Postural Equilibrium and Vestibular Response at 49.5 ATA.

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Title: Postural Equilibrium and Vestibular Response at 49.5 ATA.
Author: Braithwaite, WR; Berghage, TE; Crothers, JC
Abstract: In response to the relatively high incidence of vestibular symptoms reported during deep experimental saturation dives, the U.S. Navy included measures of postural equilibrium and vestibular function in its 1600-fsw chamber dive protocol. Six subjects were pressurized in 6 days to 49.48 ATA. After spending 7 days at this pressure, they were decompressed in 19 days to the surface. The tests administered prior to, during, and following the dive included electronystagmography with mental alerting, pendulum tracking, optokinetic stimulation, cold caloric stimulation, and positional testing, along with three balance rail tests and two statometer tests. During the dive all of the measures of vestibular function stayed within normal limits; the tests of standing steadiness all showed statistically significant deviations from surface values. Performance on both the balance rail and the statometer showed a striking deterioration associated with increased pressure and some adaptation with time at depth. The decrements observed were very complex in nature with statistically significant interactions among all of the experimental variables. Experimental variables in the study included ambient pressure, individual differences, time at 1600 fsw, dive phase (compression versus decompression), and, in the case of the statometer, response frequency. (Author)
Description: Citation Status: Active; Citation Classification: Unclassified; Title Classification: Unclassified; Report Classification: Unclassified; Identifier Classification: Unclassified; Abstract Classification: Unclassified; Distribution Limitation(s): 01 - APPROVED FOR PUBLIC RELEASE; Information provided by the Department of Defense and the Defense Technical Information Center ( is considered public information and may be distributed or copied unless otherwise specified. Use of appropriate byline/photo/image credits is requested.
Date: 1975

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