Medical Sciences Bulletin Contents
Reprinted from the November 1994 issue of Medical Sciences Bulletin, published by Pharmaceutical Information Associates, Ltd.
Commercial airline passengers sometimes experience barotrauma of the middle ear that requires treatment by a physician. A recent article by Thomas P. Brown, a US Navy physician, explains how such trauma occurs, how it can be prevented, and how it should be treated. During aircraft ascent, ambient pressure decreases slowly, causing the tympanic membrane to bulge outward. When the pressure differential reaches 15 mm Hg -- approximately every 122 m (400 ft) in increased altitude -- the properly functioning eustachian tube vents the positive pressure. On descent, the ambient pressure increases; the tympanic membrane bulges inward, and the eustachian tube resists the positive inward flow. Passengers experience discomfort when the differential reaches 60 mm Hg. At 90 mm Hg, the eustachian tube locks up, preventing the equalization of pressure by whatever means. A 100- to 500-mm Hg differential causes the tympanic membrane to rupture, relieving the pain but often resulting in vomiting, loss of hearing, dizziness, and vertigo.
During barotrauma, the tympanic membrane becomes distorted with respect to color, shape and integrity. As barotrauma progresses, the tympanic membrane mucosa becomes edematous, there is hemorrhaging, and a transudate forms in the middle ear. The tympanic membrane sometimes ruptures because of weakness of the tympanic membrane, inadequate transudate or hematoma formation, or too rapid a change in pressure.
The most effective means of combating middle ear block is to avoid flying while experiencing upper respiratory tract infection. Passengers should yawn, chew, or swallow -- activities that open the eustachian tube momentarily and allow for pressure equalization. Valsalva's maneuver, taking a small breath, holding the nose, and attempting to force air through the closed nostrils, is especially effective in equalizing pressure during descent. If flying in a small plane with few passengers, the pilot may be asked to reascend.
One hour before takeoff and again 30 minutes before, two puffs of oxymetazoline hydrochloride will constrict the arterioles of the nasal mucosa, permitting the eustachian tube to function efficiently. Oral decongestants (e.g., pseudoephedrine and phenylpropanolamine), which affect areas that sprays don't reach, may be initiated 1 or 2 days before a flight. Newer antihistamines without sedating effects may also be effective. Severe or unremitting earblock may be treated by a physician using a Politzer bag. With the patient seated, one nostril is occluded and the flange of the bag is inserted into the other nostril. While the patient rapidly repeats the letter K or takes small sips of water, the bulb is compressed. The Politzer bag is effective in clearing ear block in 50% of cases. If the patient has excruciating pain or still has earblock after one week of the treatments described, myringotomy may be required.
For children, pseudoephedrine may be initiated 1 day before the flight. Two hours before the flight (and again 30 minutes before descent from a long flight), two drops of 0.125% phenylephrine solution may be initiated. (Brown T. Postgrad Med. 1994; 96: 135-142.)
Medical Sciences Bulletin Contents
Pharmaceutical Information Associates
Homepage
PharmInfoNet Homepage