基于小波变换的心阻抗微分信号去噪及特征点检测研究

利用心阻抗微分信号的特征点可计算出多个血流动力学参数,进而判别心功能状态,因此特征点的准确提取显得尤为重要。本文应用实验室自行设计开发的KF_ICG型无创心功能检测仪采集了健康人和重庆市大坪医院22例患者数据,应用小波阈值法对采集的数据进行降噪处理,对降噪后的信号采用bior3.7小波进行6层分解后定位特征点。结果表明,该法无论对健康人还是存在诸多噪声干扰的临床患者数据都能有效实现特征点的精确定位,有助于实现阻抗法无创检测血流动力学参数的临床应用。     

基于脉搏波传导时间的连续血压测量系统

针对现有连续无创血压测量系统采样频率和计算精度较低的问题,我们设计了一套基于STM32F103T4和DSP TMS320C5535芯片的双核血压测量系统。利用STM32和DSP芯片在信号高速采样及高精度运算上的优势,实现了对脉搏波信号的高速采样和计算,改善了连续无创血压测量方法的精度。实验测量30名随机受试者,其医用水银血压计和本系统测量结果的差值均符合美国医疗仪器促进协会(AAMI)标准要求,通过Bland-Altman差值法对两种方法进行一致性检验分析,结果表明两者具有很好的一致性。本研究设计的连续无创血压测量系统可初步在家庭和临床医疗方面进行人体血压的动态跟踪测量。     

胸外按压质量的无线监测与传输系统研制

目的:介绍了基于蓝牙无线传输的胸外按压质量监测系统。方法:本系统主要由硬件电路部分与软件部分组成。硬件电路部分由双电源电路、信号发生电路、信号检测与放大电路、单片机与蓝牙传输模块等部分组成。通过在胸外按压过程中采集、无线传输、分析胸阻抗信号等参数的变化,实现对胸外按压质量的时监测。电源产生电压信号,通过电极片传至人体,由接收的电流信号的变化得到人体阻抗的变化。在胸外按压过程中,持续采集信号,信号被电极片接收通过各级电路放大、滤波、整形等得到稳定的信号,通过51单片机进行实时采样,经蓝牙传输至监测端,通过软件处理将结果最终反映在手机上,对胸外按压的效果进行评估。软件部分:数据处理是通过基于MATLAB的GUI界面,对信号处理并予以呈现。蓝牙通信部分采用C51编程,实现利用主机控制器接口HCI层建立点对点的蓝牙异步无链接数据传输通道。结果:设计了基于蓝牙无线传输的胸外按压质量监测系统,整个系统可以实时稳定的对胸外按压效果进行有效监测。结论:通过对本系统硬件结构、软件功能及特点的介绍,指出了其在临床急救方面潜在的应用价值。     

基于指-趾脉搏波传导速度的无创动脉硬化检测系统设计

本文提出一种新型的无创动脉硬化检测方法,并设计相应的系统。传统仪器多采集肱部、踝部脉搏波计算传导速度,而本文提出的检测方法利用光电容积法采集手指、脚趾人体末梢脉搏波,从而实现计算,并把测量结果命名为指-趾脉搏波传导速度。初步的实验结果表明基于指-趾脉搏波传导速度的无创动脉硬化检测系统的测量重复性良好,与传统的检测仪器测量结果基本一致。传统仪器需要采用充气泵、放气阀和袖带来进行测量,而该系统使用光电容积法,只需连接光电探头即可完成测量,大大减小仪器体积和重量,为实现动脉硬化检测移动化、便携化提供了可能。     

血糖无创检测原理及仪器实现研究

阐明了无创血糖检测是血糖检测技术的发展方向。它可以实现对血糖浓度更加及时地监控,减少或减轻糖尿病人的并发症,对糖尿病的诊断和治疗具有重大意义。对人体血糖无创检测方法和仪器的现状进行了讨论,重点介绍了三种有仪器面世的方法,包括实现血糖无创检测的基本原理、试验验证结果以及仪器研究进展,并讨论了每种方法在实现血糖无创检测中存在的问题。最后对当前无创血糖检测中的难点进行了进一步的讨论,并在此基础上分析指出了未来无创血糖检测技术的发展方向。     

心功能无创检测监护仪器

心功能无创检测监护仪器ＴＰ—ＣＢＳ血压／心脏功能无创检测监护仪是根据国家自然科学基金研究课题和国家火炬计划的要求研制的系列产品，目前包括标准型、袖珍型、普通监护型和动态监护型四种型号。该系列仪器采用特制的传感器，从人体挠动脉拾取脉博信号，经电脑处理分...     

