the skin.

METHODS

The methods presented in this work include image processing analysis combining morphology, statistics, geometry, and neural network detection designed to quantify the microcirculation and to follow its evolution. To illustrate the combination of these techniques and methods, different examples of their application are described, in dermatology (hypertension, venous insufficiency, age-related changes) as well as in cosmetology (rosacea and erythrosis assessment).

CONCLUSION

The determination of structural or dynamic changes in the cutaneous microcirculation belongs to the noninvasive techniques of the biometrological domain. Thus, every capillary modification resulting from topical cosmetic products, or chemical agents can be observed. In pathology, numerous conditions can be better examined with this system. Associated with the potential of numerical image analysis, capillaroscopy techniques will probably extend their application fields to the assessment of the influence of arterial and venous diseases on the skin nutritional circulation.

A new technique to map vulva microcirculation using laser Doppler perfusion imager

The location of the vulva has had limited technologic progress in the assessment of the skin microcirculation and its application to clinical practice. Our group previously demonstrated increased perfusion in vulvar cancer compared to adjacent uninvolved skin with the laser Doppler flowmetry (LDF). The LDF is severely limited by its low spatial resolution ( approximately 1 mm(2)) and pressure involved in positioning of the probe, which may affect value of the underlying tissue perfusion. Topographic perfusion mapping of the whole vulvar skin using LDF is also time consuming and is not clinically practical. We describe for the first time the application of the novel laser Doppler perfusion imager (LDPI) to map vulvar skin blood flow and give example in two cases with well-defined vulvar pathology-psoriasis and lichen sclerosus with invasive neoplasia-and discuss the potential of LDPI to study vulvar skin blood flow.

Nailfold capillary microscopy in healthy children and in childhood rheumatic diseases: a prospective single blind observational study

OBJECTIVES

To develop an objective method of nailfold capillaroscopy (NFC), applicable to a wide age range of paediatric patients. To compare the morphological characteristics of the nailfold capillaries in different rheumatology patient groups and controls.

METHODS

A colour digital video camera attached to a stereomicroscope was used to capture nailfold capillary images. Computerised image processing was used to analyse and store data. Subsequent quantitative and qualitative morphological analysis was performed in the following paediatric patient and control groups: 18 children with connective tissue diseases (CTD: juvenile dermatomyositis, systemic sclerosis, and undifferentiated connective tissue disease), eight with systemic lupus erythematosus, nine with primary Raynaud's disease, three with primary vasculitis, 15 with juvenile idiopathic arthritis, 17 healthy children and 20 healthy adults. Images were analysed by a single assessor who was unaware of the patient details.

RESULTS

The NFC technique was simple to perform and gave reproducible results, although some intra- and intersubject variation was noted. Capillary density and width was age related, with younger children having fewer and wider capillaries than older children and adults. Linear capillary density was significantly higher in healthy adults (mean (SD) 8.6 (1.6) capillaries/mm) compared with healthy children (HC 6.9 (0.9) capillaries/mm). The group with CTD had the most abnormal findings, with lower linear density (4.9 (1.7) capillaries/mm) and increased capillary loop width (10.7 (7.3) mm) compared with HC (3.5 (1.7) mm). In addition, 11/18 (61%) patients in the CTD group had more than two definitely abnormal capillaries in at least two nailfolds, an abnormality not seen in other subjects. Two qualitative measures, the degree of avascularity and general disarrangement of capillary pattern, were more commonly observed in the CTD group than in HC. The proportion of tortuous capillaries did not differ significantly between study groups.

CONCLUSIONS

This study is unique in measuring objective quantitative and qualitative parameters of the nailfold vasculature across a wide spectrum of age and disease. Differences in capillary morphology and frequency in children with CTD compared with other paediatric diseases and healthy controls were demonstrated. In the clinical situation, an assessment of the general degree of disarrangement may offer a fast tool for assessment of the nailfold vasculature which correlates well with NFC data.

