The Eustachian tube and its significance in flight

Use of the nine-step inflation/deflation test and resting middle-ear pressure range as predictors of middle-ear barotrauma in aircrew members

“…5 This means that people on board aircraft are exposed to pressure variation of 190 mmHg during take-off and landing. 5 This means that people on board aircraft are exposed to pressure variation of 190 mmHg during take-off and landing.…”

“…(1) The tympanogram records resting middle-ear pressure. (5) The tympanogram records the extent of equilibration. The subject swallows to equilibrate middle-ear over-pressure.…”

“…Otic barotrauma suffered during air travel is defined as an acute or chronic traumatic inflammation of the middle ear caused by a pressure difference between the air in the middle ear and the surrounding environment. [3][4][5] Difficulty with clearing the ears during flight is a common cause of temporary or even permanent grounding of aircrew. 2 Aircrew members must be able to equilibrate the pressure on both sides of the tympanic membrane; this is possible only with normal tubal function.…”

Otic barotrauma from air travel

“…If the eustachian tube is not opened by, for example, swallowing, then the middle ear gas, with a relatively positive pressure, will continue to expand until the tympanic membrane is pushed laterally to its limit, an effect which can be seen with an otoscope during flight. 6 At a pressure differential of 15 mmHg, the eustachian tube (if functioning properly) passively opens and vents off the positive pressure air, thereby equalizing the ambient and middle-ear pressures. This process of passive venting is rarely a problem on ascent and occurs at about every 122 m (400 ft) of increasing altitude.…”

“…This can be proved at tympanotomy and successfully closed by means of a fat graft. 6 Despite cabin pressurization bringing the ambient pressure up to three-quarters that of ground air pressure, a descent from the typical cruising altitude of most commercial aircraft is sufficient to create an 80 mmHg gradient. 5 Dickson and King 12 found that the severity of barotrauma sustained in flight is related to the rate of descent from altitude, and hence to the rate of pressure change.…”