Measurements Of Cerebral Blood Flow in Postasphyxiated Newborns by Color Doppler Imaging（CDI）

Cerebral blood flow of 10 asphyxiated term newborns was continuously measured during the first 7 days of life and compared with that of 10 normal term infants by CDI. Frequency spectrum and blood flow variables in the anterior, middle and posterior cerebral arteries were studied. The results showed evidently lower systolic amplitude in patients than that in normal subjects. End diastolic amplitude was zero in part of vessels, and values of bloed flow variables were all lower in day 1 of the life as compared with the control groups. Frequency spectrum recovered to normal patterns in 9 survived infants in day 2. but blood flow variables recovered to normal by day 7. Values of resistance index (RI) rose to 1 in some vessels of moderate hypoxic ischemic encephalopathy (HIE) infants and stayed at 1 in the severe HIE infants. It is concluded that low CBF plays a key role in brain damage of post-asphyxiated newborns and RI may be an important parameter in the evaluation prognosis.

Mucosal blood flow measurements using laser Doppler perfusion monitoring

Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insuff iciency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of pe- ripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastroin-testinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

A New Method for Evaluating Regional Cerebral Blood Flow Changes:Laser Speckle Contrast Imaging in a C57BL/6J Mouse Model of Photothrombotic Ischemia

The present study aimed to improve the processing of data acquired from laser speckle contrast imaging（LSCI） to provide a standardization method to explore changes in regional cerebral blood flow（r CBF） and to determine the correlations among r CBF, cerebral ischemic lesion volume and microvascular density over time in a focal ischemic region. C57BL/6J mice were subjected to focal photothrombotic（PT） ischemia. r CBF was measured using LSCI at different time points before and after PT ischemia through an intact skull. Standardized r CBF（Sr CBF）, defined as the ratio of r CBF measured in the ipsilateral region of interest（ROI） to that in the corresponding contralateral region, was calculated to evaluate potential changes. In addition, the volume of the ischemic lesion and the microvascular density were determined using Nissl staining and immunofluorescence, respectively. The relationships among the ischemic lesion volume, microvascular density and Sr CBF were analyzed over time. The results showed that the cortical r CBF measured using LSCI following PT ischemia in the C57BL/6J mice gradually increased. Changes in the cerebral ischemic lesion volume were negatively correlated with Sr CBF in the ischemic region. Changes in the microvascular density were similar to those observed in Sr CBF. Our findings indicate that LSCI is a practical technique for observing changes in murine cortical r CBF without skull opening and for analyzing the relationships among the ischemic lesion volume, microvascular density and Sr CBF following focal cerebral ischemia. Preliminary results also suggest that the use of LSCI to observe the formation of collateral circulation is feasible.

Dynamic Non-Invasive Detection of NADH Based on Blood Flow-Mediated Skin Fluorescence (FMSF) Method

Nicotinamide adenine dinucleotide (NADH/NAD+) is involved in important biochemical reactions in human metabolism, including participation in energy production by mitochondria. The changes in fluorescence intensity as a function of time in response to blocking and releasing of blood flow in a forearm are used as a measure of oxygen transport with blood to the tissue, which directly correlates with the skin microcirculation status. In this paper, a non-invasive dynamic monitoring system based on blood flow-mediated skin fluorescence (FMSF) technology is developed to monitor the NADH fluorescence intensity of skin tissue during the process of blocking reactive hyperemia. Simultaneously, laser speckle contrast imaging (LSCI) and laser Doppler flowmetry (LDF) were used to observe blood flow, blood oxygen saturation (SOt2) and relative amount of hemoglobin (rHb) during the measurement process, which helped to explore NADH dynamics relevant physiological changes. A variety of parameters have been derived to describe NADH fluorescence curve based on the FMSF device. The experimental results are conducive to understanding the NADH measurement and the physiological processes related to it, which help FMSF to be a great avenue for in vivo physiological, clinical and pharmacological research on mitochondrial metabolism.

