We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model o...We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model of the entire cardiovascular system (CVS) is developed through an integration of one-dimensional (1D) modeling of the large systemic arteries and veins, and zero-dimensional (0D) lumped-parameter modeling of the heart, the cardiac-pulmonary circulation, the cardiac and venous valves, as well as the microcirculation. A versatile junction model is proposed and incorporated into the 1D model to cope with splitting and/or merging flows across a multibranched junction, which is validated to be capable of estimating both subcritical and supercritical flows while ensuring the mass conservation and total pressure continuity. To model gravitational effects on global hemodynamics during postural change, a robust venous valve model is further established for the 1D venous flows and distributed throughout the entire venous network with consideration of its anatomically realistic numbers and locations. The present integrated model is proven to enable reasonable prediction of pressure and flow rate waveforms associated with cardiopulmonary circulation, systemic circulation in arteries and veins, as well as microcirculation within normal physiological ranges, particularly in mean venous pressures, which well match the in vivo measurements. Applications of the cardiovascular model at different postures demonstrate that gravity exerts remarkable influence on arterial and venous pressures, venous returns and cardiac outputs whereas venous pressures below the heart level show a specific correlation between central venous and hydrostatic pressures in right atrium and veins.展开更多
目的:探索术前体位改变引起的心率变异性能否预测剖宫产腰麻后的低血压。方法:随机选择50例产妇在腰麻下进行择期剖宫产术,在剖宫产前1 d进行了体位变化检查。按仰卧位、左侧卧位和仰卧位的顺序记录无创血压(NIBP)、心率(HR)、心电图(E...目的:探索术前体位改变引起的心率变异性能否预测剖宫产腰麻后的低血压。方法:随机选择50例产妇在腰麻下进行择期剖宫产术,在剖宫产前1 d进行了体位变化检查。按仰卧位、左侧卧位和仰卧位的顺序记录无创血压(NIBP)、心率(HR)、心电图(ECG)和LF/HF比。采用5 min记录1次参数,在每个位置记录BP 3次,持续监测心电图。为了分析心率变异性,从监护仪获得ECG信号,并将其输入到计算机中以分析RR间期。使用Mem Calc软件进行心率变异性(HRV)分析,每5秒计算1次LF、HF和LF/HF(低高频率比),在第1次仰卧位记录的LF/HF值作为对照值(基线LF/HF)。从左侧卧位到仰卧位时,LF/HF比增长2倍以上的产妇分到阳性组,2倍以下分到阴性组。手术当天的产妇均进行ECG、HR、NIBP和氧饱和度的监测,并在仰卧位静脉滴注晶体液[4~6 m L/(kg·h)]。产妇仰卧时测的HR和BP为基线值。取左侧卧位,L3~4间隙进行腰麻,药物为0.75%罗哌卡因2 m L,注射后产妇转为平卧位。每分钟测量无创血压,直到血压平稳。结果:根据体位改变检测结果,将产妇分为阳性组(23例)和阴性组(26例),71.4%(35/49)产妇发生低血压,阳性组占60.0%(21/35),阴性组占40.0%(14/35)。PCT阳性组低血压发生率为91.3%(21/23),高于阴性组的53.8%(14/26),差异有统计学意义(P<0.01)。在腰麻(SA)剖宫产期间,PCT预测产妇低血压的敏感性和特异性分别为60.0%[95%CI(52.4,62.3)]和87.5%[95%CI(63.5,98.2)]。PCT的阳性预测值(PPV)和阴性预测值(NPV)分别为91.3%[95%CI(52.4,62.3)]和53.8%[95%CI(37.6,55.7)]。PCT作为产妇低血压的预测因子为0.76[95%CI(0.60,0.92)]。结论:术前体位改变引起的心率变化可预测剖宫产腰麻后低血压。展开更多
基金supported by a Grant-in-Aid for Scientific Research (Grant 17300141)Japan Society for the Promotion of Science and Research and Development of the Next Generation Integrated Simulation of Living Matter, JST,a part of the Development and Use of the Next Generation Supercomputer Project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japanthe RIKEN Junior Research Associate Program
文摘We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model of the entire cardiovascular system (CVS) is developed through an integration of one-dimensional (1D) modeling of the large systemic arteries and veins, and zero-dimensional (0D) lumped-parameter modeling of the heart, the cardiac-pulmonary circulation, the cardiac and venous valves, as well as the microcirculation. A versatile junction model is proposed and incorporated into the 1D model to cope with splitting and/or merging flows across a multibranched junction, which is validated to be capable of estimating both subcritical and supercritical flows while ensuring the mass conservation and total pressure continuity. To model gravitational effects on global hemodynamics during postural change, a robust venous valve model is further established for the 1D venous flows and distributed throughout the entire venous network with consideration of its anatomically realistic numbers and locations. The present integrated model is proven to enable reasonable prediction of pressure and flow rate waveforms associated with cardiopulmonary circulation, systemic circulation in arteries and veins, as well as microcirculation within normal physiological ranges, particularly in mean venous pressures, which well match the in vivo measurements. Applications of the cardiovascular model at different postures demonstrate that gravity exerts remarkable influence on arterial and venous pressures, venous returns and cardiac outputs whereas venous pressures below the heart level show a specific correlation between central venous and hydrostatic pressures in right atrium and veins.
文摘目的:探索术前体位改变引起的心率变异性能否预测剖宫产腰麻后的低血压。方法:随机选择50例产妇在腰麻下进行择期剖宫产术,在剖宫产前1 d进行了体位变化检查。按仰卧位、左侧卧位和仰卧位的顺序记录无创血压(NIBP)、心率(HR)、心电图(ECG)和LF/HF比。采用5 min记录1次参数,在每个位置记录BP 3次,持续监测心电图。为了分析心率变异性,从监护仪获得ECG信号,并将其输入到计算机中以分析RR间期。使用Mem Calc软件进行心率变异性(HRV)分析,每5秒计算1次LF、HF和LF/HF(低高频率比),在第1次仰卧位记录的LF/HF值作为对照值(基线LF/HF)。从左侧卧位到仰卧位时,LF/HF比增长2倍以上的产妇分到阳性组,2倍以下分到阴性组。手术当天的产妇均进行ECG、HR、NIBP和氧饱和度的监测,并在仰卧位静脉滴注晶体液[4~6 m L/(kg·h)]。产妇仰卧时测的HR和BP为基线值。取左侧卧位,L3~4间隙进行腰麻,药物为0.75%罗哌卡因2 m L,注射后产妇转为平卧位。每分钟测量无创血压,直到血压平稳。结果:根据体位改变检测结果,将产妇分为阳性组(23例)和阴性组(26例),71.4%(35/49)产妇发生低血压,阳性组占60.0%(21/35),阴性组占40.0%(14/35)。PCT阳性组低血压发生率为91.3%(21/23),高于阴性组的53.8%(14/26),差异有统计学意义(P<0.01)。在腰麻(SA)剖宫产期间,PCT预测产妇低血压的敏感性和特异性分别为60.0%[95%CI(52.4,62.3)]和87.5%[95%CI(63.5,98.2)]。PCT的阳性预测值(PPV)和阴性预测值(NPV)分别为91.3%[95%CI(52.4,62.3)]和53.8%[95%CI(37.6,55.7)]。PCT作为产妇低血压的预测因子为0.76[95%CI(0.60,0.92)]。结论:术前体位改变引起的心率变化可预测剖宫产腰麻后低血压。
