Laser Dopplers to determine cutaneous blood flow

One-Pot Synthesis of Bioadhesive Double-Network Hydrogel Patch as Disposable Wound Dressing

Inventions of materials to achieve biocompatibility, bioadhesion, and easy manufacturing are the urgent demand for promoting wound healing in clinical treatment. Hyaluronic acid (HA) is probably the ideal candidate for current dressing materials due to its well-known biocompatibility. However, the unavoidable problem for HA dressings is their inherent low adhesiveness to wounds, which severely impairs their treatment efficacy, especially during body movement. Here, we report a one-pot facile fabrication of hybrid double-network polydopamine-HA (PDA-HA) hydrogel with significantly enhanced adhesiveness compared to the HA hydrogel. Besides the easy manufacturing and promoted effectiveness, the PDA-HA hydrogel could be vacuum-dried to form a patch, further benefitting from the convenience for storage and distribution. When applied on the wound, the PDA-HA patch quickly rehydrated by absorbing exudate and stuck tightly to the wound. The applied PDA-HA patches keep the wounds covered for more than 7 days against strenuous exercise. Thus, mouse full-thickness wounds treated with the PDA-HA patches exhibited increased healing rates, where epithelization was finished within 14 days. Moreover, the hydrogel dressing exhibited promoting effects on vascularization and cell proliferation/migration. Together with the easy manufacturing procedure, good adhesion/adaptation, and promotion of wound healing, the PDA-HA patch holds great potential for future clinical translation.

Optical spectral diagnostics of the oxygenation level in periodontal tissues and photodynamic therapy using methylene blue in children with cerebral palsy

Dental diseases occur in children with cerebral palsy three times higher than in healthy children. Low values of the unstimulated salivation rate (<0.3 ml per minute), pH and buffer capacity, changes in enzyme activity and sialic acid concentration, as well as increased saliva osmolarity and total protein concentration, which indicates impaired hydration, are the factors in the development of a gingiva disease in case of cerebral palsy. This leads to increased bacterial agglutination and the formation of acquired pellicle and biofilm, leading to the formation of dental plaque. There is a tendency toward an increase in the concentration of hemoglobin and a decrease in the degree of hemoglobin oxygenation, as well as an increase in the generation of reactive oxygen and nitrogen species. Photodynamic therapy (PDT) with the use of photosensitizer methylene blue improves blood circulation and the degree of oxygenation in periodontal tissues, as well as eliminates a bacterial biofilm. Analysis of back diffuse reflection spectra makes it possible to conduct non-invasive monitoring determine tissue areas with a low level of hemoglobin oxygenation for precision photodynamic exposure.

Aim

To improve the effectiveness of phototheranostics methods using, namely PDT with simultaneous optical-spectral control, for the treatment of gingivitis in children with complex dental and somatic status (cerebral palsy).

Methods

The study involved 15 children (6-18 y.o.) with various forms of cerebral palsy, in particular, spastic diplegia and atonic-astatic form and with gingivitis. The degree of hemoglobin oxygenation was measured in tissues before PDT and on the 12th day. PDT was performed using laser radiation (λ = 660 nm) with a power density of 150 mW/cm² with a five-minute application of 0.01% MB. The total light dose was 45 ± 15 J/cm². For statistical evaluation of the results, a paired Student's t-test was used.

Results

The paper presents the results of phototheranostics using methylene blue in children with cerebral palsy. An increase in the level of hemoglobin oxygenation from 50 to 67% (p < 0.001) and a decrease in blood volume in the microcirculatory bed of periodontal tissues were shown.

Conclusion

Photodynamic therapy methods with application of methylene blue make it possible to assess the state of the gingival mucosa tissue diseases objectively in real time, and to provide effective targeted therapy for gingivitis in children with cerebral palsy. There is a prospect that they can become widely used clinical methods.

Cellular reactions in capillary and venous blood in northerners to a short-term period in a climatic chamber

PURPOSE

The purpose is a comparative study of the cellular reactions in capillary and venous blood in northerners under general hypothermia in a climatic chamber during different photoperiods. The authors examined 108 relatively healthy people (80 women and 28 men aged 21- to 50-years old).

METHODS

The study included determining the hemogram, neutrograms, monocytograms, lymphocytograms, and phagocytic activity neutrophil granulocytes, enzyme immunoassay, flow cytometry, indirect immunoperoxidase, bioluminescence, systolic and diastolic blood pressure, and body temperature in the ear canal and on the skin of the rear left side of the right hand of volunteers before the effect of general cooling in the room at an air temperature and after 5 minutes of exposure to cold air.

RESULTS

It was established that total neutrophil count in venous blood was lower by 8.07% ± 0.41%, monocyte count by 51.32% ± 1.03%, and basophil count by 50.21% ± 1.24% than in capillary blood, but the lymphocyte count was higher by 25.23% ± 0.41% due to smaller forms that are known to be recirculating. After a 5-minute period in a climatic chamber at -25°C in 27.53% of individuals during a polar night and in 16.51% volunteers during a polar day had elevated levels of neutrophils in the venous blood due to the increase in the levels of tumor necrosis factor-α in blood and decrease in noradrenaline, adrenaline, and irisin.

