[abstract] FAILURE OF THE STRAIGHT-LINE BOUNDARY BETWEEN SAFE AND UNSAFE DECOMPRESSIONS WHEN EXTRAPOLATED TO THE HYPOBARIC REALM.

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[abstract] FAILURE OF THE STRAIGHT-LINE BOUNDARY BETWEEN SAFE AND UNSAFE DECOMPRESSIONS WHEN EXTRAPOLATED TO THE HYPOBARIC REALM.

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dc.contributor.author Conkin, J
dc.contributor.author Van Liew, HD
dc.date.accessioned 2008-03-21T01:12:33Z
dc.date.available 2008-03-21T01:12:33Z
dc.date.issued 1991
dc.identifier.uri http://archive.rubicon-foundation.org/6395
dc.description.abstract The lowest pressure to which a diver can safely ascend (P2) after becoming equilibrated at some higher pressure (P1) is a straight-line function: P2 = m*P1+ b,where the intercept b has a negative value. Such lines have been observed experimentally in man and animals, and are fundamental to several models for decompression tables and dive computers. Our objective is to test whether extrapolation of a line which is valid for divers will predict safe decompression to altitude. The use of tissue nitrogen pressures (P1N2) instead of P1 values allows us to plot a straight line of P2 vs P1N2; this transformation is based on the assumption that P1N2 is the primary determinant of bubble formation and growth after decompression. Data from hypobaric exposures can be plotted on the new P2 vs P1N2 diagram even if the subject breathes oxygen before ascent; the P1N2 of the relevant tissue, assumed to have a 360 minute halftime, is calculated using an exponential equation. From literature reports of human decompressions in hypobaric chambers we accumulated 1085 exposures which fell in the region of a P2 vs P1N2 plot where the extrapolation from hyperbaric data predicted that the decompression should be safe. Of these, 253 exposures (24%) resulted in decompression sickness. This finding appears to invalidate the extrapolation to altitude. The best separation between safe and unsafe decompressions over the entire pressure range seems to be a curve which approximates a straight line in the hyperbaric region but bends toward the origin in the hypobaric region. en
dc.format.extent 193 bytes
dc.format.mimetype text/plain
dc.language.iso en_US en
dc.subject hypobaric en
dc.subject altitude en
dc.subject decompression en
dc.subject DCS en
dc.subject human en
dc.subject extrapolation en
dc.subject model failure en
dc.subject prebreathe en
dc.subject O2 en
dc.subject decompression sickness en
dc.subject pressure ratio en
dc.subject altitude extrapolation en
dc.subject altitude adjustment en
dc.subject altitude correction en
dc.title [abstract] FAILURE OF THE STRAIGHT-LINE BOUNDARY BETWEEN SAFE AND UNSAFE DECOMPRESSIONS WHEN EXTRAPOLATED TO THE HYPOBARIC REALM. en
dc.type Other en

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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