The use of sensory-sympathetic coupling indices for diagnosing of sympathetically maintained pain with laser Doppler flowmetry

For the first time the objective diagnosis of sympathetically maintained pain was created with laser Doppler flowmetry (LDF), directed specially to discovery of skin sensory-sympathetic coupling at 49 patients with posttraumatic complex regional pain syndrome. Sensory-sympathetic coupling was diagnosed as combination of sympathetic vasomotor activity with the existence of sensory peptidergic blood flow oscillations in frequency range of 0.047-0.069 Hz in LDF wavelet-spectrum. The results of LDF diagnosis were compared with clinical evaluation of sympathetically maintained pain carried out after desympathization surgery (thoracoscopic clipping above and below the Th3 ganglion of sympathetic chain at 33 patients and perivascular sympathectomy at the level of brachial artery and veins at 16 patients). Sensitivity of preoperative LDF-diagnosis was 90.2%, specificity--87.5%, positive predictive value--97.3%, negative predictive value--63.6%, diagnostic effectiveness--89.8%.     

Significance of the follicular pathway for dermal substance penetration quantified by laser Doppler flowmetry

The understanding of transdermal substance penetration pathways remains an important field for the development of future topical drugs and cosmetics. Laser Doppler flowmetry is a well‐established method for evaluating cutaneous perfusion. In a study on 6 healthy male volunteers, we topically applied the vasoactive substance benzyl nicotinate on two test areas with open and obturated hair follicles and measured changes in the blood flow by Doppler flowmetry. Contrary to occluded follicles, the application onto the test area with open follicles led to a statistically significant perfusion increase within the first 5 minutes, emphasizing the importance of the follicular pathway for epidermal penetration.

     

Continual measurement of intramedullary blood perfusion with laser Doppler flowmetry in intact and ostectomized tibiae of rabbits

Blood flow is important for the healing of bone fractures. Until now, however, there have been no publications on the daily, continual measurement of intramedullary blood perfusion using laser Doppler flowmetry (LDF) in the conscious animal. In this study, a model for the daily, continual measurement of intramedullary blood perfusion by LDF and the temperature near the cortex both in intact and ostectomized tibiae in the conscious rabbit is described. The probes for blood perfusion and temperature measurement were implanted permanently at three different localizations into the right tibia of 10 adult New Zealand White rabbits. The probes were held in place by a bilateral, single-plane external fixator. In five of these animals, a midshaft tibial ostectomy was created in order to simulate a fracture. Intramedullary blood perfusion and temperature were measured daily over 49 days. While in intact tibiae no significant (P > 0.05) differences were found in blood perfusion readings taken at various time points, for mean values or for blood perfusion over time, in ostectomized tibiae the differences were significant: various time points (P = 0.0056), mean values (P = 0.0034) and blood perfusion over time (P = 0.0337). Blood perfusion readings at the centre probe were elevated compared with those at the proximal and distal probes. Thus, a revascularization in the ostectomy gap during the fracture healing was proven by means of the LDF. No influence of the blood perfusion on the temperature in the ostectomy area could be determined during healing of the ostectomy. The described model seems suitable for the continual measurement of intramedullary blood perfusion both in intact and ostectomized tibiae in the conscious rabbit.     

Heterogeneity of laser Doppler flowmetry in perfused muscle indicative of nutritive and nonnutritive flow

Laser Doppler flowmetry (LDF) signal responses have been compared with metabolic changes using both a surface macroprobe and randomly placed implantable microprobes in muscles of the constant-flow-perfused rat hindlimb. Changes in response to total flow and to vasoconstrictors that are known to increase (norepinephrine, NE) or decrease (serotonin, 5-HT) hindlimb oxygen uptake were assessed. The surface macroprobe (anterior end of biceps femoris) identified only one type of LDF response characterized by increased signal in response to NE and decreased signal in response to 5-HT. Implanted microprobes (tibialis, gastrocnemius, vastus, or bicep femoris) identified sites that gave three LDF responses of differing character. These responses were where the LDF signal increased with NE and decreased with 5-HT (56.7%), where the LDF signal decreased with NE and increased with 5-HT (16.5%), or where there was no net response to either vasoconstrictor (24.7%). The data are consistent with discrete regions of nutritive and nonnutritive flow in muscle where flow in each as controlled by vasoconstrictors relates directly to the metabolic behavior of the tissue.     

