Lung volume, capacity and shape in microgravity: A systematic review and meta-analysis

The advent of consumer spaceflight raises the issue of individuals with health conditions being exposed to periods of microgravity. Terrestrial lung function is gravitationally dependent, so it is important to understand the key lung functional changes currently understood to occur with a change in gravitational load. The aim of this systematic review was to summarise the effects of a microgravity (0G) environment on various volume, capacity and shape measurements on the human lung relative to normal Earth gravity (1G). Thirty studies including parabolic flights (10–25 s), short-duration spaceflight (≤30 days) and long-duration spaceflight (>30 days) were analysed. Parameters including lung shape, volumes and capacities reported in 1G (before flight) and 0G (in-flight) were extracted from these sources. While no change was seen in lung volume and capacity measurements between 0G and 1G in long-duration spaceflight, there were slight or no changes in parabolic and short-duration spaceflight. Additionally, no consistent effects were observed in lung shape in microgravity compared to 1G.