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Rodales Dive Medicine
DAN
Divers Alert Network - Scuba Diving and Dive Safety
Taking
the Scuba Diving Plunge
By
Jason Cook
HealthSouth Information Center
WebMD Medical News
Maybe
it's the lure of magnificent coral reefs, mysterious shipwrecks,
or to simply
"get away from it all." Whatever the reason, scuba diving
has become more popular
than ever, with more than 8.5 million Americans taking the
plunge in quarries,
rivers, lakes, and oceans throughout the world.
But
while recent advances in equipment have made the sport more
accessible for
people of all genders and ages (not to mention, shapes and
sizes), scuba diving still
has serious risks, ranging from simple aches and pains to
death. Compounding these
risks is that little medical research on recreational diving
has actually been documented.
"Clearly,
scuba diving is thought to be a nice and relaxing sport,"
says Ruben Peņaranda,
MD, a pulmonologist at HealthSouth Doctors' Hospital in Coral
Gables, Florida.
"However, it's really important to be educated as far as who
should dive and who
should not dive."
Several
studies have found that a physically fit diver is a better,
safer diver. In fact,
many dive accidents can be linked to the poor physical fitness
of the diver. Unfortunately,
however, there is no universally accepted criteria for determining
if a recreational
diver is in tip-top diving shape.
Rodale's
Scuba Diving magazine has outlined three areas in which a
minimal level
of fitness is required for diving. Foremost is moderate aerobic
fitness. Although scuba
diving is considered a low-stress sport, its peak demands
can be as high as any other
physical activity. Rodale's recommends that the diver be able
to perform 10 minutes
of moderate exercise without the huffing and puffing that
can overwork a regulator.
Also
important for the diver is moderate torso strength, particularly
in the back, arms,
and upper body, for hauling gear, donning and doffing equipment,
and negotiating
the dive boat without strain. Another recommendation for divers
is moderate body fat.
High body fat has been linked to a higher chance of decompression
sickness and
cardiovascular disease, two leading causes of dive accidents
and fatalities.
"Diving
equipment has evolved to the point where anyone can make a
dive, whether
they're in great shape or they've gotten out of shape because
they've gotten older, or
they were never in shape to begin with," says Charlie Matthews,
an instructor with
Underwater Unlimited in Coral Gables, one of the oldest dive
shops in South Florida.
"In the days of old, it was the physically fit, young men
diving. Now the diver profile
has changed quite a bit."
The
Diver's Alert Network, commonly known as DAN, is a nonprofit,
international
organization that promotes safety, education, and research
in the scuba diving
community. The organization has found that divers tend to
overestimate their diving
abilities, both mental and physical, as well as underestimate
the diving conditions.
This often leads to dangerous situations that result in panic.
When
panic sets in, the diver's competence in scuba-related skills
is decreased, which
leads to a decrease in self-confidence. The diver is then
left with few coping skills in an
emergency situation.
"Divers
who have proper training have very few accidents because they
know what could
happen," says Matthews, who has logged more than 6,000 dives
in his 32 years as a diver.
"Knowing what could happen then helps you to take steps to
prevent those things
from occurring."
"Really
the precautions for diving are mostly being well informed,
well conditioned, and
just abiding by the rules," adds Peņaranda. "Those who are
well-instructed on these details
will be able to enjoy diving for a long time."
Both
Matthews and Peņaranda advise potential divers to undergo
a physical examination
prior to beginning the certification process. For a physical
that takes diving into account,
DAN recommends finding a doctor familiar with diving medicine.
The organization
maintains an in-depth list that can be accessed by calling
919 684-2948 or logging onto http://www.diversalertnetwork.org/.
WebMD Medical News
Common
Motion Sickness Drug Could Impair Divers' Judgment
Enhances Depth Effects of Anxiety, Disorientation
By Norra MacReady Reviewed by Dr. Aman Shah
WebMD Medical News
Scuba
diving can be an intoxicating experience. But scientists at
the University of
Pittsburgh have found that a common seasickness medication,
Dramamine, taken just
before a dive could produce the mental equivalent of "one
too many," possibly
impairing judgment and raising the risk of an accident. A
second study by the same
team, however, shows that pseudoephedrine, a drug found in
many sinus medications
such as Sudafed, has only modest effects on brain function
and is probably safe for divers.
Both studies appear in this month's issue of the journal Pharmacotherapy.
Scuba
divers are particularly vulnerable to the mind-altering effects
of certain drugs
because of the way air is delivered from the tank. Nitrogen
makes up about three-quarters
of the air we breathe. When compressed into a scuba tank and
inhaled under the
high pressures encountered at depths of 33 feet or more, it
can have a disorienting effect
-- kind of like taking a few drinks. Indeed, Kevin O'Toole,
MD, one of the study authors,
tells WebMD that every 33 feet a diver descends is the equivalent
of drinking one martini
in its effect on the brain. Scientists call this condition
"nitrogen narcosis," but divers know
it by a more poetic name -- "rapture of the deep."
To
study the effects of two popular, over-the-counter drugs when
combined with nitrogen
narcosis, the scientists placed 30 experienced scuba divers
in a hyperbaric chamber that
simulated the pressure of a 66-foot dive (two martinis). While
in the tank, the divers breathed
the same type of compressed air they would have in a scuba
tank.
