scientific-1990-1995

Scientific papers 1990 - 1995

This report explains experimentations made on 32 US Navy divers immersed in a water at 3 celcius degrees for periods up to 8 hours. Electrical resistance heated and warm water perfused gloves were tried. However, hands and feet remained dry by communication with the drysuit Date of publication: September 1990

This report explains experimentations made in correction of the US Navy saturation procedures published in 1978 that had triggered occasional vestibular decompression sickness (DCS) cases after upward excursions from storage depths between 800 and1000 feet of seawater. Date of publication: June 1990

This document explains experimentations made on animals to determine whether toxic events accumulated over a relatively long oxygen exposure reversed on return to normoxia at the same rates as those of shorter oxygen exposures. Date of publication: June 1991

This paper describes experimentations that demonstrated that microbubbles impair the blood-brain barrier integrity to protein, causing focal edema. Year of publication: 1991

This paper describes COMEX procedures used in November 1992 to reach 701 msw, which is still the world record. This successful experimental dive aimed to demonstrate that the use of Hydreliox enhances the divers’ effectiveness and working capabilities and provides improved safety and comfort for human intervention on undersea oil production facilities.

32 - A Boussuges, p. Ambrosi, G. Habib, D. Cartran, B. Gardette, JM Sainty: Detection of circulating bubbles with 2D echocardiography and pulsed dopler.

This document discusses the detection and assessment of venous gas emboli (bubbles) resulting from decompression in divers. It highlights the use of ultrasonic methods, particularly continuous-wave Doppler and echocardiography, to detect these bubbles. It also addresses the subjectivity and potential inaccuracies in grading bubble signals, the need for better detection methods in sport diving, and the authors' efforts to evaluate and propose a methodology for using 2D echocardiography and pulsed Doppler to quantify circulating bubbles.

This document explains procedures for the use of nitrox. Date of publication: June 1991

This paper, published in 1995, is another study that has been used by other scientists later on. It thoroughly investigates the various noise sources during diving operations, including saturation, and provides accurate measurements. This document has been provided by Francis Hermans

This study verified the hypothesis that deep heliox diving might influence postural control and the vestibular system. Multiple postural controls were made in four divers before, during, and after an onshore experimental heliox saturation dive of 32 days. The depth was 450 msw. Downward excursions to 470 msw were also performed. Clinical Otolaryngology (also called ENT or Ear, Nose, Throat) and otoneurological examinations, including bithermal caloric vestibular testing with electronystagmography (ENG), were performed.

55 - CO2 retention during hyperbaric exercise while breathing 40/60 nitrox. Authors: D Kerem, Y. I. Daskalovic, R Arieli, A Shupak

The authors evaluated CO2 retention in 24 Navy construction divers breathing air at 1 atm abs (101.3 kPa) and 40% O2 (40/60) nitrox at 4 atm abs (PO2 of 162.1 kPa) inside a pressure chamber.

The "oxygen window" causes a partial pressure difference of inert gas between the inside and outside decompression bubbles. Estimates of PO2 and PCO2 in tissue are necessary for O2 window calculations and any calculations about the growth or decay of decompression sickness bubbles, but the estimates involve many uncertainties. Using simplifying assumptions, the authors estimated the O2 window range of environments for tissues having a wide range of O2 extractions

In this study, published in 1991, the risk of decompression sickness (DCS) during dives on various nitrogen/oxygen breathing mixes is analyzed using likelihood maximazation

Authors: M. Jette, K. Sidney, G Blumchen This article summarizes and presents energy expenditure values in METS and watts units. Despite its limitations, the MET concept provides a convenient method to describe an individual's functional capacity or exercise tolerance as determined by progressive exercise testing and to define a repertoire of physical activities in which a person may participate safely without exceeding a prescribed intensity level.

This report contains a summary of all known results from controlled human exposures to hyperbaric O2 at the time of its publication in January 1993. The data were collected to analyze and develop predictive models relating to the risk of developing a symptom of central nervous system O2 toxicity as a function of time, depth, and exposure conditions.

This report, published in 1993, discussed the decompression model ZH-L8 from professor Buhlman. The decompression algorithm ZH-8 was based on eight compartments, as suggested. It gave rise to sport diving decompression tables known under the name "Buhlman Tables", and massively used by many European sport divers. Many pioneer manufacturers of diving computers also used it. It has been followed by the ZH-12 and the ZH-16, which many diving computer manufacturers still use.

