基于径向基函数神经网络的肺部加权频差电阻抗成像方法

目的 对肺通气过程进行床旁实时连续图像监控，是机械通气患者和临床医生的迫切需求。肺部电阻抗成像（EIT）可反映呼吸引起的胸腔电特性变化分布，在肺通气监测方面具有天然的优势。本文目的在于建立基于径向基函数神经网络（RBFNN）的肺部加权频差电阻抗成像（wfd-EIT）方法，实现对肺通气的高空间分辨率成像。方法 利用肺部wfd-EIT成像方法实时描绘胸腔电导率分布状况，再通过RBFNN将目标区域可视化并精准识别其边界信息。首先通过数值分析模拟，在各个激励频率利用COMSOL与MATLAB软件建立2 028个仿真样本，分为训练样本集和测试样本集，验证所提出成像方法的可行性和有效性。其次，为了验证仿真结果，建立肺部物理模型，选用具有低电导特性的生物组织模拟肺部通气区域，对其进行成像实验，并采用图像相关系数（ICC）和肺区域比（LRR）定量数据衡量成像方法的准确性。结果 wfd-EIT方法可以在任意时刻进行图像重建，并能够准确反映出目标区域的电特性分布；利用基于RBFNN的算法能够增强目标区域的成像精度，ICC可达0.94以上，更好地凸显其边界轮廓信息。结论 通过wfd-EIT成像方法，利用多频阻抗谱同步测量实现目标区域的快速可视化，并结合RBFNN网络逼近任意非线性函数的优点，实现对目标区域电特性变化的精准识别，为下一步进行临床肺通气的EIT图像监测奠定了理论和技术基础。     

急性缺血性脑卒中不同水平血压管理应用效果及其对近期预后及认知功能的影响

摘要 目的：急性缺血性脑卒中不同水平血压管理应用效果及其对近期预后及认知功能的影响。方法：选择我院2021年7月-2022年9月收治的急性缺血性脑卒中患者180例作为本次研究对象,分为对照组及观察1组、观察2组,对照组不进行降压治疗,将观察1组患者急性期血压控制120/80 mmHg,观察2组血压控制在140/90 mmHg,观察各组患者临床治疗效果、近期预后改善情况及对认知功能的影响。采用美国国立卫生研究院脑卒中量表对患者治疗效果和NIHSS测量评定。结果：治疗后各组NIHSS评分较入院时明显降低,且治疗期间NIHSS评分变化12 d＞8 d＞4 d,观察1组、观察2组患者治疗4 d、8 d、12 d后NIHSS评分较对照组明显降低（P＜0.05）;治疗后观察1组和观察2组总有效率较对照组患者显著提高（P＜0.05）,观察1组与观察2组相比无统计学意义（P＞0.05）;观察1组、观察2组患者治疗后MMSE和MoCA评分较对照组明显升高（P＜0.05）,观察1组和观察2组MMSE和MoCA评分差异无统计学意义（P＞0.05）。Logistic回归分析提示血压控制和入院NIHSS评分则与脑卒中患者近期预后显著相关（P＜0.05）。结论：急性脑缺血性脑卒中急性期对患者进行血压控制能够有效提高患者预后效果,促进患者神经功能恢复,但血压控制120/80 mmHg与140/90 mmHg血压管理方案效果相似。     

