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Subject: Research to Improve the Safety of Divers
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Status: R
Sea Grant June 1995
Challenges Volume 3, Number 2
SEA GRANT LOOKING TO THE FUTURE
Research to Improve the Safety of Divers
Millions of dives are performed each year by U.S. civilian
divers. Most of this activity by recreational, commercial,
scientific, and governmental organizations occurs in states that
are served by a Sea Grant program. Therefore, Sea Grant is
uniquely suited, through its university-based network and its
outreach programs, to support research beneficial to divers and
to communicate those useful research findings to them.
Several Sea Grant programs are involved in research concerning
the prevention and treatment of decompression sickness (DCS), a
health hazard associated with diving and working underwater. It
is marked by pains in the joints, cramps, paralysis and,
potentially, death unless prevented by gradual decompression or
treated with recompression.
Scuba divers using compressed air breathe mostly nitrogen. While
underwater, the diver's tissues accumlate dissolved nitrogen.
Typically, too rapid a return from high pressure underwater to
surface pressure causes nitrogen bubble formation and DCS.
Therefore, safely eliminating nitrogen from the body is important
for preventing or treating this sickness.
Although it is well known that breathing oxygen hastens nitrogen
elimination, New York Sea Grant researchers have shown that when
the amount of oxygen inhaled is increased, it constricts blood
vessels, thereby lowering the heart's pumping performance and
slowing the elimination of nitrogen from the tissues. Thus,
researchers believe that the increased levels of oxygen are less
effective in washing out nitrogen than commonly thought,
indicating a need to modify present decompression tables by
lengthening them.
In another approach to eliminating nitrogen, New York researchers
are investigating the potential use of medications for the
prevention and treatment of DCS. They tested volunteers who had
been prescribed various medications and identified two drugs that
increased the nitrogen elimination rate up to 20 percent.
Researchers believe that if there are no side effects to taking
these medications, they could be used to enhance nitrogen washout
during recompression treatment or after a dive.
Hawaii Sea Grant researchers are evaluating the role the blood's
complement system plays in DCS. The complement system is part of
the body's defense system against invasion by foreign substances.
Researchers believe bubbles in the blood, which are common during
and after decompression, may activate this system. Currently,
they are investigating the possibility of minimizing the
activation of the complement system or deactivating it to prevent
or alleviate DCS.
In addition, a greater understanding of the complement system may
enable scientists to predict an individual's susceptibility to
DCS. Researchers at Sea Grant programs in New York and Hawaii are
investigating the complement system's role in the large
variations that exist between individual divers' susceptibility
to DCS. This work could lead to the screening of divers and to
decompression procedures that could be carried out on an
individualized basis.
Divers having untreated DCS with limb bends are in danger of
developing hyperbaric osteonecrosis, a degenerative form of bone
disease that can permanently disable divers and tunnel workers.
Using sheep, Wisconsin Sea Grant researchers found that
recompression therapy of limb bends within four hours of onset
prevented the development of bone necrosis. This finding appears
consistent with successful clinical outcomes in recompressed
commercial divers, and the study is being extended to include
semi-professional and recreational divers. The researchers are
now trying to discover the effects on bones of delaying
recompression treatment.
Another potential problem for scuba divers is panic or near-panic
behavior. Wisconsin Sea Grant researchers surveyed 500 scuba
divers and found that 54 percent have experienced this behavior.
Additionally, they found that responses to stress can be
influenced by personality structure, gender, protective clothing,
and water temperature. These findings have led to the development
of a Body Awareness Scale, which has proven valid and reliable in
evaluating 600 male and 300 female volunteers. This scale is
currently being applied by Wisconsin Sea Grant researchers in
efforts to modify the stress response of scuba divers.
For the foreseeable future, wet diving techniques will continue
to be a focus of Sea Grant scientific research. The major benefit
of this research will be to reduce human suffering and the loss
of human lives from diving accidents. In addition, it will
increase productivity for working divers and enjoyment for
recreational divers. (For details, Gene Smith, 301/713-2427)