Forty-five
minutes before going on the "dive," each subject took a pill
containing
pseudoephedrine, a decongestant many divers take to relieve
pressure in the sinuses or
middle ear; dimenhydrinate, the active ingredient in most
anti-seasickness products such as Dramamine; or a dummy pill.
The experiments were designed so that each person
was tested with each drug.
The
investigators chose these drugs because they are popular among
scuba divers, and
because each has been associated with side effects that could
distort a diver's judgment,
especially when combined with nitrogen narcosis. Pseudoephedrine
has been linked with nervousness, excitability, and restlessness
and may also cause a rapid or irregular
heartbeat. Dimenhydrinate can make people extremely dizzy
or drowsy.
While
in the chamber, the subjects performed various tasks of memory,
verbal ability,
and manual dexterity. Each person also wore a monitor that
recorded his or her heart
rate and rhythm. They went through the same battery of tests
while resting in the
chamber at normal atmospheric pressure.
Even
without the drugs, the participants exhibited increased anxiety
and decreased
verbal fluency at conditions simulating 66 feet under water,
the researchers found.
Pseudoephedrine produced a slight increase in heart rate and
interacted with the
depth effect to increase the decline in verbal fluency, but
overall, the authors write
that "it is unlikely that pseudoephedrine adds significant
risk to the diver."
Dimenhydrinate,
on the other hand, was associated with much lower scores on
a test
that required the subjects to switch rapidly between two tasks
and is a measure of
mental flexibility. "We showed a definite impairment [from
dimenhydrinate], especially
in combination with narcosis, and the deeper you go, the greater
your decline," says
O'Toole, an experienced diver who directs the hyperbaric medicine
program at the
University of Pittsburgh. "I would not recommend that someone
take this drug and dive."
Add
dimenhydrinate to the effects of narcosis "and you're really
zonked," says
Murray Grossan, MD, a Los Angeles-based otolaryngologist and
a scuba diver
since 1970. He tells WebMD that many fatal diving accidents
occur because divers
ignore or forget to watch the monitors that tell them they're
low on air, which could
be the result of impaired judgment produced by narcosis. Grossan
was not involved
in the study.
However,
the potential effects of pseudoephedrine on heart function
should not be
dismissed, warns Claes Lundgren, MD, PhD, director of the
Center for Research and
Education in Special Environments at the State University
of New York in Buffalo.
People diving at great depths may experience an immersion
effect, in which blood
travels away from the limbs and into the chest, where it may
distend the heart and
render it more vulnerable to the effects of drugs that affect
heart rhythm. "This could
be responsible for a number of scuba deaths that remained
unexplained," he tells WebMD.
Grossan
says that his patients have found the scopolamine patch to
be a good antidote
to seasickness. They can remove it just before diving or wear
it in the water if they
dive with a hood. Some people also have had good luck with
wristbands that compress
certain pressure points and are reported to relieve nausea.
"It's
worth noting that neither of these drugs is permitted for
commercial pilots," says
Lundgren. "Risk is a relative concept. [When it comes to diving
after taking one of
these drugs], it's really for the individual to define for
him- or herself what is acceptable."
WebMD Medical News
Staying Afloat Ear Problems
By Flash Gordon, M.D.
WebMD Medical News
Question: When diving into water or placing
my head below water, my ears become
clogged and stay that way even after I leave the water. I'm
preparing to take scuba
lessons, but I'm concerned about my ears. Is there a way to
prevent or treat clogged ears?
Answer:
It sounds like water stays in your ear canal after you've
gone swimming.
While this is common, you're right to be concerned about it.
If you take scuba
lessons, you should first receive the go-ahead from your doctor.
Talk with him or her
about your history of ear problems.
If
your ears don't dry out on their own, you can get "swimmer's
ear" (otitis externa),
which is an infection of the ear canal caused by too much
dampness. In some cases,
it's possible to clear out the water simply by turning your
head to the side, grasping
the ear that's facing down, pulling it backwards and wiggling
it. This straightens the
ear canal, which can help it drain.
You
can also put in some drops of an alcohol and water solution
to lower the surface
tension in your ear, which allows the water to drain. Alcohol
helps the ear dry faster,
and may even help prevent swimmer's ear. You can make your
own solution by mixing
equal parts of water and rubbing alcohol. Your local drugstore
also may sell drdops
to treat swimmer's ear.
Have
your doctor examine you for "surfer's ear" as well. This common
condition often
goes unrecognized since you can't see into your own ear canal.
With surfer's ear,
repeated intrusion of cold water causes bony growths to develop
within the ear canal.
Think of this as a natural defense to keep cold water from
hitting the delicate eardrum.
In extreme cases, surfer's ear results in the ear canal closing
off entirely, requiring
surgical correction. You can prevent less severe cases of
surfer's ear from progressing
by using silicone "surfers' earplugs." These partially close
the ear canal and keep water
from rushing in. Instead, water slowly enters the ear canal,
which lets you equalize
pressure while scuba diving. Wearing a neoprene hood while
diving can help, too.
But
remember: Talk to your doctor about your ears before you take
scuba lessons or
if you have a history of ear problems.
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