基于脉搏波特征参数的无创血压测量改进算法

解决目前利用脉搏波特征参数无法准确计算出病理及生理血压(高血压、低血压和正常血压)的问题。利用主成分分析得到脉搏波主成分参数,利用脉搏波主成分参数和血压进行线性回归得到初步血压计算模型,借助较大的数据库和逐步逼近法建立多级模型,提高模型计算值的精度。改进后的算法能够使用脉搏波特征参数建立普适的血压计算模型,计算出的血压值精度较高。本研究提出的基于脉搏波特征参数的无创血压测量改进算法能够有效扩大血压计算范围,实现包括高血压、低血压和正常血压在内的无创血压测量。     

脉搏波传导时间的血压估计模型

为提高动脉血压估计的准确性,提出一个以脉搏波传导时间和脉搏波波形特征参量K值为基础的血压估计双参数模型。采用麻省理工学院MIMIC数据库,通过心电和光电容积脉搏波信号计算得到脉搏波传导时间和特征参量K值,通过有创动脉血压信号计算平均动脉血压,对比分析提出的双参数模型和以脉搏波传导时间为基础的单参数模型血压估计的效果。结果表明相比单参数模型,建立的双参数模型血压估计均方根误差减少1 mm Hg,估计准确率最大提高了10%。引入脉搏波特征参量K值建立的双参数模型在一定程度能改善血压估计效果。     

基于脉搏波特征参数的无创连续血压测量研究进展

脉搏波与血压变化息息相关，可以通过脉搏波特征参数进行无创连续血压测量。本研究首先介绍脉搏波特征参数以及通过脉搏波特征参数进行无创连续血压测量的原理；总结了当前利用脉搏波特征参数计算血压的测量模型，主要有一元线性回归模型、多元线性回归模型和神经网络模型，并主要分析了这些模型的测量原理和研究进展，以及各种模型的优缺点；最后对基于脉搏波特征参数进行血压测量，研究方向进行了展望。     

利用脉搏波连续检测家兔血压的实验研究

目的:研究利用脉搏波连续检测血压方法的准确性和可行性.方法:采用动脉插入法连续测量10只健康成年家兔的血压,并同步记录脉搏波信号.提取某一时段的每搏血压值及相应的脉搏波特征参数进行逐步回归分析,并形成回归方程.利用该回归方程和另一时段的脉搏波特征参数计算该时段的每搏血压值.结果:计算血压值与真实血压值的偏差很小.平均偏差在1 mmHg以内.结论:该方法具有良好的准确性,今后有望应用于实际.     

血压变异性和容积脉搏波特征参数变异性的关联分析

目的 分析血压变异性和容积脉搏波特征参数变异性的相关性,确定相关性较好的参数,为利用容积脉搏波特征参数的变异性来估计血压变异性提供理论依据.方法 同步连续采集运动前后19个样本的容积脉搏波信号和血压信号,根据容积脉搏波信号的波形特征,提取8个特征参数,利用皮尔森相关系数分析血压变异性和容积脉搏波特征参数变异性在时域的相...     

基于脉搏波信号和血管弹性腔模型的动脉血压连续测量方法

目的为满足健康监护中的连续测量血压的要求,研究并实现一种基于脉搏波信号和血管弹性腔模型的动脉血压拟合计算方法。方法利用自制的穿戴式人体生理参数监测系统收集测试对象的脉搏波信号、心电信号以及血压数据。根据心电信号与脉搏波信号的时间关系,推导出收缩压和脉搏波传导时间的回归分析方程,而舒张压的测量,则是通过脉搏波的波形系数分析以及血管单弹性腔模型的参数计算完成。结果试验结果表明,该方法血压测量结果的平均偏差和标准偏差为(0.51±0.74)kPa([384±5.54)mmHg],达到了美国医疗仪器促进协会建议的(0.665±1.064)kPa([5±8)mmHg]标准。结论结合脉搏波信号和弹性腔模型可以估算人体血压值,为连续血压测量提供了新的实现方法。     

