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Comparison of techniques for measuring +Gz tolerance in manTwo objective methods and one subjective method for measuring +Gz tolerance (inertial vector in a head-to-foot direction) were compared on the human centrifuge. Direct eye-level blood pressure (Pa), blood flow velocity in the superficial temporal artery (Qta), and subjective visual symptoms were used to determine tolerance to rapid-onset acceleration (1 G/s) on the USAFSAM human centrifuge. Seven 'relaxed' subjects with extensive centrifuge experience were exposed to gradually increasing +Gz plateaus until the subject reported 100% loss of peripheral centrifuge gondola lights (PLL) and 50% loss of central light (CLD); viz., blackout. Zero forward Qta occurred 6 s (range 4-9 s) before subjective blackout and when mean eye-level blood pressure had reached 20 + or - 1 mm Hg (SE). The results of this study indicate that flow changes in the superficial temporal artery reflect flow changes in the retinal circulation during +Gz stress.
Document ID
19750050739
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Krutz, R. W., Jr.
Rositano, S. A.
Mancini, R. E.
(NASA Ames Research Center Sunnyvale; Santa Clara, University, Santa Clara, Calif., United States)
Date Acquired
August 8, 2013
Publication Date
June 1, 1975
Publication Information
Publication: Journal of Applied Physiology
Volume: 38
Subject Category
Man/System Technology And Life Support
Accession Number
75A34811
Distribution Limits
Public
Copyright
Other

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