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Thread: hard hit data

  1. #1
    RBW Member bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer's Avatar
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    hard hit data

    I am familiar with Bret Gilliam's study with ~70,000 dives. Other than this and anyone point me in the direction of other similar studies? Thus far all I have found are studies with small sample sizes or chamber studies. Are there any other large scale real world studies with known numerators and denominators? Doesn't have to be breather specific.

    I found the DAN study in the 2010 proceedings (for some perverse reason listed in their 2008 section) dealing with temperature effects quite interesting, but it was quite limited in sample size.

    thanx

  2. #2

    Re: hard hit data

    Project Dive Explorer conducted by DAN is the largest collection of "real world" dive data. Most studies are not conducted in open water because it introduces to many discrepancies in the data. For the most part wet chamber studies provide better quality data and more useful results.

  3. #3
    New Member Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell's Avatar
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    Re: hard hit data

    Quote Originally Posted by bowzer  View Original Post
    I am familiar with Bret Gilliam's study with ~70,000 dives. Other than this and anyone point me in the direction of other similar studies? Thus far all I have found are studies with small sample sizes or chamber studies. Are there any other large scale real world studies with known numerators and denominators? Doesn't have to be breather specific.

    I found the DAN study in the 2010 proceedings (for some perverse reason listed in their 2008 section) dealing with temperature effects quite interesting, but it was quite limited in sample size.

    thanx
    Hello,

    An ongoing problem in the world of diving medicine, and invariably the denominator is the issue.

    However, there have been various attempts over the years to establish an incidence of death and decompression sickness in recreational scuba diving. They can be categorised as:

    1. Experimental studies - in which a rate per number of experimental dives is reported. These data are obviously accurate, but such studies are rare and their relevance to "everyday diving" is difficult to establish because the diving protocols are usually intended to be provocative so that the effect of some intervention or risk factor can be investigated. Examples:

    Gerth WA et al. The influence of thermal exposure on diver susceptibility to decompression sickness. NEDU TR 06-07, 2007.

    Doolette DJ et al. Redistribution of decompression stop time from shallow to deep stops increases incidence of decompression sickness in air decompression dives. NEDU TR 11-06, 2011.

    2. Surveys and cohort studies- in which divers volunteer their histories (number of dives and number of DCS events). These are obviously accurate too, but extrapolation to the wider diving community is complicated by potential bias in diver recruitment (ie do the divers involved represent a real world sample? - and frequently they don't). Sometimes such studies have a focus on a particular risk factor which is present in some participants but absent in others (eg a PFO). Examples:

    Klingmann C et al. Decompression illness reported in a survey of 429 recreational divers. Aviat Space Environ Med 2008;79:123-8

    Torti et al. Risk of decompression illness among 230 divers in relation to the presence and size of patent foramen ovale. European Heart J 2004;25:1014-1020.

    Billinger M et al. Patient foramen ovale closure in recreational divers: effect on decompression illness and ischaemic brain lesions during long-term follow up. Heart 2011;97:1932-7.

    3. True population studies - in which there is an attempt to study an entire population with some sort of denominator estimate. Hard to do and rare. Indeed, I am only aware of one, in which the number of tank fills in British Columbia was taken as the denominator for number of dives, and number of cases treated at hyperbaric units was the numerator.

    Ladd G et al. The Abacus Project: establishing the risk of recreational scuba death and decompression illness. SPUMS J 2002;32:124-8

    There is one very good study of mortality rates in recreational scuba where the population of actively insured DAN members was used as the denominator... but this is for deaths not DCS:

    Denoble PJ et al. Scuba injury death rate among insured DAN members. Diving Hyperbaric Med 2008;38:182-8

    Finally, of specific note for rebreather divers, Andrew Fock's reworking of the Deep Life rebreather death list, in which he has removed / ignored all the agenda-driven fiction and derived a soft denominator by means he describes, will be published on June 13 in Diving and Hyperbaric Medicine. This is mortality data... not DCS rates.

    Fock AW. Analysis of recreational closed-circuit rebreather deaths 1998-2010. Diving Hyperbaric Med 2013;43:78-85.

    Simon M
    Last edited by Simon Mitchell; 18th May 2013 at 21:56.

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    Re: hard hit data

    I will definitely be watching for Andrew's publication.

    Bruce
    The greatest enemy of knowledge is not ignorance. It is the illusion of knowledge.
    http://www.shearwater.com

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    hard hit data

    Quote Originally Posted by bgpartri  View Original Post
    I will definitely be watching for Andrew's publication.

    Bruce
    It might actually be a useful database once the fiction is filtered out
    Cheers,

    Dave....

    www.wedivebc.com

  6. #6
    RBW Member bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer is a jewel in the rough bowzer's Avatar
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    rEvo

    Re: hard hit data

    Thanks guys. In particular Simon. Seems I have some reading to do.

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    RBW Member dreamdive has disabled reputation dreamdive's Avatar
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    Re: hard hit data

    Thank you Simon for the head-up on the upcoming publication.

  8. #8
    New Member Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell's Avatar
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    Re: hard hit data

    Quote Originally Posted by dreamdive  View Original Post
    Thank you Simon for the head-up on the upcoming publication.
    Hello Claudia and Bruce,

    The next edition of DHM is very technical diving oriented and contains papers on rebreather-related mortality (by Andrew as mentioned above), a paper on oxygen toxicity in technical diving (also written by Andrew), an introductory paper on technical diving (for non-technical diver physicians) written by David Doolette and myself, a paper on decompression from deep technical dives (again written by David and I) and a paper on the feasibility of airway protection and ventilation in an unconscious diver underwater by a European group. Members of this site will obviously find Andrew's paper fascinating. High end technical divers won't learn much from our introductory paper, but I suspect the decompression paper will attract a lot of interest - we address a number of contemporary controversies like gas switching and deep stops.

    Simon M

  9. #9
    New Member Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell has a reputation beyond repute Simon Mitchell's Avatar
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    Re: hard hit data

    Quote Originally Posted by bowzer  View Original Post
    Thanks guys. In particular Simon. Seems I have some reading to do.
    At least some of the references I mentioned will be available through Gene's hard work on the Rubicon site. If you are having trouble obtaining any that are of particular interest to you let me know.

    Simon

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