PRACTICAL ASPECTS OF HYPERBARIC THERAPY
Equilibration of Middle Ear Pressure
Probably the most common patient side effect of hyperbaric chamber
use is the difficulty that some patients experience in equilibrating the pressure
in the middle ear. This problem is manifested as acute pain, stretching or tearing
of the tympanic membrane, and hemorrhage into the middle ear (referred to as ear
"squeeze"). Difficulty equilibrating middle ear pressure may rarely result in labyrinthine
window (round or oval window) rupture.[166]
Equilibration
may be accomplished with several techniques, such as performing intermittent Valsalva
maneuvers, swallowing while the nose is pinched, thrusting the jaw forward, or simply
swallowing intermittently during compression. Children can often be induced to equalize
their ears adequately by having them drink small amounts of liquid during compression.
Most patients can learn the technique; however, others may be unable to clear their
ears, sometimes because of acute respiratory tract infection. In these patients,
equilibration can sometimes be aided by the application of a topical nasal vasoconstrictor
(e.g., 0.05% oxymetazoline [Afrin], a vasoconstrictor that shrinks the nasopharyngeal
mucosa and increases the patency of the eustachian tube). For patients who cannot
equalize despite these measures or for obtunded or intubated patients, myringotomy
may be required. In patients who cannot equalize and who require hyperbaric therapy
beyond 2 or 3 days, placement of tympanostomy tubes will ensure a patent opening
into the middle ear. Squeeze may occasionally also affect the sinuses and result
in acute pain. Despite the common occurrence of middle ear or sinus squeeze on compression,
symptoms on decompression, caused by the inability of gas to exit through the eustachian
tubes or sinus ostia (reverse squeeze), are extremely rare.
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