基于ARM7的新型开放式多功能医用信号仪的研制

目的现有的常用信号发生器或生理信号发生器不能同时输出常用信号和模拟生理信号,本文提出一种新型开放式多功能医用信号仪,用于检测各种生理信号,听取不同频率、不同信号的声音及输出常用信号等。方法该仪器以STM32F103RF和高性能集成芯片MAX038为核心。此医用信号仪包括硬件和软件两部分,其中硬件含有ARM7单片机控制单元、按钮组输入单元、数据存储单元等12个单元,软件用C语言编写,并采用keil C进行编译。结果该仪器不仅能输出常用的正弦、方波、三角波、锯齿、矩形信号,还能输出医学中常用的多种生理信号如心电、脉搏波等,且信号波形频率、幅度、类型、波形均采用直观的LCD液晶显示。此外,该仪器具有一个高驱动能力的接口,可直接驱动耳机等,以方便对人耳频率特性和人体阻抗特性的研究和教学。同时,为了便于使用一般示波器能观察各种生理信号,对同一种生理信号可输出不同的频率。结论本仪器使用方便,可广泛应用于科研、教学、测试和仪器维修等。     

基于体表生理信号的呼吸功能监测仪研制

目的：研制一款基于体表心电、膈肌电和胸阻抗信号的呼吸功能监测仪原理样机,可在家庭、医疗急救等场合实现对呼吸功能的持续监测。方法：以STM32F411VET6单片机开发系统为平台,用一对Ag/AgCl电极作为高频激励信号的输出和心电、胸阻抗信号的检测电极,另一对Ag/AgCl电极作为膈肌电信号检测电极,两对电极同时检测心电、膈肌电和胸阻抗信号。系统硬件主要包括心电信号检测电路、胸阻抗信号检测电路、膈肌电信号检测电路、恒流源激励电路以及微控制器。系统采用12 V可充电锂电池供电,模拟信号通过单片机A/D转换成数字信号,通过SDIO接口存储于SD卡。在完成样机制作和性能测试之后,采集13例因呼吸功能障碍实施机械通气患者和13例健康成年人的信号,计算15个与呼吸功能相关的参数,比较机械通气患者与健康对照组参数之间的差异,验证了呼吸功能监测仪的可靠性。结果：样机采集信号的信噪比>10 dB、共模抑制比>80 dB,样机漏电流<30μA。机械通气患者的吸气时间、呼气时间、潮气量、胸阻抗峰峰值、胸阻抗1 s变化量、膈肌电低频功率、膈肌电高频功率、高频比低频、膈肌放电面积、膈肌放电时...     

5—10 用AppLE—Ⅱ微机检测心功能动力学指标

近十余年来,随着现代科学技术在医学中的应用,无创心功能检查方法得到蓬勃的发展。它与创伤方法相比有安全、可重复检查等优点。对于老年保建,早期发现心脏病患者及健康检查等更是创伤性方法不能代替的。用阻抗法或导纳法检测心血管系统的动力学指标,由于计算公式较多。人工测算极为费时,使这一方法在临床的应用受到很大的限制。若能用微机进行检测处理,对上述检测方法在临床中的推广应用一定会带来好处。我们选用价格比较便宜的AppLE—Ⅱ通用微型计算机和三道生理记录仪。把心电     

一种新型胃动力检测系统的设计与实现

目的 以生物阻抗技术为基础设计胃动力检测系统.方法 检测系统由采集平台和分析平台2部分构成.前者实现胃电和胃动力阻抗信号的同步采集和数据传输,后者对提取的胃动力阻抗信号和胃电运用小波多分辨分析进行处理,并提取信号的时域、频域和支配频率等参数完成统计分析.结果 实验结果表明功能性消化不良患者（病理组）的胃运动正常节律百分比（PNF）和正常功率百分比（PNP）明显小于健康大学生志愿者（对照组）,病理组的节律变异系数（FIC）和功率变异系数（PIC）大于对照组.结论 胃动力检测系统的实现不仅使胃电和胃阻抗信息得到同步获取,同时为胃动力研究和临床检测提供一种电-机复合过程的检测方法.     

