scientific-1996-1998

Scientific papers 1996 - 1998

15 - The incidence of decompression sickness arising from commercial offshore air-diving operations in UK sector of the North Sea during 1982/83.

Authors: Doctors Shield & Lee This report is part of the documents that have initiated the implementation of the UK HSE diving bottom time limits that are in force in British waters. Also, they have been adopted by IOGP in the recommended diving practices of the association.

20 - B. W. Hamill, J. E. Hendrix, L. J. Crepeau, J. D. Pelton, M. D. Miley, E. E. Kadlec: Speech intelligibility assessment in a helium environment - The speech intelligibility index.

This document relates experiments where speech Intelligibility was measured with US Navy divers participating in deep saturation dives and a group of non- divers to test different communication systems and their components.

35 - R. Gelfand, C. J. Lambertsen, J. M. Clark, E. Hopkin: Hypoxic ventilatory sensitivity in men is not reduced by prolonged hyperoxia (Predictive Studies V and VI)

The investigations described in this report included observing the development rates of visual, auditory- vestibular, neurological, pulmonary, cardiac, mental performance, and respiratory effects of hyperoxia over the O2 pressure range of 1.5–3.0 ATA. Year of publication: 1998

46 - Yasuhiro Manabe, Kenichi Sakai, Kenichi Kashihara, Toshikiyo Shohmori: Presumed venous infarction in spinal decompression sickness.

This document describes the Magnetic Resonance Imaging (MRI) findings in a patient with spinal decompression sickness. The authors conclude that Magnetic Resonance Imaging (MRI) may facilitate the early diagnosis of spinal decompression sickness. Date of publication: September 1998

13 - Evaluation of decompression sickness risk in saturated air and nitrox dives juged on the basis of changes in haemostasis.. Authors: Romuald Olszanski, Zbigniew Baj, Andrzej Buczynski, Maciej J. Konarski, Ryszard Klos, Stanislaw Skrzynski, and Krzysztof Zeman.

The evaluation of decompression tables and individual sensitivity to decompression disease is primarily based on the detection of symptoms. Thus, not on physiological but pathophysiological criteria. The above situation imposes research into such diagnostic methods that would allow for the evaluation of the decompression system applied. Apart from the "bends" criteria and Doppler monitoring of gas bubbles and blood flow, hemostasis evaluation may well be an indicator that the decompression is correct

Authors: Van Liew, Hugh D., and Soumya Raychaudhuri The authors previously outlined the fundamental principles governing stabilized bubbles' behavior, such as the microbubbles being put forward as ultrasound contrast agents. In this document, their goal is to develop the idea that there are limits to the stabilization and to provide a conceptual framework for comparing bubbles stabilized by different mechanisms.

Authors: Philip P Foster, Johnny Conkin, Michael R. Powell, James M. Waligora, & Raj S. Chhikara The authors hypothesize that metabolic gases play a role in the initial explosive growth phase of bubble formation during hypobaric exposures. Models that account for optimal internal tensions of dissolved gases to predict the probability of occurrence of venous gas emboli were statistically fitted to 426 hypobaric exposures from National Aeronautics and Space Administration tests. The presence of venous gas emboli in the pulmonary artery was detected with an ultrasound Doppler detector. The model fit and parameter estimation were done using the statistical method of maximum likelihood.

02 - Statistically Based Decompression Tables IX: Probabilistic Models of the Role of Oxygen in Human Decompression Sickness. Author: Paul K Weathersby

While probabilistic models of human decompression sickness (DCS) have been successful in describing both the level and timing of DCS risk in a wide variety of N2- O2 data, they have failed to account for the observed DCS risk in the currently available collection of dives with significant periods of 100% oxygen breathing. The best model to date, calibrated with over 2300 air and N2-O2 dives, under-predicts the DCS risk of these O2 dives by 60%, whether O2 is breathed during in-water decompression or during surface decompression procedures. This overestimation of the benefit of O2 is due to an exaggerated acceleration of N2 wash-out during O2 breathing.

