基于脉搏波的心输出量监测技术研究进展

心输出量（CO）是人体血流动力学监测的核心参数,对心血管疾病的诊断和治疗具有重要意义,而脉搏波包含了丰富的生理病理信息,其波形特征与血流动力学参数的变化密切相关,因此在CO监测上有着广泛的应用。脉搏波主要分为压力脉搏波和容积脉搏波两类,前者在CO监测上已有成熟的产品,后者则仍在科研阶段,尚未有能满足应用要求的技术产品。本文首先分别介绍压力脉搏波和容积脉搏波各自的特点以及计算CO的理论基础,然后从微创及无创两个方面,介绍几种基于两类脉搏波的CO监测技术,并分析它们的基本原理和优缺点,最后对监测技术的发展和应用做了展望。     

脉搏波法无创检测心输出量的实验研究

监测心输出量的变化,是观察判断心脏功能的重要血流动力学指标.作者应用TP—CBS型心血管血流参数检测仪,通过动物实验与临床常用的有创心输出量检测法——热稀释法及电磁流量计法进行同步测试比较,以验证这种无损伤脉波法对心输出量检测的准确性和可信性,为临床推广应用提供实验依据.通过16只犬的对照性测试结果,与热稀释法比较相关系数(r)在0.7～0.9之间.与电磁流量计法比较相关系数(r)在0.8～0.9之间,得到了较好的相关性.表明应用无创伤脉波法监测心输出量,对临床判断心功能有重要参考价值.     

一种无创脉搏波检测分析系统的研制

研制了一套无创脉搏信号检测分析系统，系统采用生理压力传感器同时采集两路脉搏波信号，实现了脉搏波信号的实时采集、存储、动态显示、波形波速度分析和诊断报告的打印，能够较全面的评价心血管系统的功能。该系统采用单片机与计算机结合的设计方式，同时具有单片机小型化、便携的特点和计算机强大的数据存储、分析、处理的能力。初步临床实验表明，该系统操作方便，稳定性好，检测的可重复性较好。     

Kubicek每搏心输出量计算公式的三维有限元仿真研究

我们从 Kubicek模型三维有限元仿真的角度对 Kubicek每搏心输出量计算公式的临床应用价值进行了研究。在计算机仿真研究中 ,我们对比了模型仿真结果、具体采用 Kubicek每搏心输出量计算公式所得结果以及所设模型的理论计算结果。仿真结果表明 :模型中阻抗改变与主动脉中血液容积改变之间存在着近似的线性关系 ,证明了 Kubicek每搏心输出量计算公式具有一定的临床应用价值 ,同时也为心阻抗血流图基础理论提供了新的研究途径。     

无创光电容积脉搏波检测分析系统

目的 光电容积脉搏波（photoplethysmography,PPG）信号是目前心血管生理病理研究的应用热点之一.针对准确、快速的应用需求,本文设计一种无创PPG检测分析系统.方法 该系统分为前端采集装置和信号处理两部分,其中前端装置以MSP430为核心,完成指端PPG信号的采集、处理与传输;计算机（personal computer,PC）则根据指端PPG信号分析受试者血管弹性信息.在检测过程中,采集前端实时获取心率（heart rate,HR）和血氧饱和度（blood oxygen saturation,SaO2）信息,PC计算的参数有血管硬化系数（stiffness index,SI）和血管反射系数（reflect index,RI）.结果 通过年轻组和年长组的对比实验证明,系统能快速准确采集指端PPG形态特征,能准确描述SI和RI参数变化,其对动脉弹性的评估具有一定参考价值.结论 该系统是适用于PPG信号采集与分析的实验装置.     

基于光电容积脉搏波描记法的无创连续血压测量

为了摆脱传统血压计充气袖带的束缚、实现长期连续的血压监测,很多学者开展了基于PPG实现无创、连续血压监测的研究。阐述基于光电容积脉搏波描记法(PPG)实现无创、连续血压测量的基本原理。将当前基于PPG无创血压监测的研究分为3类,分别为心电(ECG)与PPG结合的血压测量技术、两路PPG结合的血压测量技术、脉搏波特征参数血压测量技术,分析这3类技术的基本测量原理、测量精度及其优缺点。在此基础上,论述基于PPG实现无创、连续监测血压的发展方向。     

基于重搏波谷点的脉搏波波形特征量分析

目的 脉搏波包含许多重要的血流动力学信息.罗志昌教授前期研究,曾提出一个以脉图面积变化为基础的脉搏波波形特征量K.但是在长期的实验中发现相同的K值有着不同的脉搏波波形.方法 在脉搏波波形特征量K的基础上提出以重搏波谷为界将脉搏波波形分为两部分,相应地波形特征量也分为K1,和K2.结果 脉搏波波形特征量K1和K2的变化能够反映人体心脏、血管、血压、微循环功能的变化.结论 脉搏波波形特征量K值分为K1和K2后,解决了原来相同K值而生理状态不同的问题.     

