基于小波变换的充气法测量血压的算法研究

目的探索腕部充气测量血压的方法及原理,实现小波变换提取脉搏波以及无创血压的计算,为现有腕式电子血压计提供更精确的算法。方法采用小波变换对采集的袖带脉搏压力混合信号进行去噪处理,并分离脉搏波与袖带压。在此基础上采用差分法与阈值法寻找脉搏波峰值点并修正波形干扰点,再对脉搏波峰值点进行高斯曲线拟合法拟合出平滑包络线,并采用改进的幅度系数法进行收缩压、舒张压的计算,并对30名测试者用本方法与听诊法进行对比测试,观察相关性。结果该方法的测试结果与听诊法对比相关性良好,测量血压速度快,舒适度高。结论基于小波变换的充气法测量血压的算法相比传统方法去噪效果好,脉搏波提取精确度高,血压计算结果符合AAMI标准,但需在软件处理算法中做进一步简化研究。     

测量方法导致的血压值差异

目的探讨不同方法测量血压的差异.方法对3组病人(每组50人)分别测量右上肢、左上肢;餐前、餐后;听诊器胸件置于正常位置和塞进袖带的血压数值.结果除左右上肢的舒张压外,收缩压舒张压数值均有非常显著差异.结论测量方法的不规范导致血压值的误差,这是基础护理需重视的问题.     

测量方法导致的血压值差异

目的　探讨不同方法测量血压的差异 .方法　对 3组病人 (每组 5 0人 )分别测量右上肢、左上肢 ;餐前、餐后 ;听诊器胸件置于正常位置和塞进袖带的血压数值 结果　除左右上肢的舒张压外 ,收缩压舒张压数值均有非常显著差异 结论　测量方法的不规范导致血压值的误差 ,这是基础护理需重视的问题 .     

一种袖带测量过程的物理模型及基于这种模型的新型收缩 …

传统的波动法血压无创测量技术由于利用统计学原理，因此必须造成测量的个体误差。本文地袖带测量的物理过程进行了研究，在首先发明了袖带波我失真提取的基础上，提出了一种袖带测量过程的物理模型，并对这一模型进行了证实。另外，根据这一模型提出了人体血压的无创测量方法，该方法不像传统方法那样采用统计学原理，从而避免了所有个体采用统一的血压判据而导致的个体测量误差，实际实验表明，该技术的测量准确性要优于传统的波动     

面向家庭健康监护的血压监护模块设计

目的:血压是反映人体循环系统机能的重要生理参数,血压的监测在临床和医疗保健中有着重要的地位。本文根据示波法测量人体血压的原理,研制出了一种面向家庭健康监护的血压监护系统。方法:系统采用s3c2440作为数据采集,传输及气动电路的控制核心,算法部分采用三次样条插值法来获取脉搏波包络线,最终通过幅度系数法求得舒张压和收缩压。结果:通过该系统对人体进行测试,并和柯氏音法进行了对比,得到了比较满意的结果。结论:实验结果显示本系统稳定,可靠,误差率小,可适用于家庭健康监护。     

非创伤性血压测量的理想化力学模型及其参数辨识

传统的非创伤性测量方法大多根据用脉压袋压迫动脉血管所产生的内部血流信息特征来判断血压。本文通过对脉压袋和肱动脉力学特性的分析,论证了脉压波包络线上的拐点是动脉壁内外侧压强的平衡状态,提出了一个测量收缩压和舒张压的理想化力学模型。通过一百余例实际测试,并与听诊法测量结果进行统计相关分析,证明了该模型的实用性。     

基于SVR的桡动脉血压预测

目的现有的电子血压计主要使用示波法及示波改进法等方法进行血压判定。当患者体征不同时,其脉搏波形也各不相同,可能无法找到脉搏波形中对应的血压值点。本文拟根据临床采集到的桡动脉脉搏波数据使用支持向量回归(support vector regression,SVR)的方法完成与之相对应的血压的预测。方法使用欧姆龙血压计采集到的6581个任意波形的血压样本作为实验数据,其中约3/4样本作为训练集。SVR利用血压样本统计信息进行血压预测。结果实验中95%以上测试样本的收缩压和舒张压误差在[-3%,3%]以内,这表明SVR能够很好地对各类波形样本对应的血压值进行预测。结论使用SVR进行任意波形脉搏波的血压预测是可行且有效的,可以用于桡动脉处血压值的预测。     

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。     

柯氏音法与示波法相结合的新型血压测量仪研究

为提高电子血压计的准确性,研制出将柯氏音法与示波法结合的新型血压测量装置.首先在研究测量过程和信号处理方法的基础上,设计基于驻极体麦克风和电容式压力传感器的电子血压计系统架构;再利用柯氏音和脉搏波的密切相关性,建立基于统计规律的时域窗函数对柯氏音声强信号进行选择性放大,并设计相关实验验证了该方法的有效性;然后提出利用柯氏音法准确性和示波法稳定性的血压值综合求算逻辑.通过初步测试实验和分析,证实了该装置测量结果具有较高的准确性和稳定性.研究表明,利用柯氏音与脉搏波的关系进行综合信号处理和血压值测算,有望获得高准确性的血压自动测量方法.     