Multifractality in the peripheral cardiovascular system from pointwise holder exponents of laser Doppler flowmetry signals

We study the dynamics of skin laser Doppler flowmetry signals giving a peripheral view of the cardiovascular system. The analysis of Hölder exponents reveals that the experimental signals are weakly multifractal for young healthy subjects at rest. We implement the same analysis on data generated by a standard theoretical model of the cardiovascular system based on nonlinear coupled oscillators with linear couplings and fluctuations. We show that the theoretical model, although it captures basic features of the dynamics, is not complex enough to reflect the multifractal irregularities of microvascular mechanisms.In clinical and physiological investigations, the cardiovascular system dynamics can be considered from a central or from a peripheral point of view. Heart-beat interval sequences, reflecting a central view of the human cardiovascular system, have been analyzed and the results have shown that they display multifractal properties for healthy subjects (1). A peripheral view of the cardiovascular system dynamics is possible by studying microvascular blood flow signals given by the laser Doppler flowmetry technique (2). These signals have complex dynamics, with fractal structures and chaos (3,4). However, are these data, reflecting the underlying mechanisms acting at the microscopic level of the human physiology, as irregular as those giving a central view point of the system dynamics? Is a single fractal exponent sufficient to characterize them? Moreover, a set of nonlinear coupled oscillators has recently been proposed as a standard theoretical model of the cardiovascular system (5–8). Is the dynamics of the corresponding simulated data close to the one of real cardiovascular signals?Herein we report that skin laser Doppler flowmetry signals display multifractal properties on young healthy subjects at rest. By estimating Hölder exponents of signals recorded on the finger, we show that the dynamics of peripheral signals can be irregular, as central data are. We also conclude that the use of a standard theoretical model of the cardiovascular system, based on five nonlinear coupled oscillators with linear couplings and fluctuations, is not complex enough to model the multifractal properties of the cardiovascular system. To our knowledge, it is the first time that multifractality of experimental and simulated laser Doppler flowmetry signals is studied.The rapid changes in a time series are called singularities and a characterization of their strength is obtained with the Hölder exponents (9). When a broad range of exponents is found, signals are considered as multifractal. A narrow range implies monofractality. One of the most widely used monofractal signal models is the fractional Brownian motion. In opposition, multifractal signals are more complex and inhomogeneous. The multifractal formalism has been established to account for the statistical scaling properties of time series observed in various physical situations. A singularity spectrum D(h) of a signal is the function that gives, for a fixed h, the Hausdorff dimension of the set of points x where the Hölder exponent h(x) is equal to h. The Hölder exponent h(x₀) of a function f at the point x₀ is the highest h value so that f is Lipschitz at x₀. There exists a constant C and a polynomial P_n(x) of order n so that for all x in a neighborhood of x₀ we have (10,11)(1)The Hölder exponent measures the degree of irregularity of f at the point x₀.We analyze experimental skin laser Doppler flowmetry signals reflecting microvascular blood flow. The signals are recorded with a frequency sampling of 20 Hz on the finger of seven young healthy people between 20 and 35 years old (12). A laser Doppler flowmetry signal is shown in Fig. 1. For each recording, 15,601 pointwise Hölder exponents are taken into account. They are computed with a parametric generalized quadratic variation based estimation method (13). Open in a separate windowFIGURE 1Skin laser Doppler flowmetry signal recorded on a young healthy subject at rest.For the skin laser Doppler flowmetry signals, we find a minimum Hölder exponent of 0.56, a maximum of 0.71, a mean value of 0.63, and a standard deviation of 0.03 (average values over seven signals). The difference between the minimum and maximum Hölder exponents is therefore of 0.15. An example of Hölder exponent time series is shown in Fig. 2. To compare the results with known mono and multifractal data, we generate a fractional Brownian motion (monofractal signal) and a multifractional Brownian motion (multifractal signal) (14). For each data, 15,601 pointwise Hölder exponents are taken into account. Open in a separate windowFIGURE 2Hölder exponents for a skin laser Doppler flowmetry signal recorded on a young healthy subject at rest.