基于脉搏波传导时间和脉搏波特征参数的连续血压无创检测

本研究为克服在基于脉搏波传导时间(pulse transit time,PTT)方法无创血压检测中个体差异对测量准确性的影响,分析了个体脉搏波特征参数与血压值的相关性,并将个体脉搏波特征参数中与血压值相关度高的参数作为优化脉搏波特征参数加入PTT与血压的校正模型中,以提高模型普适性。基于偏最小二乘法(partial least squares,PLS)对50名志愿者200组PTT和脉搏波特征参数数据进行训练建模,得到舒张压、收缩压的预测模型。再选取5名新志愿者的PPT和脉搏波特征参数进行预测,最大预测误差小于5 mm Hg,满足AAMI国际电子血压计标准。将优化的脉搏波特征参数和PTT引入到连续血压预测模型当中,有助于提高血压预测模型的准确度和普适性,有助于无创连续血压检测的临床应用。     

两种计算正常成年人短时心率变异性方法的比较研究

目的利用光电容积脉搏波法分析心率变异性,为通过心率变异性(heart rate variability,HRV)参数表征自主神经系统的变化提供新的研究方法。方法对46个健康成年受试者分别同步采集自主呼吸状态下的心电信号和光电容积脉搏波信号,利用二阶差分极大值提取心电图的RR间期,搜索脉搏波极大值提取脉搏波主波波峰间期PP,然后计算通用HRV参数SDNN、RMSSD和LF/HF,并利用回归的统计学方法结合Bland-Altman随机分析法对这两种方法获取的HRV结果进行比较。结果两种方法计算得到的心率变异性参数结果的Pearson相关系数分别为0.998、0.995和0.992,均显著相关(P0.01),Bland-Altman分布图也均在一致性区间内,说明这两种方法在计算心率变异性上具有一致性。结论利用光电容积脉搏波法分析心率变异具有可行性。     

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.     

基于容积血流脉搏波的心血管血流参数监护模块的研制

为解决临床血流参数的实时、连续监护的难题,研制了一种基于容积血流脉搏波的心血管血流参数监护模块.该模块利用容积血流脉搏波可以无创、连续、实时地获得心排出量、心脏指数、外周阻力等重要的心血管血流参数.模块由光电容积脉搏波传感器获得容积血流脉搏波,经信号调理电路放大滤波后,通过A/D转换进入单片机进行实时处理,得到相应的参数.本模块的检测方法简便、无创,除可用于临床监护外,还可以用于社区或家庭检测心血管血流参数;如结合网络技术,还可实现远程医疗,为心血管血流参数的监测提供了简便易行的方法.     

Sham-feeding decreases cardiac output in normal subjects.

The cardiovascular effect of sham-feeding was measured in seven healthy non-obese human subjects by the Fick principle using the carbon dioxide rebreathing method. The subjects were resting in the sitting position and were exposed to the sight and smell but not the taste of a breakfast meal. Cardiac output decreased significantly from a mean value of 4.0 1 min-1 to 3.5 1 min-1 during sham-feeding (Friedman, P = 0.004). The cardiac output returned to basal values in all seven subjects when the sensory stimulus was removed. The decrease in cardiac output was due to a decreased stroke volume, whereas heart rate and blood pressure did not change. The mechanism of the decrease in cardiac output during sham-feeding remains to be established.     

Non-invasive evaluation of the adaptations of cardiac function in the neonatal period: a comparison of healthy infants delivered by vaginal route and caesarean section

Postnatal adaptations of cardiac hemodynamics in infants born vaginally or by caesarean section may be different. These cardiac functions were evaluated by Doppler echocardiography to assess adaptation differences. Cardiac output, heart rate, stroke volume, mean arterial pressure, total systemic vascular resistance, ejection fraction, and ductus arteriosus diameter were determined and compared at 1, 24 and 72 h of life in 22 infants born vaginally (group 1) and 23 born by caesarean section (group 2). One hour after delivery, heart rate, mean blood pressure, and total systemic resistance were found to be higher in group 1 infants (P < 0.01, P < 0.05, P < 0.05 respectively). Stroke-volume measurements were significantly higher in group 2 (P < 0.05). The ejection fraction and cardiac output values were similar in both groups. At 24 and 72 h, no significant differences were observed in measurements of infants born vaginally or by caesarean section. We did not find a parameter negatively affecting healthy newborns in either mode of delivery. However, under pathological conditions affecting the cardiovascular system at 1 h of life, including perinatal infections and hypoxemia, a lower stroke volume, higher heart rate, higher mean blood pressure, and higher peripheral resistance may cause additional work load to the cardiovascular system in infants born vaginally.     