37 - A model for predicting central nervous system toxicity from hyperbaric oxygen exposure in man: Effect of immersion exercise , and old and new data.

Authors: A L Harabin, S S Survanshi, L D Homer This paper, published in March 1994, discussed of analyzed central nervous system (CNS) oxygen toxicity symptoms from 1726 controlled human hyperbaric exposures at PO2 levels ranging from 0.3 to 2.9 atmospheres (atm) using risk models and maximum likelihood analysis and tested specific hypotheses with likelihood ratios. The data were sorted into dry, immersed, no-exercise, and exercise conditions.

Author: Erik C. Baker Robert D Workman (1885-1977) made a revision of Haldane tables and found that the "tissue ratios" for tolerated overpressure varied by half-time compartment and by depth. The data showed that the faster half-time compartments tolerated a greater overpressure ratio than the slower compartments and that for all compartments, the tolerated ratios became less with increasing depth. Instead of using ratios, he described the maximum tolerated partial pressure of nitrogen and helium for each compartment at each depth as the "M-value". This concept is still used by most modern decompression tables.

The salivary flow rate and composition of 2 groups of 31 subjects, one group at each extreme of the seasickness susceptibility scale, were compared. No significant differences were found between the two groups in flow rates and electrolyte concentrations of whole resting and stimulated saliva. Analyse activity and rate of secretion in resting saliva were significantly higher in subjects susceptible to seasickness as compared with non- susceptible subjects. Also, the total protein rate of secretion in resting saliva was significantly higher in the susceptible group.

Forty-one percent of the dives were performed within the decompression limits of the US Navy standard decompression tables. Risk factors were fatigue, circumstances suggesting dehydration, and extreme physical effort. The most common presenting symptoms were paresthesias, weakness of the legs, lower back pain, or abdominal pain. Full recovery was achieved in 79% of the patients. Spinal symptoms appeared immediately on surfacing in six of the eight patients who continued to have multiple neurological sequelae.

Authors: judith Aharon-Peretz, YohaiAdir, Carlos R. Cordon, Shahar Kol, Nachum Cal, Yefruda Melamed

Although pulmonary barotrauma (PBT) is a well-known clinical entity, its recognition in divers is sometimes delayed and its implications for future diving often are unappreciated. The pulmonary complications of diving activities range from mere discomfort from mediastinal emphysema or pneumothorax, or both, to life-threatening gas embolization. In nine cases described in this paper, only minor manifestations were associated with PBT which occurred at or close to the surface, but three of these four divers were found to have abnormal pulmonary function.

Author: K Todnem, H Nyland, H Skeidsvoll, R Svihus, P Rinck, B K Kambestad, T Riise, J A Aarli. The increased hyperbaric pressure influences the nervous system during deep dives. The divers may experience hand tremors, postural instability, gastrointestinal problems, somnolence, and cognitive dysfunction. The neurological symptoms and signs that may occur have been termed high-pressure neurological syndrome (HPNS). This syndrome has been known for more than twenty years.

Authors: J How, A Vijayan, T M Wong The Singapore Mass Rapid Transit (MRT) projectstarted compressed air work in Oct 1984. Eleven km of underground tunnels out of 20 km were built using this method. Cases of decompression sickness (DCS) arising from compressed air work are rare with working pressures less than 1 bar gauge. However, there were 10 cases of DCS in the MRT project who were exposed to less than 1 bar pressure. The authors present their clinical features and attempt to explain the observations in relation to theories of bubble nuclei formation, gas loading and rate of decompression.

Publisher: American Academy of Underwater Sciences Proceedings of a workshop held at Duke University Medical Center in Durham, USA, in March 1991.

Publisher: American academy of underwater sciences Proceedings of a workshop held in La Jola, California, USA, in May 1991. This workshop was sponsored by the National Science Foundation, Polar Biology, and the American Academy of Underwater Sciences.

Authors: R.B. Philp & D.J. Mclver The authors studied the effects of elevated pressures of inert and narcotic gases on calcium-dependent functions and cytosolic calcium levels in human blood platelnts, marine sponge cells and cultured human SK-N-SH neuroblastoma cells using the intracellular calcium indicator fura-2 AM. They found that many of the effects of narcotic gases and of pressure (He) could be explained by their influence on stimulated free cytosolic Ca2+ levels.

