scientific-2008

Scientific papers 2008

12 - Mitchell & Doolette: Selective vulnerability of the inner earto decompression sickness in divers with right-to-left shunt: the role of tissue gas supersaturation.

This paper has been published by the department of anesthesiology of the university of Auckland (New Zealand), and the Naval experimental diving unit, Panama City, Florida, USA.

Diving-related pulmonary effects are due mostly to increased gas density, immersion-related increase in pulmonary blood volume, and (usually) a higher inspired PO2. Higher gas density produces an increase in airways resistance and work of breathing and a reduced maximum breathing capacity. An additional mechanical load is due to immersion, which can impose a static transrespiratory pressure load as well as a decrease in pulmonary compliance.

Authors: Nico A.M. Schellart, Jan-JaapBrandt Corstius, Peter Germonpré, and Wouter Sterk. It is claimed that performing a “deep stop,” a stop at about half of the maximal diving depth (MDD), can reduce the amount of detectable precordial bubbles after the dive and may thus diminish the risk of decompression sickness. In order to ascertain whether this reduction is caused by the deep stop or by a prolonged decompression time, the team wanted to test the “deep stop” theory without increasing the total decompression time.

Exercising before, during, or after diving is proscribed because of the assumption that it would increase the incidence of decompression sickness. The authors say that their findings show that exercise performed in a timely fashion before diving or during decompression will reduce the number of venous gas bubbles formed. Exercise after diving did not increase the number of bubbles. The authors also say that nitric oxide seems to play a protective role.

Author: Keith A. Gault (US Navy) Generation III Air Navy Dive Computers (AIR III) were used to record 315 ship husbandry dives conducted by divers breathing air at the Puget Sound Naval Shipyard from November 2007 to January 2008. For each profile, decompression status was assessed from the air tables in Rev. 6 of the U.S. Navy Diving Manual, and from the AIR Ills, thirty-five dives were repetitive dives (within 12 hours of previous exposure), so 280 are distinct profiles for analysis.

Abstract: Exposure to the underwater environment for recreationalor occupational purposes is increasing. Approximately 7 million divers are active worldwide and 500 000 more are training every year. Diving related illnesses are consequently an increasingly common clinical problem with over 1000 cases of decompression illness reported annually in the USA alone.

7 - Preventive effect of pre-dive hydration on bubble formation in divers.

Authors: E Gempp, J E Blatteau, J-M Pontier, C Balestra, & P Louge. To investigate whether pre-hydration 90 minutes before a dive could decrease bubble formation and evaluate the consequent adjustments in plasma volume (PV), water balance, and plasma surface tension (ST), eight military divers participated in a crossover trial of pre-dive hydration using saline–glucose beverage, and a controlled dive with no pre-hydration. Drink volume was 1300 ml and drinking time was 50–60 min. The diving protocol consisted of an open sea field air dive at 30 msw depth for 30 min followed by a 9 min stop at three msw. Haemodynamic parameters, body weight measurements, urine volume, and blood samples were taken before/after fluid intake and after the dive. Decompression bubbles were examined by a precordial pulsed Doppler.

This review aims to outline advances addressing the role that reactive species of oxygen and nitrogen play in the therapeutic mechanisms of hyperbaric oxygen. The study will be organized around major categories of problems or processes where controlled clinical trials have demonstrated clinical efficacy for hyperbaric oxygen therapy. Reactive species are now recognized to play a major role in cell signal transduction cascades, and the discussion will focus on how hyperbaric oxygen acts through these pathways to mediate wound healing and ameliorate postischemic and inflammatory injuries.

Authors: Jean- Éric Blatteau, Emmanuel Gempp, Costantino Balestra, Tony Mets, and Peter Germonpre. This study investigated the influence of a far infrared-ray dry sauna-induced heat exposure before a simulated dive on bubble formation, and examined the concomitant adjustments in hemodynamic parameters.

Authors: T. Randsøe, T. M. Kvist, and O. Hyldegaard The authors of this report visually followed the in vivo changes of micro air bubbles injected into adipose tissue of anesthetized rats at 101.3 kPa (sea level), after which they were decompressed from 101.3 kPa to and held at 25 kPa (10,350 m), during breathing of oxygen or a heliox (34:66) mixture (34% helium and 66% oxygen). Furthermore, bubbles were studied during oxygen breathing preceded by a 3-h period of preoxygenation to eliminate tissue nitrogen before decompression.

This small study records the various contaminants that can be found in compressed gas and the control measures to implement to eliminate them.

