Combining protection of different anti-g techniques to +12 gz: a computer simulation study.

The aim of this study is to investigate the upper limit of protection afforded by various protective equipment and techniques that used in combination and used individually. A multi-element, nonlinear mathematical model, which was previously used to produce cardiovascular response to +Gz stress and protection afforded by anti-G suits, was modified by incorporating pulmonary-respiration model, as well as detailed vessel models of abdomen and lower extremities into previous model. Using the model, hemodynamic responses of cardiovascular system to +Gz and to different combination of protection measures were simulated. Simulation results indicate that when appropriate counter-pressure is exerted to lower body, the combination of extended coverage anti-G suit with appropriate positive pressure breathing could provide effortless protection around +9Gz. For higher no-staining protection to +12 Gz, tilt-back seat with angles greater than 55 should be used. It also suggests that for anti-G techniques that enhance +Gz tolerance by means of elevating intrathoracic pressure or increasing blood volume, such as ECGS, PBG, and AGSM, their combined protection may be expressed as an additive sum of their individual effects. However, the combined protection of tilt-back seat with other anti-G techniques is higher than the simple addition.