Medical Information Technology (MedIT), Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, D-52074 Aachen, Germany.
QinetiQ, Farnborough, United Kingdom.
Physiol Meas. 2021 Sep 27;42(9). doi: 10.1088/1361-6579/ac1c63.
. During launch and atmospheric re-entry in suborbital space flights, astronauts are exposed to high G-acceleration. These acceleration levels influence gas exchange inside the lung and can potentially lead to hypoxaemia. The distribution of air inside the lung can be monitored by electrical impedance tomography. This imaging technique might reveal how high gravitational forces affect the dynamic behavior of ventilation and impair gas exchange resulting in hypoxaemia.. We performed a trial in a long-arm centrifuge with ten participants lying supine while being exposed to +2, +4 and +6 G(chest-to-back acceleration) to study the magnitude of accelerations experienced during suborbital spaceflight.. First, the tomographic images revealed that the dorsal region of the lung emptied faster than the ventral region. Second, the ventilated area shifted from dorsal to ventral. Consequently, alveolar pressure in the dorsal area reached the pressure of the upper airways before the ventral area emptied completely. Finally, the upper airways collapsed and the end-expiratory volume increased. This resulted in ventral gas trapping with restricted gas exchange.. At +4 G, changes in ventilation distribution varied considerably between subjects, potentially due to variation in individual physical conditions. However, at +6 Gall participants were affected similarly and the influence of high gravitational conditions was pronounced.
在亚轨道太空飞行的发射和大气层再入过程中，宇航员会暴露在高 G 加速度下。这些加速度水平会影响肺部的气体交换，可能导致低氧血症。肺部内部的气体分布可以通过电阻抗断层成像技术进行监测。这项成像技术可以揭示高重力如何影响通气的动态行为，并损害气体交换，从而导致低氧血症。
我们在一个长臂离心机中进行了一项试验，让十名仰卧的参与者暴露在+2、+4 和+6 G（胸部到背部的加速度）下，以研究亚轨道太空飞行中所经历的加速度大小。首先，断层图像显示，肺部的背部区域排空速度快于腹部区域。其次，通气区域从背部向腹部转移。因此，背部区域的肺泡压力在腹部区域完全排空之前达到了上呼吸道的压力。最后，上呼吸道塌陷，呼气末容积增加。这导致了腹部气体滞留和气体交换受限。
在+4 G 时，通气分布的变化在受试者之间差异很大，这可能是由于个体身体状况的差异所致。然而，在+6 G 时，所有参与者都受到了类似的影响，并且高重力条件的影响非常显著。
