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EXPERIMENT INFORMATION

Mechanical and Gravitational Countermeasures to Ocular Changes during Strict Head-down Tilt Bedrest (Ocular_Changes_HDT)
Research Area:
Biomedical countermeasures
Species Studied
Scientific Name: Homo sapiens Species: Human

Description

OBJECTIVES:

Space flight-associated neuro-ocular syndrome (SANS) is associated with structural and functional ocular and brain changes, including optic disc edema, and develops in approximately two-thirds of astronauts during long-duration space flight. Due to the potential of irreversible functional vision changes during exploration-class space flight missions, a countermeasure capable of preventing SANS is needed. Currently, the mechanisms underlying the development of SANS are unknown, however, exposure to a constant headward fluid shift during extended space flight is hypothesized to play a major role. Exposure to 30 days of strict 6° head-down tilt (HDT) bed rest has shown to produce optic disc edema, a hallmark sign of SANS.1 Thus, NASA plans to use this as a ground-based analog model to further understand the mechanisms underlying SANS and test potential countermeasures. NASA plans to implement two control groups in this study, a posture control group that will be upright (seated) 16 hours a day, and a strict 6° HDT bed rest control group.

This study has the following specific aims:

1. Determine if daily exposure to actual upright posture and simulated LBNP hydrostatic pressure gradients prevents ocular and cerebral structural changes during 30 days of strict 6° head-down tilt bed rest.

2. Determine if daily exposure to actual upright posture and simulated LBNP hydrostatic pressure gradients prevents ocular functional changes during 30 days of strict 6° head-down tilt bed rest.

3. Determine if daily exposure to actual upright posture and simulated LBNP hydrostatic pressure gradients prevents vascular and cerebrospinal fluid changes during 30 days of strict 6° head-down tilt bed rest.


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Keywords
Blood flow velocity
Carbon dioxide (CO2)
Cerebrospinal fluid
Jugular veins
Optic nerve

Data Information
Data Availability
Archiving in progress. Data is not yet available for this experiment.

Parameters
Arterial flow rate
Bicarbonate concentration
Brachiocephalic vein blood flow velocity
Cardiac output
Cerebral spinal fluid center of gravity
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source