一种简化的袖带测量模型及在收缩压测量中的应用研究

传统的波动法血压无创测量技术由于利用了统计学原理，因此必须造成测量时的个体误差。作者对袖带测量的物理进行了研究，根据已有的结论，提出了一种袖带测量过程的物理模型，根据这一模型提出了一种人体血压的无创测量方法，该方法不象传统方法那样采用统计学原理，从而避免了所有个体采用统一的血压判据而导致的个体测量误差，实际实验表明，该技术的测量准确性要优于传统的波动法测量技术，这对改善医学临床血压无创自动测量技术     

Theory of the oscillometric maximum and the systolic and diastolic detection ratios

It is proposed that the maximum in cuff pressure oscillations during oscillometry is due to the buckling of the brachial artery under a cuff. This theory is investigated by means of a mathematical model of oscillometry that includes the mechanics of the occlusive arm cuff, the arterial pressure pulse waveform, and the mechanics of the brachial artery. A numerical solution is provided for the oscillations in cuff pressure for one cycle of cuff inflation and deflation. The buckling pressure is determined from actual arterial data and the von Mises buckling criteria. The buckling of an artery under a cuff occurs near — 2 to 0 mm Hg transmural pressure. This effect corresponds with a maximum arterial compliance and maximum cuff pressure oscillations when cuff pressure is nearly equal to mean arterial pressure (MAP), in support of the suggested theory. The model was also found to demonstrate the basic characteristics of experimental oscillometry, such as an increasing and decreasing amplitude in oscillations as cuff pressure decreases, the oscillations that occur when cuff pressure is above systolic pressure, maximum oscillation amplitudes in the range of 1 to 4 mm Hg, and an oscillatory maximum at cuff pressure equal to MAP. These findings support the case that the model is representative of oscillometry. Finally, the model predicted values for the systolic and diastolic detection ratios of 0.593 and 0.717, respectively, similar to those found empirically. These ratios alter with blood pressure, but the tightness of the cuff wrap did not change their value.     

Oscillometric blood pressure devices and simulators: measurements of repeatability and differences between models

PRIMARY OBJECTIVE: To measure the repeatability and pressure pulse envelope of simulators used for testing oscillometric non-invasive blood pressure (NIBP) devices; to study the effect of different envelopes on NIBP devices, and to measure the difference between NIBP devices due to different oscillometric algorithms. METHODS: Three different models of NIBP simulator and 18 different patient monitors with NIBP function were studied. We developed a pressure measurement system (accuracy 0.048?mmHg) to measure the repeatability of simulators. The effect of changing the envelope was measured by using three simulators with one NIBP device. Differences between 18 NIBP devices were measured using one simulator at seven blood pressure settings. MAIN OUTCOMES AND RESULTS: Simulators generate repeatable pressure pulse envelopes (< 0.2 mmHg) but the magnitude and shape depends on the model of simulator. Oscillometric NIBP devices are highly repeatable (< 2 mmHg) when presented with a repeatable pressure pulse envelope, but different devices employ different algorithms and give different results. For a simulated standard blood pressure setting of 120/80 mmHg, estimates of systolic pressure ranged from 112.6 to 126.6 mmHg (sd of 3.0 mmHg), and diastolic pressure ranged from 74.8 to 86.9 mmHg (sd of 3.5 mmHg). CONCLUSIONS: Simulators and NIBP devices are sufficiently repeatable for clinical use, but further systematic clinical studies are required to better characterize the pressure pulse envelope for different patient groups.     

一种袖带测量过程的物理模型及基于这种模型的新型收缩压测量方法的研究

传统的波动法血压无创测量技术由于利用了统计学原理，因此必然造成测量的个体误差。本文对袖带测量的物理过程进行了研究，在首先发明了袖带波动信号无失真提取技术的基础上，提出了一种袖带测量过程的物理模型，并对这一模型进行了证实。另外，根据这一模型提出了一种人体血压的无创测量方法，该方法不像传统方法那样采用统计学原理［１］，从而避免了所有个体采用统一的血压判据而导致的个体测量误差，实际实验表明，该技术的测量准确性要优于传统的波动法测量技术，这对改善医学临床血压无创自动测量技术的现状是有很大意义的     

Estimation of mean arterial pressure from the oscillometric cuff pressure: comparison of different techniques

Mean arterial pressure (MAP) is determined in most automated oscillometric blood pressure devices, but its derivation has been little studied. In this research, different techniques were studied and compared with the auscultatory technique. Auscultatory systolic and diastolic blood pressure (SBP and DBP) were obtained in 55 healthy subjects by two trained observers, and auscultatory MAP was estimated. Automated MAP was determined by six techniques from oscillometric cuff pressures recorded digitally and simultaneously during manual measurement. MAPs were derived from the peak and foot of the largest oscillometric pulse, and from time domain curves fitted to the sequence of oscillometric pulse amplitudes (4th order and three versions of the 6th order polynomial curve). The agreement between automated and auscultatory MAPs was assessed. Compared with the auscultatory MAP, the automated MAP from the baseline cuff pressure at the peak of the 6th order polynomial curve had the smallest mean paired difference (−1.0 mmHg), and smallest standard deviation of paired differences (3.7 mmHg). These values from the peak of the largest oscillometric pulse were −1.3 and 6.2 mmHg, respectively. Determining MAP from a model of the oscillometric pulse waveform had the smallest differences from the manual auscultatory technique.     