Effect of swimming training on neural microcirculation in rats with sciatic nerve compression A study based on laser Doppler flowmetry

Microcirculation of the peripheral nerve is necessary for neural growth and regeneration. However, technical limitations have limited studies in this area. The few studies conducted have concerned active exercise effects on microcirculation of the peripheral nerve. Using an animal experiment, this study evaluated the effect of swimming training on microcirculation of injured peripheral nerve by laser Doppler flowmetry. The results showed that the blood vessel at the distal end of the peripheral nerve was the main blood supply for the nerve, and the internal blood supply for the nerve had strong compensatory ability. Swimming training promoted the functional recovery of rats with sciatic nerve injury and the regeneration of myelin sheath and blood vessels, but had no impact on neural blood flow.

Characterization of cerebral blood flow dynamics with multiscale entropy

Based on the laser speckle contrast imaging(LSCI)and the multiscale entropy(MSE),we study in this work the blood flow dynamics at the levels of cerebral veins and the surrounding network of microcerebral vessels.We discuss how the phenylephrine-related acute peripheral bypertension is refected in the cerebral circulation and show that the observed changes are scale dependent,and they are signifcantly more pronounced in microcerebral vessels,while the macrocerebral dynamics does not demonstrate authentic inter-group distinctions.We also consider the permeability of blood-brain barrier(BBB)and study its opening caused by sound exposure.We show that alterations associated with the BBB opening can be revealed by the analysis of blood flow at the level of macrocerebral vessels.

THE EXPERIMENTAL STUDY OF STRESS-RELATED PATHOLOGICAL CHANGES IN CEREBRAL VENOUS BLOOD FLOW IN NEWBORN RATS ASSESSED BY DOCT

In experiments on newbom rats with stress related intracrani al hemorhage(ICH)using Doppler optical coberence tomognaphy(DOCT)we have shown that latent stage of ICH(4 h after stress)is characterized by decrease of venous blood outflow and the loss of sensitivity of sagittal vein to vasoconstrictor ffect of adrenaline.The incidence of ICH(24 h after stress)was accompanied by progressi on of early pathological changes in cerebral venous blood flow(CVBF)and development of venous insufficiency.Taking into consideration of this fact,we suggest that the suppression of CVBF related to the severity to the deleterious effect of stress on the brain hemodynamics in newborn rats.These facts allow us to conclude that the venous insufficiency with the loss of vasoconstrictor response to adrenaline is an informative and sensitive component of pattern of CVBF that can be important diagnostic criteria of risk of ICH development in newborns.

Changes of Gastric Mucosal Blood Flow in the Healing Process of Peptic Ulcers

Changes of gastro-duodenal mucosal blood flow (GDMBF) in the healingprocess of 82 patients with gastric ulcer,130 with duodenal ulcer and 9 with active ul-cer induced by gastric polypectomy were studied by endoscopic laser Doppler flowme-try.In 108 normal subjects,the mucosal blood flow at the angle and antrum of the les-ser curvature and on the anterior wall of the duodenal bulb was the smallest (P【0.01).In patients with gastric ulcer,gastric mucosal blood flow (GMBF)significantly decrea-Sed at the active stage and increased at the healing stage (P【0.01 ).GDMBF significan-tly increased (P【0.01) at the active stage and returned to normal at the healing stage ofduodenal ulcer.GDMBF was unchanged in the healing process of the active ulcer inducedby gastric polypectomy.The mucosal blood flow at ulcer centre and margins significan-tly decreased at the active stage and markedly increased at the healing stage as compa-red with that of surrounding mucosa.We conclude that GMBF plays an importantrole in the developing and healing process of peptic ulcers.

VISUALIZATION AND MEASUREMENT OF VORTEX FLOW IN SPINNING SHELL-CASE

The characteristics of a flow in spinning devices are one of the fundamental problems innew-type spinning.In this paper the vortex flow in interior of the shell-case was studied by usingexperimental methods,which include flow visualization and laser doppler techniques.The flow sur-vey by measurement has been compared with that photographed by flow visualization method,andshows a fairly good conformity.The results of experiments are similar to those by numericalevaluation.

