The influence of probe fiber distance on laser Doppler perfusion monitoring measurements

Laser Doppler perfusion monitoring (LDPM) is a noninvasive technique for monitoring skin microcirculation. The aim of this article was to investigate the influence of fiber separation on clinical LDPM measurements. A dual-channel LDPM system was used in combination with a probe that consists of two sets of detection fibers, at 0.2 and 1.0 mm from the illuminating fiber. Measurements were performed at the big toe of 8 healthy subjects and 11 subjects who had vascular disorders. In most cases, fluxes detected at both fiber distances showed very similar fluctuations. For each fiber separation, flux values of healthy subjects and patients were not significantly different. Furthermore, skin temperature (range: 22-34 degrees C) influenced the toe's pulp microcirculation markedly, increasing similarly at both probe separations, with a higher flux at a separation of 1.0 mm than at 0.2 mm. The flux ratio signal, obtained by dividing the flux at 0.2 mm by the flux at 1.0 mm, was significantly different between the two groups (p &< 0.05). In conclusion, the flux detected in vivo by means of LDPM, is influenced by the distance between the optical fibers. Use of the flux ratio with a multiseparation probe deserves attention as it is a possible marker for discriminating normal tissue perfusion from pathological skin tissue perfusion, independently from tissue temperature.     

Regional myocardial perfusion reserve determined using myocardial perfusion magnetic resonance imaging showed a direct correlation with coronary flow velocity reserve by Doppler flow wire

Aims: Quantitative analysis of rest–stress myocardial perfusionmagnetic resonance imaging (MRI) can provide assessments ofregional myocardial perfusion reserve (MPR). The purpose ofthis study was to compare regional MPR determined by myocardialperfusion MRI with coronary flow reserve (CFR) by intracoronaryDoppler flow wire. Methods and results: Twenty patients with suspected coronary artery disease (CAD)were studied. Average peak velocity was measured by Dopplerflow wire in the resting state and during adenosine triphosphate(ATP) stress in 36 coronary arteries. CFR measurements for eachpatient were performed in the culprit and one non-culprit non-stenoticartery. First-pass, contrast-enhanced myocardial perfusion MRimages were obtained in the resting state and during ATP stresswithin the week before the Doppler wire procedure. Regionalmyocardial blood flow (MBF) was quantified in 16 myocardialsegments by analysing arterial input and myocardial output usinga Patlak plot method. MPR was calculated as stress MBF dividedby rest MBF. CFR measured by Doppler flow wire was comparedwith MPR in the myocardial segments corresponding to vesselterritories. The average MPR measured by perfusion MRI was 1.77± 0.62 for the culprit arteries and 3.45 ± 0.78for the non-culprit arteries, respectively (P < 0.001). Theaveraged CFR by Doppler flow wire was 1.72 ± 0.44 inthe culprit arteries and 3.14 ± 0.74 in the non-culpritarteries, respectively (P < 0.001). For both culprit andnon-culprit vessel groups, significant direct correlations wereobserved between MR assessments of MPR and Doppler assessmentsof CFR (culprit artery: R = 0.87, Non-culprit artery: R = 0.86)On Bland–Altman analysis, the mean differences betweenMPR determined by myocardial perfusion MRI and CFR measuredby Doppler wire were 0.05 in culprit arteries (95% limit ofagreement; –0.65 to 0.56) and 0.36 in non-culprit arteries(95% limit of agreement; –1.24 to 0.44). The sensitivityand specificity of MR measurement of MPR for predicting physiologicallysignificant reduction of Doppler CFR (<2) was 88% (95% CI61.7–98.5) and 90% (95% CI 68.3–98.8), respectively. Conclusion: The current results using Doppler flow wire as a reference methoddemonstrated that quantitative analysis of stress–restmyocardial perfusion MRI can provide a non-invasive assessmentof reduced MPR in patients with CAD.     

