It is anticipated that there will be a reduced alveolar NO and an enhanced alveolar - to - blood diffusion in microgravity due to a more optimal gas-blood interface compared to normal gravity. These effects are expected to be more marked in hypobaric environment, where the rate of NO diffusion also in the gas phase of the lungs is enhanced.
The experiment specific goals and detailed objectives for Airway Monitoring are as listed below.
- To determine in detail the pulmonary NO turnover in microgravity.
- To determine in detail the pulmonary NO turnover in combined microgravity, hypobaric, and hypoxic environment.
- To obtain the goals a) and b) by determining exhaled NO at at least 3 different exhaled flows in order to compute alveolar and conductive - airway contributions to exhaled NO.
- To obtain goals a) and b) by determining the diffusing capacity for NO.
- To obtain goal d) by using an experiment-specific gas administration device together with premixed gases, the first one containing approx. 1% SF6 and the second one containing 400 ppm NO.
- To mimic as much as possible, the environment in a future lunar habitat with respect to ambient pressure and oxygen partial pressure in one experimental condition, the other inflight condition being air breathing at normal ISS pressure.
- To perform preflight BDC during the same atmospheric conditions as will be used inflight, both at approx. 1000 and 700 hPa. The air pressure during BDC should be within ±5 hPa of the expected inflight air pressures.
The primary goal is to determine how gravity and microgravity influence the turnover of NO in the lungs. There is no way by which the microgravity part of such experiments can be simulated on the ground or during parabolic flight (where the transient periods of microgravity are too short for the lung physiology experiments of the present kind, where changes in for example metabolic production of NO might occur). The mechanisms behind the recently found marked reduction of exhaled NO in microgravity is only partly understood and further studies will provide new insights in NO physiology for the benefit of patients with airway inflammation on earth.
Lars Karlsson, MSc, PhD
Dept of Physiology and Pharmacology
171 77 Stockholm, Sweden
Tel: +46-8-5248 6890
Mobile: +46 70 300 22 12
Tim peake traning the Airway monitoring experiment with support from DAC employee. (PHOTO: ESA)