Use Of Laser Doppler Flowmetry Research Articles

Comorbid Condition Induced by Lichenoid Tuberculosis of the Skin and Lichen Planus. Significance of a Multidisciplinary Approach to Timely Diagnosis and Treatment

In Ukraine, all cases tuberculosis (TB) of the skin are classified as «extrapulmonary TB», which complicates the accurate determination of disease prevalence. Clinical cases of skin TB require a multi­disciplinary approach for diagnosis, particularly for differential diagnosis from chronic dermatoses with similar morphological skin lesions and for treatment. Objective — to conduct a differential diagnosis and determine the presence of comorbid pathology in a patient exhibiting clinical manifestations typical of both lichenoid tuberculosis of the skin and lichen planus. This involves utilising a suite of modern diagnostic procedures, including pathohistological analysis and Doppler laser flowmetry. Materials and methods. We observed a patient, B., born in 2005, who presented with skin lesions characteristic of both lichenoid TB of the skin and lichen planus. According to the patient's history, the duration of the disease was 4 years. Using laser Doppler flowmetry with a Vingmed SD-100 flowmeter (Medata, Sweden), we measured microcirculation and its standard deviation, coefficient of variation and maximum amplitude of slow, fast and pulse oscillations in the affected areas and visually unchanged skin (3—4 cm from the rash elements). Pathohistological examinations were also conducted in the areas of efflorescence. Results and discussion. Considering the clinical examination data, results of comprehensive laboratory and pathohistological research, and indicators of laser Doppler flowmetry in the areas of skin lesions, a comorbid condition caused by lichenoid TB of the skin and lichen planus was diagnosed. The patient was referred to a phthisiologist at his place of residence for comprehensive specific treatment with antitubercu­lar drugs. The patient was also recommended to undergo dermatological monitoring to assess the effectiveness of the pathogenetic therapy prescribed for lichen planus. Conclusions. The variety of clinical forms of skin TB and a number of chronic dermatoses, particularly lichen planus, as well as the similarity in the clinical picture of morphological elements of the skin rash in these diseases, necessitate a multidisciplinary approach and the execution of a complex of clinical, specialised laboratory, pathohistological and modern diagnostic instrumental studies. These enable timely differential diagnosis of skin lesions, including comorbid conditions, and the prescription of rational comprehensive therapy. The use of laser Doppler flowmetry to determine the state of dermal blood circulation in the affected skin areas is an important additional diagnostic test in the differential diagnosis of some chronic dermatoses or in determining a comorbid state.

Laser flowmetry of microcirculation of the finger depending on the external temperature and the limb position

Introduction. The use of laser Doppler flowmetry (LDF) makes it possible to assess the condition and disorders of blood microcirculation, improving the quality of diagnosis of various cardiovascular diseases. Additional functional tests with laser flowmetric measurements are used to assess the state of the mechanisms that regulate the tissue blood flow. Objective. To identify patterns of blood flow changes in the microcirculatory bed when combining a postural test and a change in air temperature. Materials and methods. The study was conducted on a group of 20 subjects, which included an equal number of girls and boys aged 21–23 years, who were considered healthy and did not have cardiovascular diseases. The experiment was carried out in two stages: first in a room with an air temperature of 201 °C, then at 301 °C. To assess the difference in data between arm positions within the same study phase at the same temperature, the Student’s t-test was used to compare quantitative variables in two dependent samples. The Wilcoxon test was used to assess statistical differences in data for the same hand position but at different air temperatures. Changes were considered statistically significant at p<0.05. The subjects were measured the microcirculation of peripheral blood vessels on the phalanx of the finger in three positions relative to the level of the heart using a portable laser Doppler flowmeter LAZMA PF (Russia). Results. It is shown that an increase in ambient temperature leads to an increase in the difference in microcirculation of peripheral vessels when the arm position changes relative to the level of the heart. When a person is in a room with a temperature of 301 °C, dilation of blood vessels and changes in their tone occur, which explains the increase in microcirculation values in relative perfusion units. Conclusions. The results of the study showed an increase in statistically significant differences according to the Student’s t-test between the different hand positions with increasing room temperature (p<0.0001). In a comparative sample between the first stage (at an air temperature of 20±1 °C) and the second stage of the study (at an air temperature of 30±1 °C), statistically significant results (p<0.001) were obtained according to the Wilcoxon test for the hand position at the heart level and the raised arm.

