Ed Harris’s character, oil rig diver Bud Brigman, uses an experimental diving suit that allows him to breathe a specific oxygenated liquid instead of air near the climax of James Cameron’s 1989 underwater thriller The Abyss. To defuse a nuclear weapon, he must dive to the bottom of a deep ocean trench, but he can avoid the deadly effects of tremendous water pressure by doing this. Although it makes for an interesting story point, isn’t this technology utterly out of this world?
Although Ed Harris held his breath throughout the filming of the diving suit scenes, the oxygenated perfluorocarbon (the film’s breathing fluid) genuinely exists. Additionally, a scene in which a rat is submerged in the fluid was shot using real footage. Although the most well-known example of liquid breathing is The Abyss, the technique has been tested for more than a century. Although it isn’t yet suitable for deep-sea diving, it could have potentially life-saving uses in medicine.
To aid in the healing of poison gas-damaged troops’ lungs, doctors investigated the use of oxygenated saline solutions soon after the First World War, which led to the first tests with liquid breathing. The United States Navy started looking for techniques to let sailors escape a sinking submarine without decompression sickness in the late 1950s, during the height of the Cold War. However, the study did not start in earnest until then.
The Bends, or decompression sickness, is a medical emergency that can occur when breathing pressurized air. Nitrogen from the air dissolves more and more in a diver’s tissues as they descend and the water pressure rises. The quick ascent to the surface triggers the nitrogen to escape its solution, creating microscopic bubbles that pose a threat of serious injury or death due to air embolisms, strokes, joint discomfort, or both. As a result, divers need to take it easy as they climb and make plenty of decompression pauses so their bodies can slowly release nitrogen.
The necessity to decompress and the prevention of nitrogen accumulation may be achieved if, instead of air, a diver or fleeing submariner could breathe an oxygenated liquid. Nitrogen narcosis, often known as “Rapture of the Deep,” is an intoxication similar to alcohol that can be generated by breathing nitrogen under pressure. Liquid breathing would help minimize or eliminate this risk, among others.
The phenomenon known as oxygen poisoning occurs when the concentration of oxygen in the air becomes too high below a specific depth. Dive masks that dilute the oxygen and nitrogen with helium, like Heliox or Trimix, protect divers from severe side effects. However, this is only effective up to a certain altitude; breathing helium causes High-Pressure Nervous Syndrome, which includes tremors and other neurological symptoms, below around 160 meters. Consequently, no diver has been able to descend more than 701 meters while breathing compressed gas, and that was in a land-based diving chamber.
To dissolve enough oxygen in the fluid, a team led by Dr. Johannes Klystra of Duke University was able to pressurize a saltwater solution to 160 psi in 1962, allowing mice and other small creatures to breathe it. However, the animals succumbed to respiratory acidosis, also known as carbon dioxide poisoning, shortly after the breathing was maintained in this way for around an hour.
Although breathing fluid can provide the body with enough oxygen, it is far less effective at removing carbon dioxide exhaled, which has been a big drawback of liquid breathing for researchers ever since this was discovered. Acidosis can only be prevented if the average person can maintain a breathing rate of 5 liters per minute when at rest and 10 liters per minute while exercising, both of which are much beyond the capacity of the human lungs. Therefore, similar to hospital-grade mechanical ventilators, any viable fluid breathing device would necessitate the active pumping of fluid into and out of the lungs.
When American scientists Leland Clark and Frank Gollan substituted an unusual liquid known as perfluorocarbon (PFC) for Klystra’s oxygenated saline in 1966, they achieved a significant advance in the field of liquid breathing research. The colorless liquid PFC, which was initially created as a component of the WWII Manhattan Project, is made up of carbon and fluorine. The extremely strong link between these two components renders PFC non-reactive and incapable of causing any biological reaction.
This breathing fluid is perfect because it is twice as dense as water but only 1/4 as thick, and it can carry roughly 20 times as much oxygen and carbon dioxide as water. In the beginning, Clark and Gollan would only let rats and mice breathe normally while immersed in PFC that had been oxygenated. Although the animals had trouble breathing due to the fluid’s high density, they were able to remain submerged for up to twenty hours before suffering any harm. Forced ventilation was necessary for larger animals to avoid carbon dioxide accumulation, but PFC was shown to be viable as a breathing fluid in trials with anesthetized dogs.
