头高位倾斜时心血管反应的仿真

仿真头高位倾斜时心血管系统的反应，进一步研究有关立位应激的生理机制。方法以仿真下体负压时心血管反应的模型为基础，在血液重新分配子模中引入了重力致血液重新转移的环节，在压力反射控制子模型中考虑了心水平与颈动脉压力感受器间的流体静压差。

The simulation of cardiovascular response to head up tilt

AIM To simulate the cardiovascular response to head up tilt (HUT) and to further study the physiological mechanism of orthostatic stress. METHODS Based on the developed model that had been employed to simulate the cardiovascular response to lower body negative pressure (LBNP), the effect of blood shift induced by the gravitation factor was incorporated into the blood redistribution sub model. The hydrostatic difference between the heart and carotid arterial receptor was considered in the baroreflex control sub model. Six healthy men participated in a serial of 300, 450, 600 and 750 HUT experiments. Blood pressure and heart rate were observed during HUT. RESULTS The simulation results indicated that diastolic blood pressure, mean blood pressure and heart rate increased, while the cardiac output decreased during HUT, which basically consisted with the human experiment results. CONCLUSION The model developed can be used to reproduce the cardiovascular response to HUT. The same physiological and physical mechanisms may be involved in the cardiovascular response to HUT and LBNP. Our mathematical model is a good tool to investigate the physiological mechanism of orthostatic stress.