CONCLUSION

The systematic effect of general cooling, especially during the polar night, leads to a reduction in reserve adaptability with the formation of neutropenia, deficiency of phagocytic defense, and functional insufficiency of T-lymphocytes.

Hematological reactions in the inhabitants of the Arctic on a polar night and a polar day

PURPOSE

The purpose of this study is to identify the features of hematological reactions in the inhabitants of the Arctic territory of the Kola Peninsula on a polar night and a polar day.

METHODS

The study included determining the hemogram, neutrograms, monocytograms, lymphocytograms, and phagocytic activity neutrophil granulocytes, enzyme immunoassay, flow cytometry.

RESULTS

It was established that during the polar night, there is an increase in the activity of migration of leukocytes from the marginal pool to the circulating pool, an increase in the intensity of phagocytosis by neutrophils, an increase in the concentrations of noradrenaline, cortisol, as well as an increase in hyperergic reactions involving immunoglobulin E and inhibitory processes due to an increase in interleukin-10.

CONCLUSION

A prolonged lack of sunlight causes a decrease in the reserve capacity for regulating homeostasis and forces the body to use proliferative reactions, which is reflected in the increase in stab neutrophils, large lymphocytes in the structure of the lymphocytogram and CD10+ lymphocytes. In winters, the frequency of neutropenia registration also increases to 13% of cases, the deficit of phagocytic activity of neutrophils; lymphopenia is recorded in 20% with T-helper deficiency (37%). A part of the population probably has a relatively high degree of vulnerability to the action of natural environmental factors and is not able to completely restore the initial levels of the effectiveness of adaptation reactions in the summer. So at the end of the polar day in 8% of adults born in the north, neutropenia is recorded and in 21%-lymphopenia.

The immediate effects of kinesiology taping on cutaneous blood flow in healthy humans under resting conditions: A randomised controlled repeated-measures laboratory study

BACKGROUND

Kinesiology taping (KT) is used in musculoskeletal practice for preventive and rehabilitative purposes. It is claimed that KT improves blood flow in the microcirculation by creating skin convolutions and that this reduces swelling and facilitates healing of musculoskeletal injuries. There is a paucity of physiological studies evaluating the effect of KT on cutaneous blood microcirculation.

OBJECTIVES

The purpose of this parallel-group controlled laboratory repeated measures design study was to evaluate the effects of KT on cutaneous blood microcirculation in healthy human adults using a dual wavelength (infrared and visible-red) laser Doppler Imaging (LDI) system. KT was compared with rigid taping and no taping controls to isolate the effects associated with the elasticity of KT.

METHODS

Forty-five healthy male and female human adults were allocated to one of the three interventions using constrained randomisation following the pre-intervention measurement: (i) KT (ii) ST (standard taping) (iii) NT (no taping). Cutaneous blood perfusion was measured using LDI in the ventral surface of forearm at pre-intervention, during-intervention and post-intervention in a normothermic environment at resting conditions.

RESULTS

Mixed ANOVA of both infrared and visible-red datasets revealed no statistically significant interaction between Intervention and Time. There was statistically significant main effect for Time but not Intervention.

CONCLUSION

KT does not increase cutaneous blood microcirculation in healthy human adults under resting physiological conditions in a normothermic environment. On the contrary, evidence suggests that taping, regardless of the elasticity in the tape, is associated with immediate reductions in cutaneous blood flow.

Imaging techniques in the diagnosis and monitoring of psoriasis

Plaque psoriasis is a chronic, immune-mediated disease, which has a multifactorial etiopathogenesis. Practical non-invasive techniques to monitor plaque psoriasis progression and treatment are necessary. Imaging techniques available for psoriasis assessment may vary in terms of resolution, depth of penetration and visual representation. This review summarizes the current developments in the field of psoriasis non-invasive imaging techniques, such as dermoscopy, conventional ultrasound and high frequency ultrasonography (HFUS), videocapillaroscopy (VC), reflectance confocal microscopy (RCM), optical microangiography (OMAG), laser Doppler imaging (LDI), multiphoton tomography (MPT) and optical coherence tomography (OCT). The aim was to collect and analyze data concerning types, indications, advantages and disadvantages of modern imaging techniques for in vivo psoriasis assessment. We focused on two main methods, videodermoscopy and HFUS, which can be included in daily dermatologists' practice and which may assist in establishing diagnosis, as well as monitoring response to topical and/or systemic therapy of psoriasis. Dermoscopy may be useful for a first evaluation and may offer an understanding of the type and distribution of blood vessels, as well as the color of the scale and the background of the lesion. Videodermoscopy allows magnification and offers a detailed evaluation of the vessel type. The utility of HFUS consists mainly in monitoring therapy response. These methods may be comparable with virtual histopathology.

