Babbs C F, Ralston S H, Geddes L A
Ann Emerg Med. 1984 Sep;13(9 Pt 1):660-71. doi: 10.1016/s0196-0644(84)80722-2.
Recent animal studies and preliminary clinical observations suggest that the addition of interposed abdominal compressions (IAC) to ventilation and chest compression of standard cardiopulmonary resuscitation (CPR) augments blood flow, blood pressures, and immediate survival. To investigate the physical basis for enhanced circulation during IAC-CPR, we developed an electrical model of the circulation. Heart and blood vessels were modeled as resistive-capacitive networks, pressures as voltages, blood flow as electric current, blood inertia as inductance, and the cardiac and venous valves as diodes. External pressurization of the heart and great vessels, as would occur in CPR, was simulated by application by half-sinusoidal voltage pulses between vascular capacitances and ground. Closed-chest CPR was simulated by pressurization of all intrathoracic capacitances. IAC was simulated by similar pressurization of the inferior vena cava and abdominal aorta, 180 degrees out of phase with chest compression. During simulation of CPR, IAC improved cranial and myocardial perfusion at all levels of chest compression pressure by amounts linearly related to peak abdominal pressure, suggesting that the abdomen can function as a second, independent blood pump during CPR. Brain and heart flow were improved further during simulated vasoconstriction in kidneys, abdominal viscera, and extremities. Based on the fundamental properties of the cardiovascular system represented in the model, abdominal counterpulsation provides a rational basis for flow augmentation during CPR.
近期的动物研究和初步临床观察表明，在标准心肺复苏（CPR）的通气和胸外按压中增加腹部压迫（IAC）可增加血流量、血压并提高即时生存率。为了研究IAC-CPR期间循环增强的物理基础，我们建立了一个循环的电学模型。心脏和血管被建模为阻容网络，压力被建模为电压，血流量被建模为电流，血液惯性被建模为电感，心脏和静脉瓣膜被建模为二极管。通过在血管电容和地之间施加半正弦电压脉冲来模拟CPR中会出现的心脏和大血管的外部加压。通过对所有胸内电容进行加压来模拟闭胸CPR。通过对下腔静脉和腹主动脉进行类似的加压来模拟IAC，其与胸外按压的相位相差180度。在CPR模拟过程中，IAC在所有胸外按压压力水平下均改善了颅脑和心肌灌注，改善程度与腹部峰值压力呈线性相关，这表明在CPR期间腹部可作为第二个独立的血泵发挥作用。在模拟肾脏、腹部脏器和四肢血管收缩时，脑和心脏的血流量进一步增加。基于模型中所代表的心血管系统的基本特性，腹部反搏为CPR期间的血流增加提供了合理的基础。