Sex Differences in the Relation of Body Composition to Cardiovascular Parameters and Functions in Korean Adolescents: A School-Based Study

ObjectiveObesity in adolescence is associated with increased cardiovascular risk. The patterns of obesity and body composition differ between boys and girls. It is uncertain how body composition correlates with the cardiovascular system and whether such correlations differ by sex in adolescents.MethodsBody composition (fat-free mass (FFM), adipose mass, waist circumference (WC)) and cardiovascular parameters and functions were studied in 676 healthy Korean adolescents aged 12-16 years. Partial correlation and path analyses were done.ResultsWC correlated with stroke volume (SV) and cardiac output (CO), systolic blood pressure (SBP) and pulse pressure (PP), cardiac diastolic function (ratio of early to late filling velocity (E/A ratio)), and vascular function (pulse wave velocity (PWV)) in boys. Adipose mass was related to SV, CO, SBP, PP, left ventricular mass (LVM), and PWV in girls – and to E/A ratio in both sexes. FFM affected SV, CO, SBP, and PP in both sexes and LVM in boys. Cardiac systolic functions had no relation with any body composition variable in either sex.ConclusionIn adolescence, the interdependence of the cardiovascular system and the body composition differs between sexes. Understanding of those relations is required to control adolescent obesity and prevent adult cardiovascular disease.Key Words: Adolescent, Body composition, Cardiac output, Blood pressure, Pulse wave velocity     

基于LabVIEW的心血管动力学参数分析与研究

目的:根据脉搏波理论设计出一套基于虚拟仪器的心血管动力学参数分析系统。方法:本文以LabVIEW7.0作为软件开发平台,根据示波法原理和弹性腔理论总结提炼出收缩压、平均压、舒张压、心率、每搏心输出量、每分心输出量、外周阻力等参数。结果:通过心血管动力学参数的分析能判断心血管病患者与正常人的差异性,对心血管病的预防及疾病早期发现都能发挥很大的作用。大量的实测结果表明系统有较好的准确性和稳定性。结论:此采集分析系统有操作便捷,灵活性高,可扩展性好的特点,可以直观地观测病人的心血管状况以便及时的对心血管疾病采取措施和进行预防,为心血管动力学参数的分析研究提供了一种简便有效的途径。     

一种可监测人体脉搏波的汽车方向盘辅助装置

目的脉搏波的波形特征与心血管疾病密切相关。本文拟设计一种安装在汽车方向盘上的能独立实时监测脉搏波信号的辅助装置,在驾驶员无意识下获取其血流动力学的相关信息,为监测健康状况提供数据支持。方法该装置利用置于方向盘套表面的反射式脉搏波光电传感器采集脉搏波信号。经过滤波、放大和A／D转换,利用嵌于方向盘助力器内的配套装置对脉搏波信号进行数字处理,实现对脉搏波信号周期的确定、心率和平均动脉压数据的计算,以及信号和数据的存储。最后将处理后的脉搏波波形、心率数据及平均动脉压显示在配套装置的液晶显示屏上,还可通过配套装置中的SD卡接口进行数据传输及存储。结果经受试者实际测试,传感器能够准确测出手指脉搏波并输出,使得方向盘套和助力器具有测量脉搏波、心率及平均动脉压的功能。结论该汽车方向盘辅助器可为用户实时监测脉搏波、心率和平均动脉压,帮助使用者实时监测自己的健康状况。     

Behaviorally-evoked plasma catecholamine response and 24-hour excretion of urinary catecholamines among cardiac and vascular reactors