Effects of anodyne treatment on local blood flow and cutaneous sensation of the foot in a patient with peripheral neuropathy secondary to acromegaly

Acromegaly is an excessive amount of serum growth hormone, which may present with sensorimotor polyneuropathy, affecting sensation and/or blood flow in the limbs. Symptoms include numbness, tingling or pain with impaired sensation including kinesthesia and proprioception. We report here of a 48-year-old male with a defined diagnosis of acromegaly and surgical excision of a pituitary adenoma 20 years ago. Recently he reports feet stepping on, and not feeling, objects under foot and balance problems starting 10 years ago. This study used a single-subject A-B-A design to show that behavioral changes are evident only in the presence of an intervention. Intervention consisted of Monochromatic Infrared Light Energy (MIRE), delivered by the Anodyne Therapy System (ATS). The DRT-4 laser Doppler measured red blood cell flux (flow), concentration and velocity. Levels of significance utilized the two standard deviation band method. Peripheral sensation of eight sites on each foot assessed using Semmes-Weinstein monofilaments (SWM) revealed a lack of sensation in the feet. A treatment effect as exhibited by blood flow velocity and red blood cell concentration was detected after the third week of treatment indicating peripheral dilation of the microvasculature. MIRE was an effective intervention for the treatment of acromegaly - induced polyneuropathy in this patient.

High-speed microscopy for in vivo monitoring of lymph dynamics

The lymphatic system contributes to body homeostasis by clearing fluid, lipids, plasma proteins and immune cells from the interstitial space. Many studies have been performed to understand lymphatic function under normal conditions and during disease. Nevertheless, a further improvement in quantification of lymphatic behavior is needed. Here, we present advanced bright-field microscopy for in vivo imaging of lymph vessels (LVs) and automated quantification of lymphatic function at a temporal resolution of 2 milliseconds. Full frame videos were compressed and recorded continuously at up to 540 frames per second. A new edge detection algorithm was used to monitor vessel diameter changes across multiple cross sections, while individual cells in the LVs were tracked to estimate flow velocity. The system performance initially was verified in vitro using 6- and 10-μm microspheres as cell phantoms on slides and in 90-μm diameter tubes at flow velocities up to 4 cm/second. Using an in vivo rat model, we explored the mechanisms of lymphedema after surgical lymphadenectomy of the mesentery. The system revealed reductions of mesenteric LV contraction and flow rate. Thus, the described imaging system may be applicable to the study of lymphatic behavior during therapeutic and surgical interventions, and potentially during lymphatic system diseases.

Novel capsaicin-induced parameters of microcirculation in migraine patients revealed by imaging photoplethysmography

Background

The non-invasive biomarkers of migraine can help to develop the personalized medication of this disorder. In testing of the antimigraine drugs the capsaicin-induced skin redness with activated TRPV1 receptors in sensory neurons associated with the release of the migraine mediator CGRP has already been widely used.

Methods

Fourteen migraine patients (mean age 34.6 ± 10.2 years) and 14 healthy volunteers (mean age 29.9 ± 9.7 years) participated in the experiment. A new arrangement of imaging photoplethysmography recently developed by us was used here to discover novel sensitive parameters of dermal blood flow during capsaicin applications in migraine patients.

Results

Blood pulsation amplitude (BPA) observed as optical-intensity waveform varying synchronously with heartbeat was used for detailed exploration of microcirculatory perfusion induced by capsicum patch application. The BPA signals, once having appeared after certain latent period, were progressively rising until being saturated. Capsaicin-induced high BPA areas were distributed unevenly under the patch, forming “hot spots.” Interestingly the hot spots were much more variable in migraine patients than in the control group. In contrast to BPA, a slow component of waveforms related to the skin redness changed significantly less than BPA highlighting the latter parameter as the potential sensitive biomarker of capsaicin-induced activation of the blood flow. Thus, in migraine patients, there is a non-uniform (both in space and in time) reaction to capsaicin, resulting in highly variable openings of skin capillaries.

Conclusion

BPA dynamics measured by imaging photoplethysmography could serve as a novel sensitive non-invasive biomarker of migraine-associated changes in microcirculation.

Effects of Human Adipose-Derived Stem Cells on the Survival of Rabbit Ear Composite Grafts

Background

Composite grafts are frequently used for facial reconstruction. However, the unpredictability of the results and difficulties with large defects are disadvantages. Adipose-derived stem cells (ADSCs) express several cytokines, and increase the survival of random flaps and fat grafts owing to their angiogenic potential.

Methods

This study investigated composite graft survival after ADSC injection. Circular chondrocutaneous composite tissues, 2 cm in diameter, from 15 New Zealand white rabbits were used. Thirty ears were randomly divided into 3 groups. In the experimental groups (1 and 2), ADSCs were subcutaneously injected 7 days and immediately before the operation, respectively. Similarly, phosphate-buffered saline was injected in the control group just before surgery in the same manner as in group 2. In all groups, chondrocutaneous composite tissue was elevated, rotated 90 degrees, and repaired in its original position. Skin flow was assessed using laser Doppler 1, 3, 6, 9, and 12 days after surgery. At 1 and 12 days after surgery, the viable area was assessed using digital photography; the rabbits were euthanized, and immunohistochemical staining for CD31 was performed to assess neovascularization.

