[abstract] A CUMULATIVE OXYGEN TOXICITY INDEX WHICH CAN DECREASE WITH SUBTOXIC BREATHING MIXTURES.

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[abstract] A CUMULATIVE OXYGEN TOXICITY INDEX WHICH CAN DECREASE WITH SUBTOXIC BREATHING MIXTURES.

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Title: [abstract] A CUMULATIVE OXYGEN TOXICITY INDEX WHICH CAN DECREASE WITH SUBTOXIC BREATHING MIXTURES.
Author: Hills, BA
Abstract: Quantitative methods for prescribing oxygen during decompression and bends treatments are badly needed irrespective of the mechanism(s) underlying toxicity. The time to convulse has been measured in 20 rats exposed to two different oxygen histories, each consisting of four consecutive exposures to widely differing inspired 02 partial pressure (p). The dose-time curve has been established for the same animals. From these data, it has been shown that the principle of superposition applies to the prediction of neurologic oxygen toxicity to within ± 11%. This leads to a particularly simple CUMULATIVE OXYGEN TOXICITY index (COTi) for predicting the imminence of symptoms by describing any oxgen history, however irregular, as a number of step changes. If the nth change in inspired 02 is made from p(n-1) to p(n) at time t(n) from the start, and we desire to know the imminence -of toxcity at t, then the subject may display symptoms if: COTi = sum[(p(n) -p(n-1))/Pi(n)] > 1 where Pi is the constant partial pressure of 02 for toxicity at time (t-t(n)). This simple calculation method allows for regression on subtoxic mixes and can be used for any species, including man, provided the corresponding dose-time (Pi vs. t) curve is used. It probably also holds for pulmonary oxygen toxicity where the Pi vs. t must now, of course, refer to pulmonary symptoms only. Thus, if COTi > 1 at any point in a decompression profile, then the subject is more likely to display symptoms than if he were exposed at a constant 02 partial pressure to a point on the dose-time curve derived for the same symptoms. One index based upon the U.S.N. 02 dose:time table may be used but separate neurologic and pulmonary (COTi)s are preferred.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held May 12-13, 1976. Carillon Hotel, Miami Beach, FL (http:www.uhms.org)
URI: http://archive.rubicon-foundation.org/5249
Date: 1976

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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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