Authors: C. L. Shake, P. K. Weathersby, B. G. Coras, & arid J. W. Parker A disabled submarine (DISSUB) crew exposed to increased atmospheric pressures resulting from flooding, rupture of air lines, or emergency breathing apparatus use may incur a decompression obligation and will require gradual decompression to avoid decompression sickness (DCS). Decompression in a nitrogen-oxygen mixture is not always operationally feasible, and decompression from an air exposure in helium and oxygen could result in isobaric counter-diffusion DCS.

In this document, Bruce Wienke and Timothy O’Learly, who are reputed authors on this subject explain their comprehention on mixed gas diving.

Authors: F. M.N.H. Schramel, A.R.J. Van Keimpena, J. P. Janssen, R. P. Golding, & P. E. Postmus The aim of the present study was to analyse pulmonary function parameters of patients with spontaneous pneumothorax (SP) in relation to the extent of emphysema-like changes (ELCs). Pulmonary function tests were performed in 85 patients with unilateral SP, 6 weeks after video-assisted thoracoscopy (VAT). In 63 patients, thoracic computer tomography (CT) was obtained.

Author: O. Hyldegaard, M. Møller, J. Madsen This paper relates to experiments in which air bubbles were injected into the spinal white matter of rats and studied at 1 bar after decompression from exposure to air at 3.1 bar (absolute) for 4 hours to observe the effects of heliox, pure oxygen, and nitrous oxide/oxygen breathing on bubble reduction.

Authors: O. Hyldegaard, M. Møller, J. Madsen Decompression sickness and spinal cord function for at least three hours after decompression to I atm abs (101 kPa) following exposure to air at 3.8 atm abs (385 kPa) for 1 hour were studied using rats. Three groups of animals were given either air, oxygen, or heliox (80/20) to breathe at 1 atm abs for three hours after decompression. Both oxygen and heliox breathing impeded the development of DCS significantly. The effect of heliox seemed to be superior to that of oxygen.

Authors: O. Hyldegaard, J. Madsen This study aimed to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during air, helium-oxygen (heliox, 80:20), or oxygen breathing. Air bubbles were injected into skeletal muscles or tendons in rats after decompression from a l-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at one atm abs (101 kPa) during either air-breathing, or air-breathing followed by heliox or O2 breathing..

Click on the octopus to return to the top of the page

Authors: JP Imbert & S Montbarton In 1974, Comex began using a computer system to process its dive reports and to access this information efficiently. The system was named the Comex Diving Database and ran until the end of the company's diving activities, with several revisions and updates. This database enabled remarkable achievements, notably the development of decompression procedures that are still in use today. It can be seen as an example of a commercially operated diving database.

Author: JP Imbert In this presentation, Jean Pierre Imbert demonstrates that by utilizing commercial diving databases, distinguishing between the two types of decompression sickness, and applying the arterial bubble model, it is evident that surface decompression has a "natural" safe limit, closely aligning with the guidelines set by the UK Department of Energy Safety Memorandums. Exceeding this limit generally results in a higher incidence of type 2 decompression sickness compared to continuous decompression.

Authors: P. K. Weathersby, S. S. Survanshi, L.D. Homer, E. Parker, and E. D. Thalmann The researchers previously used probabilistic models and maximum likelihood estimation to predict decompression sickness (DCS). They improved their method by including when DCS symptoms occur, which made their predictions more accurate in a study of nearly 1,000 exposures. This improvement helps to distinguish better between models that can predict both the timing and occurrence of DCS symptoms and those that only predict occurrences.

Authors: P.K. Weathersby, S.S. Survanshi, R.Y. Nishi, E.D.Thalmann Probabilistic models for decompression sickness (DCS) require accurate data on diving profiles and DCS incidents to effectively predict DCS risks. Over 400 experimental dives from the U.S., U.K., and Canada since 1977 have been compiled, checked, and prepared for these models. This report outlines the data sources, review and formatting process, and provides summaries of the data collection.

Authors: Lawrence E. Armstrong, Carl M. Maresh, John W. Castellani, Micheael F. Bergeron, Robert W. Keriefick, Kent E. LaGasse, and Deborah Riebe Urinary indices are used to assess the hydration status of patients, determining whether they are well-hydrated, euhydrated, or hypohydrated. This document describes laboratory studies conducted to determine if urine color accurately indicates hydration status and to clarify the interchangeability of color, urine osmolality, and urine specific gravity in research.

Publisher: The Undersea and Hyperbaric Medical Society The facilitators and participants of this workshop, which focused on evaluating the feasibility of diving for individuals with asthma, engaged in a productive discussion that highlighted key areas that need further study. The panel ultimately distilled these discussions into 12 consensus statements, offering more precise and flexible guidelines for determining the suitability of individuals with asthma.

