用近红外光谱对组织氧测量方法的研究

在多层生物组织模型下，提出了一种利用近红外光谱技术定量无损检测组织氧饱和度的方法，讨论了受试者具有不同的外层组织时，如何采用适当的校准方法使半定量测量组织血氧浓度变化值具有可靠性和可比性；自行设计的监测系统，结构较为简洁，其探头包括光源和2个检测器，光源采用双波长LED，检测器为集成光学器件，2个检测器分别放置在与光源不同距离的位置上；以240mmHg压力进行人体前臂组断，氧合血红蛋白HbO2、还原血红蛋白Hb的浓度变化和组织氧饱和度tSO2的测试结果与时间分辨光谱TRS方法所得结果一致；系统基线平稳，具有较好的稳定性和检测精度。     

无创血氧饱和度检测仪的设计

介绍了无创血氧饱和度测量原理,即红外光根据人体组织中不同的血红蛋白氧舍状态具有不同的光吸收谱特征,利用这些特征即可检测人体组织血氧饱和度。系统采用单片机C8051F020为核心,设计了无创血氧饱和度检测仪的各硬件部分和软件流程图,并通过可控数字电位器替代了传统的反馈电阻实现了增益自动调节,克服了个体差异造成的血氧信号只通过固定增益影响了测量精度的缺点。该系统结构稳定,功耗小,成本低,为临床测量提供连续有效的监测信息,适用于临床测量与研究,具有广阔的应用前景。     

基于近红外光谱在皮瓣移植术后的监测系统

皮下组织血氧参量是反映皮瓣移植术后皮瓣存活状况的重要依据。为了无创、连续、实时地监测皮肤组织氧饱和度，采用近红外光谱法进行了理论分析和实验验证，提出了一种电流-电压(I-V)转换思路并搭建了测量系统。利用该系统进行了稳定性验证实验、前臂静脉阻断模拟皮瓣血管栓塞实验。结果表明，不同人体、不同部位的组织氧饱和度存在微小差异，差异幅度均在0.05左右；静脉阻断下系统组织氧参量发生显著改变，最大降幅0.25。该系统具有较高灵敏度，能够连续测量组织氧饱和度参量、反映组织氧变化趋势，可以为临床检测术后皮瓣血氧运输状态提供重要参考。     

组织血氧参数近红外无损检测技术及自主创新之路

用近红外光谱方法无损、实时、连续检测人体组织中的血氧参数,可直接得到大脑皮层、肌肉等组织中微细血管血液的氧饱和度、血红蛋白浓度的平均值.与有创血气分析和检测指端脉搏血氧饱和度等现有技术相比,具有不可替代的特色和优势.本课题组通过10余年的不懈努力,在原理算法、测试技术、临床应用等方面取得了大量创新性的成果.现已成功地将实验室样机转化为具有独立自主知识产权、达到国际先进水平的产品(TSAH-100).在新生儿医学、运动医学、组织移植、体外循环、药物疗效评定、基础研究等领域得到推广应用,已测试900余例受试者.在长期的工作中,建立了高校、医院、企业紧密合作的科研体制,为研发具有自主知识产权的先进医疗仪器提供了有益经验.     

基于空间频域成像的人体皮肤组织光学和生理参数的提取

人体皮肤组织的光学参数和生理参数对于众多疾病的检测与监测具有重要意义,基于空间频域成像技术提取光学、生理参数具有潜在的临床应用价值。空间频域成像技术需要至少在两个波长下提取氧合血红蛋白和脱氧血红蛋白浓度;在反演人体皮肤组织中的氧合血红蛋白和脱氧血红蛋白浓度时,皮肤中的黑色素会增加结果的不确定度。本课题组搭建了一套空间频域成像系统,在反演人体皮肤组织生理参数的算法中引入最小二乘法和最小误差准则,以解决不确定度问题。实验结果表明：该系统获得的梯度漫反射板的测量值与准确值线性相关,且获取的组织仿体的吸收系数与直接测量法获取的吸收系数的偏差在0.3%～9.6%之间,验证了该系统测量光学参数的有效性。通过对不同黑色素含量的组织仿体进行测量后发现,系统的测量浓度与配制浓度之间显著相关。血液仿体实验和动脉闭塞实验结果表明,系统测量的氧合血红蛋白、脱氧血红蛋白、总血红蛋白浓度以及血氧饱和度随时间变化的趋势符合血液实验变化趋势和闭塞条件的变化趋势,进一步验证了空间频域成像算法提取生理参数的准确性。在体和离体实验结果均说明空间频域成像方法可以用于组织体中血氧饱和度的测量,为实现相关疾病的无创、快速检测提供...     

