Characterisation of gravity-induced facial skin oedema using biophysical measurement techniques

Background/aims: In humans, the microgravity environment can be expected to induce swelling of facial tissues and shrinking of the tissues in the lower limbs, together with a loss in body weight. To evaluate fluid shifts in skin, the head‐down bed‐rest model was used. The aim of the present study was to evaluate the appearance of facial oedema in subjects undergoing anti‐orthostatic bed‐rest at an angle of −10°. Methods: The forehead of each of four subjects was measured before and after 1, 10 and 24 h in this head‐down tilt position. At these time points, interstitial fluid migration and facial oedema were assessed using a high resolution B‐scan ultrasound and a device for measuring the skin's mechanical properties. Results: The results obtained showed a progressive increase in dermal thickness and initial stress, and a reduction in stiffness and elasticity of the skin during the study period. Conclusions: This preliminary study has demonstrated the feasability of the method in measuring fluid displacement and retention in the skin. Furthermore, it highlights the influence of fluids on the mechanical behaviour of the skin. These techniques could be used for studying the redistribution of liquid masses during periods spent in space.