Question Problems while breathing perfluorocarbon under pressure?

[DiveDoc87]

I've been reading the research into breathing perfluorocarbon (remember the movie The Abyss?) as a way to prevent gas narcosis and DCS, and many problems remain, such as work of breathing, and hypercapnia. What I haven't seen discussed in the research is how one would equalize pressure in the middle ear and sinuses? Replacing air in those spaces with perfluorocarbon, and removing it later seems like it would be a serious obstacle in actual diving conditions. The articles I've read in which humans have breathed perfluorocarbon appear to have done so under 1 ATM pressure where equalization wouldn't be an issue. I'd be especially interested in hearing from otolaryngologists and hyperbaric medicine specialists.

 

[Duke Dive Medicine]

I've been reading the research into breathing perfluorocarbon (remember the movie The Abyss?) as a way to prevent gas narcosis and DCS, and many problems remain, such as work of breathing, and hypercapnia. What I haven't seen discussed in the research is how one would equalize pressure in the middle ear and sinuses? Replacing air in those spaces with perfluorocarbon, and removing it later seems like it would be a serious obstacle in actual diving conditions. The articles I've read in which humans have breathed perfluorocarbon appear to have done so under 1 ATM pressure where equalization wouldn't be an issue. I'd be especially interested in hearing from otolaryngologists and hyperbaric medicine specialists.

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Divers could probably be trained to allow fluid into their sinuses and middle ears, some free divers do it with sea water, but the infection risk would still be there. And, that's assuming you've overcome the laryngospasm issue.

Best regards,
DDM

 

[John C. Ratliff]

In December of 1974, my dive buddy and I dove off the Oregon coast, got rolled by a 20+ foot wave on the way in (sea state had changed while we were underwater), stayed offshore until a U.S. Coast Guard boat came looking for us and found us. We were taken to Depot Bay (world’s smallest bay) by the Coast Guard cutter, where we re-united with our girl friends who had called the Coast Guard. I was putting on my clothes, when I bent over and out poured a bunch of sea water from my sinuous areas. I had no infection from that experience, and it is possible to get the sinuous cavities full of sea water or other fluids (but don’t do it with a 20 foot wave). .

SeaRat

 

[Akimbo]

What I haven't seen discussed in the research is how one would equalize pressure in the middle ear and sinuses?

Flooding and draining sinuses wouldn't be that tough, but the inner ear could be challenging. I understand that the flooded lung experiments never went very far because they could not adequately remove the perfluorocarbon from test animals lungs.

General Comments (not directed to DiveDoc87)​

Mechanical fluid circulation/ventilation, oxygenation, CO2 scrubbing and heating would be critical for working humans. We can't make mixed gas rebreathers reliable enough that divers don't have to carry bailout gasses. Solving thermal regulation problems alone is a much tougher problem.

Perfluorocarbon is roughly 20x more thermally conductive than air. A diver would be dead from hyper or hypothermia in minutes with a fluid heating failure because their core temperature would raise or drop so fast. Remember that the surface area of the human lung is about the size of half a tennis court.

Another problem is audio communications would be impossible. The vocal cords and eardrums can't function in such a high density media. It is hard for recreational divers to appreciate how critical voice communications is to a working diver's productivity and safety. The only option I have seen is for the diving supervisor to use a ROV (Remote Operated Vehicle) and use light as a medium for Morse Code.

 

[JohnN]

Flooding and draining sinuses wouldn't be that tough, but the inner ear could be challenging. I understand that the flooded lung experiments never went very far because they could not adequately remove the perfluorocarbon from test animals lungs.

General Comments (not directed to DiveDoc87)​

Mechanical fluid circulation/ventilation, oxygenation, CO2 scrubbing and heating would be critical for working humans. We can't make mixed gas rebreathers reliable enough that divers don't have to carry bailout gasses. Solving thermal regulation problems alone is a much tougher problem.

Perfluorocarbon is roughly 20x more thermally conductive than air. A diver would be dead from hyper or hypothermia in minutes with a fluid heating failure because their core temperature would raise or drop so fast. Remember that the surface area of the human lung is about the size of half a tennis court.

Another problem is audio communications would be impossible. The vocal cords and eardrums can't function in such a high density media. It is hard for recreational divers to appreciate how critical voice communications is to a working diver's productivity and safety. The only option I have seen is for the diving supervisor to use a ROV (Remote Operated Vehicle) and use light as a medium for Morse Code.

As long as we are speculating how many angels can dance on the head of a pin. . . wouldn't the hypo/hyper thermia problem be solved by a redundant temperature regulation mechanism? My guess would be something like that is already done for EVA suits for space "walks"

 

[Akimbo]

As long as we are speculating how many angels can dance on the head of a pin. . . wouldn't the hypo/hyper thermia problem be solved by a redundant temperature regulation mechanism? My guess would be something like that is already done for EVA suits for space "walks"

Precisely maintaining fluid temperatures in a lab or in space is a lot different than in the deep ocean. There is a MUCH wider acceptable temperature range in air or Oxygen. The temperature range on HeO2 dramatically narrows and Helium's thermal conductivity is only 6.9x higher than air compared to 20+ for perfluorocarbon.

The comfort range in sat chambers with 99% Helium and 1% Oxygen is about +/- 1/2° F or 1/4° C. Skin temperature regulation is much more forgiving than gas temperature. A difference of 4° F/2° C can be the difference between sweating like a sumo wrestler and teeth chattering in a sat chamber deeper 850'/260m.