维持性血液透析患者透析期血压波动的危险因素及其对生存状况的影响

摘要 目的：观察维持性血液透析（MHD）患者透析期血压波动的状况,分析其危险因素及其对生存状况的影响。方法：从江苏省人民医院选取于2018年4月~2021年7月期间接受治疗的210例MHD患者。将患者根据△收缩压（SBP）的绝对值大小,分为血压低波动组（84例,△SBP的绝对值大小<10 mmHg）和血压高波动组（126例,△SBP的绝对值大小≥10 mmHg）。收集两组患者的一般资料和实验室资料,MHD患者血压波动的危险因素采用Logistic回归模型进行分析。以门诊复查或电话的形式随访1年,统计两组预后情况。结果：单因素结果显示,MHD患者透析期血压波动与透析龄、体质量指数（BMI）、收缩压（SBP）、舒张压（DBP）、磷（P）、白蛋白（ALB）、血红蛋白（Hb）、全段甲状旁腺激素（iPTH）、尿素清除指数（Kt/V）、超滤量有关（P<0.05）。而与年龄、性别、血肌酐（Scr）、尿素氮（BUN）、钙（Ca）、总胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）无关（P>0.05）。多因素Logistic 回归模型结果显示：透析龄越长、iPTH升高、Kt/V下降、P升高、BMI升高是导致MHD患者透析期血压波动的危险因素,ALB上升为保护因素（P<0.05）。两组患者1年生存率、死亡率组间对比无统计学差异（P>0.05）。结论：MHD患者透析期血压波动受到透析龄、iPTH、Kt/V、P、ALB、BMI变化的影响,MHD患者透析期血压波动均会导致患者发生死亡风险。     

老年肥胖型正常高值血压患者24h-动态血压变异特点及与动脉僵硬度的相关性研究

摘要 目的：探讨老年肥胖型正常高值血压患者24h-动态血压变异特点及与动脉僵硬度的相关性。方法：选择2018年1月~2020年5月期间在我院住院的老年正常高值血压患者174例作为研究对象,根据腰围分为腹型肥胖组（n=85）和非腹型肥胖组（n=89）。所有受试者监测24h-动态血压[包括24h平均收缩压（24h-SBP）、白昼平均舒张压（dDBP）、24h平均舒张压（24h-DBP）、夜间平均收缩压（nSBP）、白昼平均收缩压（dSBP）、夜间平均收缩压（nDBP）、血压变异系数（CV）]和颈-桡动脉脉搏传导速度（crPWV）,分析24h-动态血压变异性、节律性特点和crPWV的影响因素。结果：腹型肥胖组患者非杓型血压、24h-SBP-CV、24h-DBP-CV、dSBP-CV、nSBP-CV、夜间SBP下降率以及crPWV均高于非腹型肥胖组（P<0.05）,腹型肥胖组患者动脉僵硬度增高发生率高于非腹型肥胖组患者（P<0.05）。控制混杂因素后,腹型肥胖组患者腰围与夜间SBP下降率（r=0.338）、24h-SBP-CV（r=0.279）、24h-DBP-CV（r=0.259）、dSBP-CV（r=0.208）、nSBP-CV（r=0.317）、crPWV（r=0.543）呈正相关性（P<0.05）。经多元线性回归分析结果显示,腰围、LDL-C、夜间SBP下降率、24h-SBP-CV和nSBP-CV是crPWV的重要影响因素（P<0.05）。结论：腹部脂肪沉积对老年正常高值血压患者24h动态血压变异性和动脉僵硬度有显著影响,部分24h-动态血压参数与动脉僵硬度有关,控制腰围对预防动脉硬化有着重要的意义。     

维持基线心输出量和血压治疗腹腔高压致急性肾损伤的实验研究

摘要 目的：对腹腔高压(IAH)致急性肾损伤模型,采用强心药物维持血压至基线水平,以改善肾脏灌注,探讨其保护和治疗作用。方法：将12只健康小香猪,随机分为两组各6只,均在全麻后收集单位时间的尿量,使用PiCCO连续监测血流动力学数据和激光多普勒血流灌注成像仪监测肾脏表面血流;采用二氧化碳气腹法建立IAH模型,连续监测腹腔内压(IAP),获得MAP、IAP和APP。两组动物IAP均从基线逐步升高至10 mmHg、15 mmHg、20 mmHg和25 mmHg,然后在25 mmHg水平维持8 h后处死动物行肾组织病理学检查。基线血压组（BBP组）动物在IAP 25 mmHg维持15分钟后通过静脉泵入多巴酚丁胺提高心输出量,提高血压,维持血压于基线水平,对照组无干预,监测两组动物肾脏表面灌注、血Cr、TNF-α、IL-6和尿IL-18随IAP的变化状况。结果：随着IAP的升高,两组动物肾脏表面血流均显著下降(P<0.05);对照组血Cr和尿IL-18在IAP 25 mmHg维持8 h后显著升高(P<0.05),尿量明显减少,可以诊断AKI,血清TNF-α、IL-6明显升高(P<0.05)。BBP组提高心输出量和血压治疗后,肾脏表面灌注显著改善(P<0.05),血Cr及尿IL-18较对照组明显下降(P<0.05),尿量明显增加(P<0.05),而血TNF-α、IL-6较对照组无显著差异(P＞0.05)。多组肾脏病理学检查均表现为肾小球肿胀和肾小管水肿,差异不明显。结论：在IAH 25 mmHg维持8 h能造成急性肾损伤模型,采用多巴酚丁胺方法可以明显提高心输出量和血压,进而改善肾脏表面灌注,发挥肾保护作用。     

