Babbs C F, Thelander K
Biomedical Engineering Center, Purdue University, West Lafayette, IN 47907-1293, USA.
Acad Emerg Med. 1995 Aug;2(8):698-707. doi: 10.1111/j.1553-2712.1995.tb03621.x.
To use an electronic model of human circulation to compare the hemodynamic effects of different durations of chest compression during external CPR, both with and without interposed abdominal compression (IAC).
An electrical analog model of human circulation was studied on digital computer workstations using SPICE, a general-purpose circuit simulation program. In the model the heart and blood vessels were represented as resistive-capacitive networks, pressures as voltages, blood flow as electric current, blood inertia as inductance, and cardiac and venous valves as diodes. External pressurization of the heart and great vessels, as would occur in IAC-CPR, was simulated by the alternate application of damped rectangular voltage pulses, first between intrathoracic vascular capacitances and ground, and then between intra-abdominal vascular capacitances and ground. With this model compression frequencies of 60, 80, and 100 cycles/min and duty cycles ranging from 10% to 90%, both with and without IAC, were compared.
There was little difference in hemodynamics when the overall compression frequency was varied between 60 and 100 cycles/min, but the effects of duty cycle were substantial. During both standard CPR and IAC-CPR, total flow and coronary flow were greatest at chest compression durations equal to 30% of cycle time. Interposed abdominal compression substantially improved simulated systemic blood flow and perfusion pressure at all duty cycles, compared with standard CPR without abdominal compression. Mean arterial pressure > 75 mm Hg and artificial cardiac output > 2.0 L/min could be generated by 30% duty cycle compression with IAC. Coronary perfusion in the model is clearly optimized at 30% chest compression (i.e., high-impulse chest compression technique).
Combined high-impulse chest compressions and IACs maximize blood flow during CPR in the electrical analog model of human circulation.
使用人体循环电子模型，比较在实施体外心肺复苏（CPR）时，不同时长胸外按压以及有无腹部按压（IAC）时的血流动力学效应。
使用通用电路仿真程序SPICE在数字计算机工作站上研究人体循环的电模拟模型。在该模型中，心脏和血管用阻容网络表示，压力用电压表示，血流用电流表示，血液惯性用电感表示，心脏和静脉瓣膜用二极管表示。通过交替施加阻尼矩形电压脉冲来模拟IAC - CPR中发生的心脏和大血管外部加压，先是在胸内血管电容与地之间，然后在腹内血管电容与地之间。利用该模型比较了按压频率为60、80和100次/分钟以及占空比在10%至90%之间，有和没有IAC时的情况。
当整体按压频率在60至100次/分钟之间变化时，血流动力学差异不大，但占空比的影响显著。在标准CPR和IAC - CPR期间，当胸外按压时长等于心动周期时间的30%时，总血流量和冠脉血流量最大。与无腹部按压的标准CPR相比，在所有占空比下，腹部按压均显著改善了模拟的全身血流量和灌注压。通过IAC进行30%占空比的按压可产生平均动脉压>75 mmHg和人工心输出量>2.0 L/min。在该模型中，冠脉灌注在胸外按压30%（即高冲击胸外按压技术）时明显达到最佳状态。
在人体循环电模拟模型中，高冲击胸外按压与IAC相结合可使CPR期间的血流量最大化。