Development of a wearable multi-frequency impedance cardiography device

Abstract

Cardiovascular diseases as well as pulmonary oedema can be early diagnosed using vital signs and thoracic bio-impedance. By recording the electrocardiogram (ECG) and the impedance cardiogram (ICG), vital parameters are captured continuously. The aim of this study is the continuous monitoring of ECG and multi-frequency ICG by a mobile system. A mobile measuring system, based on ‘low-power’ ECG, ICG and an included radio transmission is described. Due to the high component integration, a board size of only 6.5?cm?×?5?cm could be realized. The measured data can be transmitted via Bluetooth and visualized on a portable monitor. By using energy-efficient hardware, the system can operate for up to 18?hs with a 3?V battery, continuously sending data via Bluetooth. Longer operating times can be realized by decreased transfer rates. The relative error of the impedance measurement was less than 1%. The ECG and ICG measurements allow an approximate calculation of the heart stroke volume. The ECG and the measured impedance showed a high correlation to commercial devices (r?=?0.83, p?<?0.05). In addition to commercial devices, the developed system allows a multi-frequency measurement of the thoracic impedance between 5–150?kHz.     

Application of computer modelling and lead field theory in developing multiple aimed impedance cardiography measurements

Conventional impedance cardiography (ICG) methods estimate parameters related to the function of the heart from a single waveform that reflects an integrated combination of complex sources. We have previously developed methods and tools for calculating measurement sensitivity distributions of ICG electrode configurations. In this study, the methods were applied to investigate the prospects of recording multiple aimed ICG waveforms utilizing the 12-lead electrocardiography (ECG) electrode locations. Three anatomically realistic volume conductor models were used: one based on Visible Human Man cryosection data and two on magnetic resonance (MR) images representing end diastolic and end systolic phases of the cardiac cycle. Based on the sensitivity distributions obtained, 236 electrode configurations were selected for preliminary clinical examination on 12 healthy volunteers and 9 valvular patients. The model study suggested that a variety of configurations had clearly enhanced sensitivity to the cardiovascular structures as compared to conventional ICGs. Simulation data and clinical experiments showed logical correspondence supporting the theoretically predicted differences between the configurations. Recorded 12-lead ICG signals had characteristic waveforms and landmarks not coinciding with those of conventional ICG. Furthermore, configurations showing resemblance to invasive data and morphological variations in disease are of interest. The results indicate the applicability of the modelling approach in developing ICG measurement configurations. However, the level of clinical relevance and potential of the 12-lead method remains to be explored in studies employing dynamic modelling and acquisition of invasive reference data.     

Application of computer modelling and lead field theory in developing multiple aimed impedance cardiography measurements

Conventional impedance cardiography (ICG) methods estimate parameters related to the function of the heart from a single waveform that reflects an integrated combination of complex sources. We have previously developed methods and tools for calculating measurement sensitivity distributions of ICG electrode configurations. In this study, the methods were applied to investigate the prospects of recording multiple aimed ICG waveforms utilizing the 12-lead electrocardiography (ECG) electrode locations. Three anatomically realistic volume conductor models were used: one based on Visible Human Man cryosection data and two on magnetic resonance (MR) images representing end diastolic and end systolic phases of the cardiac cycle. Based on the sensitivity distributions obtained, 236 electrode configurations were selected for preliminary clinical examination on 12 healthy volunteers and 9 valvular patients. The model study suggested that a variety of configurations had clearly enhanced sensitivity to the cardiovascular structures as compared to conventional ICGs. Simulation data and clinical experiments showed logical correspondence supporting the theoretically predicted differences between the configurations. Recorded 12-lead ICG signals had characteristic waveforms and landmarks not coinciding with those of conventional ICG. Furthermore, configurations showing resemblance to invasive data and morphological variations in disease are of interest. The results indicate the applicability of the modelling approach in developing ICG measurement configurations. However, the level of clinical relevance and potential of the 12-lead method remains to be explored in studies employing dynamic modelling and acquisition of invasive reference data.     

The measurement of systolic time intervals. A microprocessor based system for long-term registration of the impedance cardiogram and the systolic time intervals

The systolic time intervals (STI) are reliable parameters for the characterization of left ventricular heart function. The non-invasive methods for the determination of STI are here introduced and compared. The disadvantage of all these methods is their manual evaluation of time intervals which makes a continuous monitoring of STI impossible. Therefore, a microprocessor based system was developed for the automatic registration of STI, stroke time volume (SV) and heart rate from the impedance cardiogram (ICG) and the electrocardiogram (ECG). In this article the preliminary results are discussed of the long-term monitoring of these parameters with the help of this device.     