基于卷积神经网络的大肠杆菌启动子预测

目的 基于位点特异性打分矩阵（position-specific scoring matrices,PSSM）的预测模型已经取得了良好的效果,基于PSSM的各种优化方法也在不断发展,但准确率相对较低,为了进一步提高预测准确率,本文基于卷积神经网络（convolutional neural networks,CNN）算法做了进一步研究。方法 采用PSSM将启动子序列处理成数值矩阵,通过CNN算法进行分类。大肠杆菌K-12（Escherichia coli K-12,E.coli K-12,下文简称大肠杆菌）的Sigma38、Sigma54和Sigma70 3种启动子序列被作为正集,编码（Coding）区和非编码（Non-coding）区的序列为负集。结果 在预测大肠杆菌启动子的二分类中,准确率达到99%,启动子预测的成功率接近100%;在对Sigma38、Sigma54、Sigma70 3种启动子的三分类中,预测准确率为98%,并且针对每一种序列的预测准确率均可以达到98%以上。最后,本文以Sigma38、Sigma54、Sigma70 3种启动子分别和Coding区或者Non-coding区序列做四分类,预测得到的准确性为0.98,对3种Sigma启动子均衡样本的十交叉检验预测精度均可以达到0.95以上,海明距离为0.016,Kappa系数为0.97。结论 相较于支持向量机（support vector machine,SVM）等其他分类算法,CNN分类算法更具优势,并且基于CNN的分类优势,编码方式亦可以得到简化。     

胆囊结石患者结石形态学特征及血浆脂多糖水平与急性胆源性胰腺炎的关系研究

摘要 目的：探讨胆囊结石患者结石形态学特征及血浆脂多糖（LPS）水平与急性胆源性胰腺炎（ABP）的关系。方法：选取2015年10月~2018年9月期间武汉大学人民医院收治的胆囊结石患者164例为研究对象,分析结石形态学特征与并发ABP的关系,同时采用Logistic回归分析ABP发生的危险因素。将所有患者根据LPS水平分为低LPS组（n=65,<10 pg/mL）以及高LPS组（n=99,≥10 pg/mL）,分析血浆LPS水平对不同结石大小、不同总胆固醇（TG）水平患者并发ABP的影响。结果：多发胆囊结石、球状结石、<3 mm结石、软碎型结石患者并发ABP的概率明显高于单发胆囊结石、不规则状结石或泥沙状结石、3~10 mm结石或>10 mm结石、硬型结石或胶冻型结石（P<0.05）。Logistic回归分析结果显示,多发胆囊结石、球状结石、<3 mm结石以及软碎型结石均是ABP发生的高危因素（P<0.05）。当患者处于高TG水平时,高LPS组并发ABP的概率高于低LPS组（P<0.05）,在细小结石患者中,高LPS组并发ABP的概率高于低LPS组（P<0.05）。结论：依据结石形态学特征可对胆囊结石患者并发ABP的可能性作出早期的判断,同时血浆LPS水平升高是高TG以及细小胆囊结石患者易并发ABP的重要因素之一。     