TABLE 1

Value for the minimum, maximum, range, mean, and standard deviation of the Hölder exponents computed for skin laser Doppler flowmetry (LDF) signals (average value computed over seven signals), for a monofractal signal (fBm), and for a multifractal signal (mBm)

The estimation of microcirculation state in cerebrovascular disorders by data of laser Doppler flowmetry and hemorheological parameters

The study was aimed to evaluate microvascular blood flow and theological blood properties in healthy volunteers (n = 27) and patients with cerebral accident (n = 30). To study cutaneous blood flow we used the multifunctional laser analyzer of blood microcirculation LAKK (LAZMA, Moscow) with spectrophotometric channel and wavelet analysis of blood flow oscillations. Viscosity of the whole blood, plasma, RBC aggregability and deformability were assessed. Results: microcirculation index was by 25% (p < 0.05) lower in patients compared to the control group. Computing amplitude-frequency range of blood flow oscillations revealed notable changes in the blood flow regulation mechanisms under cerebrovascular accident: the amplitudes of all active rhythms (endothelial, neurogenic and myogenic ones) were increased. In spite of such activization of regulatory mechanisms, aimed to keep essential blood supply to tissue, index of specific oxygen consumption by tissue was decreased by 21% (p < 0.05) under cerebrovascular disorders. Blood rheological properties in patients group were impaired compared to the healthy group: blood viscosity was increased because of elevated plasma viscosity, increased RBS aggreagation and decreased erythrocyte deformability. Thus, our results demonstrated the decrease of tissue perfusion, activization of vasodilating mechanisms, impaired blood rheology and the decrease of oxygen supply to tissue in patients with cerebrovascular accident. Statistical analysis revealed a number of significant correlations between the hemorheological parameters and passive rhythms of microcirculation in norm. In patients blood viscosity correlated to the amplitude of active regulatory rhythms (endothelial, neurogenic and myogenic oscillations). Close interralations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue.     

Comparison between ambulatory measurement of effective thermal conductivity and laser Doppler flowmetry method to assess skin microcirculatory activity

The main objective of this paper was to assess the performance of the ambulatory device μHematron to measure indirectly skin blood flow relative to the well-established Laser Doppler flowmetry method. The μHematron device is dedicated to the non-invasive measurement of effective thermal conductivity of living tissues, based on the thermal clearance method. Its major advantage is its ambulatory functionality, as available methods for evaluation of microcirculatory activity are non-ambulatory methods. An experiment was conducted on ten healthy women exposed for one hour in three different thermal environments (22 °C, 25 °C and 30 °C). Skin microcirculatory activity was analyzed after an acclimatization period of 30 minutes. The time between each exposure was at least one hour. Performances of the μHematron device were assessed and a comparative study with a laser Doppler perfusion monitor (LDPM) was performed. Good correlation coefficients between the two devices (r = 0.71 at T1 = 22 °C, r = 0.77 at T2 = 25 °C and r = 0.83 at T3 = 30 °C) were obtained while the LDPM signal was filtered by a low pass filter (0.1 Hz). These results showed that continuous monitoring of effective thermal conductivity was possible in neutral and warm ambiences. Then, the μHematron device could be considered as a complementary tool to Doppler techniques for the investigation of skin blood flow, when ambulatory conditions are required.     