Establishment of novel detection system for embryonic stem cell-derived hepatocyte-like cells based on nongenetic manipulation with indocyanine green

Hepatocytes derived from embryonic stem cells (ESCs) are expected to be useful for basic research and clinical applications. However, in several studies, genetic methods used to detect and obtain them are difficult and pose major safety problems. Therefore, in this study, we established a novel detection system for hepatocytes by using indocyanine green (ICG), which is selectively taken up by hepatocytes, based on nongenetic manipulation. ICG has maximum light absorption near 780?nm, and it fluoresces between 800 and 900?nm. Making use of these properties, we developed flow cytometry equipped with an excitation lazer of 785?nm and specific bandpass filters and successfully detected ESC-derived ICG-positive cells that were periodic acid-Schiff positive and expressed hepatocyte phenotypic mRNAs. These results demonstrate that this detection system based on nongenetic manipulation with ICG will lead to isolate hepatocytes generated from ESCs and provide the appropriate levels of stability, quality, and safety required for cell source for cell-based therapy and pharmaceutical studies such as toxicology.     

In vivo fluorescence confocal microscopy: indocyanine green enhances the contrast of epidermal and dermal structures

In recent years, in vivo skin imaging devices have been successfully implemented in skin research as well as in clinical routine. Of particular importance is the use of reflectance confocal microscopy (RCM) and fluorescence confocal microscopy (FCM) that enable visualization of the tissue with a resolution comparable to histology. A newly developed commercially available multi-laser device in which both technologies are integrated now offers the possibility to directly compare RCM with FCM. The fluorophore indocyanine green (ICG) was intradermally injected into healthy forearm skin of 10 volunteers followed by in vivo imaging at various time points. In the epidermis, accurate assessment of cell morphology with FCM was supplemented by identification of pigmented cells and structures with RCM. In dermal layers, only with FCM connective tissue fibers were clearly contoured down to a depth of more than 100 μm. The fluorescent signal still provided a favorable image contrast 24 and 48 hours after injection. Subsequently, ICG was applied to different types of skin diseases (basal cell carcinoma, actinic keratosis, seborrhoeic keratosis, and psoriasis) in order to demonstrate the diagnostic benefit of FCM when directly compared with RCM. Our data suggest a great impact of FCM in combination with ICG on clinical and experimental dermatology in the future.     

Sources of error in computerized neuropsychological assessment

Computerized neuropsychological assessment has integrated slowly into research and practice since the introduction of the personal computer. Though initial integration of technology to the laboratory and clinical setting utilized specialized hardware and software, newer generation assessment tools are integrated with “off-the-shelf” operating systems. Further, neuropsychological assessment is beginning to find Internet-based application for remote assessment. As these applications are more broadly applied, it is essential to understand potential errors that can be created both in test administration and in reaction time measurement due to hardware and software interactions. In this article, user considerations are specifically addressed for resident and Internet-enabled assessment software. Potential hardware and software conflicts are defined and potential remediation is suggested. Computerized assessment is a valuable tool for neuropsychologists as long as it is used responsibly with an understanding of the potential technical complications.     

High-resolution determination of the R-R interval.

A preprocessor is described that determines the time interval between successive R waves of the electrocardiogram with an error of less than 0.2 ms. It accomplishes this by sepearting in hardware the function of determining the approximate location of the R wave from the function of localizing with great accuracy the peak of the wave form. With this device it is possible to detect abnormal heart rate patterns characterized by exceedingly small beat-to-beat variability. The approach may be useful for other bioelectric signals.     

GPU-accelerated voxelwise hepatic perfusion quantification

Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using compute unified device architecture-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, nonlinear least-squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30?times using a NVIDIA Tesla C2050 GPU compared to a 2.67?GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626?400 voxels in a patient's liver, it takes 0.9?min with the GPU-accelerated voxelwise computation, compared to 110?min with the CPU, while both methods result in perfusion parameters differences less than 10(-6). The method will be useful for generating liver perfusion images in clinical settings.     

基于智能手机提取PPG测心率方法准确性研究

利用智能手机摄像头采集手指图像,进行脉搏波绘制及心率检测。将采集的图像进行色彩分离,对红色通道的数据进行处理,获得光电容积脉搏波(PPG)数据,手机上进行PPG实时绘制,在图像上以相邻上升坡度起始点的时间作为近似心电RR间期,以此计算心率。该方法获得心率与标准心电图结果比较,准确率达96%,无显著性差异。将该方法能实时检测心率。