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Ear Barotrauma. Causes, Symptoms, Preventions

Source: Scuba Diver Life
Author: Jessica Vyvyan-Robinson

An ear barotrauma is an injury to the ear caused by abrupt changes in pressure, and can be brought on by several circumstances, as well as by diving with a cold. Barotraumas come in several different forms, and together constitute the most common scuba-diving injuries. Middle-ear barotrauma alone affects 30 percent of first-time divers and 10 percent of experienced divers. Injuries of this kind can be incredibly serious, even resulting in permanent hearing loss, and as I discovered, can be excruciatingly painful. I was lucky — my injury was mild, and healed after just two weeks; some cases of barotrauma keep divers out of the water for many months. It’s easy to prevent ear barotrauma if you follow the proper precautions and procedures. Here we aim to help divers learn more about these injuries, and how to keep them from happening.

Why Does Barotrauma Occur?
In order to understand ear barotrauma, it’s important to first understand the anatomy of the human ear. Our ears are comprised of three sections: the outer ear and two internal sections known as the middle and inner ear. The part of the ear that we see is called the auricle, which channels sound (and during a dive, water) into the ear. The ear hole opens into a canal, at the end of which is the eardrum. Also known as the tympanic membrane, the eardrum separates the outer ear from the middle ear, a section filled with air that contains the three tiny bones that conduct sound, the ossicles. Importantly for understanding barotrauma, the middle ear is connected to the back of the throat by the Eustachian tubes. When we equalize during a descent, air passes along these tubes to balance the pressure inside the middle ear with the ambient pressure acting on the other (outer) side of the eardrum. The middle ear is separated at its other end from the inner ear by two exceptionally thin membranes known as the round window and the oval window. If these membranes become perforated, fluid can leak from the inner ear into the middle ear, causing considerable damage.

Preventing Barotrauma
According to Boyle’s Law, as ambient pressure increases, a gas-filled volume in contact with that pressure decreases, and vice versa. This is the physical law relating to ear barotrauma, which occurs when increasing ambient pressure on the descent (or decreasing ambient pressure on the ascent) causes the volume of the gas-filled spaces in the ear to either contract or expand. As the spaces change, the sensitive tissues that make up the ear are distorted, eventually causing them to become damaged. In order to prevent injury, it’s important that the gas spaces inside the ear are kept equalized, i.e., at an equal pressure to the water entering the outer ear. A pressure difference of just 2 psi is sufficient to cause significant discomfort, while a difference of 5 psi is enough to cause the eardrum to rupture. A barotrauma can occur at any depth, but because the greatest pressure change per foot occurs in shallow water, a diver is most susceptible to this kind of injury in the first 14 feet of a descent from the surface. This explains why we are taught to equalize early and often, and because ambient pressure continues to change as we descend, we need to equalize every few feet to prevent a pressure imbalance.

The Dangers of Decongestant
Although these injuries are most common on the descent, it is also possible for them to occur on ascent, particularly if a diver has taken decongestion medication that has subsequently worn off. As we ascend and the ambient pressure decreases, the gas in the middle ear expands. If the Eustachian tubes have become blocked due to congestion, this expanding air cannot escape and the membranes at either end of the middle ear compartment are liable to distort or even rupture as a result. This situation, known as a reverse block, is how I suffered middle-ear barotrauma. It was incredibly scary: already at depth, I had no choice but to surface eventually. I tried delaying my ascent, descending a few feet and giving the trapped air time to escape, but ultimately I was forced by air and no-decompression limits to ascend despite knowing that doing so would cause an injury. The resulting barotrauma was undoubtedly the worst pain I have ever experienced (including multiple broken bones), and converted me in the space of one dive from a reckless congestion diver to one with a healthy respect for the rules.

Other common causes of ear barotrauma include ineffective equalization techniques, the failure to equalize either at all or frequently enough, and equalizations that are too forceful. Unfortunately, some divers have naturally tight Eustachian tubes that may prevent them from equalizing effectively. In those cases, individuals should seek medical advice as to whether or not they are able to dive.

There are several different types of ear barotrauma:

* The most common is middle-ear barotrauma, usually caused by ineffective or failed equalization, or a blockage of the Eustachian tubes. It is characterized by an inability to equate the pressure in the middle ear to that of the surrounding water pressure, resulting in the creation of a vacuum on descent, or a build-up of pressure on the ascent. The eardrum and the tissues of the middle ear sustain damage, causing the compartment to fill with blood and fluids. Symptoms include a feeling of fullness inside the ear, hearing that is either muffled or lost completely, and an eardrum that appears red and either swollen outwards or retracted inwards. Usually, these symptoms will develop upon surfacing, but can appear several hours later.

* Inner-ear barotrauma typically occurs when divers equalize too forcefully or cannot equalize at all. The practice of holding the nose and blowing is known as a Valsalva maneuver. If performed too hard when the Eustachian tubes are blocked, the fluid in the inner ear becomes over pressurized, causing the round window to rupture. Inner-ear barotrauma can also occur if a diver fails to equalize on the descent. In that case, the vacuum created in the middle ear affects not only the eardrum but the oval window as well. If the oval window contracts too far towards the middle ear, the ossicles can puncture it, causing fluid to enter the middle ear. Symptoms of this kind of barotrauma include sudden vertigo, vomiting, a roaring sound in the ears and hearing loss.

* Outer-ear barotrauma occurs when the ear canal itself is blocked, possibly by a tight-fitting hood, ear buds, or earwax buildup. The obstruction creates an air pocket between itself and the eardrum, which turns into a vacuum as ambient pressure increases. This can cause the superficial rupture of blood vessels in the ear canal or, more seriously, damage to or perforation of the eardrum itself. Typical symptoms of this kind of barotrauma include bleeding and seeping fluids from the ear, and possible hearing loss. If you suspect this kind of barotrauma, you should not put any kind of drops in your ear, as the barrier between your outer and middle ear has now been compromised and liquid entering the middle ear will cause extreme vertigo.
Any suspected barotrauma requires immediate medical attention, and an abstinence from diving until advised otherwise. To prevent the injuries from occurring in the first place, follow several basic guidelines. First, always remember to equalize early and often, particularly during the first 14 feet of your descent. The best method is to hold your nose and blow gently, while tilting your head from side to side. You can also move your jaw from side to side or swallow, if that works for you. Practice equalizing on land before entering the water, particularly if you frequently have problems clearing your ears. Importantly — never force equalization. If it doesn’t happen easily, abandon the dive. If you have recurring equalization problems, visit an ear, throat and nose specialist who may be able to advise you on how to safely proceed. Never wear ear buds underwater, or hoods that fit too tightly, and above all, never, ever dive with a cold. Take it from someone who knows: it’s just not worth it.

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