多媒体计算机系统虚拟红外诊断仪

0　引言不同的光波对人体的穿透能力不同 ,肉眼和摄像机对不同光波的反应也不同。近红外光谱对人体有一定的穿透力 ,尤其是对人体软组织 ,如脂肪 ,纤维组织 ,乳腺腺体都有较强的穿透性 ,其穿透程度与物质密度有关。近红外线的穿透能力还具有一定的选择性。血红蛋白对近红外线有吸收作用。因此 ,因血红蛋白的吸收特性会在近红外的图像上产生吸收阴影。这种阴影的范围和灰度等级将直接反映出人体局部组织含血红蛋白的多少。而血红蛋白的多少也正是医务人员判断人体组织病变的依据之一。再辅以血管影像对诊断皮下肿瘤有很大帮助。红外诊断仪是…     

基于近红外光的无创血红蛋白含量检测系统设计

为了实现无创快捷的人体血红蛋白定量检测，为医生和病人带来方便，设计并实现了一套基于近红外光的无创血红蛋白含量检测系统，系统通过测量人体手指处的漫反射光谱，对血液中各物质浓度和光吸收度进行回归分析，从而定量检测血红蛋白含量，对实验对象的测量结果与标准值的相对误差在7％以下，实验结果说明该系统设计方案合理，能够用于人体血红蛋白含量的检测。     

一种基于关键点的红外图像人体摔倒检测方法

针对已有人体摔倒检测方法在复杂环境场景下易受光照影响、适应性差、误检率高等问题,提出了一种基于关键点估计的红外图像人体摔倒检测方法。该方法采用红外图像,有效避免了光照等因素的影响,经过神经网络找到人体目标中心点,然后回归人体目标属性,如目标尺寸、标签等,从而得到检测结果。使用红外相机采集不同情况下的人体摔倒图像,建立红外图像人体摔倒数据集并使用提出的方法进行检测,识别率达到97%以上。实验结果表明提出的方法在红外图像人体摔倒检测中具有较高的精度与速度。     

基于深度学习的人体摔倒检测算法设计

针对传统检测算法对人体摔倒检测不准确以及实效性不够的前提下,提出一种改进的YOLOV7算法。将一种即插即用的Transformer模块插入到YOLOV7的骨干网络与检测头网络中。替换YOLOV7中高效聚合网络中的3*3卷积,在保证检测速度的同时提升模型的检测精度,其中平均精度提升12.32%、准确率提升5.01%、召回率提升3.33%。改进的YOLOV7人体摔倒检测模型可以满足不同应用场景中对各种设备的部署与高效地检测。     

光学相干层析无创血糖检测中相关性分析及标定

在光学相干层析无创血糖检测中,由于人体皮肤各层组织物质分布并不均匀,且不同种类组织对于血糖变化的相关性也并不一致,因此如何正确地选择皮肤内部用于标定的组织相关区域,最大限度地排除来自皮肤其他层组织无关信号的干扰成为亟需解决的问题之一。通过研究皮肤内部不同深度区域的组织散射系数与血糖变化的相关性,提出一种相关性标定分析算法,利用此算法可以得到皮肤散射系数与血糖变化最相关的组织区域来进行标定,消减了背景噪声以及皮肤内与血糖无关组织层信号的干扰。此算法有利于提高血糖值的预测精度,对于光学相干层析无创血糖检测的研究具有一定的应用价值。     

Optical monitoring of tissue viability parameters in vivo: from experimental animals to clinical applications