Evaluation of phasic blood flow velocity in the great cardiac vein by a laser Doppler method

Summary In the present study, characteristics of the phasic flow pattern in the great cardiac vein and the mechanism of such pattern formation were investigated using a laser Doppler velocimeter with an optic fiber probe. The laser Doppler velocimeter allowed measurements of venous blood velocity under more physiological conditions than were possible with previous methods. Moreover, venous blood flow measurement in the great cardiac vein mirrors the effects of myocardial contraction on the venous flow more directly than does measurement in the coronary sinus. Thus, our method is considered very useful. Results obtained from the present study are as follows: 1) Measurement of the phasic flow in the great cardiac vein was made in 11 anesthetized dogs using our laser Doppler method. The blood velocity curve obtained in the great cardiac vein was always characterized by a prominent systolic flow wave (SFW). The mean value for the maximum velocities under control conditions in 11 cases was 40±13 cm/s. The blood velocity increased with the onset of left ventricular ejection and decreased gradually after the peak formation at mid- or late systole. — 2) Besides the above SFW, one or two small wave components were frequently observed during the atrial contraction period and/or during the isovolumic contraction phase. On the waveform during the atrial contraction period, two cases showed forward flow, while one case showed reverse flow. The small reverse flow waves during the isovolumic contraction phase were found in seven cases. — 3) Pharmacological interventions of dipyridamole and isoproterenol increased the maximum velocity. Compared with dipyridamole, isoproterenol accelerated the rate of rise in the SFW. — 4) No significant coronary venous flow was observed during the diastolic period prolonged by vagal nerve stimulation. However, after coronary vasodilator drugs were administered, there was a transient significant coronary venous flow during the prolonged diastole. This may be the overflow from the coronary capacitance vessels. — 5) During a reactive hyperemic response, the flow velocity of the great cardiac vein increased with the increment of the blood flow volume of the left anterior descending artery. However, its phasic change did not always correspond to that of intramyocardial pressure.The present study was partially supported by a Research Scholarship of the Japanese Foundation of Cardiology     

Analysis of hemodynamics during blood purification therapy using a newly developed noninvasive continuous monitoring method

Advancement in blood purification therapy extends not only to consoles and dialyzers, but also to patient management during blood purification therapy. However, no monitor has been devised for hemodynamics during blood purification therapy that is carried out continuously and non-invasively. By studying the laser Doppler flowmeter (LDF), we have developed a probe that can continuously measure changes in blood flow in tissues of the head and lower extremities during blood purification therapy. By applying the improved LDF, we have developed a non-invasive continuous monitoring method (NICOMM). Hemodynamics in various types of blood purification therapies were also studied by simultaneously measuring with an automatic oscillometric sphygmomanometer.     

A laser Doppler velocimetry study of the effect of hypoglycaemia on retinal blood flow in the minipig

Summary The effect of acute hypoglycaemia (plasma glucose <2.2mmol/l) on retinal venous blood flow in the minipig has been determined using bidirectional laser Doppler velocimetry and red free retinal photography. In six pigs the mean flow in a retinal vein increased from 19.3 (±2.8 SEM) l/min to 29.7 (±7.5) l/min during hypoglycaemia (p<0.05) with a return to 18.6 (±3.6) l/min when euglycaemia was restored. Retinal blood flow is affected by hypoglycaemia or its haemodynamic consequences.     

Comparison between laser speckle contrast imaging and laser Doppler imaging to assess skin blood flow in humans

Objective

We tested the linearity between skin blood flux recorded with laser speckle contrast imaging (LSCI) and laser Doppler imaging (LDI), comparing different ways of expressing data. A secondary objective was to test within-subject variability of baseline flux with the two techniques.

Methods

We performed local heating at 36, 39, 42, and 44 °C on the forearm of healthy volunteers, and measured cutaneous blood flux with LDI and LSCI. Biological zero (BZ) was obtained by occluding the brachial artery. We expressed data as raw arbitrary perfusion units (APUs) and as a percentage increase from baseline (%BL), with and without subtracting BZ. Inter-site variability was expressed as a within subject coefficient of variation (CV).

