Can Humans Breathe Liquid?

[Music] venturing into the deep sea is something that humans were not designed for deep water can be fatal in the obvious way drowning but can also kill you in not so obvious ways like decompression sickness oxygen toxicity or complications arising from nitrogen narcosis but as I discussed in the last video these complications don't come from the high pressure of the deep alone they all arise from breathing air under pressure this is why the deepest scuba dive ever recorded is only 332 meters which took 12 minutes to reach and 15 hours to return from and the deepest saturation dive was 701 meters the deepest a human has ever been outside a submersible going any deeper with current technology becomes excessively dangerous but for reference many offshore oil fields lie beneath much deeper water than this and all of them require constant maintenance the perdido oil field lies under nearly two thousand four hundred and fifty meters of ocean and the oil rigs that exist there are the world's deepest remotely operated vehicles have to be used for the deepest work and this is not without its disadvantage even the best ROV operators are no substitute for having a human on the scene atmospheric diving suits have been invented to try to bridge the gap between saturation divers and ROV s keeping the person inside at one atmosphere of pressure but these suits are extremely heavy hard to maneuver and can only operate at a max depth of around 600 meters if there was a way to remove the limitations that breathing air at depth imposes on the body then humans could in theory dive much deeper than they currently can as deep as the deepest oil rigs maybe even to the bottom of the Mariana Trench but you can't remove the need to breathe from the equation and you can't remove the immense pressure that exists at the bottom of the ocean but what you can remove is the need to breathe air if humans could breathe liquid instead of air many of the problems that deep-sea divers face could be completely eliminated while the idea seems crazy the concept is straightforward on the surface instead of breathing oxygen-rich air you breathe the oxygen rich liquid as long as the alveoli and our lungs can receive an exchange enough oxygen they surprisingly don't care how it gets there and in theory liquid breathing could allow divers to go deeper than they ever have because liquids can't be compressed in the same way that gas can as the diver descends with lungs full of liquid they won't be exposed to the huge partial pressure changes that happen when the lungs are filled with gas as I mentioned in the last video when breathing normal air under pressure each breath taken contains many more molecules of oxygen and nitrogen than a breath taken at the surface due to the increased pressure and under more pressure more and more nitrogen builds up in the body's tissues this becomes a problem when the diver ascends and the nitrogen comes out of solution and creates dangerous bubbles causing the condition known as the bends but with liquid in the lungs instead of air the body would not become saturated with nitrogen at all decompression sickness and the long decompression times needed to avoid it could in theory be completely eliminated nitrogen narcosis too could be avoided and oxygen toxicity would not be a problem since the level of oxygen being delivered to the body would remain constant but in theory is the key phrase here it all sounds good on paper but can this actually work in real life it's long been a part of the sci-fi world notably the James Cameron movie the abyss where it plays a central role but ultimately it's just special effects right well for the humans it is but for the rat that is not a special effect it is actually breathing liquid so if the rat can do it can we how far off from reality is this idea for humans the idea of liquid breathing has been around since the 1960s where it was first studied by the Office of Naval Research to try to increase the escape depth from submarines scientists immersed mice in oxygenated saline in pressures of up to a hundred and sixty atmospheres which is the pressure one mile below the surface depending on the pressure temperature and composition of the breathing medium the mice could survive for several minutes and sometimes up to several hours breathing liquid so the concept of liquid breathing was proven in a way but something was still ultimately killing the mice they could not survive indefinitely in these experimental conditions scientists learned that they didn't die from too little oxygen being delivered to their bodies as you might guess but rather from too much carbon dioxide remaining in it respiratory acidosis is the condition that occurs when the lungs can't remove enough carbon dioxide produced by the body the oxygenated saline solutions were not allowing enough co2 to dissolve into it from the lungs ultimately killing the mice and this brings us to the first major challenge with liquid breathing to try to get around this problem scientists knew that they needed to find a liquid medium that could dissolve large amounts of both oxygen and co2 very few liquids have this property except for silicone oils and perfluorocarbons or PFCs after more experiments with mice silicone oils proved to be toxic and only PFCs remained as a possible solution to the co2 problem PFC czar a type of synthetic liquid a hydrocarbon with the hydrogen replaced by fluorine they are clear and odorless and chemically and biologically inert and on top of this they are great at carrying oxygen and co2 chemically pfcs are an ideal medium for carrying respiratory gases but physically using them to breathe is still extremely difficult in reality and this brings us to the second major hurdle with liquid breathing even though they carry oxygen and co2 well PFCs have nearly twice the density of water which make them much more difficult to breathe in and out than air the lungs and diaphragm did not evolve to push that much mass in and out the average male lung capacity is six liters and the average