Klystra quickly picked up where Clark and Gollan left off with PFC. From 1969 to 1975, she used both humans and animals in what is considered to be the most extensive study on liquid breathing ever. Francis J. Falejcyk, a diver for the United States Navy, made history as the first person to breathe oxygenated saline and PFC simultaneously during this study. They had trouble emptying the fluid from Falejcyk’s lungs, which led to his pneumonia, but he didn’t find the process very painful, even though he only received local anesthesia to help with intubation.
James Cameron, who was 17 years old when he attended a lecture by Falejcyk about his experiences in 1971, was inspired to compose the short narrative that would later become the screenplay for The Abyss. According to Klystra’s findings, inhaling PFC for up to one hour without experiencing carbon dioxide poisoning—so long as one doesn’t exert themselves too much—makes liquid breathing a feasible option for evading a sinking submarine.
Klystra also tried out PFC/Sodium Hydroxide emulsions for more practical uses; they had the potential to increase blood CO2 absorption. But in the end, none of these methods were ever put into practice in actual situations. Several divers sprained or fractured their ribs while testing liquid breathing techniques in the early 1980s when the Navy SEALs allegedly tried it out.
The use of venous shunt devices, which remove carbon dioxide from the bloodstream directly, has been suggested as a potential remedy to the acidosis issue. The obvious physiological and logistical problems with such a gadget mean that liquid breathing is still a ways off from being a practical method for deep-sea diving. The treatment of preterm infants is one area where it might be useful in medicine.
Nearly Half a Billion Alveoli Are Located in Our Lungs
They are little sacs of tissue that allow our blood to absorb oxygen. The alveoli can stay open because the body creates pulmonary surfactant, a mixture of lipids that lowers the surface tension of water. Without it, the alveoli would collapse like a wet paper bag. But because they can’t make enough surfactant, premature infants have trouble breathing because most of their alveoli collapse the second they’re born.
Conventional mechanical ventilators have been around for a while and have helped premature babies breathe, but the high pressures they create are harmful to their fragile lungs. However, liquid ventilation works by introducing breathing fluid into the lungs, simulating the environment in the womb. This opens up the alveoli, which enhances gas exchange significantly. Additionally, the method offers a practical way to inject medicine straight into the lungs.
In 1989, J.S. Greenspan of Philadelphia’s Temple University Hospital was the first to use neonatal liquid ventilation; he kept thirteen premature babies on the machines for 24 to 96 hours. Out of the thirteen, eleven showed significant enhancements in lung function after being weaned back to breathing air; however, six of them subsequently passed away from reasons unconnected to the trial. In 1995, R.B. Hirschl performed a comparable study on 19 patients ranging in age from neonates to adults. The results showed that liquid ventilation was effective, and 11 out of the 19 patients survived with better lung function.
Full liquid ventilation requires complicated and costly equipment, therefore in 1991 B.P. Fulman created a simpler method called partial liquid ventilation (PLV). When a patient is on partial lung ventilation (PLV), a standard mechanical ventilator is used to fill the lungs with air rather than inhaling liquids. The result is a more effective exhalation of carbon dioxide as the breathing fluid opens up about 40% of the alveoli in the lungs.
If patients would prefer not to breathe in pure fluid, another method is to give them an aerosol mixture of breathing fluid and air or oxygen, which would have the same effect but be much easier on their respiratory systems. The use of liquid breathing to induce therapeutic hypothermia was proven by Mike Darwin and Steven Harris in 1995. This is the process of reducing body temperature after a cardiac arrest to lessen the severity of brain and other tissue damage.
When compared to other methods, Darwin and Harris’s perfusion of chilled PFC into the lungs resulted in a cooling rate of half a degree Celsius per minute. These and other developments led the FDA to designate liquid perfusion as a “fast-track” development method, allowing for the expedited delivery of this potentially life-saving product to patients.
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