Results

Twelve participants were enrolled. Inter-site variability at baseline was lower with LSCI (CV = 9.2%) than with LDI (CV = 20.7%). We observed an excellent correlation between both techniques when data were expressed as raw APUs or APU − BZ (R = 0.90; p < 0.001). The correlation remained correct for %BL (R = 0.77, p < 0.001), but decreased for %BL − BZ (R = 0.44, p = 0.003). Bland-Altman plots revealed a major proportional bias between the two techniques.

Conclusion

This study suggests that skin blood flux measured with LSCI is linearly related to the LDI signal over a wide range of perfusion. Subtracting BZ does not affect this linearity but introduces variability in baseline flux, thus decreasing the correlation when data are expressed as a function of baseline. Finally, systematic bias makes it impossible to assimilate arbitrary perfusion units provided by the two systems.     

Gastric mucosal blood flow and hepatic perfusion index in patients with portal hypertensive gastropathy

Endoscopic laser Doppler velocimetry is a simple non-invasive method to measure gastric mucosal blood flow. The present study is an attempt to determine a correlation, if any, between gastric mucosal blood flow and the hepatic perfusion index in patients with portal hypertensive gastropathy and their relationship to the severity of liver disease. Thirty patients with portal hypertensive gastropathy due to cirrhosis of the liver (eight class A, 13 class B, nine class C, according to Child-Pugh Classification) and six normal subjects were recruited into the study. In all subjects, the gastric mucosal blood flow and venous vasomotor reflex response was measured at two sites: the lesser and greater curvature, using endosoopic laser Doppler velocimetry. The hepatic perfusion index was measured using dynamic liver scintigraphy. The hepatic perfusion index (ratio of arterial/portal venous perfusion) in normal subjects and patients with portal hypertensive gastropathy belonging to Child-Pugh class A, B and C were 0.36 ± 0.02, 0.53 ± 0.08, 0.62 ± 0.14 and 1.04 ± 0.28, respectively. The gastric mucosal blood flow was similar in Child's A, B and C cases, while the venous vasomotor reflex response was reduced according to the Child-Pugh score (Child's A 37.4 ± 5.4%, normal control 62.3 ± 10.9%, Child's B 38.3 ± 18.2%, Child's C 22.5 ± 15.2%) and was statistically significant. The gastric mucosal blood flow and hepatic perfusion index are inversely correlated. The hepatic perfusion index altered with grading of cirrhotic change. This study confirms that the severity of portal hypertensive gastropathy is correlated with Child-Pugh score.     

不同多普勒取样容积对血流速度测量的影响

为探讨脉冲波多普勒不同取样容积（ＳＶ）对最大血流速度（Ｖｍａｘ）测量的影响，我们用内径５．０ｍｍ模拟血管和肝素化人全血，分别以不同血泵流率和ＳＶ为１．５ｍｍ，５．０ｍｍ及１０．０ｍｍ，在仪器其它条件不变的情况下，进行体外模拟脉动血流速度频谱实验。当流率为２００ｍｌ／ｍｉｎ至５００ｍｌ／ｍｉｎ时，ＳＶ为１．５ｍｍ与ＳＶ为５．０ｍｍ和１０．０ｍｍ所测多普勒频谱的Ｖｍａｘ值间差异显著（Ｐ＜０．０１），而ＳＶ为５．０ｍｍ与ＳＶ为１０．０ｍｍｒ测值间差异不显著（Ｐ＞０．０５）。提示在临床工作中，根据所测血管内径，尽可能增大ＳＶ长度，以减少通过时间效应所致频谱增宽，更能准确获得血流速度信息。     

Reproducibility of cutaneous thermal hyperaemia assessed by laser Doppler flowmetry in young and older adults

Objectives

The primary objective of this study was to assess the inter-day reproducibility of cutaneous thermal hyperaemia, as assessed using integrating-probe laser Doppler flowmetry (LDF), in young and older men. A secondary objective was to identify the most reproducible form of data expression.

