期刊
AVIATION SPACE AND ENVIRONMENTAL MEDICINE
卷 85, 期 1, 页码 3-8出版社
AEROSPACE MEDICAL ASSOC
DOI: 10.3357/ASEM.3750.2014
关键词
microgravity; Doppler; central retinal artery; optic nerve sheath diameter
资金
- NSBRI Braslet Investigation Grant (NSBRI Grant) [NNJ07ZSA002N]
Background: Ocular changes have been noted during long-duration spaceflight; we studied central retinal artery (CRA) blood flow using Doppler before, during, and after long-term microgravity exposure in astronauts compared with data from a control group of nonastronauts subjected to head-down tilt (HDT). Methods: Available Doppler spectra of International Space Station (ISS) crewmembers were obtained from the NASA Lifetime Surveillance of Astronaut Health database, along with 2D ultrasound derived measurements of the optic nerve sheath diameter (ONSD). CRA Doppler spectra and optic nerve sheath images were also obtained from healthy test subjects in an acute HDT experiment at 20 min of exposure (the ground-based analogue). Results: HDT CRA peak systolic velocity in the ground-based analogue group increased by an average of 3 cm center dot s(-1) (33%) relative to seated values. ONSD at 30 degrees of HDT increased by 0.5 mm relative to supine values. CRA Doppler spectra obtained on orbit were of excellent quality and demonstrated in-flight changes of +5 cm center dot s(-1) (50%) compared to preflight. ONSD increased in ISS crewmembers during flight relative to before flight, with some reversal postflight. Discussion: A significant ONSD response to acute postural change and to spaceflight was demonstrated in this preliminary study. Increases in Doppler peak flow velocities correlated with increases in ONSD. Further investigations are warranted to corroborate the relationship between ONSD, intracranial pressure, and central retinal blood flow for occupational surveillance and research purposes.
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