The use of laser doppler flowmetry to assess the microcirculation of the kidney before and after percutaneous nephrolithotomy

The use of laser doppler flowmetry to assess the microcirculation of the kidney before and after percutaneous nephrolithotomy

ОСОБЕННОСТИ КЛИНИКО-ЭКСПЕРТНОГО СОПРОВОЖДЕНИЯ АВИАЦИОННЫХ СПЕЦИАЛИСТОВ С ХРОНИЧЕСКИМИ ВИРУСНЫМИ ГЕПАТИТАМИ

Functional state of skin microcirculation vessels was studied in female subjects during 3-d dry immersion (DI). Microcirculation was investigated on the forehead, shin, forearm, fingers and toes with the use of laser Doppler flowmetry (LDF) and computer based video capillaroscopy. LDF showed that DI induced local changes in the level of perfusion, largely due to an increased myogenic control of the microvascular tone. Video capillaroscopy detected an upward trend in the number of functioning capillaries after DI; dimensions of the pericapillary zone remained unchanged.

ФУНКЦИОНАЛЬНОЕ СОСТОЯНИЕ МИКРОЦИРКУЛЯТОРНОГО РУСЛА КОЖИ ЗДОРОВЫХ ЖЕНЩИН В УСЛОВИЯХ «СУХОЙ» ИММЕРСИИ

Functional state of skin microcirculation vessels was studied in female subjects during 3-d dry immersion (DI). Microcirculation was investigated on the forehead, shin, forearm, fingers and toes with the use of laser Doppler flowmetry (LDF) and computer based video capillaroscopy. LDF showed that DI induced local changes in the level of perfusion, largely due to an increased myogenic control of the microvascular tone. Video capillaroscopy detected an upward trend in the number of functioning capillaries after DI; dimensions of the pericapillary zone remained unchanged.

Labral Reconstruction via Capsular Augmentation Maintains Perfusion to the Acetabular Labrum and Locally Transferred Autograft: An in Vivo Laser Doppler Flowmetry Analysis.

The purpose of the present study was to examine the effects of arthroscopic labral repair with capsular augmentation on blood flow in vivo with use of laser Doppler flowmetry (LDF) to measure microvascular perfusion of the labrum and autograft tissue. The present prospective case series included patients ≥18 years old who underwent arthroscopic acetabular labral repair with capsular augmentation; all procedures were performed by a single surgeon between 2018 and 2022. The LDF probe measured microvascular blood flow flux within 1 mm3 of the surrounding labral and capsular tissue of interest. Mean baseline measurements of flux were compared with readings immediately following capsular elevation and after completing labral augmentation. Blood flux changes were expressed as the percent change from the baseline measurements. The present study included 41 patients (24 men [58.5%] and 17 women [41.5%]) with a mean age (and standard deviation) of 31.3 ± 8.4 years, a mean BMI of 24.6 ± 3.4 kg/m2, a mean lateral center-edge of angle 35.3° ± 4.9°, a mean Tönnis angle of 5.8° ± 5.8°, and a mean arterial pressure of 93.7 ± 10.9 mm Hg. Following capsular elevation, the mean percent change in capsular blood flow flux was significantly different from baseline (-9.24% [95% confidence interval (CI), -18.1% to -0.04%]; p < 0.001). Following labral augmentation, the mean percent change in labral blood flow flux was significantly different from baseline both medially (-22.3% [95% CI, -32.7% to -11.9%]; p < 0.001) and laterally (-32.5% [95% CI, -41.5% to -23.6%]; p = 0.041). There was no significant difference between the changes in medial and lateral perfusion following repair (p = 0.136). Labral repair with capsular augmentation sustains a reduced blood flow to the native labrum and capsular tissue at the time of fixation. The biological importance of this reduction is unknown, but these findings may serve as a benchmark for other labral preservation techniques and support future correlations with clinical outcomes. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The study of microcirculation and tissue metabolism as early diagnostic criteria for the risk of diabetic foot development

To assess the state of the microvasculature, tissue metabolism and its reserve capabilities for the purpose of early intervention for the prevention of diabetic foot syndrome. Thirty patients were examined. The patients were divided into three groups depending on the hypoglycemic therapy (metformin, empagliflozin, dapagliflozin). The comparison group consisted of 12 volunteers who did not have carbohydrate metabolism disorders. It was found: the HbA1c indicator significantly decreased in all three groups; significant dynamics in the state of the microvasculature was not observed in any of the three groups; in all groups, there was an improvement in tissue metabolism, however, in this case, no significant dynamics were observed in any of the 3 groups, which indicates the need for provocative tests. For this purpose, the authors recommend the method of combined use of laser Doppler flowmetry and laser fluorescence spectroscopy. This technique allows diagnosing the state of the microvasculature and tissue metabolism and its reserve capabilities, using thermal and cold tests.