经直肠剪切波弹性成像技术联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值研究

摘要 目的：研究经直肠剪切波弹性成像技术（TRSWE）联合血清癌胚抗原（CEA）、前列腺特异性抗原（PSA）、游离前列腺特异性抗原（FPSA）对前列腺良恶性病变的鉴别诊断价值。方法：选取合肥市第二人民医院2019年1月～2022年6月收治的90例前列腺病变患者,根据病理检查分为前列腺癌组（47例）和前列腺良性病变组（43例）。对所有前列腺病变患者均行TRSWE检查,分析前列腺良恶性病变的图像差异以及弹性模量最大值（Emax）、弹性模量平均值（Emean）。检测所有前列腺病变患者的血清CEA、PSA、FPSA水平并进行对比。采用受试者工作特征（ROC）曲线分析明确Emax值、Emean值以及血清CEA、PSA、FPSA水平联合诊断前列腺良恶性病变的效能。结果：前列腺癌组Emax值、Emean值均高于前列腺良性病变组（均P＜0.05）。前列腺癌组血清CEA、PSA及FPSA水平均高于前列腺良性病变组（均P＜0.05）。经ROC曲线分析发现,Emax值、Emean值以及血清CEA、PSA、FPSA水平联合检测诊断前列腺良恶性病变的效能优于上述5项指标单独检测。结论：TRSWE联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值较高,可有效提升前列腺癌的检出率,可能值得临床推广应用。     

间歇性θ节律经颅磁刺激改善大鼠工作记忆的海马与前额叶跨脑区神经网络效应研究

目的 间歇性θ节律刺激（iTBS）作为一种新型的经颅磁刺激模式，已经广泛应用于探索大脑认知功能和神经调控等方面，但其电生理调控机制尚不清晰，探索iTBS对大脑认知功能的影响及其电生理机制，对脑疾病的治疗和磁刺激的临床应用具有重要意义。方法 本文利用iTBS制备磁刺激大鼠模型，采集记录大鼠在执行工作记忆（WM）任务过程中腹侧海马（vHPC）和内侧前额叶皮层（mPFC）的局部场电位（LFPs）信号，应用格兰杰因果网络分析方法，研究了iTBS对大鼠WM过程中vHPC与mPFC跨脑区神经网络协同和信息交互的影响。结果 iTBS增强了大鼠的学习记忆能力，使其完成工作记忆任务所需时长减少（2.67±1.63）d（P<0.05），iTBS显著改善了大鼠的行为学表现；同时iTBS增强了大鼠在WM期间vHPC与mPFC脑区的自因果网络连接，增加了网络连接强度、连接密度和全局效率（P<0.05）；并且iTBS增强了vHPC与mPFC脑区的跨脑区网络连接，增加了vHPC-mPFC跨脑区的节点度和因果流向（P<0.05）。结论 iTBS磁刺激对大鼠工作记忆行为学及相关脑区神经网络均有显著的积极作用，iTBS可以促进大鼠认知能力，提高大脑神经网络的信息交互和传递效率，iTBS的神经调控机制可能是通过增强大脑vHPC与mPFC之间的网络连接和信息交互来提高工作记忆能力。     

达格列净联合利拉鲁肽对肥胖型T2DM患者的血糖控制、胰岛素功能的影响及安全性分析

摘要 目的：探究达格列净联合利拉鲁肽对肥胖型2型糖尿病（T2DM）患者的血糖控制、胰岛素功能的影响及安全性分析。方法：将106例肥胖型T2DM患者按照治疗方法分为两组：联合组患者采用达格列净联合利拉鲁肽治疗（55例）、对照组采用利拉鲁肽治疗（51例）。记录对比两组治疗疗效、不良反应发生情况。检测两组治疗前后血脂代谢指标[脂联素(APN)、总胆固醇（TC）、甘油三酯（TG)]、胰岛素功能指标[稳态胰岛 β 细胞分泌功能指数（HOMA-β）、胰岛素评价指数（HOMA-IR）]、血压[收缩压（SBP）、舒张压（DBP）]以及身体质量指数（BMI）变化。结果：联合组治疗总有效率高于对照组（P＜0.05）,不良反应总发生率高于对照组（P＜0.05）。治疗后,观察组外周血TC、TG水平、HOMA-IR以及SBP、DBP低于对照组（P＜0.05）,APN浓度、HOMA-IR以及BMI高于对照组（P＜0.05）。结论：达格列净联合利拉鲁肽可有效控制肥胖型T2DM患者的血糖、血脂以及血压水平,保护胰岛功能,但也可能导致更多的不良反应。     