Results

The survival of composite grafts increased significantly with the injection of ADSCs (P<0.05). ADSC injection significantly improved neovascularization based on anti-CD31 immunohistochemical analysis and vascular endothelial growth factor expression (P<0.05) in both group 1 and group 2 compared to the control group. No statistically significant differences in graft survival, anti-CD31 neovascularization, or microcirculation were found between groups 1 and 2.

Conclusions

Treatment with ADSCs improved the composite graft survival, as confirmed by the survival area and histological evaluation. The differences according to the injection timing were not significant.

[Icrocirculatory changes I bulbar conjunctiva in various diseases]

The article presents a literature review of the latest achievements in visualizing microcirculation and studying anatomical and physiological characteristics of microcirculation in the bulbar conjunctiva in various diseases.

Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa

Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations.

Donor site healing dynamics: molecular, histological, and noninvasive imaging assessment in a porcine model

Understanding the physiology of donor site healing will lead to advances in how these wounds are treated and may ultimately allow faster healing, more frequent autografting, and more effective care of the burn-injured patient. Unfortunately, a paucity of data exists regarding perfusion metrics over the course of donor site healing. Furthermore, there are no studies that interrelate indices of perfusion with the molecular and cellular processes of donor site healing. Male Duroc pigs were anesthetized and donor site wounds were created using a Zimmer dermatome at a depth of 0.060 inch (1.52 mm). Digital photographs, laser Doppler images, and punch biopsies were obtained before and after excision and on days 2, 4, 7, 9, 11, 14, and 16 until wounds were healed. RNA isolation was performed and quantitative polymerase chain reaction was used to examine differential gene expression over the time course. Formalin-fixed biopsies were embedded in paraffin, sectioned, stained, and examined. Wound surfaces were 83% re-epithelialized by day 16. Perfusion peaked on day 2 then declined, but it remained significantly elevated compared to before excision (P < .05). From day 9 onward, mean perfusion units were not significantly different from baseline (P < .05). Twenty-two representative genes were selected for examination. RNA expression of collagen, tenascin-cytoactin, inflammatory cytokines, remodeling enzymes, growth factors, and Wnt was increased. Inflammatory cells and cytokines were demonstrated histologically. Nuclei per high powered field peaked at day 7 and neodermal thickness increased daily to day 14. A novel porcine model for donor site wound healing that interrelates re-epithelilaizationand perfusion with molecular and cellular indices has been demonstrated.

The correlation between preputial blood flow and microvessel density in distal hypospadias: a prospective clinical study

OBJECTIVE

A prospective clinical study was designed to investigate the correlation between preputial blood flow (BF) and microvessel density (MVD).

PATIENTS AND METHODS

A total of 44 children were included in the study. The hypospadias group consisted of 16 children undergoing distal hypospadias repair, and the control group consisted of 28 age-matched healthy children undergoing circumcision. BFs were measured using a laser Doppler flowmeter on the most distal part of the dorsal prepuces, and then the tissue samples were harvested from the same location. They were immunostained with an antibody against CD31 in order to assay MVD. The statistical analyses were carried out using Student's t test and Pearson's correlation analysis.

RESULTS

The preputial MVD was found to be significantly decreased in the patients with hypospadias compared with the healthy children (33.95 ± 9.79 vs. 48.25 ± 10.08; p < 0.05), whereas there was no difference in terms of the BF (40.58 ± 16.16 vs. 33.09 ± 19.65; p > 0.05).

CONCLUSIONS

We found no correlation between the preputial MVD and BF in the present study. This result suggests that reduced preputial MVD does not have any influence on BF in distal hypospadias.

Assessment of speed distribution of red blood cells in the microvascular network in healthy volunteers and type 1 diabetes using laser Doppler spectra decomposition

We applied a recently reported method of decomposition of laser Doppler power density spectra for in vivo monitoring of speed distributions of red blood cells (RBCs) in the microvascular network. The spectrum decomposition technique allows us to derive the distribution of RBC speed (in absolute units (mm s(-1))) versus RBC concentration (in arbitrary units). We carried out postocclusive reactive hyperaemia (PORH) test in 15 healthy volunteers and 21 diabetic patients in which the duration of type 1 diabetes was longer than 10 years. Measurements were carried out simultaneously with the use of a typical laser Doppler commercial instrument and speed resolved laser Doppler instrument utilizing the new technique based on decomposition of the laser Doppler spectra. We show that for the classical laser Doppler instrument, none of the PORH parameters revealed a statistical significance of difference between the groups analyzed. In contrast, the RBC speed distributions obtained from laser Doppler spectra during rest in the control group and type 1 diabetes are statistically significant. This result suggests that speed distribution measurements in the rest state (without any kind of stimulation test) allows for the assessment of microcirculation disorders. Measurements carried out in healthy subjects show that the first moment of speed distributions (mean speed of the distributions) is 2.32 ± 0.54 mm s(-1) and 2.57 ± 0.41 mm s(-1) for optodes located on the toe and finger of the hand, respectively. Respective values in type 1 diabetes were higher: 3.00 ± 0.36 mm s(-1) and 3.10 ± 0.48 mm s(-1).

