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We have all experienced some degree of ear
pain during descent with diving (middle ear barotrauma). This occurs in
experienced divers most commonly in the setting of a cold, sinusitis or
hay fever but can also occur out of the blue. Usually it is relieved by
ascending a metre or two then continuing on with the dive. If I looked at
your eardrum after such a dive, it would be very common to see mild
redness or bruising on the drum. In more severe cases the middle ear
(behind the drum) might contain fluid or blood, or the drum might even be
perforated – you would know if this had happened!
So why does this happen? The eardrum (tympanic membrane or TM) separates
the outside world from the middle ear. The middle ear is connected to the
back of the throat by the Eustachian tube which is closed when it is at
rest. |
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As we descend into
the water, pressure builds up on the TM via the external canal and the
TM starts to bow inwards. This is soon painful unless the pressure on
the other side of the TM (in the middle ear) is equalised with the
ambient (water) pressure. The TM pulls in to the middle ear and the
middle ear starts to fill with fluid or blood until the pressure is
equalised. Once the pressure is equalised the pain may subside but as
you can imagine hearing may be muffled. So a better way to equalise
the pressure is to introduce air at equal pressure into the middle ear
via the Eustachian tube.
Diving with a cold may not only cause problems with equalising
(because the Eustachian tube is swollen or blocked) but can have other
implications. A friend of mine recently went diving with a cold and
the next day had an acute middle ear infection. Presumably bacteria
had been pushed up the Eustachian tube into his middle ear to generate
the acute otitis media. The next day his TM perforated (much to his
relief as the pain was very severe) and he will now miss at least 6
weeks diving. |
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Another interesting
case came through my office last week. A woman went diving 12 months
ago and suffered acute ear barotrauma whilst ascending ("reverse
squeeze" occurs when the expanding gas cannot escape via a blocked
Eustachian tube). On surfacing she described severe nausea, dizziness
and pain in the ear. She also noted hearing loss in that ear. She was
diagnosed with inner ear barotrauma and was advised to rest quietly
for up to a week. This occurs when pressure ruptures the round window
and allows the fluid in the inner ear to leak out. The inner ear
contains the electrical components of hearing and the balance system,
hence the commonest symptoms are sudden nausea, dizziness, hearing
loss, ringing in the ear and deafness. The leak will often seal with
bed rest and avoiding straining. In this ladies case, she still has
symptoms 12 months later and is facing surgery to solve the leak. She
is particularly interesting because she vomits whenever the barometer
drops!
A final word on the use of sprays and decongestants when you have a
cold. The danger often quoted is that the medication may wear off
during the dive leaving you with difficulty equalising during ascent.
For a mild cold taking such medication is probably reasonable to
smooth things along but if you are truly unwell then dive another day.
The other concern with such medication is that some may predispose to
abnormal heart rhythms, they may be sedating or stimulant and so in
theory could contribute to narcosis or oxygen toxicity respectively. |
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