Methods

Cutaneous thermal hyperaemia was assessed on the forearm in 14 young (25 ± 1 year) and 14 older (65 ± 1 year) men, using integrating-probe LDF. The test was repeated 7-14 days later. The baseline, initial peak, and plateau phases of the data traces were identified and expressed as raw cutaneous vascular conductance (CVC), CVC normalised to baseline (%CVC_BL), and CVC normalised to 44 °C vasodilatation (%CVC_MAX). Reproducibility was assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) statistics.

Results

The inter-day reproducibility was dependent on how the data were expressed. The reproducibility of the initial peak and plateau was equally acceptable in both young and older adults when data were expressed as %CVC_MAX (e.g., CVs ranging from 4 to 11%). However, the baseline phase was poorly reproducible in both groups irrespective of the data presentation method used (e.g., CVs ranging from 25 to 35%). Furthermore, expressing data as raw CVC or as %CVC_BL generally showed poor reproducibility for both groups and all phases of the test (e.g., CVs ranging from 15 to 39%).

Conclusion

Integrating-probe LDF is a reproducible technique to assess cutaneous thermal hyperaemia on the forearm when data are expressed as %CVC_MAX in healthy young and older adults without history of hypertension or taking system drugs.     

Effects of smoking on coronary blood flow velocity and coronary flow reserve assessed by transthoracic Doppler echocardiography

BACKGROUND: Smoking is a well-known risk factor for cardiovascular disease. Coronary blood flow velocity (CFV) can be measured directly with transthoracic Doppler echocardiography (TTDE) which is conducted immediately after smoking. PURPOSE: The purpose of this study was to evaluate the chronic and acute effects of smoking on coronary blood flow and coronary flow reserve (CFR) by the use of TTDE. METHODS: Healthy volunteers (11 smokers and 9 nonsmokers) with a mean age of 27 +/- 3 years were included. Smoking was abstained for at least 4 hours before the study. CFV was measured at the distal left anterior descending coronary artery by TTDE at baseline and during intravenous adenosine infusion (140 microg/kg per minute) in all participants. For smokers, CFV was measured immediately after consecutively smoking two cigarettes and during adenosine infusion. RESULTS: CFR and coronary vascular resistance index (CVRI) showed no significant difference between nonsmokers and smokers (CFR: 3.5 +/- 0.8 vs 3.6 +/- 0.6, P = ns, CVRI: 0.28 vs 0.28, P = ns) at baseline. CFR significantly decreased (3.6 +/- 0.6 to 2.8 +/- 0.7, P = 0.008) and CVRI markedly increased (0.28 to 0.35, P = 0.012) after smoking. CONCLUSION: After 4 hours of abstinence from smoking, CFR and CVRI in smokers were similar to those of nonsmokers. However, consecutively smoking two cigarettes acutely reduced CFR and increased CVRI. These findings suggested that smoking could reduce coronary blood flow immediately, even in healthy people.     

原发性高血压早期肾损害超声 多普勒肾血流测定的评价

目的探讨原发性高血压（EH）早期肾损害超声多普勒肾血流测定的诊断价值。方法对60例EH患者按血、尿β     

彩色多普勒血流显像评价“肾通注射液”对急性肾功能衰竭家兔肾血流量的影响

目的　采用彩色多普勒血流显像评估“肾通注射液”对急性肾功能衰竭家兔肾血流量的影响。方法　 30只健康雄性大耳白兔分为正常组、模型组、肾通治疗组 ,每组 10只 ,肌注 5 0 %甘油等渗盐水制造急性肾小管坏死模型 ,正常对照组同法注射等容量生理盐水。造模后 1h,治疗组腹腔注射肾通注射液 (肾通组 ) ,正常组和模型组腹腔注射等容量 5 %葡萄糖 ,生化法监测肾功能 ,彩色多普勒血流显像动态观察各组家兔治疗后 2 4 h、4 8h、72 h肾血流动力学变化。结果　肾通组肾血流量较模型组显著升高 ,各级动脉阻力指数显著降低。肾功能各项指标均有显著改善。结论　“肾通注射液”可改善急性肾功能衰竭家兔肾血液供应 ,彩色多普勒血流显像可定量检测肾血流量     