Intraoperative prediction of postoperative flap outcome using the near-infrared fluorophore methylene blue

Methylene blue (MB) is a near-infrared fluorophore that provides a stable visual map of skin perfusion after intravenous injection. We explored the capability of MB to predict submental flap postoperative outcome using a single intraoperative measurement. Submental flaps were created in N = 15 pigs and imaged using the FLARE imaging system immediately after surgery and at 72 hours. Using the first 3 pigs, optimal MB dosing was found to be 2.0 mg/kg. Training and validation sets of 6 pigs each were then used for receiver operating characteristic analysis. In the training set, a contrast-to-background ratio (CBR) threshold of 1.24 provided the highest sensitivity and specificity to predict tissue necrosis at 72 hours. In the validation set, this threshold provided a prediction sensitivity of 95.3% and a specificity of 98.0%. We demonstrate that a single intraoperative near-infrared measurement can predict submental flap outcome at 72 hours.

Microcirculation on a large scale: techniques, tactics and relevance of studying the microcirculation in larger population samples

The role of microcirculatory dysfunction is increasingly being recognized in the etiopathogenesis of cardiovascular disease. Whilst the importance of detailed mechanistic studies to determine the exact nature of these disturbances is without question, it was large-scale population-based studies that first identified the associations between deranged microvascular perfusion, autoregulation or structure, and subsequent target organ damage. This is the subject of considerable studies to establish whether there is a causal effect in either direction, or simply represents shared risk factors, although it is most likely to be a complex combination of bidirectional interactions. The techniques for investigating microcirculatory function have evolved almost exponentially over the last 75 years: So too have the strategies for investigation. Current epidemiological studies are focusing on attempting to untangle the inter-relationship between risk factors and pathological mechanisms to attempt to determine whether these represent therapeutic targets or simple markers of unmeasured risk. We plan to review the techniques used for these population-based studies, the advances made, and the clinical implications derived.

In vivo assessment of peripheral vascular function by tcpO₂ and skin blood flow modelling

There are multiple techniques and methods to assess peripheral vascular function in vivo but not without limitations. More discriminative, sensitive and also practical evaluation strategies are needed to fully characterize the peripheral vascular function. In the present work, a new quantitative descriptor, the 'elimination half-life time' was developed from flow-related variables as a non-invasive microcirculatory rate parameter to describe vascular dynamics. Fifty-four healthy volunteers and six type 2 diabetic patients, both genders, were submitted to a dynamical procedure consisting in the inhalation of a 100% saturated atmosphere of oxygen for 10 min. The tcpO(2) and microcirculatory blood flow [Laser Doppler Flowmetry (LDF)] were measured in a randomly selected leg with a Periflux 5000 system before, during and after the procedure. A monocompartmental model was adjusted to tcpO(2) and LDF data. The tcpO(2) constant elimination rate, expressed as the Oxygen elimination half-life, was used as an indicator of the vulnerability of peripheral tissue and compared in healthy versus non-healthy individuals. Under normal conditions, the saturated ventilation increases the tissue's O(2) availability, as an expression of the natural capacity to adjust the tissue hemodynamics to new metabolical/perfusion conditions. Diabetic patients are expected to suffer vascular impairment and ischemia. Under O(2) overloading conditions, those hypoxic territories tend to uptake all the delivered oxygen, expressed as a significant increase in the O(2) elimination half-life. This approach allows to propose 'elimination half-life time' as the first quantitative descriptive parameter combining miogenic, hemodynamic and metabolic aspects of the microcirculatory physiology and to help to identify the individual's vascular vulnerability.

Application of a new laser Doppler imaging system in planning and monitoring of surgical flaps

There is a demand for technologies able to assess the perfusion of surgical flaps quantitatively and reliably to avoid ischemic complications. The aim of this study is to test a new high-speed high-definition laser Doppler imaging (LDI) system (FluxEXPLORER, Microvascular Imaging, Lausanne, Switzerland) in terms of preoperative mapping of the vascular supply (perforator vessels) and postoperative flow monitoring. The FluxEXPLORER performs perfusion mapping of an area 9 x 9 cm with a resolution of 256 x 256 pixels within 6 s in high-definition imaging mode. The sensitivity and predictability to localize perforators is expressed by the coincidence of preoperatively assessed LDI high flow spots with intraoperatively verified perforators in nine patients. 18 free flaps are monitored before, during, and after total ischemia. 63% of all verified perforators correspond to a high flow spot, and 38% of all high flow spots correspond to a verified perforator (positive predictive value). All perfused flaps reveal a value of above 221 perfusion units (PUs), and all values obtained in the ischemic flaps are beneath 187 PU. In summary, we conclude that the present LDI system can serve as a reliable, fast, and easy-to-handle tool to detect ischemia in free flaps, whereas perforator vessels cannot be detected appropriately.

