Thread by @Gas_Craic

Starting off with some physiology! Cold immersion and hypoxia survival. #SOA21 A thread 🧵👇😗

Drs. Tipton and Mekjavic with Mr Lemons talking at this session. #SOA21

Chris Lemons tells us his fascinating story about working as a commercial saturation diver, at the extremes of human exploration. He's going to tell us about back in 2012 - 'The Topaz Incident'. energyvoice.com/oilandgas/nort… #SOA21

Heliox is breathed in saturation dive situations, the helium replacing the nitrogen in standard air... pubmed.ncbi.nlm.nih.gov/32176950/ #SOA21

Chris's boat above him, with him on the seafloor, started to move away from him in a large storm... 😲and the 'umbilical cord' connecting him to the boat became stuck... and came apart.... so he now only has 9 minutes of gas left. #SOA21

Emotively discussing now him counting down the minutes to his death, which as an experienced diver, he knew would be inevitable at the end of the timer... and he did indeed pass into unconsciousness. #SOA21

Until his colleagues above got an ROV to him, coming across him on the floor bed... #SOA21

41 minutes had passed from the start of the incident before Chris was pulled into a 'diving bell' and received a couple of rescue breaths! ... and came round... Body temp of 35.5... #SOA21

Most important piece of equipment for Chris's recovery was the tea cosy! 😂#SOA21

You can watch this full story on Netflix actually! netflix.com/gb/title/80215… #SOA21

Now... on to a 'deep dive' into physiology.... #SOA21 @ICS_updates Using Chris's story as a platform to discuss physiology! #SOA21

A ~40 minute, presumably hypoxic, rescue attempt with apparently no adverse sequelae...
How and why? 🤯🤯
Some key physiological clues, including what he was breathing... #SOA21

Hypotheses? It's unlikely Chris was 'pre-cooled just by working in a cold environment. Hypothermia may be protective in drowning.... but here, particularly, why was Chris awake within 2 rescue breaths? The physiological sequelae of hypothermia aren't reversed this easily...#SOA21

Hypoxia however... we can see some of the jerks/twitches in Chris's video. "Like drifting off to sleep" certainly sounds like hypoxia. "Flashing lights" seen on recovery... an alarming phenomenon is how people report how 'comfortable' this type of hypoxia is: #SOA21

Could have been Chris's emergency oxygen supply? #SOA21

So after the bail-out supply is gone... how much O2 do you need in the body? He did hyper-oxygenate prior to dive... was he o2-toxic? The bail-out supply is high conc O2... #SOA21

Exercise and immersion, breathing a high conc of O2, generally get O2 toxicity quicker. #SOA21

There is (old!) discussion of rapid recovery from 1947! #SOA21

So of all these potentials, what is likely? Timing is obviously very important here.

What do you think? #SOA21