Did you know that middle-ear barotrauma (MEBT) is one of the most common diving injury? More than half of all divers are affected by middle-ear barotrauma (MEBT) at some point.
As a professional diver you will most likely be affected by this sooner than later during your dive career. It can be extremely painful, it can cause discomfort and more importantly it mean you will not be able to dive which will have a direct impact on your revenue stream (unless you have additional skills and can perform other work while being confined to dry duties).
So how can you prevent and manage middle-ear barotrauma (MEBT)?
Before we answer this, lets look at the Anatomy of the Ear
The ear is the organ of hearing and balance. It consists of a cavity in the skull structure lined with soft tissue, which encloses three distinctive spaces filled with air or liquid (external, middle and inner ear); these distinctive spaces host both sound transmission mechanisms and sensory apparatuses.
The external ear includes the pinna (auricle) and the ear canal up to the eardrum (tympanic membrane), which separates it from the middle ear. The lining of the external ear is skin rich with glands that produce earwax.
The middle ear is a cavity in a temporal bone lined with a thin layer of tissue similar to that found in the nose and throat. It is separated from the ear canal by the eardrum and connected to the throat via the Eustachian tube. It includes three tiny bones (auditory ossicles) forming the chain attached to the eardrum on one side and to the oval window membrane on the inner-ear side. The middle-ear space is filled with air at ambient pressure, which needs to be equalized when ambient pressure changes (as occurs in diving or flying). This is accomplished by moving air in or out through the Eustachian tubes, which connect the throat to the middle ear, using equalization techniques such as the Valsalva maneuver.
The inner ear, or labyrinth, includes the cochlea (hearing organ) and the vestibule and semicircular canals (balance organs). The cochlea and the vestibule are the origin of the auditory and vestibular nerves.
What is MEBT?
Middle-ear barotrauma is the accumulation of fluid and blood in the middle ear or rupture of the eardrum as a consequence of failed equalization of pressure in the air space of the middle ear during diving or flying.
How does it happen? Mechanisms
The air pressure in the tympanic cavity — air-filled space in the middle ear — must be equalized with the pressure of the surrounding environment. The Eustachian tube connects the throat with the tympanic cavity and provides passage for gas when pressure equalization is needed. This equalization normally occurs with little or no effort. Various manoeuvres, such as swallowing or yawning, can facilitate the process.
An obstruction in the Eustachian tube can lead to an inability to achieve equalization particularly during a descent when the pressure changes fast. If the pressure in the tympanic cavity is lower than the pressure of the surrounding tissue, this imbalance results in a relative vacuum in the middle ear space. It causes tissue to swell, the eardrum to bulge inward, leakage of fluid and bleeding of ruptured vessels. At a certain point an active attempt to equalize will be futile, and a forceful Valsalva manoeuvre may actually injure the inner ear. Eventually, the eardrum may rupture; this is likely to bring relief from the pain associated with MEBT, but it is an outcome to be avoided if possible.
Factors that can contribute to the development of MEBT include the common cold, allergies or inflammation — conditions that can cause swelling and may block the Eustachian tubes. Poor equalization techniques or a too rapid descent may also contribute to development of MEBT.
Divers who cannot equalize middle-ear pressure during descent will first feel discomfort in their ears (clogged ears, stuffed ears) that may progress to severe pain. Further descent only intensifies the ear pain, which is soon followed by serous fluid build-up and bleeding in the middle ear. With further descent, the eardrum may rupture, providing pain relief; this rupture may cause vertigo, hearing loss and exposure to infection.
While diving: When feeling ear discomfort during descent, you should stop descending and attempt equalization. If needed, ascend a few feet to enable equalization. If equalization cannot be achieved, you should safely end the dive.
First aid: When feeling fullness in one’s ears after diving, abstain from further diving. Use a nasal decongestant spray or drops. This will reduce the swelling of nasal mucosa and Eustachian tube mucosa, which may help to open the Eustachian tube and drain the fluid from the middle ear. Do not put any drops in your ear.
Treatment: Seek a physician evaluation if fluid or blood discharge from the ear canal is present or if ear pain and fullness lasts more than a few hours. If vertigo and dizziness are present, which may be a symptom of inner-ear barotrauma, you should seek an urgent evaluation. Severe vertigo and nausea after diving require emergency medical care.
Fitness to Dive
Return to diving may be considered if a physician determines that the injury is healed and the Eustachian tube is functional.
– Do not dive with congestion or cold.
– Descend slowly. If unable to equalize after a few attempts, safely end the dive to avoid significant injury that may prevent you from diving the rest of the week.
Would you like to learn more about middle-ear barotrauma (MEBT) and how to properly equalize to avoid it? Check out the various articles on Divers Alert Network.