Effects of permanent magnets on resting skin blood perfusion in healthy persons assessed by laser Doppler flowmetry and imaging

Effects on skin blood perfusion of permanent ceramic magnets [0.1 T (1000 G) surface field], individually (disk shaped, 4 cm diameter x 1 cm thick) or in the form of a 11 x 7 in pad ( approximately 28 x 17.8 cm) with an array of 16 rectangular magnets (4.5 x 2.2 cm), were investigated in 16 female volunteers (27.4 +/- 1.7 years, range 21-48 years) using three separate protocols. In protocol A, a disk magnet was placed on the palmar surface of the hand in contact with the thenar eminence (n = 5). In protocol B, the magnet was placed on the hand dorsum overlying the thenar eminence (n = 5). In protocol C, the entire palm and fingers rested on the magnetic pad (n = 6). Magnets were in place for 36 min on one hand, and a sham was in place on the other hand. Blood perfusion was measured on the middle finger dorsum by laser Doppler flowmetry (LDF) and on the index finger by laser Doppler imaging (LDI). Perfusion measurements were simultaneously taken in sham and magnet exposed hands, before and during the entire magnet exposure interval. Magnetic field effects were tested by comparing skin blood perfusion sequences in magnet and sham exposed regions. Results showed no significant changes in either LDF or LDI perfusion at magnet or sham sites during exposure, nor were there any significant differences between sham and magnet sites for any protocol. Measurements of skin temperature at the LDF measurement sites also showed no significant change. It is concluded that in the healthy subjects studied with normal, unstressed circulation, magnets of the type and for the duration used, showed no detectible effect on skin blood perfusion in the anatomical area studied.     

Dynamic evaluation of blood flow microcirculation by combined use of the laser Doppler flowmetry and high‐speed videocapillaroscopy methods

The dynamic light scattering methods are widely used in biomedical diagnostics involving evaluation of blood flow. However, there exist some difficulties in quantitative interpretation of backscattered light signals from the viewpoint of diagnostic information. This study considers the application of the high‐speed videocapillaroscopy (VCS) method that provides the direct measurement of the red blood cells (RBCs) velocity into a capillary. The VCS signal presents true oscillation nature of backscattered light caused by moving RBCs. Thus, the VCS signal can be assigned as a reference one with respect to more complicated signals like in laser Doppler flowmetry (LDF). An essential correlation between blood flow velocity oscillations in a separate human capillary and the integral perfusion estimate obtained by the LDF method has been found. The observation of blood flow by the VCS method during upper arm occlusion has shown emergence of the reverse blood flow effect in capillaries that corresponds to the biological zero signal in the LDF. The reverse blood flow effect has to be taken into account in interpretation of LDF signals.      

Evaluation of the parameters of total,nutritive, and shunt blood flows in the skin microvasculature using laser Doppler flowmetry

Examination of 28 healthy subjects and 66 patients was performed using laser Doppler flowmetry (LDF) of the skin of fingers in the red and infrared ranges and wavelet analysis of microvascular blood flow oscillations. Formulas were suggested for the total (TF), nutritive (NF), and shunt (SF) local blood flows. TF = MI × A_c × A_n /(P_m × ), where MI is the microcirculation index in perfusion units (PU), A_n and A_c are the averaged maximum amplitudes of the neurogenic and cardiac rhythms (in PU), P_m is the mean arterial pressure (in mm Hg), and is the mean square deviation of the amplitude of blood flow oscillations (in PU). NF = TF/SP, where SP is the shunting parameter. SP = A_n/A_m, where A_m is the averaged maximum amplitude of the myogenic rhythm (in PU). SF = TF - NF. Significant positive relationships between the skin oxygenation and NF (red), temperature and TF (red), and blood flow measured by hydrogen clearance and TF (infrared) were revealed by comparison of the LDF parameters with polarographic and thermographic data. The advantages of the LDF parameters compared with the MI were shown, especially in skin denervation syndromes. The TF decreased in the case of complete anatomic rupture of the median nerve and increased in reflex sympathetic dystrophy, with both cases being accompanied by a deficit of the NF (red).Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 114–119.Original Russian Text Copyright © 2005 by Krupatkin.     

Use of molecular biology methods for diagnosing fungal infections

A total of 130 various clinical materials taken from 48 children with suspected systemic fungal infection were used for the study. Clinical samples were tested by use of classical mycological procedures well as by use of molecular technique (PCR assay). The fragments of 125-bp (EO3) and 317 bp (HSP) specific for C. albicans were used for amplification. Fifty seven samples (48%) were positive for Candida albicans and eighty four (68%) by use of PCR. It should be stressed that 4 blood samples, 21 urine samples and 5 other samples were positive by use of molecular technique, only. PCR is sensitive and rapid method for detection and identification of Candida albicans from clinical materials of children with fungal infection. This technique can be applied for monitoring presence of fungal DNA in tested samples during antifungal therapy.     