Prospects for the use of laser Doppler flowmetry to assess cutaneous blood microcirculation in diabetes mellitus

The аrticle considers the scientific and clinical aspects of laser Doppler flowmetry (LDF) in the diagnosis of the state of the microcirculatory bed in diabetes mellitus. LDF is a non-invasive quantitative method of microcirculation assessment; its capabilities include the analysis of microcirculatory rhythms and functional testing with different types of provocation tests, which provides a study of the state of regulatory mechanisms of microcirculation. The difficulties with studying the microcirculation are caused by the very small size of microvessels. The prevention and treatment of various microcirculatory disorders is one of the most important problems in medical practice. The findings of some studies suggest that microcirculatory disorders are not only a pathogenetic link in the development of complications, but are also observed in patients with early disorders of carbohydrate metabolism and may precede the manifestation of diabetes mellitus. The use of LDF in scientific researches will make it possible to reveal changes in microcirculatory bed functioning that are characteristic of diabetes mellitus. The possibility of non-invasive quantitative assessment of the state of microcirculatory blood flow in real time and the relative ease of use explains the high popularity of LDF in scientific researches and makes this method promising for use in clinical practice. This method can be of important diagnostic value for the study of the state of different levels of regulation of the microcirculatory tract and dynamic monitoring of the effectiveness of the prescribed treatment. Combined use of LDF to identify the risk of developing diabetic foot syndrome will allow to personify the treatment of diabetes. Among the most promising points of application should be noted the study of microcirculation in the early diagnosis of diabetes and its complications, clarifying the risk of complications, monitoring the effectiveness of treatment. The development of optimal evaluation methods of microcirculation is a prospect for further research.

Laser doppler flowmetry as the advanced non-invasive method of evaluation оf microcirculation status in patients with diabetes mellitus

Currently, the problem of diabetes mellitus (DM) is one of the most important medical and social challenges worldwide. This is primarily due to the widespread prevalence of the disease and tendency to further increase in the incidence of diabetes mellitus.Systemic microcirculatory disorders play an impor­tant role in the pathogenesis of DM complications. They lead to the development of microangiopathy and neuropathy through the primary lesion of vessels involved in the blood supply of the peripheral parts of the nervous system. Currently, less than one-third of physicians recognize signs of peripheral neuropathy associated with diabetes. Untimely diagnosis contributes significantly to high morbidity, disability, and mortality.The authorinvestigates the experience of the use of laser Doppler flowmetry (LDF) in clinical practice as a method of studying the state of the microcirculatory bed in patients with diabetes mellitus.LDF is a non-invasive quantitative method of microcirculation assessment; its capabilities include the analysis of microcirculatory rhythms and functional testing with different types of provocative effects, which provides with investigating the state of regulatory mechanisms of microcirculation. The prevention and treatment of various microcirculatory disorders is one of the most important problems of medical practice. The difficulties of studying the microcirculation are caused by the very small size of microvessels and strong ramification of intra-organic vascular networks. The use of LDF in scientific research will make it possible toreveal the DM-specific changes in microcir­culatory bed functioning. The findings of some studies suggest that microcirculatory disorders are not only a pathogenetic link in the development of complications, but they are also observed in patients with early disorders of carbohydrate metabolism and may precede the manifestation of diabetes. However, the method has not yet become widespread in clinical practice.