Laser Dopplers to determine cutaneous blood flow

BACKGROUND

Laser Dopplers can be useful in determining the relative amount of blood flowing through superficial skin. These instruments may be useful in assessing blood flow in healing wounds, flaps, and grafts.

OBJECTIVE

To review the theory and types of laser Dopplers available.

METHODS

This work includes a review of the literature.

RESULTS

Laser Dopplers potentially have a broad range of applications in dermatologic surgery and dermatology. Because laser Dopplers can quantify blood flow, the course of wound healing over time can be studied; however, for predicting viability of skin flaps and grafts, laser Dopplers have not been able to supplant clinical assessment.

CONCLUSION

Laser Dopplers provide an additional means of assessing superficial blood flow in the skin. This blood flow, which can be quantified, may be useful in studying wound and flap and graft healing.

The cutaneous uptake of atmospheric oxygen contributes significantly to the oxygen supply of human dermis and epidermis

It has been known since 1851 that atmospheric oxygen is taken up by the human epidermis. The contribution to total respiration is negligible. Until now the significance for the local oxygen supply of the skin has remained unknown. With a newly developed sensor, the oxygen fluxoptode, it has become possible to make local measurements of the transcutaneous oxygen flux (tcJ(O2)). In this study the sensor was calibrated so that absolute values of tcJ(O2) could be reported. At rest, tcJ(O2) was determined on normal, humidified skin on the volar forearm of 20 volunteers of different age groups. In order to evaluate the contribution of the blood flow to the oxygen supply of the skin, tcJ(O2) was recorded at the end of a 5 min suprasystolic occlusion of the forearm. At normal skin surface partial oxygen pressure (163 +/- 9 Torr), tcJ(O2) was 0.53 +/- 0.27 ml O2 min(-1) x m(-2). A 5 min interruption of blood flow resulted in an increase of 9.5 +/- 6.3 % in tcJ(O2). The value of tcJ(O2) was unaffected by the age of the subject. Published data on the oxygen diffusion properties of skin and simulations of intracutaneous profiles of oxygen partial pressure indicated that under these conditions, the upper skin layers to a depth of of 0.25-0.40 mm are almost exclusively supplied by external oxygen, whereas the oxygen transport of the blood has a minor influence. As a consequence, a malfunction in capillary oxygen transport cannot be the initiator of the development of superficial skin defects such as those observed in chronic venous incompetence and peripheral arterial occlusive disease.

Improvement of microcirculatory blood flow under epidural spinal cord stimulation in patients with nonreconstructible peripheral arterial occlusive disease

Epidural spinal cord stimulation (ESCS) has been suggested as a method to improve microcirculatory blood flow and to reduce the amputation rate in vascular patients. We studied the effects of ESCS on microcirculatory blood flow in 237 patients with nonreconstructible peripheral arterial occlusive disease. Clinical status was classified as Fontaine Stage 3 (ischemic rest pain) in 169 patients and as Fontaine Stage 4 (ulcers/gangrene) in 68 patients. After a mean follow-up period of 31.2 months, major pain relief (> 75%) was noticed in patients who retained their limbs. Sixty-four patients underwent major amputation despite ESCS. Clinical improvement was confirmed by the increase in transcutaneous oxygen (TcPO2).

Evaluation of skin blood flow by laser Doppler flowmetry

Laser Doppler flowmetry is an excellent noninvasive technique for the measurement of cutaneous microcirculation. The list of applications of laser Doppler flowmetry in dermatology is long. It can be applied to monitor inflammation caused by various drugs, chemicals, and allergens related to blood flow. To measure certain inflammatory reactions a combination of other bioengineering measurements is desirable. Flaps can be monitored, and burn depth measured by laser Doppler flowmetry. Through blood flow measurement, the pathophysiology of various skin diseases can be verified and certain treatments can be partially monitored. Although it is not as directly applicable to daily clinical practice, except in a few cases, laser Doppler flowmetry is a very useful technique in various kinds of dermatologic research.