Optical monitoring of tissue physiological and biochemical parameters in real-time is a new approach and a powerful tool for better clinical diagnosis and treatment.Most of the devices available for monitoring patients in critical conditions provide information on body respiratory and hemodynamic functions. Currently, monitoring of patients at the cellular and tissue level is very rare. Realtime monitoring of mitochondrial nicotinamide adenine dinucleotide (NADH) as an indicator of intra-cellular oxygen levels started 50 years ago. Mitochondrial dysfunction was recognized as a key element in the pathogenesis of various illnesses. We developed the "CritiView" - a revolutionary patient monitoring system providing real time data on mitochondrial function as well as microcirculatory blood flow, hemoglobin oxygenation as well as tissue reflectance.We hypothesize that under the development of body O2 insufficiency the well known blood flow redistribution mechanism will protect the most vital organs (brain and heart) by increasing blood flow while the less vital organs (gastrointestinal (GI) tract or urogenital system) will become hypoperfused and O2 delivery will diminish.Therefore, the less vital organs will be the initial responders to O2 imbalances and the last to recover after the end of resuscitation. The urethral wall represents a lessvital organ in the body and may be very sensitive to the development of emergency situations in patients. It is assumed that the beginning of deterioration processes (i.e.,internal bleeding) as well as resuscitation end-points in critically ill patients will be detected.In this paper, we review the theoretical, technological,experimental and preliminary clinical results accumulated using the "CritiView". Preliminary clinical studies suggest that our monitoring approach is practical in collecting data from the urethral wall in critical care medicine. Using CritiView in critical care medicine may shed new light on body O2 balance and the development of body emergency metabolic state.     

A miniature hybrid reflection type optical sensor for measurementof hemoglobin content and oxygen saturation of whole blood

A reflection-type hybrid optical sensor was designed for continuous measurement of both hemoglobin content ([Hb]) and oxygen saturation (OS) of whole blood. The sensor was based on a theoretical model using the photon diffusion theory. The prototype sensor consists of a light emitting diode (LED) and photodiode chips mounted on a single substrate and cased in a TO-5 can with its surface covered with clear epoxy resin. The effect of hematocrit variation was eliminated. It was test in goat, calf, and human whole blood over hematocrit range of 20-45%. The modified ratio method reduced the effect of hematocrit variation of hemoglobin OS measurement with improvement in standard deviation of errors from about 7.0 to 2.0%. The standard errors in the estimation of hemoglobin content ranged from 1.5 to 0.5 gm%. The oxygen contents of whole blood derived from the prototype sensor correlated well (r=0.997) with those analyzed using a hemoximeter. The prototype sensors have been used for continuous measurement of oxygen delivery to, and oxygen consumption by, peripheral tissues in artificial heart animals for a duration of 40 days, demonstrating satisfactory performance     

Mathematical model for the hemodynamic response to venous occlusion measured with near-infrared spectroscopy in the human forearm

We propose a mathematical model to describe the hemodynamic changes induced by a venous occlusion in a human limb. These hemodynamic changes, which include an increase in blood volume, a reduction in blood flow, and modifications to the oxygen saturation of hemoglobin, can all be measured noninvasively with near-infrared spectroscopy (NIRS). To test the model, we have performed NIRS measurements on the human forearm, specifically on the brachioradialis muscle, during venous occlusion induced by a pneumatic cuff inflated around the upper arm to pressures within the range 10-60 mmHg. We have found a good agreement between parameters measured by NIRS (total hemoglobin concentration and hemoglobin saturation) and the corresponding model parameters (capacitor voltage and arterial/capillary branch current). In particular, model and experiment indicate that the time constant for blood accumulation during venous occlusion (approximately 73-79 s) is much slower than the time constant for blood drainage following cuff release (approximately 5 s). These results indicate that this mathematical model can be a valuable analytical tool to characterize, optimize, and further develop diagnostic measurement schemes that use venous occlusion approaches.     