基于脉搏-心电的便携式血压仪的研制

设计一种体积小巧,测量过程无任何束缚的基于脉搏波传导时间(pulse wave transit time,PWTT)的血压仪。从反射式容积脉搏波(photoplethysmography,PPG)和心电波形(electrocardiogram,ECG)中提取脉搏波传导时间,再综合心率、每搏输出量和外周阻力对血压的影响,通过回归分析建立血压模型,最终实现血压测量。应用样机对20名志愿者进行血压测量,同时以传统水银血压计的测量结果作为标准,结果显示收缩压和舒张压的95%一致性界限分别为(-8.3,11.6),(-9.9,12.7),说明两种方法所测的血压值有较好的一致性。血压仪样机实体小巧,使用方便,使用过程没有任何束缚,同时在理论上对基于脉搏波传导时间的血压测量方法进行优化,实现了收缩压和舒张压的测量。     

基于桡动脉脉搏波血流动力学检测的心输出量计算修正

目的心输出量是评估心血管功能的重要参数.长期以来,心输出量作为常规的心血管血流参数已被临床医生、药剂师和生理学家所接受.北京工业大学罗志昌等人通过多年研究,获得了心输出量的临床实用公式,但此公式中的一些近似是以正常健康人的生理条件为基准,在长期的实验中,发现由此得出的心输出量在一些情况下失真,因此有必要对这种失真进行修正.方法通过大量临床实验,用线性回归的方法,通过修正系数,对心输出量计算公式进行修正.结果修正系数与脉搏波特征参数K、年龄、血压和心率有关,修正后的公式计算的心输出量较为接近实际值.结论在没有经过心外科手术的无心瓣膜缺损、主动脉瘤、心衰、心率不齐等疾病的患者,以及健康的孕妇、运动员和普通的健康人中,通过脉搏波特征参数K、年龄、血压和心率计算心输出量是比较可靠的.     

脉搏波的无创检测方式

脉搏波的波形特征与心血管疾病密切相关,其检测方式和传感器的选择都会对脉搏波的检测结果产生重大影响。目前脉搏波无创检测用传感器类型包括压力传感器、压电传感器和光电传感器(反射式和透射式)。检测方式有桡动脉压力脉搏波检测和指端容积脉搏波检测。实际运用结果显示不同的传感器有不同的性能指标和适应范围,检测方式也会对脉搏波的检测产生很大影响。尽管压电传感器和光电传感器都能采集信号良好的脉搏波,但压力传感器由于误差大、强噪声和检测部位难寻等原因已经逐渐被淘汰,此外临床实验证实了桡动脉压力脉搏波检测容易受检测部位和检测个体的影响,指端容积脉搏波具有检测稳定、重复性好、易于操作等优点。     

基于容积脉搏波血流动力学检测的血流动力学参数的临床验证

目的 改进脉搏波无创检测仪的检测方式,考虑到桡动脉检测的操作复杂,因而选择操作简便的指脉检测.方法 通过大量的临床数据分析,确定指脉检测方式与桡动脉检测方式之间的转换关系,计算基于容积脉搏波的部分血流动力学参数,并和超声心动检测结果进行对比.结果 用指端容积脉搏血流方法同步检测的血流参数和超声心动检测血流参数的结果对比,差异没有统计学意义.结论 所得结果表明,在应用指端容积脉搏血流方法检测心输出量及其他血流参数是可行的.     

Dynamics of the interventricular septum and free ventricular walls during selective left ventricular volume loading in dogs

A previous study suggested that a change in the position of the interventricular septum played an important role in regulating cardiac performance during selective right ventricular volume loading. In the present study the cardiac response to selective left ventricular volume loading induced by a shunt between the subclavian artery and the left atrium was examined in anesthetized open-chest dogs. Opening the shunt increased left and reduced right ventricular stroke volume, particularly after blood volume expansion. The end-diastolic transseptal pressure difference increased. Myocardial segment length in the septum and free walls of both ventricles and the distances between the septum and the free walls were measured by an ultrasonic technique. Comparisons at similar left ventricular stroke volume with the shunt open and closed showed that the Frank-Starling mechanisms of the free wall of the left ventricle and the septum were stimulated less with the shunt open. At similar right ventricular stroke volume the end-diastolic dimension of the right ventricular free wall was larger with the shunt open. The distance decreased across the right ventricle and increased across the left ventricle when the shunt was open. We conclude that a change in the position of the septum improves left and reduces right ventricular performance during selective left ventricular volume loading.     

