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Estimating the Risk of Renal Stone Events During Long-Duration SpaceflightIntroduction: Given the bone loss and increased urinary calcium excretion in the microgravity environment, persons participating in long-duration spaceflight may have an increased risk for renal stone formation. Renal stones are often an incidental finding of abdominal imaging studies done for other reasons. Thus, some crewmembers may have undiscovered, asymptomatic stones prior to their mission. Methods: An extensive literature search was conducted concerning the natural history of asymptomatic renal stones. For comparison, simulations were done using the Integrated Medical Model (IMM). The IMM is an evidence-based decision support tool that provides risk analysis and has the capability to optimize medical systems for missions by minimizing the occurrence of adverse mission outcomes such as evacuation and loss of crew life within specified mass and volume constraints. Results: The literature of the natural history of asymptomatic renal stones in the general medical population shows that the probability of symptomatic event is 8% to 34% at 1 to 3 years for stones < 7 mm. Extrapolated to a 6-month mission, for stones < 5 to 7 mm, the risk for any stone event is about 4 to 6%, with a 0.7% to 4% risk for intervention, respectively. IMM simulations compare favorably with risk estimates garnered from the terrestrial literature. The IMM forecasts that symptomatic renal stones may be one of the top drivers for medical evacuation of an International Space Station (ISS) mission. Discussion: Although the likelihood of a stone event is low, the consequences could be severe due to limitations of current ISS medical capabilities. Therefore, these risks need to be quantified to aid planning, limit crew morbidity and mitigate mission impacts. This will be especially critical for missions beyond earth orbit, where evacuation may not be an option.
Document ID
20140003295
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Reyes, David
(NASA Johnson Space Center Houston, TX, United States)
Kerstman, Eric
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Locke, James
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
April 22, 2014
Publication Date
January 1, 2014
Subject Category
Aerospace Medicine
Life Sciences (General)
Report/Patent Number
JSC-CN-29918
Meeting Information
Meeting: Aerospace Medical Association Annual Scientific Meeting
Location: San Diego, CA
Country: United States
Start Date: May 11, 2014
End Date: May 15, 2014
Sponsors: Aerospace Medical Association
Distribution Limits
Public
Copyright
Other

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