Gastric Mucosal Blood Flow and Acid Secretion in Rats

The relationship between gastric mucosal blood flow (GMBF) and gastric acid secretionwere studied in rats by using secretory stimulant (pentagastrin)and inhibitor(cimetidine). GMBFwas measured by Laser Doppler flowmetry (LDF) and gastric mucosal pH determined by microglasspH electrode. GMBF increased and gastric mucosal pH decreased significantly after intravenous injec-tion of 6μg/kg of pentagastrin; nevertheless GMBF decreased and gastric mucosal pH increasedmarkedly after intravenous administration of 100mg/kg of cimetidine. This indicates that pentagastrincan increase GMBF and gastric acid secretion, and cimetidine can decrease GMBF and gastric acidsecretion in rats, proving the close relationship between GMBF and gastric acid secretion in rats.

Laser Doppler flowmeter study on regional cerebral blood flow in early stage after standard superficial temporal artery-middle cerebral artery bypass surgery for moyamoya disease

Background Standard superficial temporal artery-middle cerebral artery （STA-MCA） bypass surgery is an effective treatment for moyamoya disease, but recent evidence suggests that postoperative cerebral hyperperfusion can occur. In this study, the trendline of changes in regional cerebral blood flow （rCBF） after surgery were continually monitored near the site of anastomosis in order to investigate both the efficacy of the procedure for improving rCBF and the possible risk of hyperperfusion . Methods Standard STA-MCA bypass surgery was performed on 13 patients, rCBF was measured continually using laser Doppler flowmetry （LDF） until the 5th day after the operation with the LDF probe implanted adjacent to the area of the anastomosis. The trendline of rCBF changes postoperatively was recorded for the analysis performed using SPSS 13.0. Results The baseline LDF value of cortical rCBF was （84.68±14.39） perfusion unit （PU）, which was linear relative to absolute perfusion volume before anastomosis and （88.90±11.26） PU immediately after anastomosis （P 〉0.05）. The value changed significantly from before to after anastomosis （P 〈0.05）; it was （417.72±21.35） PU on the 1st day after surgery, and （358.99±18.01） PU, （323.46±17.38） PU, （261.60±16.38） PU and （375.72±18.45） PU on the following 4 days, respectively. The rCBF decreased gradually from the 2nd day until the 4th postoperative day, but still was at a high level （P 〈0.05）. However, on the 5th postoperative day the rCBF increased again to the second highest level, which was significantly different compared with the baseline value （P 〈0.05）, but not significantly different compared with the values on the other 4 days （P〉0.05）. Conclusions STA-MCA anastomosis improves the cerebral blood supply significantly in the early stage after surgery, however, the risk of symptomatic hyperperfusion may exist, which may possibly occur on the 1st day and 5th day after surgery. A LDF is useful for postoperative monitoring for both the efficacy of bypass and possible risk of neurologic deterioration or bleeding from hyperperfusion.

Effects of spinal cord stimulation on cerebrovascular flow: role of sym-pathetic and parasympathetic innervations

Objective Cervical spinal cord stimulation （SCS） has been found to augment cerebral blood flow （CBF） in a number of animal models. However, the effective use of SCS is hampered by a lack of understanding of its mechanism（s） of action. In this paper, we focus on the sympathetic and parasympathetic effects of SCS on CBF. Method SpragueDawley rats were selected for the experimental series. The animals were divided into 5 groups to underwent SCS and laser Doppler flowmeter （LDF） recordings. Control group, the animal underwent SCS and LDF recordings without any surgery of the nerve fibers and ganglia. V 1 group, the animal underwent bilateral resection of the nasociliary and post-ganglionic parasympathetic nerve fibbers. SCG group, the animal underwent bilateral resection of supper cervical ganglion. V 1 ＋ SCG group, the animal underwent both surgeries as V1- and SCG-group animals did. Sham group, the animal underwent the carotid manipulation with blunt-tipped forceps as well as the dissection of nasociliary and post-ganglionic parasympathetic nerve fibers around the ethmoidal foramen, but without cutting any nerves. Results During the SCS, the LDF was no statistical difference between the V 1 or SCG group and the control group. Yet, the effects of SCS on CBF are completely abolished in V1＋ SCG group. Conclusions Surgical interruption of both the parasympathetic and sympathetic pathways has the contradict effect on SCS-induced CBF augmentation.

