不同压力和部位压迫大鼠坐骨神经对神经血流量的影响

目的观察受压迫坐骨神经在不同压力条件下以及不同部位压迫时神经血流量的变化。方法建立可同时控制压力时间的大鼠坐骨神经卡压模型，应用气囊分5级压力压迫大鼠坐骨神经，观察不同压力下神经血流量的变化；将大鼠随机分为远端压迫组和近端压迫组，观察不同部位压迫神经对神经血流量的影响。结果不同压力压迫神经时神经血流量产生变化（P〈0．05），并且随着压力增高神经血流量出现下降趋势；近端压迫组和远端压迫组神经血流量均明显下降（P〈0．01），但后者的神经血流量下降较前者明显（P〈0．01）。结论机械压迫神经对神经血流量影响明显，坐骨神经远端血管是神经血供的主要来源。     

Regional Myocardial Blood Flow

A method is described which measures the local effectiveness of the myocardial circulation, expressed as a clearance constant. Uniform clearance constants have been demonstrated in the normal canine and human myocardium. A distinct difference in clearance constants has been demonstrated between the normal canine myocardium and areas of naturally occurring disease. Heterogeneous clearance constants have been found in a majority of human subjects with coronary artery disease-the lowest rates being noted in areas of fibrous aneurysm.     

Cerebral Blood Flow in Migraine

SYNOPSIS
Cerebral blood flow has seldom been measured during attacks of migraine and cluster headache. The literature is reviewed and five cases studied in our laboratory are described. The results of these studies confirm Wolff's hypothesis that cerebral blood flow is decreased during auras and increased during headaches. However, the distribution in time and space of the blood flow changes do not always correlate with the clinical features of the attack. Autoregulation of cerebral blood vessels may be impaired in aura and headache, and this may be a factor in intensifying and prolonging attacks.     

Brain Blood Flow and Velocity

Objective. Because transcranial Doppler sonography (TCD) is unable to measure arterial diameter, it remains unproven whether the changes in cerebral blood velocity it measures are representative of changes in cerebral blood flow (CBF). Our study was designed to compare velocity changes with flow changes measured by two magnetic resonance imaging (MRI) techniques, perfusion MRI and arterial spin labeling (ASL), using flavanol‐rich cocoa to induce CBF changes in healthy volunteers. Methods. We enrolled 20 healthy volunteers aged 62 to 80 years (mean, 73 years). Each was studied at baseline and after drinking standardized servings of cocoa for 7 to 14 days. Results. Changes in middle cerebral artery (MCA) flow by TCD were significantly correlated with changes in perfusion assessed by gadolinium‐enhanced MRI (r = 0.63; P < .03). Measurements with ASL showed a stronger correlation with borderline significance. Conclusions. Changes in flow velocity in the MCA associated with drinking cocoa were highly correlated with changes in CBF measured by the two MRI techniques using the tracer gadolinium and ASL. These results validate Doppler measurements of CBF velocity as representative assessments of CBF.     

彩色多普勒超声估测肾血流

90例正常人应用彩色多普勒超声方法估测肾血流,其中74例检出,说明这一方法检出率高。应用体外实验的两种方法对彩色多普勒超声估测肾血流的可靠性验证,实验结果相关密切,提示彩色多普勒超声测定肾血流可靠性好。从实验数据散点图的离散度小可看出彩色多普勒超声测定肾血流这一方法是可信的。     

彩色多普勒超声估测肾血流

９０例正常人应用彩色多普勒超声方法估测肾血流，其中７４例检出，说明这一方法检出率高。应用体外实验的两种方法对彩色多普勒超声估测肾血流的可靠性验证，实验结果相关密切，提示彩色多普勒超声测定肾血流可靠性好。从实验数据散点图的离散度小可看出彩色多普勒超声测定肾血流这一方法是可信的。     

Longitudinal Doppler Measurements of Spiral Artery Blood Flow in Relation to Uterine Artery Blood Flow

