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In-flight Assessment of Lower Body Negative Pressure as a Countermeasure for Post-flight Orthostatic IntoleranceIntroduction. We investigated the efficacy of combining fluid loading with sustained lower body negative pressure (LBNP) to reverse orthostatic intolerance associated with weightlessness during and immediately after Space Shuttle missions. Methods. Shuttle astronauts (n=13) underwent 4 hours of LBNP at -30 mm(Hg) and ingested water and salt ( soak treatment) during flight in two complementary studies. In the first study (n=8), pre-flight heart rate (HR) and blood pressure (BP) responses to an LBNP ramp (5-min stages of -10 mm(Hg) steps to -50 mm(Hg) were compared to responses in-flight one and two days after LBNP soak treatment. In the second study (n=5), the soak was performed 24 hr before landing, and post-flight stand test results of soak subjects were compared with those of an untreated cohort (n=7). In both studies, the soak was scheduled late in the mission and was preceded by LBNP ramp tests at approximately 3-day intervals to document the in-flight loss of orthostatic tolerance. Results. Increased HR and decreased BP responses to LBNP were evident early in-flight. In-flight, one day after LBNP soak, HR and BP responses to LBNP were not different from pre-flight, but the effect was absent the second day after treatment. Post-flight there were no between-group differences in HR and BP responses to standing, but all 5 treatment subjects completed the 5-minute stand test whereas 2 of 7 untreated cohort subjects did not. Discussion. Exaggerated HR and BP responses to LBNP were evident within the first few days of space flight, extending results from Skylab. The combined LBNP and fluid ingestion countermeasure restored in-flight LBNP HR and BP responses to pre-flight levels and provided protection of post-landing orthostatic function. Unfortunately, any benefits of the combined countermeasure were offset by the complexity of its implementation, making it inappropriate for routine application during Shuttle flights.
Document ID
20090040567
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Charles, J. B.
(NASA Johnson Space Center Houston, TX, United States)
Stenger, M. B.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Phillips, T. R.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Arzeno, N. M.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Lee, S. M. C.
(Wyle Integrated Science and Engineering Group Houston, TX, United States)
Date Acquired
September 8, 2013
Publication Date
January 1, 2009
Subject Category
Aerospace Medicine
Report/Patent Number
JSC-CN-19251
Meeting Information
Meeting: 81st Annual Scientific Meeting of the Aerospace Medical Association
Location: Phoenix, AZ
Country: United States
Start Date: May 9, 2010
End Date: May 13, 2010
Distribution Limits
Public
Copyright
Other

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