[abstract] HYDROGEN DIVE AND DECOMPRESSION.

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[abstract] HYDROGEN DIVE AND DECOMPRESSION.

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Title: [abstract] HYDROGEN DIVE AND DECOMPRESSION.
Author: Masurel, G; Gutierrez, N; Giacomoni, L
Abstract: The HYDRA IV dive one of the previous simulated dives with hydrogen performed at the COMEX - showed that hydrogen could not be used alone as a diluent. The hydrogen percentage in the recommended "hydreliox" mixture is lower than the narcosis and explodability threshold values. Taking into account the PiO2 liable to be used during decompression, the hydrogen must be removed before 200 msw. The HYDRA V dive (at 450 msw) has shown that the isobaric transition from "hydreliox" to heliox -even in two phases -results in a significant counterdiffusion phenomenon. The solution consists in decompressing by gradually reducing PiH2. In such a case both concomitant phenomena, i.e. exchanges between H2 and He and decompression must occur slowly enough to prevent the formation of bubbles in the diver's system. The detection of circulating bubbles by means of the Doppler ultrasonic detector has made it possible for us to check such a condition. During this same HYDRA V dive some divers were decompressed with gradual hydrogen removal so as to get a 70 min/msw decompression rate. In the absence of circulating bubbles the decompression rate was increased to 65. 60 and 55 min/msw up to complete hydrogen removal at 200 msw ; it was then increased to 45 min/msw with a satisfactory bubble flow. In the HYDRA VI dive (at 500 msw) decompression was carried out at 60 min/msw up to complete hydrogen temoval and then at 45 min/msw. Bubble detection findings show that the 60 min/msw decompression rate is quite safe in the first decompression phase since the bubble flows as measured according to the KM code* remain low. Bubbles were produced in only 1 diver out of 8. In view of such results selecting a higher decompression rate has been considered for future decompressions with hydreliox mixture. * KISMAN K.E., MASUREL G., GUILLERM R. : bubble evaluation code for doppler ultrasonic decompression data. Undersea Biomed Res. supplement to vol. 5, N.1. march 1978, page 28.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held May 26-30, 1987. The Hyatt Regency Hotel, Baltimore, Maryland (http://www.uhms.org)
URI: http://archive.rubicon-foundation.org/5588
Date: 1987

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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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