Epidermal wound healing in severe sepsis and septic shock in humans

Introduction

The effect of sepsis on epidermal wound healing has not been previously studied. It was hypothesised that epidermal wound healing is disturbed in severe sepsis.

Methods

Blister wounds were induced in 35 patients with severe sepsis and in 15 healthy controls. The healing of the wounds was followed up by measuring transepidermal water loss and blood flow in the wound, reflecting the restoration of the epidermal barrier function and inflammation, respectively. The first set of suction blisters (early wound) was made within 48 hours of the first sepsis-induced organ failure and the second set (late wound) four days after the first wound. In addition, measurements were made on the intact skin.

Results

The average age of the whole study population was 62 years (standard deviation [SD] 12). The mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score on admission was 25 (SD 8). The two most common causes of infections were peritonitis and pneumonia. Sixty-six percent of the patients developed multiple organ failure. The decrease in water evaporation from the wound during the first four days was lower in septic patients than in the control subjects (56 g/m² per hour versus 124 g/m² per hour, P = 0.004). On the fourth day, septic patients had significantly higher blood flow in the wound compared with the control subjects (septic patients 110 units versus control subjects 47 units, P = 0.001). No difference in transepidermal water loss from the intact skin was found between septic patients and controls. Septic patients had higher blood flow in the intact skin on the fourth and on the eighth day of study compared with the controls.

Conclusions

The restoration of the epidermal barrier function is delayed and wound blood flow is increased in patients with severe sepsis.

EMLA and Water Immersion Cause Similar Vasodilatation in Replanted Fingers

BACKGROUND

Skin wrinkling on water immersion is a reliable and simple test of sympathetic innervation. The eutectic mixture of local anesthetic (EMLA) cream has been shown to induce near identical clinical wrinkling scores and reduction in digit blood flow as that following water immersion in people with normal sympathetic innervation. This study was designed to investigate the vasomotor response to EMLA in replanted fingers that had poor sympathetic innervation.

METHODS

Laser Doppler imaging (PeriScan PIM II; Perimed AB, Stockholm, Sweden) was used to detect perfusion changes in the pulps of fourteen replanted fingers before and after 0.5 g of 5% EMLA cream application and water immersion in a 40 degrees C normal saline for 30 min, respectively. Comparisons were made with the contralateral corresponding normal fingers.

RESULTS

After water immersion and EMLA application, all of the normal fingers showed a considerable and similar decrease in blood perfusion that demonstrated in the absolute perfusion units (pU) (baseline: 1.57 +/- 0.33 pU, after water-immersion, 1.19 +/- 0.22 pU, P < 0.001; decrease: 23.6 +/- 7.7%, after EMLA application: 1.20 +/- 0.18 pU, P < 0.001; decrease: 22.4 +/- 8.9%). In contrast, all of the replanted fingers showed a statistically significant vasodilatatory response (baseline: 1.20 +/- 0.29 pU, after water-immersion: 1.36 +/- 0.28 pU, P < 0.001; increase: 15.2 +/- 9.1%, after EMLA application: 1.38 +/- 0.27 pU, P < 0.001; increase: 16.8 +/- 9.1%).

CONCLUSIONS

EMLA and water immersion both cause vasodilatation and no skin wrinkling in replanted fingers. These results imply that intact sympathetic nerve function is required to induce the vasoconstrictive effect of EMLA.

Comparison of gingival blood flow during healing of simplified papilla preservation and modified Widman flap surgery: a clinical trial using laser Doppler flowmetry

AIM

This prospective randomized-controlled clinical trial compared the gingival blood flow responses following simplified papilla preservation (test) versus modified Widman flap (control).

MATERIALS AND METHODS

Twenty contra-lateral upper sites with pocket depth > or = 5 mm after initial treatment in 10 chronic periodontitis patients were randomly assigned to either test or control treatment, using a split-mouth design. Laser Doppler flowmetry recordings were performed pre-operatively, following anaesthesia, immediately post-operatively and on days 1, 2, 3, 4, 7, 15, 30 and 60, at nine selected sites per flap.

RESULTS

Significant ischaemia was observed at all sites following anaesthesia and immediately post-operatively. At the mucosal flap basis, a peak hyperaemic response was observed on day 1, which tended to resolve by day 4 at the test sites, but persisted until day 7 at the control sites. The buccal and palatal papillae blood perfusion presented the maximum increase on day 7 in both groups and returned to baseline by day 15. Both surgical modalities yielded significant pocket depth reduction, recession increase and clinical attachment gain.