Objective. The purpose of this study was to examine the longitudinal relationship between Doppler flow velocity waveforms of the spiral artery (SA) and uterine artery (UA) in pregnant women. Methods. Ninety-seven primigravidas with uncomplicated singleton pregnancies were analyzed. Spiral artery and combined UA velocity waveforms were assessed by transabdominal color Doppler sonography at gestational ages of 11 through 13, 14 through 17, and 18 through 24 weeks; each measurement was performed twice. The pulsatility index (PI) was calculated for the left and right UA, and the results were averaged as a combined UA. In addition, the presence of UA bilateral notching was reported. Bland-Altman plots and generalized estimating equations were used to assess intraobserver variability and the longitudinal relationship between SA and UA blood velocities. Results. A total of 284 UA and 263 SA Doppler flow measurements were analyzed. Intraobserver variability rates for the SA and UA were 0.54 and 0.90, respectively. Results showed a continuous decrease of the mean PI in the SA and UA with increasing gestational age. Uterine artery bilateral notching was reported in 35%, 9%, and 3% of the cases at gestational ages of 11 through 13, 14 through 17, and 18 through 24 weeks. Generalized estimating equation analysis showed a significant correlation (r = 0.41) between the SA and UA (P < .0001). Conclusions. Uterine artery Doppler measurements in early pregnancy seem to accurately reflect peripheral resistance of SAs. Furthermore, trophoblastic invasion seems a continuous process in the first half of pregnancy, in which early UA bilateral notching is a physiologic event.     

Acupuncture Treatment for Low Back Pain and Lower Limb Symptoms-The Relation between Acupuncture or Electroacupuncture Stimulation and Sciatic Nerve Blood Flow

To investigate the clinical efficacy of acupuncture treatment for lumbar spinal canal stenosis and herniated lumbar disc and to clarify the mechanisms in an animal experiment that evaluated acupuncture on sciatic nerve blood flow. In the clinical trial, patients with lumbar spinal canal stenosis or herniated lumbar disc were divided into three treatment groups; (i) Ex-B2 (at the disordered level), (ii) electrical acupuncture (EA) on the pudendal nerve and (iii) EA at the nerve root. Primary outcome measurements were pain and dysesthesia [evaluated with a visual analogue scale (VAS)] and continuous walking distance. In the animal study, sciatic nerve blood flow was measured with laser-Doppler flowmetry at, before and during three kinds of stimulation (manual acupuncture on lumber muscle, electrical stimulation on the pudendal nerve and electrical stimulation on the sciatic nerve) in anesthetized rats. For the clinical trial, approximately half of the patients who received Ex-B2 revealed amelioration of the symptoms. EA on the pudendal nerve was effective for the symptoms which had not improved by Ex-B2. Considerable immediate and sustained relief was observed in patients who received EA at the nerve root. For the animal study, increase in sciatic nerve blood flow was observed in 56.9% of the trial with lumber muscle acupuncture, 100% with pudendal nerve stimulation and 100% with sciatic nerve stimulation. Sciatic nerve stimulation sustained the increase longer than pudendal nerve stimulation. One mechanism of action of acupuncture and electrical acupuncture stimulation could be that, in addition to its influence on the pain inhibitory system, it participates in causing a transient change in sciatic nerve blood blow, including circulation to the cauda equine and nerve root.     

彩色多普勒超声估测肾血流

90例正常人应用彩色多普勒超声方法估测肾血流,其中74例检出,说明这一方法检出率高。应用体外实验的两种方法对彩色多普勒超声估测肾血流的可靠性验证,实验结果相关密切,提示彩色多普勒超声测定肾血流可靠性好。从实验数据散点图的离散度小可看出彩色多普勒超声测定肾血流这一方法是可信的。     

应用超声微泡对肝肾微循环血流速度及血流状态的研究

目的应用超声微泡实时直接测量正常肝肾微循环血流速度并研究血流状态。方法采用10只实验犬用"DFY型超声图像定量分析仪"观测肝、肾实质正常微循环的血流速度和血流状态。结果肝、肾微循环的血流速度分别为(0.82±0.17)mm/s和(1.19±0.38)mm/s。肾微循环的平均血流速度大于肝(P0.05)。结论本实验所用方法是一种无创、动态实时、直接测量深部脏器微循环血流速度的新技术方法。微循环变化是疾病的基础病变和先期病变,血液微循环障碍的最重要表现之一,就是血流速度的减慢和停滞,因而了解微循环状态对疾病的诊治和预后判断意义重大。目前,临床上尚无无创、动态实时、直接、准确测量深部脏器微循环血流速度并观察微循环状态的实用方法。     