Authors: Leigh A. Madden, Gerard Laden In this study, the authors hypothesize that gas bubbles are not the causative agent in the progression of DCI, rather an exacerbating factor. Endothelial dysfunction caused by a temporary loss of haemostasis due to increased total oxidant status is postulated to be the cause in this at-depth endothelial dysfunction hypothesis.

Authors: Melissa K. Brown & David C. Willms The medical use of helium-oxygen mixture (heliox) was first described as a therapy for asthma and airway obstructions in 1934 by Barach. Heliox applications have expanded from airway obstruction and asthma to bronchiolitis and chronic obstructive pulmonary disease (COPD). Helium is an odorless, colorless, non-combustible, biologically inert gas, and has other physical properties that make it medically useful when mixed with oxygen.

Authors: Nico A.M. Schellart , Jan-Jaap Brandt Corstiu, Peter Germonpré, & Wouter Sterk It is claimed that performing a “deep stop” a stop at about half of maximal diving depth (MDD), can reduce the amount of detectable precordial bubbles after the dive and may thus diminish the risk of decompression sickness. To ascertain whether this reduction is caused by the deep stop or by a prolonged decompression time, the authors tested the “ deep stop ” theory without increasing the total decompression time.

Authors: F. K. Butler, C. Hagan, H. Murphy-Lavoie This paper is a review of HBOT (Hyperbaric Oxygen Treatment) for ocular indications. Because some ocular disorders require rapid administration of HBOT to restore vision, patients with acute vision loss should be considered emergent when they present. Visual acuity should be checked immediately.

Author: Valerie Flook This report derives from and clarifies those published by Unimed Scientific Ltd in 2002 and 2003 for “Well Ops UK Ltd”. The major part of the work was carried out for UK Health and Safety Executive, and the report is available from the HSE web site as research report number RR244.

Authors: Akin Savas Toklu, Seﬁka Korpinar, Mustafa Erelel, Gunalp Uzun, Senol Yildiz Air cysts or blebs in the lungs may predispose pulmonary barotrauma (PBT) by causing air trapping when there is a change in environmental pressure. The changes in the environmental pressure are also seen during hyperbaric oxygen treatments (HBOT). The aim of this study was to determine how patients were evaluated for pulmonary blebs or bullae, and PBT prevalence in different HBOT centers. HBOT centers were asked to participate in this study, and a questionnaire was sent via e-mail, to which 98 centers responded.

Authors: Tiina M. Makinen, Raija Juvonen, Jari Jokelainen, Terttu H. Harju, Ari Peitso, Aini Bloigu, Sylvi Silvennoinen-Kassinen, Maija Leinonen, Juhani Hassi This study examined whether the development of acute respiratory tract infections (RTIs) is potentiated by cold exposure and lowered humidity in a northern population. It should be linked to the humidity level in the diving breathing gasses.

Publisher: Undersea and Hyperbaric Medical Society This document is the proceedings of a workshop held at the Salt Palace Convention Center in Salt Lake City, Utah, USA, in June 2008.

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Auhor: Steve Selvin This practical guide to survival data analysis is designed for readers with a basic understanding of statistics. It explains the rationale behind the analytic methods and shows how to effectively analyze and interpret epidemiological and medical survival data using modern computer systems.

Authors: Peter Lindholm, & Claes EG Lundgren This overview covers the physiological reactions, limitations, and pathophysiological mechanisms linked to breath-hold diving. Despite approaching physiological limits, as evidenced by post-dive pulmonary issues, the pursuit of performance enhancement continues. The discussion includes the diving response of the cardiovascular system, respiratory challenges, mechanisms related to hypoxia and loss of consciousness, and the risks of decompression sickness and narcosis due to high nitrogen pressure in the lungs.

Authors: Azriel Perel, & Jean-Jacques Rouby The intent of the text is to discuss and critique recent findings on the effects of positive end-expiratory pressure (PEEP) on pulmonary recruitability in patients with adult respiratory distress syndrome (ARDS). The author references a study by Thille et al. and an accompanying editorial by Rouby, highlighting that Thille et al. concluded that PEEP levels should not be determined based on the cause of ARDS. The author contrasts this with their own older studies, which suggest that the effectiveness of PEEP does depend on the etiology of ARDS, particularly noting differences in response between patients with and without sepsis.