Biofeedback of R-wave-to-pulse interval normalizes blood pressure

We investigated whether biofeedback of the R-wave-to-pulse interval, a measure related to the pulse wave velocity, enables participants with either high or low arterial blood pressure to modify their blood pressure. Twelve participants with high blood pressure (mean systolic blood pressure = 142.6 ± 13.5 mmHg; mean diastolic blood pressure = 99.9 ± 12.3 mmHg) and 10 participants with low blood pressure (mean systolic blood pressure = 104.8 ± 6.6 mmHg; mean diastolic blood pressure = 73.2 ± 4.2 mmHg) received 3 individual sessions of RPI biofeedback within a 2-week period. Participants with high blood pressure were rewarded for decreasing and participants with low blood pressure for increasing their blood pressure. Standard arm-cuff blood pressure measurements across the sessions served as dependent variables. Participants with high blood pressure achieved significant reductions of systolic (15.3 mmHg) and diastolic (17.8 mmHg) blood pressure levels from the beginning of the first to the end of the last training session. In contrast, participants with low blood pressure achieved significant increases in systolic (12.3 mmHg) and diastolic (8.4 mmHg) blood pressure levels. The degree of blood pressure changes in this study might be of clinical relevance. With prolonged and refined training regimens, even larger effects seem to be likely.     

人体通气状态对动脉血气波浪式幅度的影响*

目的: 本研究旨在发现不同通气模式下动脉血气的变化特点。方法: 选择心功能正常,需要连续监测动脉血流动力学变化的患者6 例,4男2女,年龄（59.00±16.64）岁,体质量（71.67±10.37）kg,左心射血分数（LVEF）（61.33±2.16）%。患者签署知情同意书后,分别于正常呼吸、憋气20 s以及高潮气量过度通气状态下连续15~16次心跳桡动脉、颈静脉逐搏取血,测定PO₂,用于分析三种呼吸状态下动、静脉血气的变化特点。分别比较患者相邻最高和最低值,以验证三种呼吸状态下动、静脉血气是否都存在周期性波浪式信号变化;此外,将患者动、静脉血气周期性波浪式信号的变化幅度进行统计学t检验分析,比较有无差异。结果: 共6例ICU 住院监护患者, 抽取动、静脉血液充满肝素化细长塑化管需要15~16次心跳,即取血需要15~16次心跳,全部覆盖超过2个呼吸周期。患者正常呼吸、憋气20 s以及高潮气量通气状态下动脉血气中PaO₂呈现波浪式变化,幅度分别是（9.96±5.18）mmHg,（5.33±1.55）mmHg和（13.13±7.55）mmHg,分别是各自均值的（8.09±2.43）%,（5.29±2.19）%,（10.40±2.68）%,高通气量呼吸模式波浪式变化幅度大于正常呼吸模式（P<0.05）,正常呼吸模式波浪式变化幅度大于憋气状态（P<0.05）。正常呼吸、憋气20 s以及高潮气量通气状态下静脉血气中PO₂未呈现波浪式变化,幅度分别是（1.63±0.41）mmHg,（1.13±0.41）mmHg和（1.31±0.67）mmHg,分别是各自均值的（3.91±1.22）%,（2.92±1.12）%,（3.33±1.81）%,都显著低于同状态下动脉血气,但组间差异不明显。结论: 分别于三种通气状态下采用连续逐搏动脉取血血气分析法证实,患者高通气状态呼吸时动脉血气的周期性波浪式变化信号增强,憋气时波浪式呼吸变化信号变弱,而静脉血氧分压波浪式变化幅度于三种呼吸状态下都不明显。说明肺通气导致肺换气是影响动脉血液波浪式信号幅度的直接决定性因素。     

Changes in finger-aorta pressure transfer function during and after exercise.

