The Many Uses of Liquid Breathing
A modern day torture device or chemical savior?
I was minding my own business yesterday, scrolling through Reddit and Instagram, when I stumbled upon an older Tumblr text post that wrote of a liquid that people can breathe through when fully submerged. This had me intrigued for two reasons: One, how is that possible and two, what purpose does that serve? I was done for. I’ve spent hours combing through Wikipedia pages and scientific studies to give you the basics.
Before I started diving into my research, all I could picture was that scene from Harry Potter and the Goblet of Fire where Harry takes the gillyweed and turns into a half-teenage boy and half-frog. Obviously that’s fantasy, but perfluorocarbon (or, PFC) is a very real substance. And incredibly, you can breathe even when fully immersed.
Liquid breathing is a form of respiration in which a lunged creature breathes an “oxygen-rich liquid…rather than breathing air.” Enter perfluorcarbon. What’s insane is that PFC contains more oxygen than human blood. The term “perflurocarbon” literally means ‘a liquid made up of carbon and fluorine exclusively.’ This is one of the strongest bonds found in organic chemistry. PFC has a much higher density than water but looks very much the same as both are colorless.
But back to this Tumblr post. The writer of the post claimed that liquid breathing is used as a modern day torture device because breathing in PFC is, apparently, incredibly uncomfortable. When a person breathes it, their body reacts as if they are drowning and will sometimes lose consciousness. If that isn’t something straight out of a science fiction film I don’t know what is. Despite reading this in the post, I personally found very little evidence to this being entirely accurate in my research. Most often, PFC is used for medical procedures (especially in pediatric cases), as well as occasionally for recreational use like diving.
Divers who delve deeper than most can experience damage if not protected properly. Gas pressure increases the deeper down into the ocean a person goes. A diver, if they go too deep, could experience a collapsed or burst lung, decompression sickness, and more. I swear one time my dad told me your head could explode if you dove too far down. However, liquid breathing provides an alternative to traditional scuba diving. By putting liquid into the lungs, the diver’s body can accommodate the higher pressures around them.
This technique is not super common, though, due to the high viscosity of PFC. It doesn’t allow the body to breathe out carbon dioxide as well as on dry land, which isn’t ideal for a diver deep in the Mariana Trench. That being said, it has been suggested that “a liquid breathing system could be combined with a CO2 scrubber to connect to the diver’s blood supply” and prevent any free breathing issues. The USA has allegedly put in a patent for such a device, so we will have to wait and see if it gets approved.
Use of PFC in medical treatment is far more interesting to me, especially because the first medical use was in treatment for premature newborns in the 90's. Further, there is a lot of study in PFC use for cardiac arrest, and brain and lung inflammation. Allegedly, based on a study by Mike Darwin and Steven B. Harris, using PFC can reduce inflammation in the lungs as well as quickly lower body temperature which can help people heal faster. Unfortunately, this theory has not been thoroughly tested with humans but the studies are promising (even if they were conducted in the late 90's).
There’s so much more to liquid breathing. Even space travel has its need for liquid breathing, because liquid immersion reduces the physical stressors of G forces. Additionally it’s been proven that liquid breathing can protect against the effects of acceleration in space. There’s even a special kind of space suit (called a Libelle G-Suit) that “allows aircraft pilots to remain conscious and functioning at more than 10g acceleration by surrounding them with water in a rigid suit.”
Basically, if an astronaut is completely immersed in PFC liquid and has the liquid filling all of their body cavities, the astronaut will feel very little effects from the extreme G forces in space because “the forces on a liquid are distributed equally, and in all directions simultaneously.” But there will still be some effect because of the density differences in different body tissues. Either way, a very cool way to prevent some of the long term effects from travelling to outer space.
As for medieval style torture in the 21st century, that remains to be science fiction. There is a lot of use of liquid breathing in films, novels, and television. There are dozens of books that utilize liquid breathing and breathable water as plot devices — including the Star Trek: The Next Generation novels. The earliest I could find of a literary work noting a person who could breathe in water was a 1938 short story about the process of a man using his lungs like gills.
Liquid breathing is likely going to remain being purposed for medicine and surgery, but maybe the Space Force will utilize PFC some day.