density of PFCs is 1.9 grams per milliliter which means the diaphragm would need to push and pull around 12 kilograms of mass with each breath to fully inhale or exhale the liquid so while the PFC medium may be able to dissolve a lot of oxygen in co2 moving enough of it in and out to keep up with the body's requirements becomes almost impossible co2 build-up would still be a dangerous problem especially under any amount of exertion but determined to push on with the experiments the Office of Naval Research decided that the research progressed to the point of testing it on the first commercial diver however while this was an important milestone this human trial wasn't a resounding success lying on an operating table the diver inhaled well oxygenated liquid and was indeed able to breathe but afterwards he developed pneumonia after they failed to get rid of all of the liquid from his lungs and this is the third major problem with liquid breathing returning to breathing air from liquid can be problematic or even fatal if all of the liquid isn't removed while all these obstacles should be enough to put off most research some scientists and innovators are still trying to figure out a way to make liquid breathing for deep-sea diving a reality one inventor thinks he has come up with a plan to make it possible he proposes using a compressible chest plate that would mechanically force liquid in and out of the lungs along with a co2 scrubbing device the scrubbing device would take blood out of the body via a catheter inserted into the groins femoral vein then it would circulate the blood through an artificial Gill that would use soda-lime to absorb the co2 before returning the blood to the body so in theory the risk of respiratory acidosis could be eliminated allowing the divers to exert themselves and work for long periods under the sea but if having a machine that forces liquid in and out of your lungs by crushing your ribcage and tubes coming out of your arteries doesn't sound bad enough you are still left with the final and perhaps most horrible part of the entire idea of breathing liquid actually breathing it in you put on the helmet it fills with liquid and then you have to drown yourself in it even if you rationally know it will be okay convincing your brainstem of that fact is a tall order every instinct you have will scream at you to not breathe it in it will feel exactly the same as regular drowning except in the final moment in the last desperate gasp you just don't die no thank you it's hard to imagine any amount of training that could allow you to overcome the instinct of sheer panic with all these hurdles both biological and psychological it seems like liquid breathing for deep-sea diving is likely to remain a dream however all the research that's been done has not been for nothing liquid breathing or liquid ventilation as it's called in the medical field has huge potential to treat people with a range of lung problems premature babies born before 28 weeks in particular can have huge difficulties breathing often because their lungs have not developed enough to adjust from the liquid environment of the womb to breathing air in gas form their underdeveloped alveoli lack vital surfactants which stop the air sacs from sticking together when we exhale to combat this doctors have begun to use PFCs with remarkable success the pfcs can act as a temporary surfactant enabling gas exchange and giving the lungs time to finish developing the technique is now also being tested in adults with lung injuries and as a drug delivery mechanism for people with COPD or cystic fibrosis the medical applications for liquid ventilation will help to save countless lives and as this research progresses if an even better oxygen and co2 carrier than pfcs is discovered may be liquid breathing will one day take people to the bottom of the sea after all I have been obsessed with underwater exploration since I was a kid and the fact that so much of the ocean remains undiscovered is one of my favorite things to get excited about and even outside of the purely natural world the sea has so many hidden secrets of ancient civilizations that are waiting to be uncovered the Black Sea in particular is known for its well-preserved shipwrecks which give historians an amazing look back in time if you like learning about discoveries like this then you should check out the ocean exploration documentaries on curiosity stream curiosity stream is a streaming platform that has thousands of high quality high budget documentaries like this one called expeditions black sea wrecks which is about a team of scientists on a three-year exploration of the black sea in search of evidence of the ancient empires that sailed their ships into these unknown waters and if you're a fan of educational content and if you're looking for more quality things to watch during your quarantine then this is the perfect time to sign up because a subscription to curiosity stream now comes with a subscription to nebula nebula is a place where top educational content creators like polyphonic Wendover productions and our other channel real engineering can create videos freely without worrying about the YouTube algorithm or D monetization it's a place where we can upload our content ad free and also experiment with original content and new series the original content is my favorite part of nebula shows like real engineering logistics of d-day series the latest episode is about the 23,000 men who landed in Normandy on d-day by parachute and glider so if you sign up for curiosity stream and curiosity stream comm slash real science you'll get a subscription to curiosity stream and a subscription to nebula for just $19.99 a year by signing up you're not just supporting this channel but all of your favorite educational content create thanks for 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Channel: Real Science

Views: 1,357,294

Rating: 4.9113269 out of 5

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Id: TIGCdA2YLyY

Length: 12min 34sec (754 seconds)

Published: Sat Jun 20 2020