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Project Dive Exploration (PDE)

With Project Dive Exploration (PDE), DAN's goal is to record dive profiles to produce statistically accurate analyses of dive profiles, diver characteristics and diver behavior.

PDE is a prospective observational study of the demographics, medical history, depth-time exposure and medical outcome of a sample of the recreational diving population. PDE seeks to estimate the incidence of decompression sickness (DCS) in population subgroups and to investigate the relationship of DCS probability to depth-time profile and dive and diver characteristics. PDE also provides an injury-free control population for comparison with DAN's injury and fatality data to identify possible risk factors associated with injury and death.

PDE profiles — essentially road maps of each dive recorded on dive computers — are collected by volunteers and delivered to DAN electronically using the dive computer's dive log software. DAN researchers analyze the data to increase their understanding of the relationship of the risk of decompression illness (DCI) to a myriad of physical, medical and behavioral factors. The results of this study are likely to form the basis of future dive table and dive computer models.

PDE has multiple objectives, including:
  • Collecting real-time depth-time profiles for analysis
  • Documenting the condition of the diver 48 hours after the end of the dive series
  • Documenting any health changes in the diver, whether related to diving or not
  • Investigating the relationship between diving and health effects by using statistical analysis and modeling
  • Developing a flexible, low-risk decompression procedures for multilevel, multiday repetitive diving
  • Studying the effects of flying after diving

  • Frequently Asked Questions

    How much time is required to participate in this study?
  • The time commitment varies. Sending your dive profiles involves completing your electronic dive log, downloading your data and sending it to DAN Research. For example, an individual diver making 20 dives during a weeklong liveaboard trip should plan to spend 30-60 minutes entering data into the dive log software and exporting to DAN. Time will vary with the individual's computer skills.

  • Why is PDE being conducted as a field study rather than a laboratory study?
  • Decompression sickness (DCS) is a probabilistic phenomenon much like cancer and heart disease. There are underlying causes for these diseases, but whether an individual suffers from the 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 dive 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 dives). 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 types of DCS cases have been observed in PDE data?
  • Of the 28 recompressions from 1999 to 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 seawater. 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! All age groups are encouraged to submit their dive profiles for PDE.

  • Are there publications available about PDE?
  • Yes. A list of publications related to PDE is available online.

  • Need more information? Contact DAN Research.