DAN Medical Research
Project Dive Exploration (Statistical Analysis of the Risks of Decompression Sickness): FAQs

Where will the study be conducted?

PDE will be conducted wherever diving occurs throughout the world -- resorts, retail stores, charter boats and liveaboards.

Who may participate?

Any certified diver (who uses a downloadable dive computer) can participate in PDE. Divers are responsible for filling out forms and completing the 48-Hour Report Form. .

When did DAN Research start collecting data for PDE?

Formal data collection began on Jan 1, 1999.

How much time is required to participate in this study?

The time commitment varies. Sending your dive profiles involves downloading your data and e-mailing it to DAN Research. For example, an individual diver making 20 dives during a week-long liveaboard trip should plan to spend 30-60 minutes entering data into the divelog software and exporting to DAN. Obviously, time will vary with the individual's computer skills.

However, if you will be collecting data from others, you will have to commit more time to the data collection process. For example, you will have to describe the methods and objectives of Project Dive Exploration to volunteer participants, ask them to enter the study and donate their profiles, and collect personal data and medical history information by having them fill out the data collection forms (Enrollment, Daily Dive Log, and 48-Hour Report). You will also be responsible for data entry, uploading dive computers, and submitting data to DAN. For example, an FRC entering data from 10 divers who each made 20 dives (200 dives) should plan to spend 2-3 hours entering data into DAS software and exporting to DAN. Obviously, time will vary with the individual's computer skills.

How do I send data to DAN? See the Participate in PDE section.

I am already a volunteer, and have downloaded and used DAS. How do I get the most recent version?

Simply download the latest version of DAS.

I am having problems with the DAS. How do I get help?

Feel free to contact DAN Research or call +1-919-684-2948 x260 for assistance with any component of the Diving Data System.

Why is PDE being conducted as a field study rather than a laboratory study?

Decompression sickness (DCS) is a probabilistic phenomenon, as are cancer and heart disease. There are underlying causes for these diseases, but whether an individual suffers from disease is a matter of probability. Random chance is an important factor, just as when rolling "snake eyes" with a pair of dice. Statistical methods for estimating probability were first applied to decompression in 1984. These methods were complex and required accurate dive profile data and knowledge of DCS occurrence. Decompression trials in laboratory chambers provide the best controlled data for this purpose, but even with thousands of trials and hundreds of DCS incidents their number is insufficient to estimate DCS probability beyond reasonable question. Moreover, chamber trials are expensive, expose humans to risk of injury, and cannot investigate the effects of rapid ascent because chamber ascent rates rarely exceed 30-60 feet per minute.

Observational field studies of open-water dives are an alternative to chamber trials for acquiring diving data. Field studies became practical with the development of dive computers that record depth and time. They provide an unlimited source of low-cost dives while offering the best opportunity to investigate fast ascent rates in humans. Rapid ascent is associated with many of the serious signs and symptoms whose ambiguous clinical presentation gave rise to the term decompression illness (DCI). The disadvantages of field studies are low DCI incidence and lack of control. Chamber trials and field studies have complementary advantages and disadvantages, however, and both are needed to improve diving safety.

Have there been many decompression sickness (DCS) cases reported for PDE dives?

Yes. The overall DCS incidence for PDE divers in our data was 4 DCS cases per 10,000 dives, but the population was not homogeneous, and the DCS incidence varied widely among subgroups (liveaboard, shore / day boat, Cozumel Dive Professionals, Scapa Flow Cold-Water Wreck). At 1 DCS case per 10,000 dives, liveaboard divers had the lowest DCS incidence in our data while Scapa Flow divers had the highest incidence at 30 cases per 10,000 dives. Cozumel dive professionals often made as many as 100 dives per series.

This data is published in the Annual Diving Report, which is available online to everyone.

What type of DCS cases have been observed in PDE?

Of the 28 recompressions from 1999-2002, 10 were classified as Type I DCS (pain and / or cutaneous signs) and 16 were classified as Type II DCS (10 cases with numbness, tingling, and / or sensory deficit, four cases with muscular weakness, and two cases with cerebral symptoms). All cases resolved with recompression. Two additional cases resolved with emergency oxygen and were not classified as DCS. All divers who were recompressed had made at least one dive deeper than 40 feet of sea water (fsw; 12 meters of sea water, or msw). In addition, some 300 divers reported various symptoms, half of which were headache. About 15 divers reported transient aches or pains, and about five reported transient tingling or numbness. These were classified as not AGE or DCS.

This data is published in the Annual Diving Report, which is available online to everyone.

I am over 65 years old. Can I participate in this project?

Yes! You will participate in PDE from which we will pull all the information we need for the various age groups.

Who do I contact for more information?

Contact DAN Research or call 1-800-446-2671 x260 (+1-919-684-2948 x260) for more information about PDE.

Are there publications available about PDE?

Yes. For a list of publications related to PDE, click here.

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