Normalizing Middle-ear Pressures
When rapid ambient pressure increase occurs as in diving or aircraft descent, this pressure tends to hold the Eustachian tubes closed, preventing pressure equalization across the ear drum, with painful results. To avoid this painful situation, divers, caisson workers and aircrew attempt to open the Eustachian tubes by swallowing, which tends to open the tubes, allowing the ear to equalize itself.
If this fails, then the Valsalva maneuver may be used. It should be noted this maneuver, when used as a tool to equalize middle ear pressure, carries with it the risk of auditory damage from over pressurization of the middle ear. It is safer, if time permits, to attempt to open the Eustachian tubes by swallowing a few times, or yawning. The effectiveness of the "yawning" method can be improved with practice; some people are able to achieve release or opening by moving their jaw forward or forward and down, rather than straight down as in a classical yawn. Opening can often be clearly heard by the practitioner, thus providing feedback that the maneuver was successful.
During swallowing or yawning, several muscles in the pharynx (throat) act to elevate the soft palate and open the throat. One of these muscles, the tensor veli palatini, also acts to open the eustachian tube. This is why swallowing or yawning is successful in equalizing middle ear pressure. Contrary to popular belief, the jaw does not pinch the tubes shut when it is closed. In fact, the eustachian tubes are not located close enough to the mandible to be pinched off. People often recommend chewing gum during ascent/descent in aircraft, because chewing gum increases the rate of salivation, and swallowing the excess saliva opens the eustachian tubes.
In a clinical setting the Valsalva maneuver will commonly be done either against a closed glottis, or against an external pressure measuring device, thus eliminating or minimizing the pressure on the Eustachian tubes. Straining or blowing against resistance as in blowing up balloons has a Valsalva effect and the fall in blood pressure can result in dizziness and even fainting.
Read more about this topic: Valsalva Maneuver
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