Barotrauma and Pressure-Related Disorders
The mechanics of barotrauma
Barotrauma occurs when a gas-filled cavity cannot equalise with changing ambient pressure. On descent, external pressure rises and gas contracts, causing squeeze; on ascent, gas expands and may cause overpressure. The common sites are the middle ear, sinuses, teeth, gut and lungs.
Ear and sinus problems
The Eustachian tube equalises the middle ear. A cold, allergy or congestion blocks it, producing ear pain, muffled hearing and, in severe cases, rupture of the eardrum. Sinus squeeze causes pain over the affected sinus. Valsalva and other equalisation techniques help on descent; on ascent, gas usually escapes passively. Never fly with a heavy cold, and never force equalisation if it is painful.
Lung and other barotrauma
Lung barotrauma can follow a rapid decompression if the pilot holds the breath against a closed glottis; the correct response is to exhale during explosive decompression. Dental pain on ascent is barodontalgia, often from trapped gas under a filling. Gut gas expands on ascent and causes discomfort.
Traps in questions
A frequent trap is confusing the direction: squeeze happens on descent, expansion problems on ascent. Another is thinking equalisation is always easy; blocked Eustachian tubes are the usual cause of failure. Remember that pain is a warning, not something to push through.
Worked example
A passenger with a cold develops severe ear pain during descent. The cause is middle-ear squeeze from a blocked Eustachian tube. Rule of thumb: if you cannot equalise, stop descending, level off and try again; do not force it.