Authors: Sarah Nolan, Rachel Dixon, Keith Norman, Paul Hellewell, and Victoria Ridger The study shows that nitric oxide can regulate neutrophil migration by controlling the formation of L-selectin (Cell adhesion molecules that facilitate the leukocyte migration to sites of inflammation or injury) and P-selectin glycoprotein ligand-1 (PSGL-1), a cell adhesion molecule, enabling the tethering and rolling of leukocytes on the endothelial cells during the inflammatory response. These findings offer insights into nitric oxide's role in inflammation and neutrophil migration.

Authors: Tami A. Martino, Gavin Y. Oudit, Andrew M. Herzenberg, Nazneen Tata, Margaret M. Koletar, Golam M. Kabir, Denise D. Belsham, Peter H. Backx, Martin R. Ralph, and Michael J. Sole This document discusses how disrupted biological rhythms from sleep deprivation, shift work, and jet lag affect health. A study shows that circadian rhythm disorganization in hamsters with a specific mutation (tau) causes severe heart and kidney issues. When these hamsters are placed on light cycles matching their genotype, their health improves. Preventing circadian disruption in young adults also prevents heart problems.

Authors: H.B. Newton, J. Burkart, D.K. Pearl, W. Padilla This study examines the link between hematocrit levels and neurological complications in recreational divers with decompression illness (DCI). A review of 200 divers' charts showed that 88.5% had at least one neurological symptom. In male divers, hematocrit levels did not correlate with neurological symptoms. However, female divers with high hematocrit values were significantly more likely to experience motor weakness and severe sensory symptoms. Therefore, high hematocrit values are associated with severe neurological complications in female divers but not in male divers.

Authors: Rebekah M. Steele, Soren Brage, Kirsten Corder, Nicholas J. Wareham, and Ulf Ekelund The metabolic syndrome, marked by multiple cardiovascular and diabetes risk factors, is rising in adults and now also in children and adolescents. This review examines recent evidence on the relationship between physical activity, cardiorespiratory fitness (CRF), and metabolic risk in youth. Findings suggest that physical activity and CRF are independently associated with metabolic risk factors in young people. Further research is needed to determine the amount of physical activity required to prevent metabolic syndrome.

Authors: Claudio Marabotti, Alessandro Scalzini, Danilo Cialoni, Mirko Passera, Antonio L’Abbate, and Remo Bedini This study evaluated the cardiovascular response to body immersion and increased environmental pressure during diving in 12 healthy male subjects. Using two-dimensional Doppler echocardiography, the subjects were assessed in five conditions: out of the water, head-out immersion while breathing, fully immersed at the surface while breathing, breath-holding, and breath-hold diving at a 5- meter depth. Key measurements included heart rate, left ventricular volumes, stroke volume, cardiac output, and left ventricular diastolic function indexes.

15 - Comparative incidences of decompression illness in repetitive, staged mixed-gas decompression diving: Is dive fitness an influencing factor

Author: Martin DJ Sayer, Jim Akroyd and Guy D Williams The intent of this paper is to provide an analysis and discussion of wreck diving activities at Bikini Atoll, focusing on the frequency and nature of decompression dives, the incidence of decompression illness among divers, and the factors contributing to differences in illness rates between customer divers and dive guides. The text aims to highlight the physiological reasons behind the varying rates of decompression illness and reviews these rates across different diving populations.

Authors: Si Jack Chong, Teck Wei Tan and Jordan Yu Jin Lim This document presents the findings of a retrospective study analyzing the lung function of Republic of Singapore Navy (RSN) divers over a five-year period. The study aims to determine whether there has been any deterioration in lung function among these divers by comparing spirometric results from 2001 and 2006. The results indicate statistically significant improvements in certain lung function parameters, suggesting no decline in lung function over the period studied.

Author: Neal W Pollock This paper provides an overview of breath-hold diving, including its historical context, the evolution of performance records, the requirements for competitive performance, and the importance of safety practices. The text aims to inform readers about the current state of breath-hold diving, strategies to optimize performance, and recommendations for safe participation in the activity.

The intent of this document was to inform the reader about the 2006 Annual DAN Diving Report, which includes updated data on recreational scuba diving and breath-hold diving injuries and fatalities for the year 2004.

19 - Venous gas bubble formation and decompression risk after scuba diving in persons with chronic spinal cord injury and able- bodied controls

Authors: T Breskovic, P Denoble, I Palada, A Obad, Z Valic, D Glavas, D Bakovic, and Z Dujic This paper evaluates and compares the formation of venous gas bubbles and the risk of decompression sickness (DCS) in individuals with chronic spinal cord injury (SCI) and able-bodied diving instructors (C) following open-sea scuba dives. The study aims to assess the safety of the diving profile used by monitoring gas bubbles and estimating the probability of DCS using a decompression model. The results indicate that the diving profile is safe for both groups, as no signs of DCS were developed and the severity of exposure was within the typical range for recreational dives.