Combined assessment of intestinal viability using laser doppler flowmetry and laser fluorescence spectroscopy

Introduction. The development of an objective non-invasive method for intraoperative assessment of intestinal viability remains urgent for modern surgery. In this context, the method of laser fluorescence spectroscopy (LFS) of coenzymes of oxidative metabolism, as well as a combination of this technique with the simultaneous use of laser Doppler flowmetry (LDF) seems promising. Materials and methods. The model of ischemia-reperfusion of the small intestine of 4 Californian Rabbits was used to study the relationship of the parameters of LFS and LDF with the histological picture. A model of intraoperative ischemia was used by temporarily clamping the trunk of the cranial mesenteric vascular bundle for 90 min, followed by intraoperative and postoperative reperfusion for 60 minutes and 24 hours, respectively. LDF and LFS data were recorded from intestine at the end of the intraoperative reperfusion period. 24 hours after the surgery, the animals were subjected to histologic evaluation of intestine ischemic changes, which were compared with the LDF and LFS data. Diagnostic value of LDF and LFS, and their combination for intraoperative assessment of intestinal viability were analyzed. Results. A significant correlation was found between the parameters of LDF, LFS and the degree of ischemic changes according to the histological data. The method of isolated assessment of the difference in the fluorescence of reduced nicotin adenine dinucleotide (NADH) before and after ischemia-reperfusion (77.3 %) has the greatest diagnostic value. The method has the highest sensitivity with a combination of differences in LDF and LFS values before and after ischemia-reperfusion (85.7 %) (P&lt;0.05). Conclusions. LFS, as well as its combination with LDF, is a useful method for objective assessment of intestinal viability, which requires further research and has potential for clinical use.

P158 Performance of laser-derived imaging for assessing digital perfusion in clinical trials of systemic-related digital vasculopathy: a systematic literature review

Abstract Background/Aims Raynaud’s phenomenon (RP) and digital ulcers (DU) are important features of digital vasculopathy in systemic sclerosis (SSc). Laser Doppler flowmetry (LDF), laser Doppler imaging (LDI) and laser speckle contrast imaging (LSCI) can non-invasively quantify digital perfusion and may be useful outcome measures for clinical trials in SSc-RP and/or SSc-DU. We undertook a systematic literature review to evaluate the performance of laser-derived imaging as outcome measures in clinical trials of SSc-related digital vasculopathy. Methods Standardised searches (EMBASE and MEDLINE) identified trials that incorporated laser-derived imaging of digital vasculopathy in adult patients with SSc. Data were extracted by &amp;gt; 2 reviewers on study design, laser endpoints, and reported outcomes. Study quality was assessed using Cochrane risk of bias tools for randomized trials and the risk-of-bias assessment tool for non-randomized studies (RoBANS) (PROSPERO 2019:CRD42019142409). An additional search was undertaken following external peer review to examine the impact of extending the search terms. Results Of 126 identified articles, full data extraction was undertaken from 29 studies. Fifteen randomized and fourteen non-randomized trials (total of 689 patients with SSc with mean 23.8/study) have evaluated a broad range of oral, intravenous and topical interventions for SSc-RP (n = 11), digital perfusion alone (n = 15) and SSc-DU (n = 3). The extended search identified an additional two manuscripts reporting the use of LDF to measure perfusion of a single digit in SSc. One was a randomised trial (of 25 patients) and the second an open label study (of 13 patients). These additions did not alter the principal findings of the main review. Combining the two searches, the 31 studies were published between 1987-2019 (17/31 since 2010) and incorporated LDF (13/31), LDI (15/31) and LSCI (4/31, including one with LDF); with LSCI and LDI more commonly incorporated in recent trials (13/18 since 2010). Most studies (17/31, 55%) reported improvement in digital perfusion following intervention, often concordant with patient- and clinician-derived outcomes. Study quality has improved over time, with 7/11 studies published between 2015-2019 having low risk of bias across all study quality domains. Conclusion Establishing laser-derived methods as an objective, non-invasive assessment of SSc-related digital vasculopathy will greatly support drug development. Full-field perfusion of the digits (with/without provocation testing) is a promising clinical trial outcome measure for trials of SSc-related digital vasculopathy. Disclosure N. Hackett: None. A. Guida: None. J.D. Pauling: Consultancies; Boehringher-Ingelheim, Sojournix Pharma and Actelion pharmaceuticals. Honoraria; Actelion pharmaceuticals. Grants/research support; Actelion pharmaceuticals. P.A. Merkel: Consultancies; AbbVie, AstraZeneca, Biogen, Boeringher-Ingelheim, Bristol-Myers Squibb, Celgene, ChemoCentryx, CSL Behring, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Insmed, Jannsen, Kiniksa, Pfizer, Sparrow, and Talaris. Grants/research support; AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, Celgene, ChemoCentryx, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Kypha.

