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The Effect of Extra Vehicular Activity (EVA) and Long-Term Exposure to Microgravity on Pulmonary Function

Research project PX/6/LP/03 (Research action PX)

Persons :

Description :

The original proposal was submitted in 1996 in response to a NASA Research Announcement (96-OLMSA-01). The proposal addressed the area of Space Physiology and countermeasures and proposed a flight experiment studying the effects of long-term space flight and particularly the effects of EVA on the pulmonary system of the International Space Station crew members. As such, it has also some application in the evaluation of the optimal nitrogen washout protocols in the area of the Environmental Health. Specifically, we proposed 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 µg on the pulmonary system. From our previous studies of the lung in shorter periods of µg (up to 14 days) on Spacelabs SLS-1, SLS-2 and D-2, we know that the lung is profoundly affected by the removal of weight.

In this investigation we extend this research to study the effects of long duration exposure to g on the pulmonary system in three specific areas:

1) Changes in ventilation-perfusion inequality in the lung and closing volume caused by hypobaric environment of EVA, measured using changes in the intra-breath respiratory exchange ratio test (intra-breath R), and by changes 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. Changes in these variables might be expected due to possible remodeling of 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 µg exposure as the weight of the rib cage and shoulder girdle are removed. These tests have been chosen because they are simple to perform and require only cabin air for their performance. Thus, we avoid the need for carrying compressed gases that are required for more complicated tests of pulmonary function, and can develop a set of tests that are compatible with the operational constraints of the early phase of the ISS. Nevertheless, a comprehensive picture of the effects of EVA and long duration exposure to µg can be obtained in this manner. The tests were combined in a package that can readily be performed without the assistance of an operator at numerous points throughout the flights, and before and after EVA.

Satellite(s) or flight opportunity(ies):
- International Space Station

Field of research:

Life Science: Human Physiology

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