[HN Gopher] Deep-sea diver was cut off from his air supply for h...
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       Deep-sea diver was cut off from his air supply for half an hour. He
       survived
        
       Author : geox
       Score  : 13 points
       Date   : 2025-03-23 18:05 UTC (4 hours ago)
        
 (HTM) web link (www.cbc.ca)
 (TXT) w3m dump (www.cbc.ca)
        
       | jackyinger wrote:
       | This is a great story, but this is definitely not the best write
       | up of it.
       | 
       | This is at least a tad better https://www.bbc.com/news/uk-
       | scotland-north-east-orkney-shetl...
        
       | nradov wrote:
       | The article seems a bit confused or incomplete on the physiology.
       | It's unlikely that the use of a heliox breathing mix caused
       | hypothermia (and thus slower metabolism). While helium is an
       | excellent heat conductor, that gas wouldn't generally be used
       | inside a diver's suit. Instead commercial divers working in cold
       | water would usually have hot water piped into their wetsuit
       | through the umbilical, or a drysuit with electrical heating. In
       | either case once the umbilical was severed he would have lost his
       | heat source and then hypothermia can set in within a matter of
       | minutes.
       | 
       | The breathing mix might have protected him due to a higher oxygen
       | partial pressure. Normally divers use a breathing mix set to have
       | a PPO2 somewhat higher than the 0.21 bar we normally breathe at
       | sea level. The extra oxygen dissolved in his body may have
       | protected him from brain damage for a crucial few extra minutes.
        
         | slau wrote:
         | I don't entirely disagree with you, however him switching to
         | his emergency cylinder could still reduce his core temperature
         | very quickly, no?
         | 
         | The heliox mixture supplied by the ship/bell is most likely
         | heated/insulated (by the same warm water heating his suit).
         | Once he switches to the emergency reserve, the 2-300 bar gas
         | gets expanded to 10 bar, massively cooling it down. That
         | cylinder was most likely already at 7-10degC (whatever the
         | ambient temp was), so the heliox is probably coming out at just
         | above freezing. Thoughts?
         | 
         | I haven't dived trimix yet, but I know many in my club have
         | indicated it's easier to feel cold when diving OC trimix, and
         | recommend it as yet another reason to only dive trimix on CCR.
        
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