Humans have lots of basic requirements that need to be met in order to stay alive. Food is a necessary one, though it’s possible to go without for great stretches of time. Water is more important, with survival becoming difficult beyond a few days in its absence. Most of all, though, we crave oxygen. Without an air supply, death arrives in mere minutes.

The importance of oxygen is why airway management is such a key part of emergency medicine. It can be particularly challenging in cases where there is significant trauma to the head, neck, or surrounding areas. In these cases, new research suggests there may be an alternative route to oxygenating the body—through the rear.

When Nothing Else Works

Most of us are familiar with the usual route of human respiration. We take in air through the mouth and nose, and it passes through the windpipe and into the lungs, where oxygen diffuses into the blood. When everything in the body is functional, this system works well. However, when things go wrong, it can suddenly become very difficult to keep a body alive.

Head or neck injuries can block the airway entirely, or infections can fill the lungs with fluid, preventing the transfer of oxygen to the blood. Supportive ventilation methods can help, but can often damage the lungs themselves while in use. When the lungs themselves cease to function at all, often the only real option is the use of a technique called extracorporeal membrane oxygenation, or ECMO. This is where complicated machinery is used to manually oxygenate the blood outside the body. It’s a complex method that can result in major complications, and comes with a wide range of potential side effects, some of which can be fatal.

In these life-or-death situations, it would be desirable to have an alternative oxygenation technique that could be used when the lungs or airway are badly compromised. New research has suggested that enteral ventilation could be just the ticket. It’s a rather out of the box method, involving the use of a special oxygen-carrying liquid called perfluorodecalin. By administering this fluid rectally, it may be possible to deliver oxygen to a patient without having to rely on the function of the lungs themselves.

As you might guess by the name, perfluorodecalin is a flurocarbon. Its molecules are made up of 10 carbon and 18 fluorine atoms, and it exists as a liquid at room temperature. It’s considered chemically and biologically inert, which is key to its use in a medical context. Beyond that, it’s capable of dissolving a great deal of oxygen, with 100 mL of perfluorodecalin able to dissolve 49 mL of oxygen at a temperature of 25 C. The fluid can also carry carbon dioxide, too. Historically, it’s been used as a method to supply oxygen to specific areas of the body in a topical application, and also used as a way to preserve organs or other tissues in an oxygen-rich environment.

Thus far, research remains at an early stage. Initial testing focused on supplying a rectal dose of non-oxygenated perfluorodecalin of 25 to 1,500 mL for up to 60 minutes, at which point patients would excrete the fluid on their own terms. Patients had their vital signs monitored and were studied for any possible adverse effects. The study found that only mild side effects occurred, specifically involving abdominal bloating and pain at higher levels which resolved without further intervention after the procedure was completed. No perfluorodecalin or related compounds were detected in the bloodstream in the immediate aftermath.

The first stage of clinical testing was focused on establishing safety profiles rather than outright testing the efficacy of rectal oxygenation. Nonetheless, even in testing with non-oxygenated perfluorodecalin, the study showed a “modest increase” in oxygen saturation in patients dosed with higher amounts of the fluid (500 mL and 1000 mL). This is a positive sign that this could be a viable route for oxygenation, but more research will be needed to verify the findings and develop the technique into something that could have actual clinical applications. That can be a particularly slow process due to the extensive safety requirements of new medical treatments, but such regulations exist for good reason.

First Rodeos And All That

It’s not the first time that physicians have explored alternate methods of delivering oxygen to the body. Other methods of liquid ventilation have been developed, albeit with a focus on delivering oxygen-rich liquids to the lungs themselves. The aim is generally to avoid the lung damage that is often caused by traditional positive-pressure ventilation systems, which can be particularly harmful to patients who are already badly unwell. Similarly, these methods typically use oxygen-rich flurocarbons to do the job. While there have been some promising studies, ultimately the technique remains experimental and challenging to implement.

Enteral ventilation has one major benefit over liquid ventilation using the lungs, precisely because it doesn’t involve the lungs at all. The body’s main airway can remain entirely unobstructed during such a treatment, and does not have to be filled with fluids or tubes that could cause damage on their own. In cases where the airway or lungs are badly damaged or compromised, these techniques could potentially help where liquid ventilation via the lungs would simply not be possible. There can be immediate risks in delivering any kind of liquid to a patient’s lungs, particularly if the transition to liquid breathing doesn’t go to plan. The same simply isn’t true of doing so via the enteral pathway, as the regular airway remains untouched and as functional as it ever was.

As it stands, you’re unlikely to be breathing via the rectum any time soon. However, some years down the line, your local emergency room or ICU might just have another route to administer oxygen when all the standard methods fail. It might be weird and unconventional, but it could help save lives.