Noninvasive finger blood pressure has become a surrogate for central blood pressure under widely varying circumstances. We tested the validity of finger-aorta transfer functions (TF) to reconstruct aortic pressure in seven cardiac patients before, during, and after incremental bicycle exercise. The autoregressive exogenous model method was used for calculating finger-aorta TFs. Finger pressure was measured noninvasively using Finapres and aortic pressure using a catheter-tip manometer. When applying the individual TFs found during rest for reconstruction of aortic pressure during all workloads, systolic pressure was increasingly underestimated, with large variation between subjects: +4.0 to -18.1 mmHg. In most subjects, diastolic pressure was overestimated: -3.9 to +5.5 mmHg. Pulse pressure estimation varied between +4.5 and -21.9 mmHg. In all cases, wave distortion was present. Postexercise, error in reconstructed aortic systolic pressure slowly declined, and diastolic pressure was overestimated. During rest, the TF gain had a minimum between 3.65 and 4.85 Hz (Fmin). During exercise, Fmin shifted to frequencies between 4.95 and 7.15 Hz at the maximum workload, with no change in gain. Postexercise, gain in most subjects shifted to values closer to unity, whereas Fmin did not return to resting values. Within each subject, aorta-Finapres travel time was linearly related to mean pressure. During exercise, Fmin was linearly related to both delay and heart rate. We conclude that, during increasing exercise, rest TFs give an increasingly unreliable reconstruction of aortic pressure, especially at higher heart rates.     

Dynamical systems analysis of arterial blood pressure signals in relation to heart rate fluctuations in chick embryos

We attempted a new approach based on a modern dynamical system theory to reconstruct the arterial blood pressure signals in relation to heart rate fluctuations of developing chick embryos. The dynamical systems approach in general is to model a phenomenon that is presented by a single time series record and approximate the dynamical property (e.g. heart rate fluctuations) of a system based only on information contained in a single-variable (arterial blood pressure) of the system. The time-series data of the arterial blood pressure was reconstructed in 3-dimensional space to draw characteristic orbits. Since the reconstructed orbits of the blood pressure should retain information contained in the pressure signals, we attempted to derive instantaneous heart rate (IHR) from the reconstructed orbits. The derived IHR presenting HR fluctuations coincided well with the IHR obtained conventionally from the peak-to-peak time intervals of the maximum blood pressure. Movements of the reconstructed orbits of the arterial blood pressure in 3-dimensional space reflected HR fluctuations (i.e. transient decelerations and accelerations).     

有创动脉压监测在危重肝胆手术患者中的应用

目的:探讨有创动脉压监测在危重肝胆手术患者中的应用方法与价值。方法:选择2011年2月到2015年4月在我院进行危重肝胆手术的患者110例,随机分为治疗组与对照组各55例,治疗组在围手术期给予有创动脉压监测,对照组在围手术期给予无创动脉压监测。除所用传感器不一样,均采用监护仪检测患者在围手术期内血压异常、血流动力学参数变化以及并发症发生情况。结果:治疗组围手术期的血压异常率为36.4%,对照组为12.7%,治疗组的血压异常率明显高于对照组(P0.05)。治疗组术中的平均动脉压(MAP)、每搏出量(SV)、每搏指数(SI)、心输出量(CO)和心脏指数(CI)都明显高于对照组(P0.05)。两组围手术期的感染、血肿、神经损伤、皮肤坏死等并发症发生情况对比差异无统计学意义(P0.05)。结论:有创动脉压监测在危重肝胆手术患者中的应用可有效反映血压异常情况,有利于进行心功能的判定,安全性好,有很好的应用价值。     