Transcranial Doppler Blood Flow Velocity versus 133Xe Clearance Cerebral Blood Flow During Mild Hypothermic Cardiopulmonary Bypass

Objective. Transcranial doppler (TCD) is used during cardiopulmonary bypass (CPB) to assess cerebral emboli and to estimate cerebral perfusion. We sought to compare TCD middle cerebral artery blood flow velocity (V_mca) to ¹³³Xe clearance cerebral blood flow (CBF) measurements during mild hypothermic CPB thus determining its utility in cerebral perfusion assessment. Methods. Thirty-four patients undergoing mild hypothermic CPB (35 °C) were studied and had comparisons of V_mca and ¹³³Xe CBF at three time intervals, 10, 30 and 60 min after the institution of CPB. Linear regression analysis was performed on data from each of the 3 intervals as well as for pooled data from all 3 periods. Results. The correlation coefficients for the 3 time periods were, r = 0.32 (p = 0.12), r = 0.32 (p = 0.11), r = 0.48 (p = 0.02), respectively. The pooled data correlation had a coefficient of 0.34 (p = 0.003). Conclusion. These findings suggest that TCD V_mca is a relatively poor correlate of CBF during mild hypothermic CPB.     

应用超声微泡对正常和不同程度缺血心肌微循环血流速度及血流状态的研究

目的 通过单个超声微泡研究正常及不同缺血程度下的心肌微循环血流速度及血流状态.方法 采用15只实验犬用"DFY型超声图像定量分析仪"观测心肌正常微循环的血流速度.建立不同程度冠脉狭窄的心肌缺血模型,并观测缺血心肌的血流状态及速度.结果 正常心肌微循环的血流速度为(6.25±1.27)mm/s,心肌50%、90%和100%缺血时心肌微循环的血流速度分别为(2.3±0.57)mm/s、(0.1±0.04)mm/s和(0.05±0.01)mm/s.随冠脉狭窄程度加大血流速度明显减慢(P＜0.05).结论 本实验所用方法是一种无创、动态实时、直接测量心肌微循环血流速度的新技术.     

Cerebral Blood Flow in Chronic Posttraumatic Headache

Background and Purpose.-Headache is the most common neurologic symptom following minor closed head injury. There is often a lack of objective evidence supporting an organic basis of cerebral pathology in these cases. This pilot study considers the possibility of alterations in cerebral blood flow, indicating evidence of an organic disorder in posttraumatic headache.
Methods.-Regional cerebral blood flow studies of 35 patients with chronic posttraumatic headache (PTH) (International Headache Society criteria), identified retrospectively from our cerebral blood flow data base, were compared with those of 49 nonheadache controls and 92 migraineurs (Ad Hoc Committee criteria). Regional cerebral blood flow (initial slope index method) was measured using the xenon Xe 133 inhalation technique.
Results.-Compared to migraineurs and controls, and after adjusting for differences (analysis of covariance) in baseline variables such as blood pressure, hematocrit, and Pco 2 , patients with PTH had: (1) significantly lower mean initial slope indices (P<0.001, P=0.002, respectively); (2) regional interhemispheric flow differences (rlFD), with higher distribution of regional asymmetrical probe pairs (rIFD≥7%: P[PTH versus control]=0.006, P[PTH versus migraine]=0.016; rIFD≥10%: P[PTH versus control]=0.011, P[PTH versus migraine]=0.003]; and (3) more hemispheric asymmetries (P[PTH versus control]=0.023, P[PTH versus migraine]=0.57). Lower mean initial slope indices and hemispheric asymmetry (mean interhemispheric flow difference ≥3.2%) predicted PTH over control (P=0.023 and 0.002, respectively). Lower mean initial slope indices predicted PTH over migraine (P=0.002).
Conclusions.-Patients with PTH have reduced regional cerebral blood flow, and regional and hemispheric asymmetries. These cerebral hemodynamic alterations support an organic basis to chronic posttraumatic headache.     