基于光谱仪近红外光谱技术的组织氧测量研究

提出了一种基于光谱仪近红外光谱技术(Near Infrared Reflectance Spectroscopy, NIRS)的定量无损组织氧检测系统。通过用微型光谱仪代替传统信号接收处理部分,实时测出了光源波长,并用补偿算法抵消了环境的影响。对经过均值和FFT滤波后的输出光谱信号进行运算后,得出了组织氧浓度。用前臂阻断实验验证了组织血氧饱和度(Regional Saturation Of Oxygen, rSO2)测量结果的有效性。结果显示,测量结果与理论相符,表明基于光谱仪的NIRS技术可以较好地应用于监测组织的血氧饱和度,其适应性比传统方法更强。     

Simple photon diffusion analysis of the effects of multiplescattering on pulse oximetry

Photon diffusion theory is used to derive analytical expressions that relate the ac-dc intensity ratios measured by transmission-mode and reflectance-mode pulse oximeters to arterial oxygen saturation (SaO2). The effects of multiple scattering are examined by comparing the results of the photon diffusion analysis with those obtained using an analysis based on the Beer-Lambert law which neglects scattering. We show that the difference between the average lengths of the paths travelled by red and infrared photons makes the calibration curve of oximeters sensitive to the total attenuation coefficients of the tissue in the two wavelength bands, as well as to absorption by the pulsating arterial blood. Therefore, the shape of the calibration curve is affected by tissue blood volume, source-detector placement, and other variables that change the wavelength dependence of the attenuation coefficient of the tissue. After evaluating the relationship between SaO2 and the red/IR ac-dc ratio (R) under a variety of physiological conditions, we conclude that, for oximeters utilizing fixed calibration curves based on measurements obtained from normal subjects, errors introduced by interfering variables should be less than a few percent when SaO2 exceeds 70%. Predicted errors at lower oxygen saturation values are substantially greater because R is much more sensitive to interfering variables in this measurement range.     

Noninvasive Transcutaneous Monitoring of Arterial Blood Gases

Valuable clinical and physiological data concerning the function of the cardiopulmonary system can be obtained from continuous monitoring of hemoglobin oxygen saturation (SaO2), oxygen tension (PO2), and carbon dioxide tension (PCO2) in blood. While periodic blood sampling is still used clinically to determine arterial blood gases, it is becoming apparent that the recent introduction of continuous noninvasive monitoring of blood gases can offer many advantages. This paper discusses the historical development and significant accomplishments of various techniques available for transcutaneous blood gas monitoring. Four major areas are reviewed: electrochemistry, spectrophotometry, mass spectrometry, and gas chromatography. For each of these techniques, the theoretical basis, instrumentation, and clinical applications are discussed.     

Role of Light Scattering in Spectrophotometric Measurements of Arteriovenous Oxygen Difference

The role of light scattering in the spectrophotometric measurement of arteriovenous oxygen difference (a ?vO2) in whole blood was investigated. Optical absorbance of whole blood and corresponding hemoglobin solutions was measured to elucidate the contributions of true absorbance and "total scattering effects" to the total absorbance of whole blood. Twersky's radiation scattering theory, which provides a mathematical separation of absorbance and total scattering effects, was applied to the data. It is shown that, although the optical density of whole blood is a highly nonlinear function of hematocrit, the difference in optical density between venous and arterial blood is approximately a linear function of the arteriovenous difference in oxygen content. Furthermore, "total scattering effects" contribute significantly more than true absorbance to the total optical density of whole blood and hence to the actual spectrophotometric measurement of a ?vO2. Twersky's equation fits the data remarkably well and thus provides a theoretical basis for whole blood measurements. The validity of whole blood spectrophotometric arteriovenous oxygen difference analyzers is thus demonstrated both empirically and theoretically.     

A New Instrument for the Simultaneous Measurement of Total Hemoglobin, % Oxyhemoglobin, % Carboxyhemoglobin, % Methemoglobin, and Oxygen Content in Whole Blood

The IL 282 CO-Oximeter is a completely automated instrument for the simultaneous analysis of total hemoglobin (THb), % oxyhemoglobin (O2Hb), % carboxyhemoglobin (COHb), % methemoglobin (MetHb), and oxygen content (02 content) in a sample of blood.