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目的研究不同程度的血容量减少对心血管系统立位应激反应的影响 ,探讨血容量降低在航天失重后心血管失调和立位耐力降低机理中的意义。方法在仿真下体负压 (LBNP)暴露时心血管系统反应模型的血液重新分配子模型中引入血容量减少因素 ,仿真血容量减少 0～ 2 5%后LBNP时心率 (HR)和血压 (BP)变化。结果血容量减少低于总血量的 5%条件下 ,心血管系统可以通过压力反射调节作用维持LBNP时正常的HR和BP ;血容量减少超过约 1 5% ,在安静仰卧位时 ,HR和BP正常 ,但LBNP时BP迅速降低 ,系统可能失去稳定性。结论血容量减少将导致心血管系统对立位应激反应的改变。
Objective To study the effects of varying degrees of hypovolemia on the homeostatic response of cardiovascular system and to explore the significance of hypovolemia in the mechanisms of cardiovascular disorders and standing endurance after aerosoless weight loss. Methods The blood volume reduction factor was introduced into the blood redistribution sub-model of cardiovascular response model under simulated negative pressure (LBNP), and the heart rate (HR) and blood pressure (BP) of LBNP were simulated after 0 ~ 25% Variety. Results When the blood volume decreased below 5% of the total blood volume, the cardiovascular system could maintain normal HR and BP at LBNP through the regulation of pressure reflex. The blood volume decreased by about 15%. In the quiet supine position, HR and BP is normal, but BP decreases rapidly at LBNP and the system may lose stability. Conclusions Decreased blood volume will lead to changes in the cardiovascular system to the upright stress response.