A Novel Sensing Method to Detect Tissue Boundaries During Robotic Needle Insertion Based on Laser Doppler Flowmetry

This study investigates the use of Laser Doppler Flowmetry (LDF) as a method to detect tissue transitions during robotic needle insertions. Insertions were performed in gelatin tissue phantoms with different optical and mechanical properties and into ex-vivo sheep brain. The effect of changing the optical properties of gelatin tissue phantoms was first investigated and it was shown that using gelatin concentration to modify the stiffness of samples was suitable. Needle insertion experiments were conducted into both one-layer and two-layer gelatin phantoms. In both cases, three stages could be observed in the perfusion values: tissue loading, rupture and tissue cutting. These were correlated to force values measured from the tip of the needle during insertion. The insertions into ex-vivo sheep brain also clearly showed the time of rupture in both force and perfusion values, demonstrating that tissue puncture can be detected using an LDF sensor at the tip of a needle.

Novel methods to monitor and support the cutaneous microcirculation in burn wounds: A review

Background . The cutaneous microcirculation refers to the dermal ultrastructure and the microvascular physiology of the skin, in both healthy and injured states. In the specialty of burn surgery, this concept is particularly relevant owing to its strong association with wound healing. In the clinical context, our ability to assess the cutaneous microcirculation is an area of increasing research. The ability to support and optimise the cutaneous microcirculation in burn wounds is an area in which we lack experience, both clinically and academically. Objective. To collate information on methods of monitoring and supporting the cutaneous microcirculation in burn wounds. Methods . We conducted a systematic review to find new techniques used around the world to ( i ) assess the cutaneous microcirculation; and ( ii ) optimise the cutaneous microcirculation in burn wounds to improve patient outcomes. We used online and paper-based scientific databases for our search. The goal of the review was to find the techniques that showed the greatest potential in their clinical applicability to burn surgery. Results. A range of new techniques is being widely used to assess the cutaneous microcirculation. Most prominently, the use of laser Doppler flowmetry and in vivo reflectance confocal microscopy show the most promising results and the largest pool of data about their use. Both these methods are non-invasive and provide real-time in vivo information. However, the clinical applicability of these methods remains limited, and requires further research. A number of pilot studies have also been conducted using novel methods to optimise the cutaneous microcirculation in animals. These include the use of agents such as prostaglandins, doxycycline and extracorporeal shockwaves to stimulate or inhibit pathways involved in the cutaneous microcirculation. Conclusion. Although there is a growing body of research into the assessment and optimisation of the cutaneous microcirculation in burn wounds, its clinical applicability still requires further investigation. The future is promising if further in vivo studies on animals and humans are conducted

Multimodal Optical Diagnostics of the Microhaemodynamics in Upper and Lower Limbs

The introduction of optical non-invasive diagnostic methods into clinical practice can substantially advance in the detection of early microcirculatory disorders in patients with different diseases. This paper is devoted to the development and application of the optical non-invasive diagnostic approach for the detection and evaluation of the severity of microcirculatory and metabolic disorders in rheumatic diseases and diabetes mellitus. The proposed methods include the joint use of laser Doppler flowmetry, absorption spectroscopy and fluorescence spectroscopy in combination with functional tests. This technique showed the high diagnostic importance for the detection of disturbances in peripheral microhaemodynamics. These methods have been successfully tested as additional diagnostic techniques in the field of rheumatology and endocrinology. The sensitivity and specificity of the proposed diagnostic procedures have been evaluated.