06 - Statistically Based Decompression Tables X: Probabilistic Models of the Role of Oxygen in Human Decompression Sickness. Author: Paul K Weathersby

Underwater decompression meters or computers sense a diver's changes of depth in real-time and calculate a decompression schedule for the individual diver's exposure. Currently available devices compare calculated nitrogen tissue tensions to a set of stored “safe” constants. No explicit quantitative connection between these rules and the risk of decompression sickness has been established. Well calibrated probabilistic models, even though computationally more intense, can be used to specify decompression procedures tailored to control the risk of decompression sickness...

Authors: A. Boussuges, P Ambrosi, G Habib, D Cartran, B. Gardette, JM Sainty Detection of circulating bubbles can be used as an indicator of the safety of a dive and his decompression procedure. Continuous wave Doppler is the more widely used but the analysis of the signals obtained involve a degree of subjectivity. Then, the inter-rater agreement on the grading of intravascular bubble signals can be important and statistics of studies with a few records can be falsified. Others ultrasonic methods for detecting bubbles have been evaluated. Echocardiography can visualised circulating bubbles in right cavities. Transesophageal echocardiography is semi invasive and only used during experimental animal studies.

Authors: R. Arieli, A. Gutterman The development of oxygen toxicity can be delayed by intermittent periods of normoxia. In this document, doctors Arieli and Gutterman show a procedure for quantifing the recovery during normoxia, so a process that allows calculating the accumulation of oxygen toxicity and its recovery to evaluate central nervous system oxygen toxicity.

This document explains the fundamentals of oxygen sensing, uptake, and transport. It also shows examples of extreme respiratory performance, such as diving and high- altitude survival in mammals and birds, air-breathing in fish, and those few vertebrates that can survive without oxygen for several months.

This document is a presentation of the MT92 for tunneling operations requiring compressed air work, and an analysis of the 1st operations performed with this table.

This document is a study of tables made in 1998 for the Canadian Underwater Minecountermeasures (MCM) Apparatus (CUMA), a self-contained, semi-closed circuit breathing apparatus in service with the Canadian Forces (CF) for diving on underwater mines to a depth of 81 metres of seawater (msw) using a mixture of helium and oxygen (HeO2). .

Authors: A. Boussuges, S. Abdellaoui, B. Gardette, & JM Sainty Since the sixties, when Cross and Bagnis published articles on Taravana in Polynesian pearl divers, decompression sickness following breath hold diving has been a widely debated subject. In this type of dive, the quantity of dissolved nitrogen is very low and repeated exposure for several hours is required for the tissues to be oversaturated for any length of time. This study was designed to research circulating air bubbles in top level breath hold divers during training periods, using two- dimensionnal (2D) echocardiography and continuous Doppler ultrasound recordings.

Authors: C. Rostain, M. C. Gardette-Chauffour, & R. Naquet To study the effects of nitrogen addition to the breathing mixture on sleep disturbances at pressure, two dives were performed in which helium-nitrogen oxygen mixture was used up to 450 m sea water (msw). In total, sleep of 12 professional divers was analyzed (i.e., 184 night records). Sleep was disrupted by compression and by stay at 450 msw: The authors observed an increase in awake periods and in sleep stages I and II and a decrease in stages III and IV and in rapid-eye-movement sleep periods.

This paper describes studies on the effect of sulfur hexafluoride/oxygen breathing on air bubbles injected into skeletal muscle, rat-tail tendon, the anterior chamber of the eye, and spinal white matter. Decompression- induced nitrogen bubbles in adipose tissue was studied. The results were compared with previous experiments using heliox 80/20.

05 - The effects of wave conditions on dry immersion suit isolation: A comparison between humans and a manikin Author: Michel B. Ducharme, Christopher J. Brooks

This study was designed to investigate the effect of standard wave conditions (0 to 70 cm) on dry immersion suit insulation when tested on humans and a mannequin simultaneously. The objectives of the study were: • To see if the thermal insulation of suits used on a manikin and humans is equally affected by wave motion; • To determine which component of the suit is most affected by wave motion.

