Download or read book Statistically Based Decompression Tables II Equal Risk Air Diving Decompression Schedules written by P. K. Weathersby and published by . This book was released on 1985 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several sets of equal risk air decompression tables were calculated using a new methodology. Empirical decompression risk models were used to predict the probability of decompression sickness (DCS) for a given pressure exposure. These probabilistic models, earlier shown to have a considerable ability to separate tabulated experimental air dives according to DCS risk, were used to choose decompression schedules with an acceptable risk. The levels of risk used were 1% and 5% for standard air dives with an additional set of 0.5% no-decompression limits. As the new method calculates risk according to an integral over the dive and postdive period, many possible decompression schemes will have the same risk. The best schedules are defined as those requiring minimal total decompression time for the specified risk and subject to operational constraints. The constraints used here are decompression stops at even 10-ft intervals of depth for whole minutes. An algorithm was developed to obtain schedules in a partially optimal manner. The methodology can be used directly to produce tables for other operational constraints or risk levels. Because of the known limitations of source data and risk models, these tables represent considerable extrapolation from known procedures and should not be considered for use without testing.
Download or read book Statistically Based Decompression Tables 3 Comparative Risk Using U S Navy British and Canadian Standard Air Schedules written by Paul K. Weathersby and published by . This book was released on 1986 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first report of this series used probabilistic models to analyze the decompression safety of approximately 2000 single compressed air drives. The most successful model used in Report II generated new equal-risk decompression tables and was applied here to estimate the risk of bends using any of the current U.S. Navy, (U.K.) Royal Navy, and Canadian Forces standard air decompression tables. The range of risk went from less than 1% for short duration dives at most depths, to over 20% for exceptionally long exposures. The new Canadian schedules are generally safest because of their long decompression times, followed by British and then American schedules. Keywords: Diving; Decompression sickness; Saturation diving; Mathematical modeling; Likelihood estimation; Inert gas kinetics.
Download or read book Development of Iso DCS Risk Air and Nitrox Decompression Tables Using Statistical Bubble Dynamics Models written by Wayne A. Gerth and published by . This book was released on 1996 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Statistically Based Decompression Tables IV Extension to Air and N2 02 Saturation Decompression written by J. R. Hays and published by . This book was released on 1986 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent analyses have examined empirical, but statistically justifiable, models for standard air diving and used the results to develop air decompression schedule that are equal in risk. This analysis has been extended by examining air and N2-O2 saturation decompression. Some 279 exposures satisfied the rigid criteria for use as data. These exposures were analyzed alone and in combination with the earlier data by a number of gas exchange models. Several models with 2 or 3 gas exchange tissues were found to fit the data well. One of these models was chosen to produce optimum stage and continuous decompression schedules at a 1% chance of decompression sickness (DCS) for air, and for two constant PO2 mixtures at saturation depths down to 100 feet of seawater (fsw). For the same low predicted incidence of DCS, continuous decompression requires many fewer hours than needed for 10 or 5 foot staged decompression. Although the most powerful use of available data supports these schedules, they need testing to verify the actual incidence of DCS. Keywords: Mathematical model; Saturation diving; Likelihood estimation; Probability.
Download or read book Statistically Based Decompression Tables XI Manned Validation of the LE Probabilistic Model for Air and Nitrogen Oxygen Diving written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first-ever validation trial of a probabilistic decompression algorithm was conducted from 1991-92. A real time computer algorithm updated subjects' optimal decompression schedule within a numerical specification of the acceptable risk of decompression sickness (DCS). Long dives (majority over 6 hours) were chosen for testing because of operational needs and under-representation in the calibration data set: long repetitive air dives and multi-level dives - with air throughout, or with 0.7 ATA O2 during shallow transits or during the final decompression. Non-acclimatized divers wearing wet suits were immersed, chilled, and performed moderate exercise on the bottom but rested during decompression. A total of 730 dives resulted in 36 DCS cases, and another 20 cases with marginal symptoms. A subset (158 dives) were performed with the Combat Swimmer Multi-level Dive procedure, demonstrating greater safety when shallow transits were taken at 15 than at 30 feet of seawater. Overall the model was a predictive success: on none of the profiles were observed DCS incidence outside statistical uncertainty, and optimal model parameters were not greatly changed by the addition of the trial data. The real time algorithm is reliable enough for general Navy use.
Download or read book Validation of Decompression Tables written by Undersea and Hyperbaric Medical Society. Workshop and published by . This book was released on 1989 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Safety Limits of Dive Computers written by J. Wendling and published by . This book was released on 1995 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Navy Air Decompression Schedule Risk Analysis written by T. E. Berghage and published by . This book was released on 1980 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this report is to provide the diving community with an estimate of the risk associated with the use of the U.S. Navy's air decompression tables. A search of the diving data bank of the U.S. Navy Safety Center for the years 1971 to 1978 revealed 16,170 dives in which an air decompression schedule was used. These dives were sorted and tabulated by decompression schedule and decompression outcome. From these data, estimates of the incidence of decompression sickness associated with each schedule were derived. The overall incidence rate for the air decompression schedules was 1.25%; the incidence rate for individual schedules having more than 50 dives ranged from 0% to 4.8%. Only 43 of the 295 U.S. Navy air decompression schedules were used 100 times or more during the past 7 years. Over one-half of the available schedules were not used at all during this 7-year period. Although the Navy's experience with individual air decompression schedules is restricted, there is little evidence that the same incidence rate would not hold for all schedules in the air decompression table. (Author).