COMPREHENSIVE TREATMENT OF PATIENTS WITH COMMUNITY-ACQUIRED PNEUMONIA

The objective of the study: to use of laser Doppler flowmetry for the diagnosis of microcirculatory blood flow disorders in patients with community-acquired pneumonia and determine the possibility of nitric oxide in its regulation. Subjects and methods. 146 patients with community-acquired pneumonia aged from 21 to 72 years were examined and comprehensively treated. Group 1 included 49 patients who along with standard chemotherapy had therapeutic bronchoscopy and intrabronchial regional lymphatic administration of antibiotics; Group 2 included 82 patients who received complex treatment - standard antimicrobial therapy, therapeutic bronchoscopy, intrabronchial lympharegional administration of antibiotics, and additional NO-therapy; Group 3 consisted of 15 patients in whom only standard antimicrobial therapy and therapeutic bronchoscopy were used. 15 patients from each group had endobronchial laser Doppler flowmetry; LAKK-0, the laser analyzer of capillary blood flow was used for this purpose. The microhemocirculation index (MI) was recorded, then its mean-square deviation (MSD) and variation coefficient were calculated. Blood flow fluctuations were determined and the microcirculation efficiency index (MEI) was calculated. Results. All tested microcirculation parameters in patients with pneumonia were lower compared with healthy individuals. It was found out that on the 7th day from treatment start only in patients from Group 2, who received NO-therapy within comprehensive treatment, there was a significant increase in PM to 57.4 ± 1.6 pf. units, MSD - up to 8.4 ± 1.2 pf. units, MEI was 0.9 ± 0.02 s.u. By the 14th day of treatment in Group 2, microhemocirculation indices returned to normal, while in other groups there was only a positive trend. This was reflected in the time required of treatment of pneumonia, the best results (14 days on average) were in the group using NO-therapy as a part of comprehensive treatment.

Clinical and experimental studies of tissues in thermal injuries

The article is devoted to studies used in the clinic and in the experiment in the study of tissue damage caused by exposure to high temperature. Determining the area and depth of tissue damage during thermal injury is of fundamental importance not only for treatment, but also for prognosis. The use of laser Doppler flowmetry, magnetic resonance imaging, pH-metry, contactless infrared thermometry of burn wounds, the method of assessing tissue viability based on the study of dielectric parameters allows to evaluate the viability and the state of damaged tissues in dynamics. The importance of tissue research methods for establishing an accurate diagnosis, assessing the readiness of wounds for autodermoplasty and determining the extent of surgical interventions is shown. The use of morphological methods in experimental studies and in the treatment of victims with burns is substantiated. Using histological and cytological methods, the condition of the burn wound is monitored, the efficacy of surgical interventions and the use of therapeutic agents is evaluated, the wound process phase is determined, and medical tactics is planned. The histochemical method is used to study the composition and state of the tissues of a burn wound paranecrosis area, and the immunohistochemical method is used to assess the intensity of regeneration processes by determining the tissue proliferation and differentiation markers. Ultramicroscopic examination of tissues at different times after thermal injury is informative for understanding the dynamics of pathomorphological changes in burns. Review of the pathogenesis of burn disease, taking into account the data of ultramicroscopic studies, creates the prospect of developing methods for targeted correction of the condition of patients with burns at the subcellular level. The role of experimental studies in the investigation of thermal damage, preclinical trials of medicinal products used to influence the wound process, improving the existing methods and developing the new ones for treatment of burn injury has been determined.

The diagnostic accuracy of laser Doppler flowmetry in assessing pulp blood flow in permanent teeth: A systematic review.

Pulp necrosis is a frequent complication following dental trauma. The diagnosis of the state of the dental pulp can be challenging as most commonly used diagnostic tools are subjective and rely on a response from the patient, potentially making their use unreliable, especially in the child population. The aim of the study was to systematically review the evidence on the use of laser Doppler flowmetry in the assessment of the pulp status of permanent teeth compared to other sensibility and/or vitality tests. A systematic literature search, using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, www.clinicaltrials.gov and www.controlled-trials.com, in addition to citation and manual reference list searches, was conducted up to 15th January 2018. A risk of bias assessment was performed using the quality assessment for diagnostic accuracy studies tool (QUADAS-2) with all steps performed independently by two reviewers. Four studies with a high risk of bias were included in the final analysis. Laser Doppler flowmetry was reported to be more accurate in differentiating between teeth with normal pulps and pulp necrosis with a sensitivity of (81.8%-100%) and specificity of 100% in comparison to other vitality tests such as pulp oximetry (sensitivity=81.3%, specificity=94.9%) and sensibility tests such as electric pulp testing (sensitivity=63.3%-91.5%, specificity=88%-100%). Despite the higher reported sensitivity and specificity of laser Doppler flowmetry in assessing pulp blood flow, these data are based on studies with a high level of bias and serious shortfalls in study designs. More research is needed to study the effect of different laser Doppler flowmetry's parameters on its diagnostic accuracy and the true cut-off ratios over which a tooth could be diagnosed as having a normal pulp.