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Authors: N.B. Hampson and R.G. Dunford The "cold-induced pulmonary edema" syndrome was first described in 1989, affecting scuba divers in cold European waters. The authors observed six similar cases, five in Puget Sound and one in the Gulf of Mexico, involving four women and two men aged between 24 and 60. This syndrome can occur in both cold and warm waters and is not related to decompression sickness. Medical personnel should be familiar with this condition to manage it effectively.

Authors: V. Lafay, A. Boussuges, P. Ambiosi, P. Barthelemy, Y Frances, B. Gardette,and Y. Jammes This study focused on the heart's pumping ability and the blood flow during the dive. The findings showed a decrease in heart rate, which led to a reduced overall heart output, while other heart function indicators remained stable. There was no evidence of heart muscle relaxation issues, valve problems, or increased lung artery pressure. The study concluded that this type of echocardiography is a reliable method for monitoring heart function during deep dives, and the dive conditions tested did not significantly alter heart function, aside from the slower heart rate.

Authors: G. Racic, P.J. Denoble, N. Srem, L. Bojic and B. Bota This study aimed to evaluate the effectiveness of hyperbaric oxygen (HBO2) versus prednisone in treating 79 Bell’s palsy, a condition that causes temporary facial paralysis on one side of the face. The participants were divided into two groups: 42 received HBO2, and 37 took prednisone. The HBO2 group inhaled 100% oxygen at 2.8 atm abs for 60 minutes, twice daily, for up to 30 sessions or until full recovery, and also took a placebo pill. The prednisone group breathed 7% O2 at the same pressure and schedule and received 450 mg of prednisone over eight days. The findings indicate that HBO2 treatment is more effective than prednisone for treating Bell’s palsy.

Authors: N.A.M. Schellart, M. Pollen, and A. Van Der Kley The study investigated how different levels of oxygen and pressure affect color vision and sensitivity to red and green colors. The findings revealed that normal air pressure with low oxygen enhances red sensitivity by 4%, while high oxygen at the same pressure decreases it by 4%. Hyperbaric oxygen showed a minor reduction in red- green sensitivity, attributed to the counteracting effect of increased carbon dioxide levels. No changes were observed with normal air pressure and oxygen levels

Authors: K.F. Koltyn and W.P. Morgan The authors examined how wearing a wetsuit affects divers' mental and physical responses. They found that heart rate, air usage, and breathing effort increased in both trials, but these increases were more significant when divers wore wetsuits. Only in the wet suit trial did the divers' core temperature rise significantly. Divers also felt more anxious and aware of their bodies in the wet suit. Interestingly, anxiety levels dropped significantly after swimming without the wet suit. This suggests that wearing a wet suit can make divers feel more anxious, especially when it's warm, and the exercise is intense.

Authors: A. Nohara and T. Yusa In this study, 90 rats were subjected to high-pressure conditions and then rapidly decompressed to examine the effects on their brain structures. Initially, there were noticeable disruptions, but these issues were largely resolved within 24 hours. However, the problems reappeared about two to three days later. This suggests that the initial recovery might be temporary, and longer- term brain damage could occur due to the stress of decompression.

Authors: A. Boussuges, D. Carturcin, P. Ambrosi, G. Habib, j. M. Sainty, R. Luccioni This study aimed to determine how pulsed Doppler and 2D echocardiography can detect and measure blood bubbles in divers after decompression. The study concluded that pulsed Doppler was more effective than 2D echocardiography in detecting and measuring blood bubbles in divers after decompression. However, further research is necessary to compare the effectiveness of pulsed and continuous Doppler in detecting these bubbles.

Authors: P. Gemonpre, P. Dendale, P. Unger, and C. Balestra This study was conducted on sports divers to investigate whether a heart condition known as Patent Foramen Ovale (PFO) could be the cause of unexplained decompression sickness (DCS). Based on the results, PFO is linked to unexplained DCS related to the brain, but not to spinal DCS. The researchers emphasized the need for standardized methods in future studies that use this type of heart scan.

Authors: E.T. Flynn, E.C. Parker, R. Ball From 1990 to 1994, Navy and Marine Corps divers conducted 163,400 shallow no-decompression dives, ranging from 21 to 55 feet deep, following U.S. Navy no- decompression limits (USN57). During this period, 48 incidents were reported as possible decompression sickness (DCS), with the majority identified as Type II DCS, which contrasts with previous reports where Type I was more prevalent. The study also examined the potential impact of implementing more stringent no-decompression limits (USN93), assuming diving patterns remained unchanged..

