[abstract] ABSENCE OF PULMONARY DEAD SPACE CHANGES DURING HYPOBARIC DECOMPRESSIONS WITH HIGH SPENCER PRECORDIAL DOPPLER GRADES.

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[abstract] ABSENCE OF PULMONARY DEAD SPACE CHANGES DURING HYPOBARIC DECOMPRESSIONS WITH HIGH SPENCER PRECORDIAL DOPPLER GRADES.

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Title: [abstract] ABSENCE OF PULMONARY DEAD SPACE CHANGES DURING HYPOBARIC DECOMPRESSIONS WITH HIGH SPENCER PRECORDIAL DOPPLER GRADES.
Author: Norfleet, W; Davis, M; Powell, MR
Abstract: Hypobaric exposures producing a decompression stress similar to that encountered during extravehicular activities (EVA) generate high Spencer precordial Doppler bubble grades in about 50% of subjects. Previous investigations have demonstrated increases in alveolar dead space as a result of infusions of gas into the systemic venous circulation. We hypothesized that EVA-like hypobaric exposures enlarge alveolar dead space through embolization of the lungs with gaseous microemboli. Subjects were exposed for 3 hrs without an oxygen pre-breathe to 45 kPa (6.5 psi) ambient pressure while breathing 100% oxygen through an Intertechniques hood. A protocol of mild exercise was performed. Tidal volume (VT) and the composition and volume of expired gas were determined. The partial pressure of carbon dioxide (PCO2) in arterial blood was estimated through determination of both end tidal PCO2 (etPCO2) and transcutaneous PCO2 (tcPCO2). Alveolar dead space (VD) was calculated with the Enghoff-Bohr equation. [table]Time After Ascent to 45 kPa, VD (I, mean, n=9) via etPCO2, via tcPCO2; 0:24 0.41 0.44; 1:OO 0.45 0.47; 1:36 0.34 0.40; 2:12 0.45 0.45; 2:48 0.43 0.42 [end table] Alveolar dead space is not enlarged by the degree of embolization of the lungs with gaseous microemboli produced by EVA-like hypobaric exposures.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held June 23-27, 1992. Hyatt Regency Bethesda Hotel, Bethesda, Maryland (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/6958
Date: 1992

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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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