Authors: Norihiro Miyamoto, Nobuo Matsui, Itaru Inque, Hisao Seo, Kazuhiko Nakabayashi, and Hironori Oiwa This study investigates the mechanism behind increased urine flow (hyperbaric diuresis) in men exposed to a hyperbaric environment. Five male subjects participated in a dry saturation dive experiment, where they were exposed to a helium-oxygen environment at 16-21 ATA for four days. Blood and urine samples were collected at various intervals. The results suggest that hyperbaric diuresis is caused by both reduced antidiuretic hormone and increased atrial natriuretic polypeptide secretion.

Authors: Einar Thorsen, Kaire Segadal, Brit Kambestad, Amund Gulsvik This study measured pulmonary function in 152 professional saturation divers and a control group of 106 subjects. Various lung function parameters were assessed and compared with reference values from Scandinavian studies, British submariners, and the European Community for Coal and Steel (ECCS). The findings suggest minor airway dysfunction and transient lung function changes after saturation dives, indicating cumulative long-term effects of diving on pulmonary function.

Author: K Todnem, H Nyland, B K Kambestad, J A Aarli This study investigated recorded neurological signs and symptoms in 156 air and saturation divers compared to 100 controls. Divers exhibited significantly more general neurological symptoms and abnormal findings than controls, with prominent issues in concentration and memory and signs of distal spinal cord or nerve root dysfunction and polyneuropathy. These symptoms and findings were significantly correlated with diving exposure, DCS prevalence, and age.

Authors: H.Y. Tao, H.J. Chen, H. Zhang, J. Guo, and F.K. Rong lThis study investigated the effects of saturation-excursion diving at pressures equivalent to 250 and 300 meters on the urinary excretion of atrial natriuretic polypeptide (ANP), antidiuretic hormone (ADH), and electrolytes in four male divers. The divers were exposed to high- pressure environments for two days, and urine samples were collected day and night before, during, and after the exposure. The study concluded that the increase in nocturnal urine flow (nocturia) was primarily due to stimulated ANP secretion.

Authors: R. Holden, C. D. G. Morsman, and C. M. Lane The study conducted ocular fundus fluorescein angiography on 26 divers with at least ten years of safe diving practices and seven controls. The results showed no significant difference in the incidence of macular abnormalities between these groups and those from a previous study. The findings suggest that adhering to safe diving practices provides some protection against macular abnormalities associated with decompression sickness in divers.

A workshop was held at the USAF Armstrong Laboratory in October 1990 to address altitude decompression sickness (DCS), an operational limitation in aviation and space activities. The event gathered over 50 participants from the Department of Defense, NASA, and universities. The workshop aimed to document the current understanding of DCS and its operational significance, especially as future military aircraft crews are expected to encounter higher altitudes. The conclusions from this document have to be linked to the transfer to altitude or traveling by aircraft after diving

Authors: Tim D. Oury, Ye-Shih Ho, Claude A. , and James D. Crapo This paper investigates the role of extracellular superoxide anion (O2-) in central nervous system (CNS) oxygen toxicity using transgenic mice that overexpress human extracellular superoxide dismutase (ECSOD) in the brain. When exposed to hyperbaric oxygen, transgenic mice showed higher mortality compared to nontransgenic mice. The findings suggest that NO is a crucial mediator in CNS oxygen toxicity and that ECSOD increases this toxicity by inhibiting O2-mediated inactivation of NO.

Authors: E. Thorsen, K. Segadal, B.K. Kambestad This study investigates the prolonged effects of deep saturation diving on pulmonary function by measuring various lung parameters before and after 17 different diving operations to depths ranging from 5 to 450 meters of seawater. The divers' pulmonary function was assessed through static and dynamic lung volumes, transfer factor for carbon monoxide (TLCO), and closing volume. The conclusions are that hyperoxia, hyperbaric, and venous gas micro embolism all contribute to changes in pulmonary function after a single saturation dive, potentially explaining some long-term effects on divers' lung health.

Authors: E.I Eger, J. Liu, D. D. Koblin, M.J. Laster, S. Taheri, M.J. Halsey, P Ionescu, B.S. Chortkoff, and T. Hudlicky The study examined 35 types of methanes, ethanes, propanes, and butanes, including unfluorinated, partially fluorinated, and perfluorinated variants, to identify molecular properties that correlate with optimal anesthetic solubility and potency. Additional data were collected on longer-chained alkanes. The findings suggest that an ideal anesthetic would have three or four carbon atoms with single or dual hydrogenation of two carbons, particularly terminal carbons.

