使用大覆盖面抗荷服+Gz作用下中心血液动力学变化的仿真研究

目的　为阐明囊式抗荷系统是否会给心脏及大血管带来不良影响 ,对使用由不同大覆盖面积囊式抗荷服 (ECGS)与抗荷正压呼吸 (PBG)组成的抗荷系统在 8Gz 时的中心血液动力学变化进行数字仿真研究 ,以评价其对心脏的影响与防护作用。　方法　利用所建立的可仿真 Gz 与抗荷系统综合影响的多元非线性循环呼吸模型 ,对由两种ECGS(囊覆盖面积分别为 6 5 %和 90 % )与两种PBG(压力制度分别为 1 6kPa/G与 2 4kPa/G , 4Gz 启动 )组成的抗荷系统的抗荷效果及中心循环重要生理参数的变化进行仿真。　结果　仿真G耐力结果与国内外报道的人体离心机实验数据基本相符 ,验证了仿真模型的有效性。仿真结果表明 ,ECGS的抗荷性能虽随着囊覆盖面积的扩大及压力制度的提高而增加 ,但每搏输出量略有降低 ,心脏、大血管及其瓣膜受到损伤的可能性亦增大。PBG引起的高胸内压虽可使呼吸困难程度增加 ,却能在不增加心脏做功的情况下提高心水平的动脉压 ,增强防护效果 ,并可使心脏、大动脉血管及其瓣膜的跨壁压 /跨膜压幅度减小 ,从而使人体在高G防护下受损的可能性降低。　结论　由于PBG对 Gz 作用下中心血液动力学的改变具有正面影响 ,因而在抗荷装备中具有特殊应用价值。

A simulation study on central hemodynamics during +Gz with protection afforded by extended-coverage anti-G suit

Objective The aim of the present study was to simulate central hemodynamics during 8 G_z exposure with protection afforded by extended coverage anti-G suit (ECGS) together with pressure breathing during G (PBG) anti-G system,so as to evaluate the protective effectiveness of this anti-G system and its possible adverse effect on the heart. Methods Based on the multi-element,nonlinear mathematical model of human circulatory-respiratory system developed for predicting cardiovascular effects of G_z stress and protective techniques,a simulation study was performed to predict the G_z tolerance afforded by various combinations of two ECGSs (65% and 90% coverage area) with/without two PBG pressure schedules (1.6 kPa/G and 2.4 kPa/G) respectively and demonstrate their influence on central hemodynamics under 8 G_z exposure. Results The simulation results are comparable with those from human centrifuge experiments reported before. The simulation study demonstrated that though G_z protection afforded by ECGS increased along with the extension of bladder coverage area,the stroke volume of left ventricle decreased slightly and the possibility of potential injuries of heart,large vessels and valves increased. On the other hand,though the high intrathoracic pressure induced by PBG may lead to dyspnea,it elevates arterial pressure at heart level without increasing heart work,and decreases greatly the possibility of potential injuries of heart,large vessels,and valves. Conclusion As PBG exerts postive effect on central hemodynamics during G_z ,it has special applicable value in anti-G equipment.