Review of Potential Exacerbating Factors for Spaceflight-Associated Neuro-Ocular Syndrome (SANS) and Exploration of Mitigation Strategies

摘要

The space environment is characterized by microgravity, which affects and poses a significant risk to astronaut health, that will only be exacerbated by the advent of long-duration spaceflight (LDSF). Amongst the various potential health issues is the effect that microgravity has on fluid distribution in the body. A redistribution of brain extracellular fluids has been shown to have a correlation with spaceflight duration, as the loss of significant gravitational force creates a cephalad fluid shift, which results in venous congestion. Venous congestion marked by an accumulation of intrathoracic fluid during spaceflight can lead to Spaceflight-Associated Neuro-ocular Syndrome (SANS). SANS is a disease caused by a change in the gradient between intracranial and intraocular pressures that can lead to papillledema (swelling of the optic disc) and deformation of the eye. SANS findings have been documented in astronauts during and after LDSF with a post-flight degeneration in vision. The cumulative risk posed by long-duration and long-distance spaceflight needs to be determined to ensure astronauts remain healthy and capable of carrying out their duties in space. In this review, literature on the potential impact of SANS on humans on other planets (after interplanetary flight), like Mars, which have a different gravitational-field than Earth, was examined. The National Aeronautics and Space Administration (NASA) has identified spaceflight exposure factors that may exacerbate SANS. These are: resistive exercise, high oral sodium intake, high ambient carbon dioxide, and in-flight pharmaceuticals. This paper considers to what extent NASA's identified factors affect the disease process, and identifies mitigation solutions for maintaining optimal astronaut health. A literature review was used to determine which parameters contribute to those health factors and why monitoring of exacerbating factors is a crucial process for spaceflight performance. Through this study, we evalu