Understanding Alternobaric Vertigo

1.

The vestibular system plays a role in:

A. Equalisation of the middle-ear air space

B. Translating pressure changes into sound

C. Balance and equilibrium

D. Equalisation of the outer ear

E. Coordinating hearing

2.

Alternobaric vertigo (AV) is most commonly associated with a pressure change in what part of the body?

A. Inner ear

B. Middle ear

C. Brain

D. Eyes

E. Semicircular canals

3.

The ear is an interconnected system of air- and fluid-filled spaces. Normally there is a:

A. Continual movement of gas between the inner ear and the back of the throat

B. Continual exchange of gas between the middle ear and the back of the throat except during swallowing or yawning

C. Periodic absorption of fluid in the middle ear, reducing middle-ear pressure

D. Periodic fluid movement between the outer and middle ear

E. Periodic gas movement into the middle ear such as during swallowing or yawning

4.

Nystagmus, a condition often associated with alternobaric vertigo (AV), is defined as:

A. A sensation that the body is spinning

B. Involuntary rhythmic eye movement

C. Vomiting brought on by severe nausea

D. A panic response that can occur during an AV event

E. Pain caused by excessive pressure on the tympanic membrane

5.

Symptoms of alternobaric vertigo (AV) could be considered dangerous because:

A. The diver could panic, prompting an uncontrolled ascent

B. Severe symptoms may last for hours, making it difficult to surface safely

C. Elevated middle-ear pressure also means more nitrogen is trapped, increasing the risk of middle-ear bends

D. Panic could induce hyperventilation, leading to high carbon-dioxide blood concentration

E. Perforation of the oval window associated with AV leads to debilitating vertigo

6.

To reduce the likelihood of developing alternobaric vertigo (AV), a diver should use:

A. Gentle and frequent active equalisation during descent

B. Passive equalisation before descending

C. Equalisation techniques once reaching maximum depth

D. Ear plugs to help slow the equalisation of pressure in both ears

7.

DAN Europe advises that divers who repeatedly experience alternobaric vertigo (AV) should:

A. Take decongestants to make equalising easier

B. Use ear plugs to decrease pressure in the outer ear

C. Consider using nitrox to reduce damage to the middle ear caused by nitrogen in the breathing gas

D. Be evaluated by a medical professional to rule out potentially serious conditions

E. Dive no deeper than 9m to avoid excessive pressure changes

8.

Alternobaric vertigo is typically characterized by which of the following symptoms:

A. Rapid heart rate lasting several hours

B. Severe nausea lasting 24 hours

C. Loss of hearing in one or both ears lasting up to several minutes

D. Shallow-water blackout

E. Spinning sensation lasting a few seconds

9.

The most effective way to handle an alternobaric vertigo (AV) event is to:

A. Descend slowly, and maintain eye contact with a fixed visual reference until symptoms subside

B. Ascend slowly to the surface until symptoms subside

C. Maintain control, and remain at a fixed depth until symptoms subside

D. Descend as quickly as possible, and make physical contact with fixed object until symptoms subside

E. Equalise actively and frequently until symptoms subside

10.

If a diver experiences ear pain while descending, the ideal response is to:

A. Ascend to a depth at which ear pain subsides, then equalise gently while slowly descending

B. Ascend slowly, exit the water, and take decongestants before reattempting the dive

C. Continue the descend as slowly as possible, and swallow until the ears are equalised

D. Find a depth at which the pain is not bothersome, and continue the dive, equalising frequently

E. Stop descending, stabilise and continue to attempt equalisation until pain subsides

11.

A diver with persistent difficulty equalising during a descent should:

A. Continue the descent, ascending as frequently as necessary to relieve any ear pain

B. End the dive, because difficulty descending could increase the chance of later complications

C. Shorten the dive, because lengthy descent increases the chance of having alternobaric vertigo

D. Slowly surface, completely equalise and reattempt the descent

E. Stop descent, stabilise and wait for the Eustachian tube to allow passive equalisation to occur

12.

Reverse block occurs when gas volume in the middle ear:

A. Decreases during ascent and is unable to escape

B. Increases during descent and is unable to enter

C. Decreases during descent and is unable to enter

D. Increases during ascent and is unable to escape

E. Decreases during descent and is unable to escape

13.

Symptoms of vertigo that persist for more than several minutes are most likely a sign of:

A. Severe congestion that requires treatment with decongestants and antibiotics

B. Nonrhythmic nystagmus associated with a significant increase in pressure in one ear

C. Caloric stimulation brought on by a sudden temperature change in both ears

D. Sudden and significant increase in pressure in one middle ear

E. Inner ear-barotrauma

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Understanding Alternobaric Vertigo

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