Individuals differ in the cardiac and vascular processes that underlie blood pressure elevations evoked by environmental stimuli; such differences may reflect variability in sympathoadrenal response. We separated 108 healthy, young-adult males into those with predominant elevations in either cardiac output or peripheral resistance when exposed to psychological challenges. We then asked if they differed on other measures of cardiovascular response, concomitant plasma catecholamine reactions or 24-h urinary excretion of catecholamines. Cardiac reactors, relative to vascular reactors, showed reduced cardiac pre-ejection period, a smaller reduction in stroke volume, and elevated plasma epinephrine response and 24-h urinary epinephrine excretion. Vascular reactors, relative to cardiac reactors, responded to mental stress with more elevated diastolic blood pressure, a rise in peripheral resistance and pulse wave velocity, and a greater reduction in stroke volume. Vascular reactors, however, did not show plasma norepinephrine response or 24-h urinary norepinephrine excretion that was greater than cardiac reactors. The results provide partial support for the hypothesis that variability in sympathoadrenal activity contributes to individual differences in cardiac and vascular reactivity, and extend prior observations by demonstrating covariation of behaviorally-elicited cardiac reactivity with the 24-h excretion of epinephrine.     

Hyperoxia-induced alterations in cardiovascular function and autonomic control during return to normoxic breathing

Hyperoxia causes hemodynamic alterations. We hypothesized that cardiovascular and autonomic control changes last beyond the end of hyperoxic period into normoxia. Ten healthy volunteers were randomized to breathe either medical air or 100% oxygen for 45 min in a double-blind study design. Measurements were performed before (baseline) and during gas exposure, and then 10, 30, 60, and 90 min after gas exposure. Hemodynamic changes were studied by Doppler echocardiography. Changes in cardiac and vasomotor autonomic control were evaluated through changes in spectral power of heart rate variability and blood pressure variability. Cardiac baroreflex sensitivity was assessed by the sequence method. Hyperoxia significantly decreased heart rate and increased the high frequency power of heart rate variability, suggesting a chemoreflex increase in vagal activity since the slope of cardiac baroreflex was significantly decreased during hyperoxia. Hyperoxia increased significantly the systemic vascular resistances and decreased the low frequency power of blood pressure variability, suggesting that hyperoxic vasoconstriction was not supported by an increase in vascular sympathetic stimulation. These changes lasted for 10 min after hyperoxia (p < 0.05). After the end of hyperoxic exposure, the shift of the power spectral distribution of heart rate variability toward a pattern of increased cardiac sympathetic activity lasted for 30 min (p < 0.05), reflecting a resuming of baseline autonomic balance. Cardiac output and stroke volume were significantly decreased during hyperoxia and returned to baseline values (10 min) later than heart rate. In conclusion, hyperoxia effects continue during return to normoxic breathing, but cardiac and vascular parameters followed different time courses of recovery.     

Mechanical principles. Arterial stiffness and wave reflection.

Arterial (and predominantly aortic) stiffening with age is now acknowledged as the cause of isolated systolic hypertension, and the predominant cause of cardiac failure in the elderly. Aortic stiffening is gauged clinically from increase in brachial pulse pressure, but this underestimates change with age, since aortic pulse pressure increases far more than brachial (on account of substantial amplification of the peripheral arterial pressure pulse in young adults). Aortic stiffness can be measured as pulse wave velocity, but this too underestimates ill effects on the heart and central vessels, since the direct effect is amplified by early return of wave reflection. Ill effects of arterial stiffening can best be assessed through analysis of pressure wave contour from the carotid or radial site. Exploitation of relatively constant brachial transfer function enables the central aortic pressure wave to be synthesised from the radial pulse. This new clinical approach links traditional sphygmography (originally introduced in France) with conventional cuff sphygmomanometry, and is being evaluated in clinical and epidemiological studies.     

硝普钠对动物血管力学参数的影响

有研究表明硝普钠具有增加动脉顺应性的趋势和降低外周阻力的作用,但是硝普钠对血管中血流惯性的影响却不统一。本文以Coldwyn等建立的动脉系改良风箱力学模型为主要研究方法对动物动脉血管顺应性(包括中央和外周顺应性),血流惯性和外周阻力等进行了研究,并建立了动脉系总阻抗的公式。然后评价硝普钠对总阻抗的影响以及总阻抗做为一种血管力学参数的灵敏性。实验结果表明:硝普钠具有统计学意义地增加外周血管的顺应性(P<0.05);有增加中央动脉顺应性和血流惯性的趋性;并能降低外周阻力和动脉系总阻抗(P<0.05)。结果还表明动脉系总阻抗是一种灵敏度高的血管力学参数。因此,硝普钠能影响血管参数,对外周血管顺应性和血管总阻抗的作用尤其明显。