Doppler ultrasound evaluation of acute effects of cigarette smoking on portal blood flow in man

The acute systemic haemodynamic effects of cigarette smoking are well known, but there are no studies dealing with the possible smoke-related acute changes of splanchnic circulation in man. In the present study we evaluated the acute effects of cigarette smoking on portal blood flow (PBF) in normal subjects by the use of Doppler ultrasound. Twenty-three normal volunteers were asked to smoke two cigarettes with a known total nicotine content (1.1 mg each) in a supine position. Each cigarette was smoked during a 5 min period and a 5 min interval between the two cigarettes was allowed. Both mean PBF velocity and volume were evaluated at time 0 (basal values) and 8, 15, 30, 45 and 60 min after the first inhalation of the first cigarette. The basal mean PBF velocity (22 cm/s; 95% CI 20.9–24.2) was significantly decreased at 8 min (19 cm/s; 95% CI 17.9–20.8; P< 0.0007) and 15 min (20 cm/s; 95% CI 17.8–21.3; P< 0.005). Similarly, the PBF volumes at 8 min (710 mL/min; 95% CI 660–876; P< 0.002) and 15 min (750 mL/min; 95% CI 650–862; P< 0.005) were significantly lower than those measured at time 0 (850 mL/min; 95% CI 766–987). Both mean PBF velocity and volume measured at successive times did not differ significantly from basal values. The present study shows that cigarette smoking causes acute and transient reduction of PBF velocity and volume in normal subjects.     

Comparison of relative coronary Doppler flow velocity reserve to stress myocardial perfusion imaging in patients with coronary artery disease.

To compare relative coronary artery vasodilator reserve (rCVR = CVRtarget/CVRreference) to myocardial perfusion stress imaging, 48 patients with coronary artery stenoses (61% +/- 16%; mean, +/- SD; range, 30%-91%) had measurements of target and reference vessel CVR (Doppler-tipped guidewire). rCVR was computed and compared to stress 201thallium or (99m)technetium-sestamibi myocardial tomography. Compared to 24 patients with negative stress imaging studies, 24 patients with positive stress studies had angiographically more severe stenoses (74% +/- 13% vs. 44% +/- 24%; P = 0.0005) with lower CVR(target) (1.68 +/- 0.55 vs. 2.46 +/- 0.74; P = 0.002) and lower rCVR (0.72 +/- 0.22 vs. 1.0 +/- 0.26; P < 0.003). Based on receiver-operator characteristic (ROC) cut points (CVR > 1.9; rCVR > 0.75), compared to CVR, rCVR had similar agreement (Kappa 0.54 vs. 0.50), sensitivity (63% vs. 71%), specificity (88% vs. 83%), and positive predictive value (83% vs. 81%) with myocardial perfusion tomography. A concordant CVRtarget/rCVR only slightly increased sensitivity, specificity, and positive predictive values (77%, 90%, and 87%, respectively). Although rCVR, like CVR, correlates with stress myocardial perfusion imaging results, rCVR did not have significant incremental prognostic value over CVR alone for myocardial perfusion imaging. However, rCVR does provide additional information regarding the status of the microcirculation in patients with coronary artery disease and complements the CVR for lesion assessment.     

