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Objective: To evaluate the distal arterial, venous and skin changes in a group using thigh cuffs during daytime and in a control group., Method: Cardiac, arterial, venous parameters were measured by echography and Doppler. Skin thickness was measured by high frequency echography., Results & Discussion: Head down position induced plasma volume reduction, increased cerebral resistance, reduced lower limb resistance. The jugular vein increased whereas the femoral and popliteal veins decreased. All these changes were already observed in previous HDT. Common carotid diameter decreased, Front head skin thickness increased and Tibial skin thickness decreased. Eight hours with thigh cuffs increased the cardiac and carotid sizes which is in agreement with the plasma volume increase. Conversely they reduced the cerebral vascular resistance, jugular section and front head edema which may explain the sensation of comfort reported by the subjects. At the lower limb level the thigh cuffs restored the skin thickness to pre-HDT level but enlarged markedly the femoral and popliteal veins. HR, BP, CO, TPR did not change., (c 2001. Elsevier Science Ltd. All rights reserved.)

Objective: To evaluate the cardiac, arterial and venous effect of a venotonic drug (Cirkan "Ck") administrated orally daily to 6 subjects in HDT position during 5 days. These subjects underwent a second 5d HDT without Ck treatment one month later. Pre and post HDT the subjects were submitted to a stand test., Method: The cardiovascular parameters were measured by echography and Doppler., Results and Discussion: The Cirkan treatment contributed to reduce the increase in cerebral resistance, and to maintain the lower limb resistance at a higher level than on controls. It reduces the vein section at the extremities (Jugular, femoral) and in the central vein system connected to the right heart (sub hepatics). On the other hand it increases the portal vein section which means that the blood stagnation at the splanchnic level is increased. Despite these arterial and venous significant modifications the clinical and ECG and Blood pressure response to the Stand test was similar in both groups., (c 2001. Elsevier Science Ltd. All rights reserved.)

Thigh cuffs, currently named "bracelets", consist of 2 straps fixed to the upper part of each thigh, applying a pressure of approximately 30 mmHg. Initially the thigh cuffs were designed and used to improve th comfort of the cosmonauts during their stay in zero g. Except a reduction of the "puffy face" aspect no other morphological nor hemodynamic significant change was reported even when the cosmonauts weared these thigh cuffs inflight for 10h per day during several weeks or months. The objective was to evaluate the distal arterial, venous and skin changes in a group of 8 subjects in HDT for 7 days and using thigh cuffs 8h during daytime, and in a control group also in HDT for 7d but not using cuff.