Barotrauma of the ears, Otitic Barotruama (a.k.a Otic Barotruama or Aero-otitis media) can occurs during ascent or descent in flying. This can also occur during hypoxia demonstration in decompression chamber. Divers during under-water operations, and patients in hyperbaric chamber may also suffer from barotrauma. The primary reason of Otitic Barotruama is pressure differential, either negative or positive, between the air in the middle ear cavity and the atmosphere, especially in presence of sore throat or cold.
Otitic Barotaruma may affect one or both the ears. There may be complaints of mild to severe pain in the ear, deafness, vertigo and ringing noise. The pain and deafness usually lasts from a few hours to a few days. In very severe cases there may be bleeding from the ear or even rupture of the eardrum.
Middle Ear and Pressure Changes in flight
The middle ear is a cavity covered on one side by the eardrum, with the other sides being bony. It ventilates through a tube, the “Eustachian Tube”, to the throat. This tube, akin to a flutter valve, is partly rigid and party collapsible; and normally remains closed. It opens spontaneously during swallowing, yawning, or yelling. It can be opened voluntarily by building up pressure inside the mouth and throat as in Valsalva manoeuvre.
During ascent, as the ambient pressure falls, the trapped air inside the middle ear expands, as per the Boyle’s law. This pushes the eardrum outward and gives a sensation of fullness in the ear. The expanding air inside the middle ear forces the tube open almost at every500 ft of ascent in an aircraft. This allows the equalization of pressure with the ambient and the eardrum returns to its normal position. During descent, on the other hand, the outside pressure progressively increases compared to the pressure inside the middle ear. The Eustachian tube, as a flutter valve, remains closed unless opened by some active action like swallowing, chewing, yawning or Valsalva manoeuvre.
However, if the pressure is not equalized, the eardrum is increasingly pushed inward giving rise to increasing intensity of pain. Though voluntary efforts, like Valsalva, can open the tube to equalize the pressure, it has limitations. If the pressure difference is allowed to rise beyond 85-90 mm Hg, any voluntary effort becomes ineffective, giving rise to severe pain in the affected ear.
It is important to know that during a bout of common cold or related conditions, the tube remains temporarily blocked. Thus producing barotrauma in flight. Even under normal conditions inability to ventilate due to pre-occupation or ignorance may sometimes lead to this condition.
What to do, if Otitic Barotruama occurs in flight?
Early recognition of symptoms and then correct actions during flight can reduce the severity of pain. Once the pain has started, it is advisable that the affected pilot stops the descent of the aircraft and levels off. (S-)He must actively perform Valsalva manoeuvre. If not relieved, it is advisable that one gains altitude at a slow rate of ascent while performing Valsalva manoeuvre repeatedly. This may usually relieve the pain, and subsequent descent should be gradual while frequently performing Valsalva manoeuvre to ensure that the Eustacian tube is adequately ventilated.
On Landing, it is prudent to consult the squadron/airline doctor as soon as possible. This is advisable since assessment of the degree of damage to the eardrum and an early start of treatment shall help prevent complications. Flying during recovery is best avoided to prevent another attack and further complications.
Otitic Barotruama is Preventable!
Besides avoiding flying during an attack of common cold or sore throat, voluntary equalisation of pressure in the middle ear helps prevent Otitic Barotrauma. Correctly done Valsalva manoeuvre helps pilots and passengers to keep open the Eustachian tube. Valsalva manoeuvre is done by taking a deep breath in, pinching one’s nostrils and pressing the lips, to tightly close the mouth and nose and then trying to blow the air out with force, without letting it out from the mouth or the nostrils. This opens up the Eustachian tube with an audible click as the eardrum moves outward.
Delayed Otitic Barotrauma
As the name suggests, it occurs couple of hours after landing back from a sortie. It usually known to occurs in combat aircrew who inhale 100% oxygen. While breathing 100% Oxygen, particularly during night flying, the air in the middle ear is replaced with Oxygen. If a person goes to sleep soon after flying without actively ventilating his/her ears a few times, the pre-existing Oxygen in the middle ear slowly gets absorbed creating a negative pressure. This invariably wakes the aircrew from sleep, later in the night, with severe pain in one or both ears.
Delayed Otitic Barotrauma can be prevented, if the aircrew, who had been on 100% Oxygen during their night flying, must consciously do Valsalva manoeuvre several times before going to bed.
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Acknowledgement Image courtesy Wikimedia Commons