Objective
The aim of the project is to conduct an experimental dive in hyperbaric chamber in order to evaluate the limits of very deep industrial diving with hydrogen gas mixes.
Phase 1 : Hyperbaric animal experimental dives.
Thirty monkeys exposed between 7 and 12 MPa (700 and 1200 meters of sea water equivalent) in heliox, hydrox and hydreliox breathing mixtures.
a) Heliox exposures :
Two experiments realized at 7,1 and 8,1 MPa (700 and 800 msw).
a1) - First experiment with four monkeys (two animals with intracerebral electrodes and an animal with intracranial electrodes)
CLINICAL OBSERVATIONS :
. Strong HPNS at 7,1 MPa and the psychometric performances decrease.
. Death of an animal during the final decompression at 3,25 MPa (315 msw).
a2) - Second experiment with four no-instrumented monkeys.
CLINICAL OBSERVATIONS :
. Very strong HPNS at 8,1 MPa with tremor, myoclonies hyper-excitability and strong decrease of the psychometric performances.
. No problem during the decompression phase.
b) Hydrox exposures :
Two experiments realized at 8,1 and 10,1 MPa (800 and 1000 msw).
b1)- First experiment with a three monkeys team (the same of heliox exposure Nr. 1).
CLINICAL OBSERVATIONS :
. No HPNS at 8,1 MPa and normal psychometric performances
b2) - Second experiment with four monkeys (no bio-instrumentation)
CLINICAL OBSERVATIONS
- No HPNS at 10,1 MPa but hypoactivity for all animals (narcotic hydrogen effect).
c) Hydreliox exposures
Four experiments realized at 10,1/10,6 and 12,1 MPa (1000, 1050 and 1200 meters of seawater equivalent)
c1)- First experiment with four monkeys (an animal with EEG intra-cranial electrodes)
* dive's parameters . 1000 msw depth (10,1 MPa)
. slow compression
. 4 MPa of hydrogen partial pressure
CLINICAL OBSERVATIONS
- From 7 to 10,1 MPa the tremor increase and myoclomies are observed (HPNS effect).
Strong decrease of the psychometric performances at 10,1 MPa.
c2) - Second experiment with four monkeys (two animals with intracerebral electrodes and an animal with EEG intra-cranial electrodes).
* dive's parameters . 1050 msw depth(10,6 MPa)
. speedy compression
. 6 MPa of hydrogen partial pressure.
CLINICAL OBSERVATIONS :
- At 10,6 MPa very strong HPNS with tremor, myoclonies equilibrism disturbance and hyper excitability.
- Death of an bio-instrumented animal during decompression at 7 MPa.
c3)- Third experiments with three monkeys (one animal with intracerebral electrodes and an animal with EEG intra-cranial electrodes).
* dive's parameters : . 1200 msw depth
. slow compression
. 8 MPa of hydrogen partial pressure.
Beyond 300 meters depth, the diver is faced with limit factors the main ones of which are:
- The High Pressure Nervous Syndrome which is an effect of the pressure on the central nervous system. It affects the efficiency of the diver.
- The density of the gas which increases proportionally to the depth and implies breathing efforts prejudiciable to the work capacity of the diver.
The different experimental dives carried out from 1983 to 1989 by COMEX in the HYDRA development program have revealed that hydrogen reduced greatly these limit factors.
The purpose of the study is to define the following parameters:
- the optimisation of the hydrogen rate in the hydreliox ternary breathing mix (H2-He-O2)
- method of injection of hydrogen during the compression
- speed of compression.
As the objective is "over 700 msw diving", the divers will be under neurophysiological control during the compression phase and their performances (efficiency and work capacity) quantified at the maximum depth.
The project is divided into two main phases:
PHASE 1. Animal experimentation (HYDRA X)
Several experimental dives will be carried out between 700 and 1200 meters with bio-instrumented primates (macaca fascicularis). Different breathing mixes will be used:
- Heliox binary mixture (He-O2) to set up the references of the effects of the High Pressure Nervous Syndrome under high pressure.
- Hydrox binary mixture (H2-O2) to set up the references of the effects of the narcosis and the dopaminergic activity.
- Hydreliox ternary mixture (H2-He-O2) to study the parameters of very deep diving.
During these experiments psychometric tests were realized to evaluate the cognitive behaviour of each animal. Intracerebral dopaminergic and intra-cranial EEG activities were recorded for correlation studies.
PHASE 2. Manned experimental dive (HYDRA XI)
It will be carried out after handling the data of the animal experiments.
The depth to be reached will be between 700 and 800 meters.
Three divers will be pressurised under hydreliox nearly at the equivalent of 610 meters.
At this depth, the physiological measures will be compared to those of the previous dives under helium (PHYSALIE 6, SAGITTAIRE 4 and ENTEX 9). The divers will then be taken down to about 700 meters where they will stay during several days. All neurophysiological, cardio-respiratory, ergonomic and psychometric tests necessary to the valuation of their mental and physical health will be made.
To evaluate the possibilities of work in extreme underwater intervention, the divers will carry out activities in immersion (effort exerices measured on ergometer, "meccano" assembling and diving equipment tests).
Programme(s)
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DEM - Demonstration contractsCoordinator
13321 MARSEILLE
France