The goal is to define how much the exhaled nitric oxide (NO) is reduced with combined microgravity and reduced ambient pressure, and by what mechanisms. This is considered very useful for the monitoring of lung health in future exploration-class space missions. Even more important, by manipulating the alveolar uptake of NO to the blood (increased in microgravity) and the speed of diffusion of NO in the respiratory zone of the lungs (by reduced ambient pressure) this study will be able to more precisely define the location of NO formation for the benefit of the diagnostic use of exhaled NO on the ground.
APPROACH:
Three preflight BDC sessions are to be performed in a hypobaric pressure chamber at both normal and reduced pressure (70 % of normal ambient pressure), between L-150 days and launch. During the sessions, exhaled levels of NO will be monitored at three different flows. Additionally, lung diffusing capacity (the lungs ability to transfer gas from air to blood) will be measured. The lung diffusing capacity will be estimated using NO and an insoluble tracer gas, sulfur hexafluoride (SF6). No postflight BDC is planned for this investigation.
In addition, a screening session with each subject is requested as soon as consent is given to ensure that the subject’s exhaled NO levels are within the accepted “normal” range (with a lower limit – analyzer sensitivity, and an upper limit – no ongoing airway inflammation/natural too high levels).
Two inflight data collection sessions are planned: one at ambient air pressure only, and the second one should include testing both at ambient and reduced air pressure – the measurements for both conditions need to be performed back-to-back. The two sessions should be separated by at least 30 days. Data collection is planned using the Portable Pulmonary Function System (PPFS) for breath analysis in combination with two NO analyzers. The data collection session that includes the measurements under reduced air pressure, is planned to take place inside of the US airlock. Prior to the session, the crewmember should not eat food items that are rich in nitrate or nitrite during the 24 hours preceding Airway Monitoring inflight testing, and no strenuous exercises should be performed in that time frame either.
RESULTS:
This is an international experiment. NASA does not currently have an agreement with international space partners to archive their data in the LSDA.