Page 55 - AlertDiver_Spring2013

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Q:On a recent outing with my dive club, we spent
some time kneeling in the sand while practicing
skills. My knee is now irritated and covered in
red bumps. What happened?
A:This particular pattern of red bumps is most
likely the result of hydroid stings. These
organisms, which can look like plants, seaweed
or clumps of feathers, are actually invertebrates of
phylum Cnidaria. Like their relatives, fire corals and
jellyfish, these animals have tiny stinging cells known
as nematocysts. Hydroids are carnivores and use their
nematocysts to catch passing plankton and shrimp.
The stinging nematocysts may also fire into the skin of
unsuspecting divers, which results in a cluster of red
welts and bumps that burn and itch.
To treat these injuries, rinse the skin immediately with
seawater. Try to refrain from rubbing the area, as this
may induce further nematocyst discharge (this is easier
said than done). Never use fresh water as it may actually
cause undischarged nematocysts present on the skin to
fire. Once the area is well irrigated with salt water or
saline, apply white household vinegar (4 to 6 percent
acetic acid) to help neutralize remaining nematocysts. If
vinegar is not available, isopropyl (rubbing) alcohol may
be used. Pain can be treated with the local application of
heat or hot water.
Once neutralized and cleaned, topical steroids such
as hydrocortisone and antihistamines such as Benadryl
(diphenhydramine) are commonly employed to reduce
local skin irritation and itching. If the reaction is
severe or persistent or an allergic reaction occurs, seek
medication attention immediately. Reduce your risk of
contacting these organisms with good buoyancy control
and exposure protection such as wetsuits or dive skins.
— Lana Sorrell, EMT, DMT, and
Nicholas Bird, M.D., MMM
Q:At the end of a recent dive, my inflator
became stuck as I was adding air to my BCD.
I made an uncontrolled ascent from 50 feet
to the surface. My computer shows that I had a total
bottom time of seven minutes. This was about five
hours ago. I don’t think I held my breath at any time,
and I feel fine now, but should I be worried?
A:An uncontrolled ascent does not necessarily
mean an injury. Your dive profile is not associated
with a significant inert gas load, which means you
have little reason to be concerned about decompression
sickness. The greater concern with uncontrolled ascents
is the possibility of pulmonary barotrauma (lung
overexpansion injury), which may result in arterial
gas embolism (AGE). Pulmonary barotrauma is most
often associated with a diver holding his breath while
ascending, with the greatest risk existing in shallow
water. The signs and symptoms of AGE occur at or near
the surface either during ascent or within minutes of
surfacing. They do not occur hours later.
People who experience an uncontrolled ascent should stay
out of the water for several hours to ensure that symptoms
do not occur. While we are unaware of an absolute safe
cutoff, the surface time you described (five hours) without
symptom onset is very reassuring, and in such cases
further medical evaluation is probably unnecessary. If
any neurological or respiratory symptoms develop, seek
immediate medical attention at a local emergency facility.
—Marty McCafferty, EMT-P, DMT
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