Authors: M.W.J. Cleeter, J.M. Coopefib, V.M. Darley-Usmard, S. Moncadad, & A.H.V. Schapira This study investigates the effect of S-nitrosoglutathione (GSNO), a nitric oxide generator, on rat skeletal muscle mitochondria. The findings suggest that nitric oxide can rapidly and reversibly inhibit the mitochondrial respiratory chain, potentially contributing to its cytotoxic effects in the central nervous system (CNS) and other tissues.

Authors: Y.C. Lin, K. Shikaki, H Takeushi, and M. Mohri This study investigates cardiovascular deconditioning (CD) in subjects exposed to a hyperbaric environment of 31 ATA and subsequent decompression to sea level. Measurements were taken before and after underwater exercise, during early, mid, and late exposure to 31 ATA, and post-dive. The conclusions are that hypovolemia is a major factor in the acute phase of hyperbaric CD, and prolonged inactivity may contribute to later phases. Moderate daily exercise was not effective in preventing hyperbaric CD.

Authors: E.D. Thalmann This document provides a detailed account of the research and testing conducted to revise the U.S. Navy's Unlimited-Duration Saturation Excursion Limits, initially published in 1978. The study describes the methodology, findings, and conclusions of a series of dives to address vestibular decompression sickness (DCS) associated with upward excursions from certain depths. It explains the empirical formula used to calculate safe excursion distances and discusses the results, including the occurrence of DCS cases and their attribution to fast saturation decompression rates rather than the excursions themselves.

10 - COMEX Report: Facteurs de suceptibility individuelle aux accidents de decompression (Factors of individual susceptibility to decompression accidents)

Author: J.Y. Massimelli, M. Comet, B. Gardette This study conducted by CNES/COMEX in September 1988 investigated the influence of individual characteristics on the risk of decompression accidents, such as age, weight, body fat percentage, sex, physical training level, history of decompression accidents, and specific biological parameters. Two groups of professional divers were compared to understand how individual characteristics affect the risk of decompression accidents. The study was intended as a preliminary step towards a larger research effort to gain knowledge to be used in preventing decompression accidents in diving activities.

Author: Mike Tipton This study evaluated the thermal protection effectiveness of two helicopter passenger immersion suits in cold water conditions. It compared the performance of a standard 'dry' suit (Suit A) with a 'dry' suit that has additional insulation through inflation (Suit B), highlighting the superior performance of Suit B in maintaining body temperature and comfort during immersion. Additionally, the text discusses the importance of realistic testing conditions for selecting appropriate immersion suits.

Authors: B. Gardette, J.Y. Massimelli, M. Comet This paper summarizes the deep diving activities COMEX and the French Navy conducted in France between 1979 and 1989. It focuses on the behavior and general impressions of the divers during these dives. Additionally, it discusses the favorable outcomes of using hydrogen in breathing gas mixtures for deep diving as part of COMEX's research program (HYDRA). The document also mentions plans for a deep dive beyond 600 meters using a hydreliox mixture in 1992, following comprehensive tests in 1991.

Authors: J. Zhang, C.E. Fife, Currie, R.E. Moon, C.A. Piantadosi, and R.D. Vann This study investigates the relationship between intravascular complement activation and decompression sickness (DCS) in humans, specifically the effects of repetitive air diving on complement activation by measuring RBC-bound C3d levels and monitoring for venous gas emboli. It aims to convey the findings that no cases of DCS occurred and that complement activation, as indicated by RBC-bound C3d, increased after repetitive dives but was independent of bubble grade.

Author: M J Tipton This document intends to analyze and critique the effectiveness of current standards, specifications, and guidelines for immersion protective equipment in preventing fatalities at sea. It aims to identify gaps in the design, selection, and evaluation of such equipment, particularly about environmental conditions and physiological responses. In addition, it concludes with recommendations for improving standards and testing to better account for hazardous responses associated with immersion.

Authors: A. Boussuges, P. Blanc, F. Molenat, E. Bergmann, J.M. Sainty This study presents research findings on the relationship between haematocrit levels and neurological decompression illness (DCI) in sport divers and determines the correlation between haematocrit levels and the prognosis of neurological sequelae in divers affected by DCI. It provides statistical analysis comparing haematocrit levels in divers with neurological DCI, those with neurological sequelae, and control divers, highlighting significant findings and their implications for prognosis.