Compromised cerebrovascular modulation in chronic anxiety:evidence from cerebral blood flow velocity measured by transcranial Doppler sonography

Objective Cerebral autoregulation （CA） is the mechanism by which constant cerebral blood flow is maintained despite changes in cerebral perfusion pressure. CA can be evaluated by dynamic monitoring of cerebral blood flow velocity （CBFV） with transcranial Doppler sonography （TCD）. The present study aimed to explore CA in chronic anxiety. Methods Subjects with Hamilton anxiety scale scores 〉14 were enrolled and the dynamic changes of CBFV in response to an orthostatic challenge were investigated using TCD. Results In both the anxious and the healthy subjects, the mean CBFV was significantly lower in the upright position than when supine. However, the CBFV changes from supine to upright differed between the anxious and the healthy groups. Anxious subjects showed more pronounced decreases in CBFV with abrupt standing. Conclusion Our results indicate that cerebrovascular modulation is compromised in chronic anxiety; anxious subjects have some insufficiency in maintaining cerebral perfusion after postural change. Given the fact that anxiety and impaired CA are associated with cardiovascular disease, early ascertainment of compromised cerebrovascular modulation using TCD might suggest interventional therapies in the anxious population, and improve the primary prevention of cardiovascular disease.

Histogram analysis of laser speckle contrast image for cerebral blood flow monitoring

Laser speckle contrast imaging （LSCI） is a powerful tool for blood flow mapping. In this paper, we described a simple algorithm based on histogram analysis of laser speckle contrast image to provide rapid differentiation between macro- and microcirculations. The algorithm was successfully verified by the study of blood flow in rat cortex under functional activation.

Laser speckle imaging and wavelet analysis of cerebral blood flow associated with the opening of the blood–brain barrier by sound

The cerebral blood flow（CBF） alterations related to sound-induced opening of the blood–brain barrier（BBB） in adult mice are studied using laser speckle contrast imaging（LSCI） and wavelet analysis of vascular physiology.The results clearly show that the opening of the BBB is accompanied by the changes of venous but not microvessel circulation in the brain. The elevation of the BBB permeability is associated with the decrease of venous CBF and the increase of its complexity. These data suggest that the cerebral veins rather than microvessels are sensitive components of the CBF related to the opening BBB.

Velocity Slip and Interfacial Momentum Transfer in the Transient Section of Supersonic Gas-Droplet Two-Phase Flows

Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for supersonic two-pha.se (gas-droplet) flow in the transient section inside and outside a Laval jet(LJ). The initial velocity slip between gas and droplets causes an interfacial momentum transfer flux as high as (2.0-5.0) x 104 Pa. The relaxation time corresponding to this transient process is in the range of 0.015-0.090ms for the two-phase flow formed inside the LJ and less than 0.5ms outside the LJ. It demonstrates the unique performance of this system for application to fast chemical reactions using electrically active media with a lifetime in the order of 1 ms. Through the simulations of the transient processes with initial Mach number Mg from 2.783 to 4.194 at different axial positions inside the LJ, it is found that Mg has the strongest effect on the process. The momentum flux increases as the Mach number decreases. Due to compression by the shock wave at the end of the LJ, the flow pattern becomes two dimensional and viscous outside the LJ. Laser Doppler velocirneter (LDV) measurements of droplet velocities outside the LJ are in reasonably good agreement with the results of the simulation.

Hidden stage of intracranial hemorrhage in newborn rats studied with laser speckle contrast imaging and wavelets

Using the laser speckle contrast imaging and wavelet-based analyses,we investigate a latent("hidden")stage of the development of intracranial hemorrhages(ICHs)in newborn rats.We apply two measures based on the continuous wavelet-transform of blood flow velocity in the sagittal sinus,namely,the spectral energy in distinct frequency ranges and a multiscality degree characterizing complexity of experimental data.We show that the wavelet-based multifractal formalism reveals changes in the cerebrovascular blood flow at the development of ICH.