Pointwise Hölder exponents of a model for skin laser Doppler flowmetry signals based on six nonlinear coupled oscillators with linear and parametric couplings: Comparison with experimental data from young healthy subjects

We study pointwise Hölder exponents of experimental and numerically simulated skin laser Doppler flowmetry (LDF) data that give a peripheral view of the cardiovascular system. The experimental signals are recorded in the forearm of young healthy subjects. The numerically simulated LDF data are computed from a model containing six nonlinear coupled oscillators reflecting six almost periodic rhythmic activities present in experimental LDF signals. Simulated LDF signals are for the first time generated with both linear and parametric couplings in order to represent cardiovascular system behaviors. Moreover, we propose the use of a parametric generalised quadratic variation (GQV) based estimation method for the estimation of the pointwise Hölder exponents. The latter identify possible multifractal characteristics of data. The GQV method is first tested on a white noise measure and then applied on the LDF data. The results of our signal processing analysis show that experimental LDF signals recorded in the forearm are weakly multifractal for young healthy subjects at rest. Furthermore, our findings show that the simulated data have a complexity similar to the one of signal recorded in young healthy subjects. However, their pointwise Hölder exponents have differences that we explain. This paper provides useful information to go deeper into the modeling of LDF data, which could bring enlightenment for a better understanding of the peripheral cardiovascular system.     

A laser Doppler scanner for imaging blood flow in skin

This paper describes a novel medical instrument that produces an image of blood flow in the capillaries under the skin surface. A laser beam is used to detect blood cell motion from the Doppler broadening of the laser light scattered from the skin. The image is generated by scanning the laser beam in a raster. The design of a practical clinical instrument is outlined and some preliminary results are presented.     

Use of a low-volume uterine flush for diagnosing endometritis in chronically infertile mares

Low-volume uterine flush (n=401) was performed in 308 infertile mares to diagnose endometritis. Mares evaluated were either barren after three or more breedings or had two or more unsuccessful embryo recovery attempts during consecutive cycles. Culture results were compared with cytological and histological findings, efflux clarity and pH to substantiate that the micro-organisms recovered were truly pathogens. Cytological specimens were evaluated for presence of epithelial and inflammatory cells, bacteria, yeast and debris. Endometrial biopsies (n=110) were examined for the presence of neutrophils in the stratum compactum. Micro-organisms were recovered in 282/401 (70%) of low-volume flushes; E. coli was most frequently isolated (42.2%), followed by beta hemolytic Streptococcus (37.6%). Efflux clarity of 318 flushes was clear (n=109), cloudy (n=149), or mucoid (n=60). Isolation of micro-organisms was highly associated with cloudy and mucoid effluxes (P<0.001), debris on cytological specimens (P<0.001), increased efflux pH (P<0.003), and neutrophils on endometrial biopsy (P<0.01). E. coli was associated with debris on cytological smear (P<0.002), whereas beta hemolytic Streptococcus was associated with increased efflux pH (P<0.002). Using the presence of neutrophils in a tissue specimen as the "best standard" for diagnosing endometritis, the sensitivity of flush culture was 0.71 and for flush cytology was 0.8, whereas the specificity was 0.86 and 0.67, respectively. Neutrophils in uterine flushes under-reported inflammation; only 86/282 positive cultures were positive on cytology. The clinical estimate of a contaminated (false positive) flush culture was 11%, if a false positive was defined as positive culture with clear efflux and no debris or neutrophils on cytology (26/228). In conclusion, a low-volume uterine flush was a rapid, accurate method for identifying mares with chronic endometritis. When micro-organisms were recovered, endometritis was confirmed by efflux clarity, pH and cytological findings of debris, bacteria, or neutrophils. E. coli was most commonly isolated and it appeared to differ in pathogenicity from beta hemolytic Streptococcus.