I'm no expert but I've heard the feeling of suffocation- panic comes not from the lack of oxygen but, the build up of carbon dioxide in the atmosphere. I think that's why people look at the SCUBA type set up for inert gas- because it removes the out breath.
I'm not sure if that's necessary if the volume of inert gas is higher though. I'm not sure how the Sarco pod works with this regard. Whether there are filters or whatever to remove the carbon dioxide. It's not a method I've researched that thoroughly though. Hopefully more knowledgeable people will know.
You could have a plastic coffin made and with a hole to let the helium in. Then you could enter with an oxygen
tank and inhale the oxygen until the plastic case is saturated with helium (are there oxygen meters to understand when the oxygen has run out?). At this point remove the mask with oxygen tank and close the tank. At least this is how this blessed Elio can work? Or is it still having problems?
