Barotrauma

Brandon G. Bentz, MD, and C. Anthony Hughes, MD

Page last modified: 10/2012

What is Barotrauma?

Barotrauma refers to injury sustained from failure to equalize the pressure of an air-containing space with that of the surrounding environment. The most common examples of barotrauma occur in air travel and scuba diving. Although the degree of pressure changes are much more dramatic during scuba diving, barotraumatic injury is possible during air travel.

Barotrauma can affect several different areas of the body, including the ear, face and lungs. Here we will focus on barotrauma as it relates to the ear.

What are the Symptoms of Barotrauma?

Symptoms of barotrauma include “clogging” of the ear, ear pain, hearing loss, dizziness, ringing of the ear (tinnitus), and hemorrhage from the ear.

Dizziness (or vertigo) may also occur during diving from a phenomenon known as alternobaric vertigo. It is caused by a difference in pressure between the two middle ear spaces, which stimulates the vestibular (balance) end organs asymmetrically, thus resulting in vertigo. The alternobaric response can also be elicited by forcefully equalizing the middle ear pressure with the Politzer maneuver, which can cause an unequal inflation of the middle ear space.

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Inner Ear Decompression Sickness

Inner ear decompression sickness (IEDCS) is an injury that closely resembles inner ear barotrauma; however, the treatment is different. This injury is more common among commercial and military divers who breathe a compressed mixture of helium and oxygen. Symptoms include hearing loss, ringing of the ears, and/or dizziness during ascent or shortly thereafter.

IEDCS most often occurs during decompression (ascent), or shortly after surfacing from a dive. In contrast, barotrauma most often occurs during compression (descent) or after a short, shallow dive. Patients with IEDCS should be rapidly transported to a hyperbaric chamber for recompression. A significant correlation exists between early recompression and recovery.

What Causes Barotrauma?

Barotrauma is caused by a difference in pressure between the external environment and the internal parts of the ear. Since fluids do not compress under pressures experienced during diving or flying, the fluid-containing spaces of the ear do not alter their volume under these pressure changes. However, the air-containing spaces of the ear do compress, resulting in damage to the ear if the alterations in ambient pressure cannot be equalized. Rarely, barotrauma may be the result of hyperbaric oxygen therapy. Slow compression hyperbaric oxygen therapy is associated with a lower risk of otic barotraumas than traditional hyperbaric oxygen therapy (Vahidova et al 2006).

Barotrauma can affect the outer, middle, or inner ear.

Outer Ear

The outer ear is an air-containing space that can be affected by changes in ambient pressure (see Figure 1). During diving, water normally replaces the air in the external ear canal. An obstruction such as wax, a bony growth, or earplugs can create an air-containing space that can change in volume in response to changes in ambient pressure. During descent, the volume of this space decreases causing the tympanic membrane to bulge outward (toward the outer ear canal). This can cause pain, small hemorrhages in the ear drum, or blebs (small blisters).

WaxFigure 1

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Middle Ear

The most common problem that occurs in diving and flying is the failure to equalize pressure between the middle ear and the ambient environment (see Figure 2). Equalization of pressure occurs through the eustachian tube, which is the soft tissue tube that extends from the back of the nose to the middle ear space. The extent of injury depends upon the degree and speed of the ambient pressure changes. The greatest relative pressure changes in diving occur near the surface. Therefore, the largest proportional volume changes, and thus the most injuries, occur at shallow depths.

Middle Ear PressureFigure 2: Equalization of pressure

As a diver descends to only 2.6 feet with difficulty equalizing the pressure of his middle ear space, the tympanic membrane and ossicles are retracted, and the diver experiences pressure and pain (see Figure 3). At higher pressures the eustachian tube may become “locked” closed by the negative pressure in the middle ear. This can occur at about 3.9 feet of water. Further increases in pressure, at depths of only 4.3 to 17.4 feet of water, can cause the tympanic membrane to rupture.

Middle EarFigure 3: Effect of blocked eustachian tube

Inner Ear

Inner ear injury during descent is directly related to impaired ability to equalize the middle ear pressure on the affected side. Sudden, large pressure changes in the middle ear can be transmitted to the inner ear, resulting in damage to the delicate mechanisms of the inner ear. This can cause severe vertigo and even deafness. More material about inner ear damage is available here. Two mechanisms are theorized to explain inner ear barotrauma: the “implosive” and the “explosive” mechanisms.

