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Members
Newsletter |
Issue
#2, January 2010 |
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Barotrauma: The Ins
and Outs of the Pops and Cracks - By Eric Hexdall, RN, CHRN, Duke Dive
Medicine
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Many of us know the feeling. We’re
on descent and realize that one of our ears hasn’t equalized.
We perform the Valsalva maneuver, and SQUEAK!
The air zips in, we may feel some momentary pain, and the pressure in
the ear goes away. We continue the dive with the ear gurgling
and snapping, and surface with the most common injury in
diving: middle ear barotrauma.
Boyle’s Law states that as pressure increases, the volume of an
air-filled space will decrease proportionally, and vice
versa. In practice, this means that all of the air-filled
spaces in and around our bodies can be affected in one way or another
by pressure. When we dive, these spaces need to be
equalized as the pressure around us changes.
The middle ear is Mr. Boyle’s primary victim. The sinuses are
also filled with air as are, of course, our lungs. Air
trapped beneath faulty dental work can cause extreme discomfort, and
gastrointestinal air can be an issue for some of us. Our
diving gear can also create air-filled spaces. Our masks trap
air against our faces, and if we use a dry suit, there is an air-filled
space between the suit and our bodies.
Typically, barotrauma of descent is called a “squeeze” or “block”, and
barotrauma of ascent is called a “reverse squeeze” or “reverse
block”. The air-filled spaces in and around our bodies may be
affected by one or both of these. Let’s examine each of them.
Read More… |
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