Effect of carotid artery stenting surgery combined with nimodipine on cerebral anterior circulation hemodynamics

Objective To evaluate the effect of carotid artery stenting combined with nimodipine on cerebral hemodynamics by comparing and analyzing the change of anterior cerebral blood flow before and after treatment through transcrania Doppler （TCD）. Methods Twenty patients with ischemic cerebrovascnlar disease were detected in blood flow velocity of bilateral middle cerebral arteries （MCA） and anterior cerebral arteries （ACA） and artery pulsatility index with TCD before and two weeks after treatment. Results After treatment, TCD examination showed dynamic changes in blood flow significantly, lpsilateral MCA flow velocity significantly increased; ipsilateral ACA flow velocity did not change significantly; there was no significant increase in the contralateral MCA flow velocity; flow rate decreased significantly in contralateral ACA. Conclusion Carotid artery stenting combined with nimodipine treatment can cause anterior cerebral hemodynamic changes in ipsilateral hemisphere and significantly improve blood flow

The Influence of Age on Blood Flow and Temperature of Acupuncture Points: A Study based on Laser Doppler Flowmetry and Infrared Thermography

Background:To date,there has been a great lack of investigation on the influence of age on blood flow and temperature of acupoints in specific regions.Objective:This study aimed to determine the association between different age categories and acupoint blood flow/temperature on the forearm.Methods:Acupoint blood flow and temperature were measured in healthy adults of different age categories using laser doppler flowmetry(LDF)and infrared thermography(IRT),respectively.A total of 60 eligible healthy volunteers were divided into the young group,mid age group and old age group.All groups received LDF and IRT examination.Shenmen(HT7),Shaohai(HT3),Taiyuan(LU9)and Chize(LU5)of the Heart and Lung meridians on the forearm were selected as 4 test acupoints.Results:Regarding blood flow of the 4 test acupoints,the PU of Taiyuan(LU9)in the old age group was sig-nificantly different compared with that of the young age group(P<0.05)and the mid age group(P<0.05),while there was no significant difference in PU of the other acupoints between 3 groups(all P>0.05).Simi-larly,regarding acupoint temperature of the 4 test sites,the temperature of Shaohai(HT3)in the old age group was significantly different compared with that of the mid age group(P<0.05),while there was no significant difference in the temperature of the other 3 acupoints between 3 age groups(all P>0.05).Conclusion:Age category tends to have notable influence on the blood flow and temperature in specific acupoints in the forearm.Therefore,particular concerns should be taken into consideration regarding the effect of age differences for future studies in this field.Nevertheless,further studies with a large sample size and more test acupoints are needed to further verify current findings.

床旁经颅多普勒超声在神经重症脑血管疾病患者中的监测价值

目的分析神经重症脑血管疾病患者监测中床旁经颅多普勒超声应用效果。方法筛选郑州人民医院2021年5月至2023年5月86例重症脑血管疾病患者作为研究对象(高血压脑出血,术后35例,未手术者7例,脑动脉瘤破裂出血,术后32例,未手术者5例,其他脑血管疾病术后4例,未手术者3例),均采用经颅多普勒超声(TCD)监测,包含经枕窗探测基底动脉(BA)、经颞窗探测双侧大脑中动脉(MCA),另监测收缩期峰值血流动力学改变、舒张末期峰值血流速度、平均峰值血流速度、血管阻力指数、血管搏动指数、血流频谱形态等了解血流动力学改变,了解血流动力学改变,依照监测结果分三组,脑血管痉挛组(n=26)、供血不足组(n=37)、血流增快组(n=29),对各组监测结果予以分析。结果患者均完成TCD监测,在不同病因中,脑动脉瘤破裂出血与高血压脑出血患者供血不足发生率最高,其次是血流增快、血管痉挛,三组发生率对比差异有统计学意义(P<0.05)。结论在神经重症脑血管疾病患者中,床旁TCD监测能为临床治疗及预后评价提供有效支持。