血流切变率与血栓形成的关系

血栓性疾病由血管血栓形成所致 ,可见于临床各科患者 ,尤其以心、脑血管血栓性疾病最为严重 ,已成为我国人口病死原因的第一位 ,而且发病率有增加趋势 ,严重危害人类健康。临床上血栓形成的机制较复杂 ,主要与血管壁异常、血液成份改变等因素有关[1 ] 。近年来研究发现 ,血流切变率与血栓形成及血栓性疾病也有密切的关系。血流切变率反映了血液流动中流场中的速度梯度。在高切变率和低切变率这两种状态下 ,都易形成血栓。血液在血管内流动时 ,一方面血液对血管壁和血细胞产生一种流体压力 ;另一方面 ,血液流动时各流层的流速不一样 ,这样血…     

Regional Myocardial Blood Flow in Awake Dogs

The objectives of this study were to test the hypothesis in awake dogs that during control conditions endocardial vessels are maximally dilated and to determine whether variables introduced by general anesthesia and thoracotomy modify distribution of myocardial blood flow or impair capacity for augmentation of flow in response to a coronary vasodilator stimulus. Myocardial blood flow was measured in relatively small, 2-3 g, left ventricular epicardial and endocardial samples by using 7-10-mum radioisotope-labeled microspheres during control conditions and during infusion of adenosine in dosages which produced maximum increases in coronary blood flow. Measurements were made initially in awake resting animals and were repeated after pentobarbital anesthesia, thoracotomy, and pericardiotomy.Blood flow (mean+/-SEM) in the epicardium and endocardium, respectively, was 0.75+/-0.06 and 0.83+/-0.06 during control conditions and 4.98+/-0.28 and 4.49+/-0.27 cm(3)/min/g during adenosine. These data demonstrate considerable capacity for vasodilation in both myocardial layers and thus refute the hypothesis that endocardial vessels are maximally dilated during control conditions. During control conditions blood flow within epicardial and endocardial layers was essentially homogeneous around the circumference of the left ventricle. In contrast to previous studies in anesthetized animals, however, transmural gradients were present in most regions, i.e., endocardium: epicardium ratio (endo/epi) 1.06-1.16. During adenosine, circumferential epicardial flows were homogeneous; however, circumferential endocardial flows were inhomogeneous and increased less than epicardial flows, endo/epi 0.81-0.99.Anesthesia, thoracotomy, and pericardiotomy increased epicardial and endocardial flow, mean values 1.08+/-0.10 and 1.11+/-0.08 cm(3)/min/g, respectively. Transmural gradients remained in only papillary muscle regions. Adenosine increased epicardial flow comparably before and after anesthesia. Although adenosine increased endocardial flow three- to fourfold after anesthesia, the increase was considerably less than epicardial flow, i.e., endo/epi 0.63-0.78.     

Bedside Cerebral Blood Flow Quantification in Neonates

Measurement of blood flow to the brain in neonates would be a very valuable addition to the medical diagnostic armamentarium. Such conditions such as assessment of closure of a patent ductus arteriosus (PDA) would greatly benefit from such an evaluation. However, measurement of cerebral blood flow in a clinical setting has proven very difficult and, as such, is rarely employed. Present techniques are often cumbersome, difficult to perform and potentially dangerous for very low birth weight (VLBW) infants. We have been developing an ultrasound blood volume flow technique that could be routinely used to assess blood flow to the brain in neonates. By scanning through the anterior fontanelles of 10 normal, full-term newborn infants, we were able to estimate total brain blood flows that closely match those published in the literature using much more invasive and technically demanding methods. Our method is safe, easy to do, does not require contrast agents and can be performed in the baby's incubator. The method has the potential for monitoring and assessing blood flows to the brain and could be used to routinely assess cerebral blood flow in many different clinical conditions.