Journal: Aerospace medicine and human performance
Knee injuries are common among paratroopers and skydivers during landing maneuvers. The aim of this study was to investigate the effects of dropping height and the use of protective knee braces on parachute landing biomechanics.
The neurocognitive effects of acute hypobaric hypoxia are still largely unknown. This study was designed to test the hypothesis that executive control, an important component of cognition, is especially vulnerable to hypoxia.
The rate of intervertebral disc degeneration (IVDD) is influenced by environmental factors. Extracellular matrix (ECM) destruction and apoptosis of intervertebral disc cells are major characteristics of IVDD. ECM degradation is closely linked to up-regulation of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMP). This study aimed to elucidate the molecular biological changes during IVDD under conditions of weightlessness and hypergravity.
Recent research has postulated increased cardiovascular mortality for astronauts who participated in the Apollo lunar missions. The conclusions, however, are based on small numbers of astronauts, are derived from methods with known weaknesses, and are not consistent with prior research.
BACKGROUND: Whether the unique environment of space affects astronaut risk of venous thromboembolism (VTE) is not known. On Earth, it is known that use of combined oral contraceptives (COCs) doubles the risk of VTE. Since some female astronauts choose to use COCs, this retrospective study examined known risk factors associated with VTE risk to determine whether the available data suggested elevated VTE risk in female astronauts.METHODS: Longitudinal health data were requested for female astronauts who flew short and long duration missions between 2000 and 2014. Pre- and postflight hematological and biochemical blood markers were available and evaluated. Astronauts' postflight measurements were compared to clinically relevant terrestrial high risk levels to determine any trend toward increased risk for VTE following spaceflight. Secondarily, a comparison of pre- and postflight changes was made, as well as an assessment of COC impact.RESULTS: A total of 38 astronaut-flights were included in this study and no VTE events were found. Analysis of potential VTE risk factors showed no evidence suggesting elevated VTE risk in female astronauts associated with spaceflight, regardless of contraceptive use.DISCUSSION: Arguably, all astronauts encounter many physiological stressors during spaceflight missions, but women using the combined contraceptive pill add a known risk factor for VTE. The risk factors analyzed within this study showed no trend toward an increased risk of VTE for female astronauts. This study provides an evidence base supporting the safety of COC use by female astronauts and also reinforces the importance of healthy lifestyle on VTE risk reduction.Jain V, Ploutz-Snyder R, Young M, Charvat JM, Wotring VE. Potential venous thromboembolism risk in female astronauts. Aerosp Med Hum Perform. 2020; 91(5):432-439.
Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 - 5000 ppm) than what is typically considered normal (i.e., 400 - 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2. The objective of this study was to determine if submariner decision-making performance is impacted by acute exposure to levels of CO2 routinely present in the submarine atmosphere during sea patrols.
Long-duration spaceflight results in a loss of muscle strength that poses both operational and medical risks, particularly during emergency egress, upon return to Earth, and during future extraterrestrial exploration. Isokinetic testing of the knee, ankle, and trunk quantifies movement-specific strength changes following spaceflight and offers insight into the effectiveness of in-flight exercise countermeasures.
INTRODUCTION: As NASA and its international partners, as well as the commercial spaceflight industry, prepare for missions of increasing duration and venturing outside of low-Earth orbit, mitigation of medical risk is of high priority. Gynecologic considerations constitute one facet of medical risk for female astronauts. This manuscript will review the preflight, in-flight, and postflight clinical evaluation, management, and prevention considerations for reducing gynecologic and reproductive risks in female astronauts.METHODS: Relevant gynecological articles from databases including Ovid, Medline, Web of Science, various medical libraries, and NASA archives were evaluated for this review. In particular, articles addressing preventive measures or management of conditions in resource-limited environments were evaluated for applicability to future long-duration exploration spaceflight.RESULTS: Topics including abnormal uterine bleeding, anemia, bone mineral density, ovarian cysts, venous thromboembolism, contraception, fertility, and health maintenance were reviewed. Prevention and treatment strategies are discussed with a focus on management options that consider limitations of onboard medical capabilities.DISCUSSION: Long-duration exploration spaceflight will introduce new challenges for maintenance of gynecological and reproductive health. The impact of the space environment outside of low-Earth orbit on gynecological concerns remains unknown, with factors such as increased particle radiation exposure adding complexity and potential risk. While the most effective means of minimizing the impact of gynecologic or reproductive pathology for female astronauts is screening and prevention, gynecological concerns can arise unpredictably as they do on Earth. Careful consideration of gynecological risks and potential adverse events during spaceflight is a critical component to risk analysis and preventive medicine for future exploration missions.Steller JG, Blue RS, Burns R, Bayuse TM, Antonsen EL, Jain V, Blackwell MM, Jennings RT. Gynecologic risk mitigation considerations for long-duration spaceflight. Aerosp Med Hum Perform. 2020; 91(7):543-564.
INTRODUCTION: The year-long mission of American astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko included the most complex biomedical experiments ever conducted on the International Space Station-and arguably in human spaceflight-to establish insight into human health risks of interplanetary exploration. Focusing on risk mitigation, NASA conducted investigations that addressed spaceflight health hazards to varying degrees. This pilot mission was initiated to gain further knowledge and monitor the physiological, psychological, and medical effects of long-duration exposure to spaceflight.METHODS: NASA’s Human Research Program and the Russian Academy of Sciences' Institute of Biomedical Problems identified more than 20 biomedical risk-reduction research investigations to be conducted on the two crewmembers before, during, and after their yearlong expedition. A database of results, as well as observations on programmatic resources, was collected to understand essential elements for future spaceflight health studies.RESULTS: Statistical rigor requires additional testing at a length of 1 yr to demonstrate the presence or absence of unacceptable deleterious effects, and to permit extrapolation to longer durations in space. Review of experimental procedures from this mission suggests potential efficiencies for future investigations.DISCUSSION: The Kelly-Kornienko 1-yr mission demonstrated the importance of continuing joint investigations with the adoption of standard measures for rigorous comparisons across disparate populations. It identified improvements to collaborative processes across national and international scientific research programs. Additional studies will inform the development of an integrated applied research methodology for the space station and future interplanetary expeditions.Charles JB, Pietrzyk RA. A year on the International Space Station: implementing a long-duration biomedical research mission. Aerosp Med Hum Perform. 2019; 90(1):4-11.
Future deep space missions will expose astronauts to more intense stressors than previously encountered. Isolation will be greater and more prolonged, living and work areas more confined, and communications and resupply channels to Earth longer and less reliable. Astronauts will need to function more autonomously, with less guidance and support from Earth. Thus, it is important to select and train astronauts who can adapt and function effectively under extreme and variable conditions. In order to identify factors linked to individual adaptability, we conducted a systematic review of the literature on cognitive and behavioral adaptation to isolated, confined, and extreme (ICE) environments.