Seadragon VI: a 7-day saturation dive at 31 ATA. V. Cardiovascular responses to a 90 degree body tilt

Rubicon Research Repository/Manakin Repository

Seadragon VI: a 7-day saturation dive at 31 ATA. V. Cardiovascular responses to a 90 degree body tilt

Show full item record


Title: Seadragon VI: a 7-day saturation dive at 31 ATA. V. Cardiovascular responses to a 90 degree body tilt
Author: Arita, H; Lin, YC; Sudoh, M; Kuwahira, I; Ohta, Y; Saiki, H; Tamaya, S; Nakayama, H
Abstract: Cardiovascular deconditioning (CD) has been reported to occur in weightlessness, bed rest, and head-out water immersion. An expanded intrathoracic blood volume results, at least initially, in all these diverse conditions. Subjects in hyperbaric environments exhibit cephalad redistribution of blood volume, which also occurs in weightlessness, bed rest, and head-out water immersion. This physiologic similarity led us to suspect that CD may also occur as a consequence of hyperbaric exposure. We examined this possibility in 3 young male subjects during a 7-d dry saturation dive at 31 ATA. Changes in blood pressure, heart rate, and stroke volume were measured before and during 15 min of the 90 degree body tilt. These changes, expressed either singly or in combination, provided indications of CD during and immediately after hyperbaric exposure. One of the principal indicators of CD was the inability to exert adequate vasoconstriction. In addition, 1 subject fainted during hyperbaric exposure, whereas no such episode occurred before or after the exposure. These findings suggest that inappropriate orthostatic reflexes may be evoked by hyperbaria and reduced physical activity over the period of confinement. It should be noted, however, that CD was already evident within 24 h of hyperbaric exposure, suggesting that the initial phase of CD was unrelated to physical confinement. We postulate that CD occurs during hyperbaric exposure as an expression of cardiovascular and neurohumoral adaptation to an expanded central blood volume with a reduced total blood volume.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: PMID: 3672653
http://archive.rubicon-foundation.org/2444
Date: 1987

Files in this item

Files Size Format View
3672653.pdf 1.910Mb PDF View/Open

This item appears in the following Collection(s)

  • Undersea Biomedical Research Journal
    The Undersea Baromedical Research journal was published by the Undersea Medical Society, Inc. (now the Undersea and Hyperbaric Medical Society) quarterly from 1974 to 1992 when the name changed to the Undersea and Hyperbaric Medicine Journal.

Show full item record

Browse

My Account