Diurnal variations and pulpal status: is there a need for FFT besides LDF?

The aim of this article was to investigate the use of laser Doppler flowmetry (LDF) combined with a fast Fourier transformation (FFT). LDF data in relation to three different scenarios were evaluated: (a) LDF records of a right central upper incisor of one patient were used for FFT analysis. These records were obtained by means of 30 pre-manufactured splints, handled by dentists without any experience in LDF recording. (b) Diurnal variations in one patient were analysed with LDF and FFT using 11 splints by one and same experienced investigator at four specific moments of the day. (c) Pulpal status was analysed using 17 splints. Eleven for a patient, standing as case model and six splints for six other patients. In this specific group, each patient had one vital and one non-vital central maxillary incisor and was analysed separately by LDF and FFT. The data of assessment (b) showed diurnal variations on LDF values of almost 80%, indicating that LDF registration is best performed in the same time period of the day. Data verification with FFT confirmed the findings without FFT of assessment (a) and (b). In assessment, (c) FFT demonstrated a clear distinction between a vital and a non-vital pulp for those cases with one vital tooth and one root canal treated tooth. In those cases with one vital incisor and the other traumatised, FFT was undeterminated. Considered that FFT was obtained after LDF recording and remained undeterminated for a decision in cases with decreasing pulpal blood flow in time, the added value of FFT in pulpal traumatology was minimal.

Effect of laser Doppler flowmetry and occlusion time on outcome variability and mortality in rat middle cerebral artery occlusion: inconclusive results

BackgroundStroke is among the leading causes of death and disability. Although intense research efforts have provided promising treatment options in animals, most clinical trials in humans have failed and the therapeutic options are few. Several factors have been suggested to explain this translational difficulty, particularly concerning methodology and study design. Consistent infarcts and low mortality might be desirable in some, but not all, studies. Here, we aimed to investigate whether the use of laser Doppler flowmetry (LDF) and the occlusion time (60 vs. 45 min) affected outcome variability and mortality in a rat stroke model. Eighty ovariectomized female Wistar rats were subjected to ischemic stroke using intraluminal filament middle cerebral artery occlusion with or without LDF and with occlusion times of 45 or 60 min. Outcome was evaluated by triphenyl tetrazolium chloride staining of brain slices to measure infarct size and a modified sticky tape test.ResultsNeither LDF nor occlusion times of 45 versus 60 min significantly affected mortality, outcome variability or outcome severity.ConclusionsDue to the unexpectedly high mortality and variability the statistical power was very low and thus the results were inconclusive.

Application of wavelet analysis to detect dysfunction in cerebral blood flow autoregulation during experimental hyperhomocysteinaemia.

The purpose of the present study was to investigate the use of laser Doppler flowmetry (LDF) signals coupled with spectral wavelet analysis to detect endothelial link dysfunction in the autoregulation of cerebral blood flow in the setting of hyperhomocysteinaemia (HHcy). Fifty-one rats were assigned to three groups (intact, control, and HHcy) according to the results of biochemical assays of homocysteine level in blood plasma. LDF signals on the rat brain were recorded by LAKK-02 device to measure the microcirculatory blood flow. The laser operating wavelength and output power density were1064nm and 0.051W/mm2, respectively. A Morlet mother wavelet transform was applied to the measured 8-min LDF signals, and periodic oscillations with five frequency intervals were identified (0.01-0.04Hz, 0.04-0.15Hz, 0.15-0.4Hz, 0.4-2Hz, and 2-5Hz) corresponding to endothelial, neurogenic, myogenic, respiratory, and cardiac origins, respectively. In initial state, the amplitude of the oscillations decreased by 38% (P < 0.05) in the endothelial range in HHcy rats than in control rats. Cerebral autoregulation was challenged by hemorrhagic hypotension. The lower limit of autoregulation raised in a rat model of chronic HHcy (71.5 ± 0.7mmHg in HHcy vs. 62.3 ± 0.5mmHg in control). The data obtained indicate that the laser Doppler method and wavelet analysis may be successfully applied to detect the dysfunction of the endothelial link in cerebral vessel tone and to reveal the pathological shift of lower limit of autoregulation.