Design and development of a new electronic sphygmomanometer

The paper introduces a new technique for the indirect measurement of the systolic and diastolic blood pressure in humans. The technique is based upon a statistically consistent relationship between the amplitude of the pulsatile pressure waveform at the systolic and diastolic points and the amplitude of pulse signals detected when the artery is fully occluded. An adaptive measurement philosophy has been implemented in the design of an electronic sphygmomanometer which, in addition to a pressure transducer, contains suitable electronic instrumentation for processing and displaying the electronic signals. Verification of overall system accuracy is accomplished with direct comparison with manual auscultatory measurements. Clinical testing of a prototype indicates a satisfactory performance; measurement errors are maintained well within proposed standards for automated sphygmomanometers.     

Cuff Pressure Oscillations in the Measurement of Relative Blood Pressure

The continuous relative blood pressure measure obtained with a partially-inflated arm blood-pressure cuff operates under the same principle as the oscillometric method of blood pressure determination. In psychophysiological studies the rise in blood pressure seen, for example, in response to an emotion-evoking question, produces a rise in cuff pressure, along with any of three pulse-amplitude changes: a decrease, no change, or an increase. These seemingly paradoxical responses which accompany an increase in blood pressure may be explained by considering the relationship of cuff pressure to the cuff pressure for maximum oscillations. Experiments were conducted in which cuff pressure and its oscillations were recorded. Indications of an increase in blood pressure, and the pulse-amplitude changes resulting there from, were obtained at different cuff pressures in the same subject. The results confirm the hypothesis that with cuff pressure below the point of maximum oscillation, an increase in blood pressure results in a decrease in pulse amplitude. With a cuff pressure just above the point of maximum oscillations, an increase in blood pressure results in an increase in pulse amplitude.     

Error Mechanisms of the Oscillometric Fixed-Ratio Blood Pressure Measurement Method

The oscillometric fixed-ratio method is widely employed for non-invasive measurement of systolic and diastolic pressures (SP and DP) but is heuristic and prone to error. We investigated the accuracy of this method using an established mathematical model of oscillometry. First, to determine which factors materially affect the errors of the method, we applied a thorough parametric sensitivity analysis to the model. Then, to assess the impact of the significant parameters, we examined the errors over a physiologically relevant range of those parameters. The main findings of this model-based error analysis of the fixed-ratio method are that: (1) SP and DP errors drastically increase as the brachial artery stiffens over the zero trans-mural pressure regime; (2) SP and DP become overestimated and underestimated, respectively, as pulse pressure (PP) declines; (3) the impact of PP on SP and DP errors is more obvious as the brachial artery stiffens over the zero trans-mural pressure regime; and (4) SP and DP errors can be as large as 58 mmHg. Our final and main contribution is a comprehensive explanation of the mechanisms for these errors. This study may have important implications when using the fixed-ratio method, particularly in subjects with arterial disease.     

脉搏波波速法无创血压测量中多模量血压计算模型研究

针对脉搏波波速法无创血压测量中血压计算模型建模困难和模型计算精度较低的问题,结合T_PTT、ln(T_PTT)及(1/T_PTT)²等模量建立多模量血压计算模型。首先,利用99名随机测试者的实验数据确定多模量模型参数,并基于实验数据计算各模型性能评价指标,其中多模量血压计算模型拟合相关系数最大,为0.891,误差方差最小,仅为6.1,实验表明,多模量血压计算模型具有更好的拟合效果和更低的计算误差。然后,利用医用水银血压计和自主设计的多模量血压测量系统两种方法采集另外36名随机测试者的收缩压和舒张压数据,并计算两种方法采集数据间的相关参数,其中收缩压差值的绝对值d<6 mmHg,差值均值E_d=0.55 mmHg,差值的标准差δ_d=2.98 mmHg;舒张压差值的绝对值d<6 mmHg,差值均值E_d=0.57 mmHg,差值的标准差δ_d=3.42 mmHg,完全符合美国医疗仪器促进协会SP10-199中对电子血压计测量差值＜8 mmHg的要求。最后,采用Bland-Altman差值法,对两种方法测量数据一致性进行检验,发现舒张压与收缩压的95 %一致性界限分别为(-5.3,6.4)和(7.2,-6.2),完全在临床血压测量可接受范围之内,较好地证明多模量血压计算模型用于无创血压测量的有效性。研究结果表明,多模量血压计算模型可以应用于脉搏波波速法无创血压测量。