Assessment of coronary blood flow in humans using phase difference MR imaging

Coronary blood flow quantification provides essential information on the hemodynamic significance of coronary artery stenoses. Recently, magnetic resonance (MR) flow mapping has emerged as a new promising method to noninvasively determine flow velocity and flow volume within the coronary arteries. The aim of this study was to compare phase difference (PD) MR flow quantification with intracoronary Doppler flow measurements in 15 patients with suspected or known coronary artery disease. Flow quantification was attempted before and after systemic application of 5mg Isosorbiddinitrate (ISDN) in order to determine possible alterations in coronary flow volume. PD MR flow mapping was performed successfully in 13 of the 15 patients. For flow velocities and flow volume values, a close correlation between PD MR and Doppler flow measurements was found (r = 0.79 and r = 0.90, respectively). However, average flow measured by PD MR was significantly lower than the invasively obtained values (9.0 ± 4.4 cm/sec vs. 11.7 ± 4.9 cm/sec; p<0.001 and 46.3 ± 28.7 ml/min vs. 53.4 ± 32.8 ml/min; p<0.05). Although the mean flow volume remained constant in the entire patient group after ISDN application, individual changes (increase in 6, decrease in 4 cases) could be documented with PD MR imaging and showed a good correlation to the Doppler method (r = 0.82). In conclusion, PD MR flow mapping is a promising method for the noninvasive quantification of coronary blood flow and therefore offers the potential of assessing coronary artery stenoses. However, technical improvements are mandatory in order to increase accuracy of the method.     

应用彩色多普勒超声检测脑血流灌注评价血管性痴呆

目的:探讨采用彩色多普勒超声检测颈内动脉及椎动脉血流估测脑血流灌注在评价血管性痴呆(VD)中的价值。方法:VD患者56例,对照组42例,采用GE Vivid 7彩色多普勒超声诊断仪,检测颈内动脉和椎动脉颅外段的血管内径、收缩期最大峰值流速(Vm)及流速-时间积分(VTI)以计算颈内动脉及椎动脉的每分血流量,2者相加获得总的血流量。结果:VD组双侧颈内动脉和椎动脉的Vm、颈内动脉血流量和总血流量均较对照组下降(P<0.05)。MMSE评分与总血流量呈正相关。结论:通过彩色多普勒超声对颈内动脉、椎动脉血流量指标进行检测,可较准确反映血管性痴呆患者脑血流灌注的改变,是一种研究血管性痴呆的有效方法和手段。     

冠脉造影血流TIMI分级及计帧值与多普勒血流速度的相关性

目的：应用血管内多普勒导丝测量血流速度（DFV）评价冠脉造影血流TIMI分级（TIMI－FG）及其计帧值（TIMI－FC）的准确性。方法：在11只猪的冠状狭窄模型和36例冠脉造影及17例行血管介入治疗的病人，比较TIMI－FG，TIMI－FC与DFV的相关性。结果：（1）随着动物模型充盈球囊造成血管狭窄程度的加重，DFV减慢，TIMI－FG下降，TIMI－FG变大，P均＜0．01；（2）17例病人25支血管在介入治疗后，DFV增加，TIMI－FG上升，TIMI－FC变小（P＜0．05－＜0．01）；（3）TIMI－FC与DFV呈负相关（冠心病人r=-0.49-0.58,猪r=-0.41)；而TIMI－FC变化差值与DFV变化差值相关性则有提高（冠心病人r=-0.62-0.66,猪r=-0.71)。结论：冠脉造影TIMI－FC推测冠心病流速度具有一定准确性，对血流速度变化的推测更佳。     

二维及彩色多普勒超声观察胃十二指肠动脉血流动力学参数

目的 :初步评估超声检测胃十二指肠动脉 （GDA ）、肝总动脉 （CHA ）的显示率与正常值范围 ,观察进食前后GDA、CHA血流参数的变化。方法 :应用二维及彩色多普勒超声分别测量 30例正常成人空腹和服用 2 5 0 g/ L葡萄糖 2 0 0 ml后 4 0 m in测 GDA、CHA的血流动力学参数的变化。结果 :正常成人 GDA二维超声与彩色多普勒显像的显示率分别为 91%和 96 % ,餐后 GDA、CHA血管内径、血流速度和血流量高于餐前 ,PI、RI变化不显著。结论 :掌握 GDA、CHA的检查方法及正常值范围对临床有重要意义 ,进餐对 GDA、CHA血流参数有显著影响。