Download or read book Statistically Based Decompression Tables I Analysis of Standard Air Dives 1950 1970 written by P. K. Weathersby and published by . This book was released on 1985 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large number of air dives was examined by a new methodology. Several essentially empirical models of decompression risk were considered that predicted the probability of decompression sickness (DCS) for a given pressure exposure to avoid the indefinitely sharp threshold parameters that have characterized previous calculation of decompression tables. The candidate models used several distinct formulations of tissue gas exchange kinetics and summed tissue overpressures that are calculated during the dive to estimate decompression risk. The models were compared to decompression outcome data using the statistical principle of maximum likelihood. Reported decompression trials from American, British, and Canadian Naval laboratories were examined individually and collectively to evaluate the probabilistic models and their parameters. Only two to five parameters were found to be justified by the available data (more than 1,700 individual exposures were considered). Diving data from various sources were only partially compatible; some of the discrepancy may arise from an evolution of diagnostic criteria over several decades. Predictions were made of the outcome for additional reported diving series, and they were only partly successful. The models were then used to estimate decompression risk for current USN air diving with a finding of a wide range of hazard. Specifically, it appears that short dives are quite safe, even to a moderately deep depth, while long exposures are very risky regardless of depth. These findings will be used to produce a set of standard air tables with a uniform and low level of DCS risk. (Author).
Download or read book Statistically Based Decompression Tables 5 Haldane Vann Models for Air Diving written by Y. J. Parsons and published by . This book was released on 1989 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report continues the analysis of air decompression diving by probabilistic models evaluated using the statistical tool of maximum likelihood. Models based on the traditional deterministic calculations of Haldane have been placed in a probabilistic formalism by Vann. The ability of these models to fit data examined in the first and fourth reports in the present series were explored here. The computationally simpler Haldane-Vann (H-V) models achieved comparable success fitting relatively homogeneous data to the risk models used in the earlier reports in this series. However, H-V models were unable to deal successfully with larger and more diverse collections of data. It appears that the Vann definition of decompression 'dose' intrinsically cannot lead to simultaneously successful predictions of both short and long air dives. Keywords: Graphs; Formula mathematics; Decompression sickness; Mathematical models; Inert gas kinetics; Risk assessment. (kt).
Download or read book Workshop on Enriched Air Nitrox Diving written by Robert W. Hamilton and published by . This book was released on 1989 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physiological Basis of Decompression written by Undersea and Hyperbaric Medical Society. Workshop and published by . This book was released on 1989 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Statistically Based Decompression Tables 6 Repeat Dives on Oxyen Nitrogen Mixes written by and published by . This book was released on 1991 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: This risk of decompression sickness (DCS) during dives on various nitrogen/oxygen breathing mixes is analyzed using likelihood maximization. Risk is treated as cumulative, resulting from periods during which the partial pressure of dissolved N2 exceeds the hydrostatic pressure in one or more hypothetical separate tissues. Gas uptake and release are assumed to follow either mono- or bi-exponential kinetics. The database consists of 2006 well- documented wet man-dives. No statistical evidence is found to justify the use of different models or different parameter values for single dives versus repeat dives or for dives on different N2/O2 mixes. Under these models, then, the single and repeat dives in our database should be considered as belonging to the same population. However, the models do not adequately predict the probability of DCS associated with a series of 128 multilevel dives (which feature ascents to 20-30 fsw interspersed with deeper excursions) while simultaneously making a plausible prediction of the risk of any other type of dive in the database.
Download or read book Statistically Based Decompression Tables 7 Selection and Treatment of Primary Air and N Sub 2 O Sub 2 Data written by and published by . This book was released on 1992 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Probabilistic models of decompression sickness (DCS) require high quality data of diving profiles and DCS occurrence to get reliable predictions of the probability of DCS, P(DCS). Over 400 experimental dives performed since 1977 in the U.S., U.K., and Canada were collected, verified, and formatted for use in probabilistic models. In most cases the dive profile precision is within 1 fsw in depth, 30 sec in time, and 0.1 ATA in PO2. DCS outcome and other medical records are of the high quality expected for test dives done in military laboratories. This report describes the data sources, steps used in the review and formatting process, and summaries of the data collection ... Decompression sickness, Hyperbaric, Diving, Data base.
Download or read book The Essentials of Deeper Sport Diving written by John Lippmann and published by Aqua Quest Publications, Inc.. This book was released on 1992 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physiological and practical considerations of scuba diving in easy-to-read format.
Download or read book Statistically Based Decompression Tables XII written by S. S. Survanshi and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
