Scuba Diving club,
Southern California
Sea Sabres
Decompression
Illness, Diving Fatalities and Project Dive Exploration
Divers Alert Network has
published the 2003 Report on Decompression Illness, Diving Fatalities and
Project Dive Exploration. The report represents a descriptive analysis of
injury, fatality and prospective dive data collected by DAN in 2001.
The annual study
summarizes reports on:
• divers who experienced decompression illness;
• divers who died; and
• divers in the DAN Project Dive Exploration (PDE) database (for whom injuries
were rare) during the previous full calendar year.
Injuries,
Fatalities and PDE in Brief
In 2001, DAN received notification that 1,170 injured divers had been
recompressed. For the first time, this number includes reports from all IDAN
organizations. DAN America reported 900 treated cases, DAN Europe 126, DAN SEAP
80, DAN Japan 53 and DAN South Africa 11. Each IDAN organization has retained
reports from their regions.
DAN America has
received 522 reports out of 900 treated cases. In 474 cases, reports pertained
to recreational divers who resided in the U.S. or Canada.
The 2003 Report is
based on the analysis of the 415 cases involving U.S. and Canadian recreational
divers.
The fatalities
section consists of 77 cases involving recreational divers. Both the injuries
and fatalities sections have slightly fewer cases than in previous years.
Due to increased
data collection and participation of volunteers, the number of dives collected
prospectively through PDE has doubled to 15,385 dives when compared with those
of the previous year. PDE is a prospective investigation of the medical
history, depth-time exposure and medical outcome of a sample of the diving
population. It also provides an injury-free control population that can be
compared with the injury and fatality populations.
What's
New in the 2003 Report?
The 2003 Report
follows the same general format from past years. However, there are two major
changes: a retrospective review of diagnoses in the injuries section and a
calculation of the true incidence of DCI in the PDE section.
"In the
injuries section, we have attempted a retrospective review, classifying cases
as 'decompression sickness (DCS),' 'arterial gas embolism (AGE),' 'ambiguous'
and 'other' (not DCI)," noted Petar Denoble, Ph.D., D.Sc., Senior Research
Director.
The review was
designed to exclude those cases that most likely were not DCI."
The review also
distinguished between DCS and AGE. "While the distinction between the two
may be sometimes impossible to make and may be of no interest to treating
physicians, we considered it important when analyzing the risks of
decompression injury," said Denoble.
Compared to the
previous year, the observed better correlation of symptoms, timing, treatment
and outcome data in the 2001 dataset might be a direct result of cleaner data.
One of the unexpected results of this analysis was that complete relief of
symptoms with recompression was more likely in cases that occurred in geographic
areas where the treatment facilities were closer to the dive site and where the
average delay to treatment was shorter. While this finding that links the
relief of symptoms to proximity to treatment facilities and shorter delays to
treatment is not conclusive, it adds new fuel to the discussion about the
effects of delays to recompression on the treatment outcome.
In the PDE section,
for the first time we have collected enough data from a variety of environments
from divers with a variety of dive styles. Thus, we were able to compare the
outcome among various groups.
There were 16 cases
of confirmed decompression injury treated in recompression chambers. Most of
the DCI cases occurred in cold-water wreck diving. We were able to calculate
the true incidence of DCI separately for several groups, because the
prospective study provided both the total number of exposures (denominator) and
the number of injuries for each group. The incidence was calculated per diver
and per dive.
The average
incidence was about 10 per 10,000 dives and 1.3 per 100 divers, but in the
cold-water wreck group, the average incidence was 37 per 10,000 dives and
nearly 4 per 100 divers.
Another group with
higher than average incidence appears to be recreational dive professionals:
dive guides and instructors. A small subgroup within the PDE divers, it
recorded 9.5 injuries per 100 divers. However, the incidence per 10,000 dives
in diving professionals was about the average, indicating that they may be hit
more often just because they do hundreds of dives per year. Recreational divers
diving from liveaboards were least affected. In fact, all of nearly 4,000 dives
recorded on liveaboards ended without decompression sickness.
The reader will
find the Report on Decompression Illness, Diving Fatalities and Project Dive
Exploration both informative and entertaining. DAN Research cautions that the
report presents basic descriptive statistics, which do not have the support of
thorough scientific analysis.
However, the
statistics raise some questions that we will pursue in more formal, scientific
research. One such project, which has begun, is an investigation of the higher
incidence of DCI among a small subset of recreational dive professionals we
studied. The study will determine whether the incidence of DCI is valid among
those divers.
We hope the dive
community will continue its support for the research that DAN conducts. Without
that support, this report and our ongoing studies wouldn't be possible.
Special note: DAN
Members can download the report for free from the Members Only section of their
website.
Posted April 3, 2003
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