CONCLUSIONS

Periodontal access flaps represent an ischaemia-reperfusion flap model. The simplified papilla preservation flap may be associated with faster recovery of the gingival blood flow post-operatively compared with the modified Widman flap.

Continuous wavelet transform of laser-Doppler signals from facial microcirculation reveals vasomotion asymmetry

Facial laser Doppler flux (FLDF) consists of a mean value and complex oscillatory components called vasomotion. Vasomotion can be expressed as spectral amplitudes (SA) after the application of continuous wavelet transform. Vasomotion is influenced by cardiac activity (frequency interval I), respiration (interval II), intrinsic myogenic activity (interval III), neural mechanisms (interval IV) and endothelial mechanisms (intervals V and VI). Asymmetry of FLDF mean value was previously documented and hereby we present homogeneity assessment for FLDF vasomotion. Mean FLDF (p<0.001), total SA (p<0.001) and SA within frequency intervals I-VI were significantly higher in both cheeks compared to forehead. Total SA (p=0.009) and SA within frequency intervals I (p=0.041), II (p=0.005), III (p=0.009), IV (p=0.001) and V (p=0.036) were significantly higher in right than in left forehead. Human face is a heterogeneous microvascular region. Angiographic characteristics of deep horizontal sub-dermal plexus, endothelial and vascular smooth muscle cell heterogeneity, and plasticity of the microvasculature, autonomic asymmetry and facial neuropsychological asymmetry are possible causes of microvascular asymmetry. The origin and significance of microvascular imbalance need to be elucidated further.

Evaluation of barrier creams ? introduction and comparison of 3 in vivo methods

Often barrier creams (BC) do not fulfil their protecting behaviour, even when promised by the manufacturers. Therefore, it is of great importance to develop standardized in vivo techniques to prove the potency of BC in humans. In the present study, 3 promising techniques for the analysis of BC were evaluated: laser scanning microscopy, laser doppler flowmetry, and the tape-stripping procedure. Sodium fluorescein and glycerol trinitrate acted as hydrophilic model-penetrating substances. By means of these methods, 3 different BC were tested and compared for their potency. The investigations showed that primarily the tape-stripping procedure and also the laser scanning microscopy are promising tools for the evaluation of BC. In contrast, the laser doppler flowmetry represents a less feasible technique. In addition, the evaluation of BC showed that Vaseline enfolds a 100% barrier on the skin surface for the penetration of a hydrophilic dye, whereas BC1 only partially showed a protective effect and BC2 exhibited almost no potency. In conclusion, it can be referred that laser scanning microscopy and the tape-stripping procedure represent 2 non-invasive in vivo techniques, which enable a fast investigation concerning the potency of BC.

[Effect of cigarette smoking on skin perfusion of the hand]

BACKGROUND

Cigarette consumption leads to postoperative wound healing disturbances by impairing skin circulation.

MATERIALS AND METHODS

Fourteen nonsmokers and 44 smokers were investigated and classified according to age (<40 and >40 years) and duration of cigarette consumption. Circulation at the tip of the middle finger was measured in both groups under standard conditions with laser Doppler imaging.

RESULTS

There was a reduction in skin blood circulation of 24% in smokers (young 39%, older 11%, P=0.001) and 30% in nonsmokers (young 35%, older 18%, P=0.019). With longer duration of cigarette consumption, the effect grew weaker (<10 years 25%, 11-30 years 18%, >30 years 15%). There was no correlation between the number of cigarettes consumed per day and impaired circulation.

CONCLUSION

Younger subjects react to cigarette consumption with a stronger reduction in circulation. In elective surgery, especially in young smokers we recommend a 6- to 8-week nicotine abstinence prior to surgical intervention.

Microcirculation in DIEP flaps: a study of the haemodynamics using laser Doppler flowmetry and lightguide reflectance spectrophotometry

The deep inferior epigastric perforator (DIEP) flap is ideally suited for breast reconstruction. The DIEP flap reduces abdominal wall morbidity when compared to a transverse rectus abdominis (TRAM) flap, however, there maybe a compromise of the flap vascularity. Early venous problems and late fat necrosis in DIEP flaps can occur. There is a limited literature on the haemodynamic and microcirculation of the DIEP flap. Sixteen consecutive patients who underwent immediate breast reconstruction with DIEP flap were prospectively monitored during the post-operative time for a minimum period of 48h using laser Doppler flowmetry (LDF) and lightguide reflectance spectrophotometry (LRS) to analyse blood flow and oxygenated haemoglobin percentage in the cutaneous microcirculation of the flap. LDF demonstrated an increase of capillary flow in comparison to the pre-operative levels. LRS showed an initial decrease of the values and a varying pattern of increase in relation to time, to reach the pre-operative levels. A correlation between lower values of post-operative LDF and LRS measurements and late fat necrosis and early venous congestion was demonstrable in this series. This study demonstrates a change in the cutaneous microcirculation of the lower anterior abdominal wall following its elevation as a DIEP flap. These findings could explain the clinical phenomenon occurring in this flap in the early post-operative period. Significant correlation between longer harvesting time and re-exploration and between longer ischaemia time and localised fat necrosis was found.

