摘要：

We will to use the earliest Utilization Phase of the International Space Station to study the effects of Extra-Vehicular Activity (EVA) and long-term exposure to microgravity on the pulmonary system. From our previous studies of the lung in shorter periods of microgravity (up to 14 days) on Spacelabs SLS-1, SLS-2, and D-2, LMS, and Neurolab we know that the lung is profoundly affected by the removal of gravity. We will extend this research in three specific areas: (1) Changes in ventilation-perfusion inequality in the lung and closing volume caused by the effects of venous gas microemboli filtered by the pulmonary vasculature. These microbubbles are likely to occur in the hypobaric environment of EVA, and the effects will be measured using changes in the intra-breath respiratory exchange ratio test (intra-breath R), and in the distribution of pulmonary perfusion measured by the hyperventilation breathhold technique; (2) Changes in small airways function measured by forced spirometry and by the intra-breath R test and changes in the subdivisions of lung volumes measured by slow spirometry. Such changes might be expected due to possible structural changes in lung tissue promoted by long-term changes in pulmonary vascular filling; (3) Changes in respiratory muscle strength measured by forced spirometry, and by maximum inspiratory and expiratory pressures. Such changes might be expected in long-term jiG exposure as the weight of the rib cage and shoulder girdle are removed. These tests, performed at numerous points throughout the flights and before and after EVA, have been chosen because they are simple to perform and require only cabin air for their performance, and are therefore compatible with the operational constraints of the early phase of the ISS. Nevertheless, they provide a comprehensive picture of the effects of EVA and longduration exposure to juG. The Pulmonary Function in Flight (PuFF) experiment is scheduled to be operational on ISS Expeditions 3 through 5 using the Human Research Facility. 2001 by the American Institute of Aeronautics and Astronautics, Inc.

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