Authors: Yasushi Suwazono, Mirei Dochi, Kouichi Sakata, Yasushi Okubo, Mitsuhiro Oishi, Kumihiko Tanaka, Etsuko Kobayashi, Teruhiko Kido & Koji Nogawa This document presents the findings of a longitudinal cohort study that investigated the association between job schedules (day work vs. alternating shift work) and weight gain, measured by increases in BMI, among male Japanese workers in a steel company. The study found that alternating shift work is an independent risk factor for weight gain. The text also suggests that efficient health screening, regular checkups, and support to control unhealthy lifestyle factors could benefit the health of Japanese shift workers.

28 - Selective vulnerability of the inner ear to decompression sickness in divers with right-to-left shunt: the role of tissue gas supersaturation

Authors: Simon J. Mitchell & David J. Doolette This study aims to present a scientific hypothesis and supporting evidence regarding the selective vulnerability of the inner ear to decompression sickness in divers with right-to-left shunts. The text explains the discrepancy between the presence of arterial bubbles and the frequent absence of cerebral symptoms by suggesting that slower inert gas washout from the inner ear after diving leads to prolonged supersaturation, making the inner ear more susceptible to decompression sickness. The text uses published models to predict tissue gas tensions and supports the hypothesis with these predictions.

Authors: Barry W. Allen, Ivan T. Demchenko, and Claude A. Piantadosi This document reviews and discusses recent research findings on the roles of reactive oxygen and nitrogen species, particularly nitric oxide (NO), in both causing and defending against oxygen toxicity. The text aims to highlight the mechanisms of toxicity and protection in hyperoxia, the influence of NO's anatomical localization, and the potential for future pharmacological interventions. Additionally, it seeks to provide insights into the pathogenesis of central nervous system oxygen toxicity and pulmonary oxygen toxicity, which could have broader implications for understanding related medical conditions.

Author: Jorge D. Erusalimsky The authors of this document aim to provide an overview and analysis of cellular senescence, particularly in the context of vascular endothelium. Therefore, the document presents evidence of senescence in vascular endothelial cells, discusses the mechanisms and factors that influence endothelial cell replicative capacity and the onset of senescence, and examines the characteristics of the senescent phenotype and its potential implications for the development and progression of vascular diseases.

Authors: Yoram Etzion, Amir Mor, & Yoram Grossman It is claimed that performing a “deep stop,” a stop at about half of the maximal diving depth (MDD), can reduce the amount of detectable precordial bubbles after the dive and may thus diminish the risk of decompression sickness. In order to ascertain whether this reduction is caused by the deep stop or by a prolonged decompression time, the team wanted to test the “deep stop” theory without increasing the total decompression time.

Authors: D.R. Pendergast, & C.E.G. Lundgren The intent of the text is to provide a detailed scientific explanation of the physiological effects of immersion in water on the human body. It discusses how immersion impacts various bodily systems, including the cardiovascular, endocrine, and renal systems, and describes the changes in blood flow, cardiac output, and respiratory function. The text also addresses how different factors such as water depth and temperature influence these physiological responses, particularly in the context of exercise performance.

Author: Michael Knauth Whether recreational diving can cause brain lesions and/or neuropsychological impairment has been the subject of several studies, but an unequivocal consensus opinion has not yet been established. This article reviews research on structural brain changes and neuropsychological testing in divers and focuses on recreational diving.

40 - Doppler ultrasound surveillance in deep tunneling compressed- air work with Trimix breathing: Bounce dive technique compared to saturation-excursion technique.

Authors: T.P. van Rees Vellinga, W. Sterk, A.G.E.M. de Boer, A.J. van der Beek, A.C. Verhoeven, F.J.H. van Dijk The authors of this paper present and evaluate the findings of a study comparing two deep-diving techniques, bounce dive and saturation-excursion, using Doppler ultrasound surveillance in the context of the Western Scheldt Tunneling Project, to determine the effectiveness and safety of these techniques, particularly in terms of bubble formation and decompression incidents. They conclude that the saturation-excursion technique is preferable for deep and long exposures in caisson work. They also suggest the incorporation of Doppler ultrasound in future compressed-air work for monitoring purposes.