Numerical study to evaluate the effect of a surface-based sensor on arterial tonometry

Abstract

Arterial tonometry is a widely used non-invasive blood pressure measurement method. In contrast to the cuff-based method, it is possible to obtain a continuous pressure profile with respect to systolic and diastolic pressures using this method. However, due to a requirement of arterial tonometry—that a sensor needs to be placed directly above a blood vessel—placement error is inevitable if the measurement device is only capable of measuring local regions. This study assumed that the plate sensor is flexible, thus reducing the placement error. We investigated the pressure distribution along the wrist surface rather than the local region through the contact simulation between the flexible plate sensor and the wrist. As a result, we concluded that there is a unique pressure distribution for any specific wrist, regardless of the length and position of the plate, and that it is possible to measure the blood pressure using the response at the wrist surface to the pressure inside the radial artery.     

Central Pressure Appraisal: Clinical Validation of a Subject-Specific Mathematical Model

IntroductionCurrent evidence suggests that aortic blood pressure has a superior prognostic value with respect to brachial pressure for cardiovascular events, but direct measurement is not feasible in daily clinical practice.AimThe aim of the present study is the clinical validation of a multiscale mathematical model for non-invasive appraisal of central blood pressure from subject-specific characteristics.MethodsA total of 51 young male were selected for the present study. Aortic systolic and diastolic pressure were estimated with a mathematical model and were compared to the most-used non-invasive validated technique (SphygmoCor device, AtCor Medical, Australia). SphygmoCor was calibrated through diastolic and systolic brachial pressure obtained with a sphygmomanometer, while model inputs consist of brachial pressure, height, weight, age, left-ventricular end-systolic and end-diastolic volumes, and data from a pulse wave velocity study.ResultsModel-estimated systolic and diastolic central blood pressures resulted to be significantly related to SphygmoCor-assessed central systolic (r = 0.65 p <0.0001) and diastolic (r = 0.84 p<0.0001) blood pressures. The model showed a significant overestimation of systolic pressure (+7.8 (-2.2;14) mmHg, p = 0.0003) and a significant underestimation of diastolic values (-3.2(-7.5;1.6), p = 0.004), which imply a significant overestimation of central pulse pressure. Interestingly, model prediction errors mirror the mean errors reported in large meta-analysis characterizing the use of the SphygmoCor when non-invasive calibration is performed.ConclusionIn conclusion, multi-scale mathematical model predictions result to be significantly related to SphygmoCor ones. Model-predicted systolic and diastolic aortic pressure resulted in difference of less than 10 mmHg in the 51% and 84% of the subjects, respectively, when compared with SphygmoCor-obtained pressures.     

Computational assessment of model-based wave separation using a database of virtual subjects

The quantification of arterial wave reflection is an important area of interest in arterial pulse wave analysis. It can be achieved by wave separation analysis (WSA) if both the aortic pressure waveform and the aortic flow waveform are known. For better applicability, several mathematical models have been established to estimate aortic flow solely based on pressure waveforms. The aim of this study is to investigate and verify the model-based wave separation of the ARCSolver method on virtual pulse wave measurements.The study is based on an open access virtual database generated via simulations. Seven cardiac and arterial parameters were varied within physiological healthy ranges, leading to a total of 3325 virtual healthy subjects. For assessing the model-based ARCSolver method computationally, this method was used to perform WSA based on the aortic root pressure waveforms of the virtual patients. As a reference, the values of WSA using both the pressure and flow waveforms provided by the virtual database were taken.The investigated parameters showed a good overall agreement between the model-based method and the reference. Mean differences and standard deviations were −0.05 ± 0.02 AU for characteristic impedance, −3.93 ± 1.79 mmHg for forward pressure amplitude, 1.37 ± 1.56 mmHg for backward pressure amplitude and 12.42 ± 4.88% for reflection magnitude.The results indicate that the mathematical blood flow model of the ARCSolver method is a feasible surrogate for a measured flow waveform and provides a reasonable way to assess arterial wave reflection non-invasively in healthy subjects.