Estimation of beat-to-beat stroke volume from the pulmonary arterial pressure contour in man

A pressure-contour method for determining the stroke volume (s.v.) from the pulmonaryartery (p.a.) pressure was employed to continuously monitor the cardiovascular status of patients. six patients with ‘normal’ p.a. pressures and three severe pulmonary hypertensives were evaluated during isoproterenol and amyl-nitrite administration, Valsalva manoeuvres and arrhythmias to vary circulatory conditions. The total range of s.v. was 5–157 ml, of heart rate 56–130 beats/min and of mean pulmonary-arterial pressure 6–44 mm Hg. Pressure-contour estimations of s.v. were compared with those simultaneously obtained from the same beat with a catheter-tip electromagnetic velocity transducer. Comparison of the two methods for determining s.v. yielded correlation coefficients ranging from 0·84 to 0·95 and standard errors of the estimate from 4·2 to 10·3 ml for each of two formulas used. Correlation between the true and computed s.v. was better during interventions which only modified cardiac output than during administration of drugs that act on vascular smooth muscle. Results obtained in patients with severe pulmonary hypertension did not differ greatly from those with ‘normal’ pulmonary-artery pressures. Despite relatively high standard errors of the estimate with some interventions the ease, rapidity and simplicity of this method have distinct advantages over standard noncontinuous methods.     

Effect of age on cardiac index,stroke index and left ventricular ejection fraction at rest and during exercise as studied by radiocardiography

Radiocardiography was used to measure cardiac output, stroke volume and left ventricular ejection fraction at rest and during muscular exercise in relation with age in 148 healthy subjects (age range: 6–78 years). A clear dependence of these parameters on age was found. The mean annual decrease at rest was 22±9 ml/min/m² for cardiac index, 0.22±0.04 ml/m² for stroke index and 0.0017±0.0003 for left ventricular ejection fraction. Male subjects had significantly (p < 0.001) greater cardiac (9±4%) and stroke indices (11±23%) than females. During submaximal exercise cardiac index increased from 3.5±0.7 l/min/m' to 8.1±1.6 l/min/m² in male subjects (mean age: 32 years) and from 3.1±0.4 l/min/m² to 7.2±1.2 l/min/ m² in female subjects (mean age: 29 years). The corresponding increases in stroke index and left ventricular ejection fraction were: from 52±7 ml/m² to 62±9 ml/m². from 46±7 ml/m² to 51±9 ml/m² and from 0.66±0.08 to 0.79±0.05 and from 0.64±0.10 to 0.72±0.10. In subjects who were 60 years and older the increases of these parameters during exercise were considerably smaller.     

Cardiac sympathetic denervation does not change the load dependence of the left ventricular end-systolic pressure/volume relationship in dogs

It has been shown that in the intact canine heart the left-ventricular end-systolic pressure/volume relation (ESPVR) depends on loading conditions: an increase in arterial vascular resistance causes a leftwards shift and a steeper slope of the ESPVR, suggesting an increased inotropic state. Our purpose was to investigate the possible contribution of the sympathetic nervous system to this load sensitivity of the ESPVR, using intact, but denervated, hearts with normal coronary perfusion and afterload. We used two types of loading intervention: venous volume infusion and gradual occlusion of the descending aorta. ESPVRs were obtained in six anaesthetized open-chest dogs, both before and after bilateral ablation of the stellate ganglia. To exclude the influence of heart rate changes, bilateral vagotomy was performed and the heart was paced. The absence of (unpaced) heart rate changes in response to pressure alterations was used to confirm total denervation. Left ventricular pressure was measured with a micromanometer and volume with a conductance catheter. ESPVRs were essentially linear and characterized by their slope (E _es) and volume intercept at 12 kPa (V ₁₂). We found that E _es (P<0.0001) and V₁₂ (P<0.05) were both significantly different during pressure and volume interventions (0.67±0.29 and 0.41±0.18 kPa/ml for E _es and 16.2±8.2 and 18.2±8.4ml for V₁₂ respectively). Denervation did not significantly affect the parameters of the ESPVR obtained by either volume infusion or aortic occlusion. Two-way analysis of variance revealed no significant interactive effect between denervation and intervention, indicating that the sympathetic nervous system does not influence the load dependency of the ESPVR. The dP/dt _max: EDV relationship behaved similarly. These results suggest that load dependency is an intrinsic property of the myocardium.     

基于指端脉搏波视频信号的心率稳定检测算法

目的:研究一种基于脉搏波的稳定检测心率的算法。 方法:提出一种基于快速独立成分分析（FastICA）算法处理指端脉搏波视频信号。首先通过手机摄像头采集手指视频,在每帧图片中提取感兴趣区域（ROI）,根据每个区域中像素灰度值的变化得到血液容积变化的时序曲线;然后通过对ROI进行RGB通道分离和FastICA后,分别选取红、绿色分量与盲源分离后的估计信号进行相关性分析,筛选出相关性最大的作为后续提取心率的信号,并与波峰法测得的心率进行对比,得到一种稳定的心率检测算法,并利用SPSS软件做相关性分析。 结果:选取R、G通道信号的一致性在95%以上,基于FastICA的算法与统计波峰法获取心率的一致性在95%以上。 结论:FastICA算法能够有效地提高心率测量的稳定性,实验结果验证了该方法的可行性和有效性,对于基于脉搏波的人体生理参数获取具有重要意义。