CARDIAC AND VASCULAR ADAPTATION TO OG WITH AND WITHOUT THIGH CUFFS (ANTARES 14 AND ALTAIR 21 DAY MIR SPACEFLIGHTS)

Cardiovascular adaptation was evaluated on 2 astronauts: one wearing t high cuffs from flight day 1 to 8 (14d flight), the second without cuf fs (21d flight). Ultrasound investigations were performed at rest and during LBNP. Results: Without thigh cuffs the cardiovascular adaptatio n consists in (1) the development of a hypovolemia with an increase of the heart rate and the cardiac output, (2) the decrease of the vascul ar tone in the deep (mesenteric and splanchnic) and peripheral (Lower limbs) vascular areas. The use of thigh cuffs maintains the volemia an d the cardiac output at the preflight level (without heart rate increa se) and prevents the loss of vascular tone in the deep and peripheral areas. Moreover the adaptative process changes since the cuffs are rem oved and even the volemia seems to be unaffected at this stage the vas cular tone decreases to a comparable extend as during the flight witho ut cuffs. Nevertheless during the flight without cuffs or 3 days after removing the cuffs hemodynamic signs of decreased orthostatic toleran ce are present during the inflight and the 3 days post flight LBNP, Pr esently the possible contribution of the thigh cuffs to the reduction of the vascular deconditioning has not been tested yet.