The implosive mechanism theory (see Figure 4) involves clearing of the middle ear during descent. The pressure is transmitted from an inward bulging eardrum, causing the ossicles to be moved toward the inner ear at the oval window. This pressure wave is transmitted through the inner ear and causes an outward bulging of the other window, the round window membrane. If a diver performs a forceful Politzer maneuver and the eustachian tube suddenly opens, a rapid increase in middle ear pressure occurs. This causes the ossicles to suddenly return to their normal positions, causing the round window to implode.

Window ExplosionFigure 4: Effect of Politzer maneuver

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The explosive theory (see Figure 5) suggests that when a diver attempts to clear a blocked middle ear space by performing a Politzer maneuver and the eustachian tube is blocked and locked, a dramatic increase in the intracranial pressure occurs. Since the fluids surrounding the brain communicate freely with the inner ear fluids, this pressure may be transmitted to the inner ear. A sudden rise in the inner ear pressure could then cause the round or oval window membrane to explode.

Window ExplosionFigure 5: Explosive theory

How is Barotrauma Diagnosed?

Diagnosis is initially based on careful history. If the history indicates ear pain or dizziness that occurs after diving or an airplane flight, barotrauma should be suspected. The diagnosis may be confirmed through ear examination, as well as hearing and vestibular testing.

How is Barotrauma Treated?

For outer ear barotrauma, the treatment consists of clearing the ear canal of the obstruction, and restricting diving or flying until the blockage is corrected and the ear canal and drum return to normal.

For middle ear barotrauma, treatment consists of keeping the ear dry and free of contamination that could cause infection. Topical nasal steroids and decongestants may be started in an attempt to decongest the eustachian tube opening. The presence of pus may prompt the use of appropriate antibiotics. Most tympanic membrane perforations due to barotrauma will heal spontaneously. If the eustachian tube demonstrates chronic problems with middle ear equalization, the likelihood of recovery is drastically reduced.

Prevention of air barotraumas to the middle ear has been attempted with dasal decongestants or vasoconstrictors with mixed results. “Pressure equalizing” ear plugs claiming to prevent in-flight barotrauma are available in many airports for purchase (Klokker et al 2005, Mirza & Richardson 2005). A trial evaluating the effect of these earplugs found them to have no effect on eustachain tube function (Jumah et al 2010).

For inner ear barotrauma, treatment consists of hospitalization and bed rest with the head elevated 30 to 40 degrees. Controversy exists whether this type of injury needs immediate surgery, though success has been reported with careful patient selection (Park et al 2012). Once healed, a diver should not return to diving until hearing and balance function tests are normal.

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How Might Barotrauma Affect My Life?

If barotrauma results from diving, you should not to return to diving until your ear examination is normal, including a hearing test and the demonstration that the middle ear can be autoinflated.

Research Studies on Barotrauma

As of 07/2012, a visit to the National Library of Medicine’s search engine, Pubmed, revealed more than 7,362 research articles concerning barotrauma published since 1940 with 236 published in the last year. At the American Hearing Research Foundation (AHRF), we have funded basic research on barotrauma in the past, and are interested in funding sound research on barotrauma in the future. Get more information about contributing to the AHRF’s efforts to detect and treat acoustic neuroma..

Acknowledgments

Figures are courtesy of Northwestern University.

This article was revised for this web site by Timothy C. Hain, MD

References

  • Bennett MH, Lehm JP, Mitchell SJ, Wasiak J. 2012. Recompression and adjunctive therapy for decompression illness. Cochrane Database Syst Rev 5: CD005277
  • Bove A. 2004. Bove and Davis’ Diving Mediciine. pp. 441.
  • Jumah MD, Schlachta M, Hoelzl M, Werner A, Sedlmaier B. 2010. Pressure regulating ear plug testing in a pressure chamber. Aviation, space, and environmental medicine 81: 560-5
  • Klokker M, Vesterhauge S, Jansen EC. 2005. Pressure-equalizing earplugs do not prevent barotrauma on descent from 8000 ft cabin altitude. Aviation, space, and environmental medicine 76: 1079-82
  • Mirza S, Richardson H. 2005. Otic barotrauma from air travel. The Journal of laryngology and otology 119: 366-70
  • Park GY, Byun H, Moon IJ, Hong SH, Cho YS, Chung WH. 2012. Effects of early surgical exploration in suspected barotraumatic perilymph fistulas. Clinical and experimental otorhinolaryngology 5: 74-80
  • Vahidova D, Sen P, Papesch M, Zein-Sanchez MP, Mueller PH. 2006. Does the slow compression technique of hyperbaric oxygen therapy decrease the incidence of middle-ear barotrauma? The Journal of laryngology and otology 120: 446-9