Air plethysmography: an alternative method for assessing peripheral circulatory adaptations during spaceflights.

A new approach to the study of peripheral vascular hemodynamics in microgravity was initiated by designing an alternative methodology: air plethysmography (AP). This is the only technique that enables the quantification of vascular hemodynamics from gross measurements performed on the limbs. This paper reports a description of the device and of the measurement protocol. A comparative study showed that AP yields results that are well correlated, although not in agreement, with those obtained by means of the reference method in the laboratory (mercury strain gauge plethysmography, MSGP; for venous capacity, correlation coefficient r = 0.8, P < 0.0001, limits of agreement--0.9 ml.100 ml-1 and 1.4 ml.100 ml-1; for arterial flow index, correlation coefficient r = 0.7, P < 0.0006, limits of agreements -20.4 ml.min-1 and 37.2 ml.min-1; for half-emptying time, correlation coefficient r = 0.9, P < 0.0001, limits of agreement -0.88 s and 0.77 s), and that are characterized by good reproducibility (coefficient of variation in general lower than 12%). Preliminary findings during spaceflight, on board the Mir Space Station, yielded data that is expected to improve our knowledge of vascular deconditioning in conditions of weightlessness.

PHYSIOLAB: a cardiovascular laboratory.

PHYSIOLAB is a cardio-vascular laboratory designed by CNES in cooperation with IMBP, with double scientific and medical goals: -a better understanding of the basic mechanisms involved in blood pressure and heart rate regulation, in order to predict and control the phenomenon of cardio-vascular deconditionning. -a real-time monitoring of cosmonauts during functional tests. Launched to the MIR station in 1996, this laboratory was set up and used for the first time by Claudie Andre-Deshays during the French mission "Cassiopeia". The scientific program is performed pre, post and in-flight to study phenomena related to the transition to microgravity as well as the return to the earth conditions. Particular emphasis was placed on the development of the real-time telemetry to monitor LBNP test. This function was successful during the Cassiopeia mission, providing the medical team at TSOUP (MIR Control Center in Moscow) with efficient means to control the physiological state of the cosmonaut. Based on the results of this first mission, IMBP and CNES will go on using Physiolab with Russian crews. CNES will take advantage of the upcoming French missions on MIR to improve the system, and intends to develop a new laboratory for the International Space Station.

[Vascular deconditioning (correction of deconditionring) in microgravity: results obtained in the french spationaut during the spatial mission EO 22]. / Deconditionnement vasculaire en microgravite: resultats obtenus sur la spationaute francaise au cours de la mission spatiale EO 22.

First results on changes in vascular physiology in the first french spationaut during the French-russian spatial mission CASSIOPEE are reported in this paper. The data, obtained by Air Plethysmography during flight, evidence at the level of lower limbs alterations of venous filling and emptying characteristics (the latter particularly depending on the muscular pump function of the calf) and of capillary circulation.