Department of Electrical and Computer Engineering, College of Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA.
Capstone College of Nursing, The University of Alabama, Tuscaloosa, AL 35487, USA.
Sensors (Basel). 2023 Mar 3;23(5):2793. doi: 10.3390/s23052793.
(1) Background: One effect of microgravity on the human body is fluid redistribution due to the removal of the hydrostatic gravitational gradient. These fluid shifts are expected to be the source of severe medical risks and it is critical to advance methods to monitor them in real-time. One technique to monitor fluid shifts captures the electrical impedance of segmental tissues, but limited research is available to evaluate if fluid shifts in response to microgravity are symmetrical due to the bilateral symmetry of the body. This study aims to evaluate this fluid shift symmetry. (2) Methods: Segmental tissue resistance at 10 kHz and 100 kHz was collected at 30 min intervals from the left/right arm, leg, and trunk of 12 healthy adults over 4 h of 6° head-down-tilt body positioning. (3) Results: Statistically significant increases were observed in the segmental leg resistances, first observed at 120 min and 90 min for 10 kHz and 100 kHz measurements, respectively. Median increases were approximately 11% to 12% for the 10 kHz resistance and 9% for the 100 kHz resistance. No statistically significant changes in the segmental arm or trunk resistance. Comparing the left and right segmental leg resistance, there were no statistically significant differences in the resistance changes based on the side of the body. (4) Conclusions: The fluid shifts induced by the 6° body position resulted in similar changes in both left and right body segments (that had statistically significant changes in this work). These findings support that future wearable systems to monitor microgravity-induced fluid shifts may only require monitoring of one side of body segments (reducing the hardware needed for the system).
（1）背景：微重力对人体的一个影响是由于静水重力梯度的消除而导致的流体重新分布。这些流体转移预计将是严重医疗风险的来源，因此必须开发实时监测它们的方法。一种监测流体转移的技术是捕获分段组织的电阻抗，但由于身体的双侧对称性，可用的研究有限，无法评估对微重力的流体转移是否对称。本研究旨在评估这种流体转移对称性。（2）方法：在 4 小时的 6°头低位身体定位期间，每隔 30 分钟从 12 名健康成年人的左右手臂、腿部和躯干收集 10 kHz 和 100 kHz 的分段组织电阻。（3）结果：在 120 分钟和 90 分钟时，分别观察到 10 kHz 和 100 kHz 测量的腿部分段电阻有统计学意义的增加，首先观察到。中位数增加约为 10 kHz 电阻的 11%至 12%和 100 kHz 电阻的 9%。手臂或躯干分段电阻无统计学意义的变化。比较左右分段腿部电阻，根据身体的一侧，电阻变化没有统计学意义的差异。（4）结论：6°身体位置引起的流体转移导致左右身体段都发生了类似的变化（在这项工作中具有统计学意义的变化）。这些发现支持未来用于监测微重力诱导的流体转移的可穿戴系统可能只需要监测身体段的一侧（减少系统所需的硬件）。