Authors: Erik C. Baker The saying "an ounce of prevention is worth a pound of cure" really applies when it comes to avoiding decompression sickness. The best way to prevent it is by following a proper decompression plan. Technical divers have noticed that including "deep stops" in their diving profiles helps prevent many problems. By understanding how decompression works, we can adjust the model to manage pressure differences better and calculate the safest and deepest stops needed.

Authors: B.D. Butler, R. Robinson, T. Little, J.E. Chelly, and M-F. Doursout The authors investigated the cardiovascular and pulmonary responses of laboratory rats to moderate decompression stress. Rats were compressed to 616 kPa for 120 minutes and then decompressed at 38 kPa/min. They concluded that moderate decompression profiles cause detectable cardiovascular and pulmonary responses in rats.

Authors: Zexu Fang, James Sonner, Michael J. Laster, Pompi Ionescu, Lori Kandel, Donald D. Koblin, Edmond I Eger and Michael J. Halsey The authors investigated the anaesthetic and convulsive properties of 16 aromatic compounds (from benzene to 1,3,5-tris(trifluoromethyl)benzene) and four cycloalkanes (from cyclopentane to cyclooctane). Some compounds, such as benzene and cyclopentane, caused excitation, while others, such as perfluorotoluene and cyclohexane, caused convulsions. The results suggest that molecular shape and size provide only limited insight into the structure of the anaesthetic site of action.

Authors: Joseph S. Beckman, & Willem H. Koppenol Nitric oxide (NO) is unique among intercellular messengers due to its rapid and isotropic diffusion through tissues, although it cannot be transported through the bloodstream because it is quickly destroyed by oxyhemoglobin. While its direct toxicity is modest, it becomes significantly more toxic when it reacts with superoxide to form peroxynitrite, a selective oxidant that modifies proteins by creating nitrotyrosines. This nitration can disrupt protein assembly, leading to pathological consequences.

Authors: Val Vallyathan & Xianglin Shi This paper explains the role of reactive oxygen species (ROS) in causing lung injuries and diseases. The review highlights both endogenous and exogenous sources of ROS, focusing on occupational and environmental exposures to various chemical substances. ROS can cause cell injury and molecular alterations through various mechanisms, including intracellular signaling and the activation of proinflammatory cytokines. Understanding these processes is crucial for preventing and mitigating lung injuries from acute and chronic toxin exposure.

Authors: R. S. Lillo, E. C. Parker, and W. R. Porter This study examined the differences in decompression risk between helium (He) and hydrogen (H2) using 1,607 unanesthetized male albino rats. The rats, subjected to dives with 2% oxygen balance at depths up to 50 ATA and bottom times up to 60 minutes, were decompressed to 10.8 ATA with varying profiles. Using maximum likelihood analysis, the study estimated the relative decompression risk ("potency") and the gas uptake and elimination rate. The findings indicated that H2 has up to 35% greater potency for causing decompression sickness compared to He.

Author: Irwin Fridovich The field of study concerning the biology of superoxide anion radicals and related free radicals has matured significantly. It is now known that superoxide and hydroxyl radicals are produced in living systems, and there are complex defense and repair systems in place to mitigate their harmful effects. New defensive enzymes, such as superoxide dismutase, catalase, and peroxidase, are continually being discovered, along with new targets affected by these radicals. The involvement of these radicals in both physiological and pathological processes is also being established.

Authors: Charles Y. Cheung, David J. Green, Gerald J. Litt, and James A. Laugharn, Jr This study demonstrated that high hydrostatic pressure can disrupt immune complexes in two model systems: prostate-specific antigen (PSA) with its antibody and epiglycanin with its specific antibody. The dissociated antibodies were able to rebind to their antigens, indicating that the pressure-induced dissociation was reversible. These findings suggest that high hydrostatic pressure could enhance the sensitivity and specificity of clinical assays.