Can Humans Breathe Liquid?

Deep water can be fatal in obvious way drowning but can also kill in not so obvious ways like decompression sickness, oxygen toxicity or complications from nitrogen narcosis; these complications don’t come from high pressure alone but arise from breathing air under pressure.

Deepest scuba dive ever recorded is only 332 meters which took 12 minutes to reach and 15 hours to return from; deepest saturation dive was 701 meters representing deepest human has ever been outside submersible.

Many offshore oil fields lie beneath much deeper water than diving records with all requiring constant maintenance; Perdido oil field lies under nearly 2,450 meters of ocean representing world’s deepest oil rigs.

Remotely operated vehicles have to be used for deepest work and this is not without disadvantage; even best ROV operators are no substitute for having human on scene.

Atmospheric diving suits have been invented to try to bridge gap between saturation divers and ROVs keeping person inside at one atmosphere of pressure but these suits extremely heavy, hard to maneuver, and can only operate at maximum depth around 600 meters.

If humans could breathe liquid instead of air many problems that deep-sea divers face could be completely eliminated; concept is straightforward on surface with oxygen-rich liquid breathed instead of oxygen-rich air.

As long as alveoli in our lungs can receive and exchange enough oxygen they surprisingly don’t care how it gets there representing fundamental respiratory physiology principle.

Liquids can’t be compressed in same way that gas can; as diver descends with lungs full of liquid won’t be exposed to huge partial pressure changes that happen when lungs filled with gas.

When breathing normal air under pressure each breath taken contains many more molecules of oxygen and nitrogen than breath taken at surface; under more pressure more and more nitrogen builds up in body’s tissues becoming problem when diver ascends and nitrogen comes out of solution creating dangerous bubbles causing the bends.

Idea of liquid breathing has been around since 1960s where first studied by Office of Naval Research to try to increase escape depth from submarines; scientists immersed mice in oxygenated saline at pressures up to 160 atmospheres representing pressure one mile below surface.

Scientists learned mice 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 condition that occurs when lungs can’t remove enough carbon dioxide produced by body.

Scientists knew they needed to find 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.

Even though PFCs carry oxygen and CO2 well they have nearly twice density of water making them much more difficult to breathe in and out than air; lungs and diaphragm did not evolve to push that much mass in and out.

Office of Naval Research decided research progressed to point of testing on first commercial diver; while this was important milestone this human trial wasn’t resounding success.

Returning to breathing air from liquid can be problematic or even fatal if all of liquid isn’t removed representing third major problem with liquid breathing.

One inventor thinks he has come up with plan to make liquid breathing possible; proposes using compressible chest plate that would mechanically force liquid in and out of lungs along with CO2 scrubbing device.

Final and perhaps most horrible part of entire idea of breathing liquid is actually breathing it in; you put on 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 tall order.

With all these hurdles both biological and psychological it seems like liquid breathing for deep-sea diving is likely to remain dream; however all research that’s been done has not been for nothing.

Liquid breathing or liquid ventilation as called in medical field has huge potential to treat people with range of lung problems; medical applications for liquid ventilation will help to save countless lives.

Premature babies born before 28 weeks in particular can have huge difficulties breathing often because their lungs have not developed enough to adjust from liquid environment of womb to breathing air; their underdeveloped alveoli lack vital surfactants which stop air sacs from sticking together when we exhale.