Wearable optical devices for assessing cosmonauts microcirculatory-tissue system responses to simulated spaceflight factors
Loktionova Yu.I.1, Kireev K.S.1,2, Zharkikh E.V.1, Lutsevich D.N.2, Yanushin V.S.1
Sidorov V.V.3, Dunaev A.V.1; 1 Orel State University named after I.S. Turgenev, Orel, Russia; 2 State Organization “Gagarin Research and Test Cosmonaut Training Center”, Zvyozdny gorodok, Russia; 3 SPE “LAZMA” Ltd., Moscow, Russia
Abstract
Spaceflight factors cause fluid redistribution, vascular responses, and metabolic shifts. Microcirculatory-tissue system (MTS) is the final link of the cardiovascular system. MTS ensures the delivery of oxygen and nutrients to tissues and is also the first to be involved in the adaptive reactions of the body. This study evaluated MTS responses of professional cosmonauts to simulated spaceflight factors such as postural test, +G-loads exposure, vestibular impacts and hypobaric hypoxia using wearable multimodal optical diagnostics.
Before, during, and after each exposure, wearable analyzers « LAZMA PF» (SPE LAZMA Ltd, Russia) implementing laser Doppler flowmetry, fluorescence spectroscopy, and thermometry were used to monitor MTS parameters in the skin of the forehead, fingers, wrists, and shins. Perfusion, regulatory oscillations, nutritive and shunt blood flow, and normalized NADH fluorescence were assessed. Protocols included 19 Roscosmos cosmonauts undergoing a passive postural test (-15°, -30°, +70°), 13 male cosmonauts exposed to +4Gx and +8Gx on an 18-m-radius centrifuge, and 18 cosmonauts during a simulated ascent to 5 km in an altitude chamber, as well as a 10-min vestibular-chair test at 0.5 rotations/s with head movements.
During antiorthostasis, forehead perfusion increased while shin perfusion decreased, reflecting cranial blood redistribution. At +70°, perfusion remained stable through adjustments in vascular tone and nutritive blood flow, whereas NADH fluorescence remained unchanged. Cluster analysis identified distinct individual response phenotypes.
During +4Gx and +8Gx-loads, forehead and shin perfusion decreased; post-load hyperemia was greater after +8Gx. Recovery showed lower contributions of active regulatory mechanisms, higher cardiac and shunt components, and relatively stable nutritive flow.
After modeling the ascent to a height of 5 km, the forehead perfusion remained significantly higher than the initial level. The increase was due to the growth of the shunt component of blood flow.
All cosmonauts completed the 10-min vestibular-chair test without pronounced nausea, although some reported discomfort. Good tolerance was associated with an initial rise in forehead perfusion followed by redistribution toward the finger and increased oscillatory activity. Satisfactory tolerance showed weaker perfusion changes but early metabolic activation.
The findings support wearable multimodal monitoring for assessing functional reserves, personalizing cosmonaut training, and evaluating countermeasures.
The work was carried out with the financial support of the Russian Science Foundation (project no. 25-25-00546).
Speaker
Loktionova Yulia
Orel State University named after I S Turgenev
Russia
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