Paradoxical response to water immersion in replanted fingers

When the fingers are immersed in water digital blood flow is reduced and the skin wrinkles, suggesting that vasoconstriction plays a role. However, is wrinkling due to sympathetic activation or some intrinsic property of the skin? To define the role of autonomic innervation in skin wrinkling we measured changes in blood perfusion (Laser Doppler Perfusion Imager) in 20 successfully replanted fingers (mean time after complete amputation 17.5 +/- 5.2 months). We compared responses in replanted fingers with those in corresponding contralateral normal fingers before and immediately after immersion in saline (0.5 mol/l NaCl at 40 degrees C). In the normal fingers, immersion caused a decrease in blood flow by 27.6 +/- 11.5% and skin wrinkling. However, in the replanted fingers blood flow increased by 22.8 +/- 19.6% and the skin did not wrinkle. The paradoxical cutaneous vasodilatation and absence of wrinkling in the denervated fingers suggests that sympathetic innervation is important in water-immersion skin wrinkling.

Evaluation of gingival blood flow by the use of laser Doppler flowmetry following periodontal surgery. A pilot study

OBJECTIVES

The aim of this pilot study was to evaluate the applicability of laser Doppler flowmetry (LDF) in recording the gingival blood flow following periodontal surgery.

MATERIAL AND METHODS

Five patients suffering from advanced chronic generalized periodontitis were included in the study. After completion of basic periodontal therapy, full-mouth plaque score, bleeding on probing, gingival recession and clinical attachment level were recorded. The upper anterior areas with a pocket probing depth of 6 mm or more were treated with an access flap. LDF recordings were performed in both the buccal and palatal aspect of the operated areas with the aid of an individual acrylic stent at the day of the surgery, prior to local anaesthesia, 3 min following anaesthesia, immediately after the operation and at days 1, 2, 3, 4, 7, 15, 30 and 60 following operation.

RESULTS

Overall, the blood flow decreased immediately following anaesthesia and remained in lower values compared to baseline immediately following operation. The gingival blood flow presented an overall increase in comparison to baseline values until the 7th day following surgery at the buccal and palatal interdental sites, as well as at the alveolar mucosa sites. By the 15th day, as well as at the following observation periods of 30 and 60 days, the gingival blood flow values at the palatal and alveolar mucosa sites were very similar to baseline. Increased blood flow changes were observed at 30 and 60 days following operation at the buccal interdental sites.

CONCLUSION

The results of the present pilot study suggest that the LDF might present clinical applicability in recording changes in gingival blood flow following periodontal surgery.

Quantifying labial blood flow using optical Doppler tomography

OBJECTIVES

Changes in the oral microvasculature occur in a variety of diseases. Optical Doppler tomography (ODT) combines laser Doppler flowmetry with optical coherence tomography (OCT) to produce high-resolution tomographic images of biological tissues that also detect the velocity and direction of blood flow. The objective of this study was to determine the feasibility of ODT to image labial blood flow. A prototype ODT imaging system was constructed that characterized and measured labial blood flow in healthy subjects.

MATERIALS AND METHODS

A prototype ODT instrument was constructed using a diode light source with a central wavelength of 1300 nanometers, a 40-nanometer spectral width and 2.4 microwatts output power. To verify the accuracy of the system, the flow rates of a phantom material (Intralipid) pumped through a capillary tube at various speeds was measured. To evaluate the clinical feasibility of the ODT prototye, the mucosal aspect of the upper and lower lips at the midline was imaged in 9 healthy volunteers. The sample arm of the instrument consisted of a fiberoptic probe with a 2-mm in diameter polished glass lens attached to the end. The probe was placed approximately 3 mm from the mucosal surface of the lip and oriented perpendicular to the surface. A motorized translation stage moved the fiber in a superior to inferior direction while the subject's head was stabilized by placing the chin into a chin rest. Imaging time for a 12-mm x 2.5-mm scan was approximately 64 seconds.

RESULTS

The phantom experiments revealed that accuracy of this novel ODT prototype to measure flow was within 5%. In vivo labial blood flow velocity ranged from 11.8 to 43.1 mm/second in the upper lip and 8.2 to 53.2 mm/second in the lower lip. There were no statistically significant differences between flow rates in the upper and lower lips. OCT images and Doppler velocity signals were successfully integrated producing in vivo images of labial blood in all of the subjects (15 images). The resulting cross-sectional images revealed microscopic details of labial structures and, to the best of our knowledge, are the first ODT images of the labial microvasculature.

CONCLUSIONS

The results of this in vivo study prove the feasibility of ODT to quantify labial blood flow and produce high spatial resolution images specifically localizing vessels anatomically. ODT provides both flow speed and flow direction information. ODT is noninvasive and offers the advantages of high volumetric flow sensitivity.