scientific-2011-2013

Scientific papers 2011 - 2013

Most diving companies use the protocol proposed and tested by Dr. E. Thalmann (US Navy) to fight otitis externa that affects numerous saturation divers. This method reduces the rate of infections from 25- 75% to 0%. However, it has been observed that some divers experience side effects from this treatment. These side effects include erythema and cracking of the outer ear canal to crystallization throughout the external canal and on the tympanic membrane. This document from the US Navy Experimental Diving Unit discusses a new protocol to avoid these side effects without diminishing the treatment's efficiency initially promoted by Dr. Thalman.

7 - Doolette, Gerth & Gault: Redistribution of decompression stop time from shallow to deep stops increases incidence of decompression sickness in air decompression dives.

Classical decompression algorithms limit hypothetical tissue gas contents and prescribe decompression schedules with most of the total stop time (TST) allocated to shallow decompression stops. More recent bubble-model-based algorithms limit hypothetical bubble profusion and size and prescribe decompressions with TST skewed toward deeper stops. This paper describes a man-trial that was organized to compare the efficiency of these approaches.

The Thalmann Algorithm parameterized with VVal-18 or VVal-18M underlies U.S. Navy air and nitrox decompression procedures.VVal-18 and VVal-18M air no- stop limits at many depths are longer than the corresponding no-stop limits in the 1957 standard air decompression table that appeared in the U.S. Navy Diving Manual from 1959 until it was replaced in Revision 6 (2008). However, the severity of DCS observed in man- trials of the longer no-stop limits was unacceptable, and consequently, in the Revision 6 air decompression tables, the 1957 air no-stop limits were arbitrarily retained in place of any longer VVal-18M-prescribed limits. This report describes VVal-79, a modification of the VVal- 18M parameter set that enables the use of the Thalmann algorithm to prescribe air diving no-stop limits and decompression obligations that can be used as it is, with no need for arbitrary edits to individual schedules.

36 - Submarine Rescue Decompression Procedure from Hyperbaric Exposures up to 6 Bar of Absolute Pressure in Man: Effects on Bubble Formation and Pulmonary Function.

Authors: Jean-Eric Blatteau, Julien Hugon, Olivier Castagna, Cédric Meckler, Nicolas Vallée, Yves Jammes, Michel Hugon, Jan Risberg, and Christophe Pény. Abstract: Recent advances in submarine rescue systems have allowed a transfer under pressure of crew members rescued from a disabled submarine. The choice of a safe decompression procedure for pressurized rescuees has been previously discussed, but no schedule has been validated when the internal submarine pressure is significantly increased, i.e., exceeding 2.8 bar absolute pressure. This study tested a saturation decompression procedure from hyperbaric exposures up to 6 bar, the maximum operating pressure of the NATO submarine rescue system. The objective was to investigate the incidence of decompression sickness (DCS) and clinical and spirometric indices of pulmonary oxygen toxicity.

This document provides summaries of the 86 topics discussed during this meeting.

Authors: Jasna Marinovic, Marko Ljubkovic, Toni Breskovic, Grgo Gunjaca, Ante Obad, Darko Modun, Nada Bilopavlovic, Dimitrios Tsikas, Zeljko Dujic. The aim of this study was to evaluate the changes in vascular/endothelial function following SCUBA diving and to assess the potential difference between two breathing gases: air and nitrox 36 (36% oxygen and 64% nitrogen). Ten divers performed two 3-day diving series (no- decompression dive to 18 m with 47 min bottom time with air and nitrox, respectively), with 2 weeks pause in between. Arterial/endothelial function was assessed using SphygmoCor and X ow-mediated dilation measurements, and the concentration of nitrite before and after diving was determined in venous blood. Production of nitrogen bubbles post-dive was assessed by ultrasonic determination of venous gas bubble grade.

Authors: Megan Brenner, Deborah Stein, Peter Hu, MS, Joseph Kufera, MA; Matthew Wooford, Thomas Scalea. The objective of this paper is to investigate the relationship between oxygenation and short-term outcomes in patients with traumatic brain injury (TBI).

Abstract: In medical emergencies, supplemental oxygen is often administrated routinely. Most paramedics and physicians believe that high concentrations of oxygen are life-saving. Over the last century, however, a plethora of studies point to the possible detrimental effects of hyperoxia induced by supplemental oxygen in a variety of medical emergencies. This viewpoint provides a historical overview and questions the safety of routine high-dose oxygen administration and is based on pathophysiology and (pre)clinical findings in various medical emergencies.

Authors: M. Rozloznik, W. Hemelryck, F. Tilmanns, V. Papadopoulou S. Theunissen, & C. Balestra. The authors of this study focused on the effect of pre-dive hydration after various preconditioning methods on decompression stress in divers. To do so, various anthropological, biochemical, and physiological parameters were collected before and after a single dive to 34m for 20 min divers undergoing no preconditioning (n=10) or pre-dive preconditioning on vibration mat (n=8) or in the sauna (n=7). The hydration level was assessed by specific urine gravity multi-frequency bioelectrical impedance analysis and was correlated to a number of venous gas bubbles as measured by transthoracic echocardiography 35 and 90 minutes after the dive.

Authors: A. Møllerløkken, S. E. Gaustad, M. B. Havnes, C. R. Gutvik, A. Hjelde, U. Wisløff, A. O. Brubakk. In recent studies, the authors have determined the impact of VGE on endothelial function in both laboratory animals and humans. They observed that the damage to the endothelium due to venous gas emboli (VGE) was dose- dependent and that the amount of VGE can be affected both by aerobic exercise and exogenous nitric oxide (NO) intervention before a dive. We observed that NO reduced VGE during decompression and pharmacological blocking of NO production increased VGE formation following a dive. The importance of micro-nuclei for the formation of VGE and how it can be possible to manipulate the formation of VGE are discussed together with the effects of VGE on the organism. In the last part of the review, the authors introduce their thoughts for the future and how the enigma of DCS should be approached.

Authors: Nicolas Vallee, Cédric Meckler, Jean-Jacques Risso, and Jean-Eric Blatteau. Nitrogen supersaturation and bubble formation can occur in the vascular system after diving, leading to death and nervous disorders from decompression sickness (DCS). Bubbles alter the vascular endothelium, activate platelets, and lead to focal ischemia with neurological damage mediated by the mechanosensitive TREK-1 neuronal potassium ion channel that sets pre-and postsynaptic resting membrane potentials. The authors report a neuroprotective effect associated with TREK-1. Mice were subjected to decompression from a simulated 90 msw dive. Of 143 mice that were wild type (WT) for TREK-1, 51.7% showed no DCS, 27.3% failed a grip test, and 21.0% died. Of 88 TREK-1 knockouts (KO), 26.1% showed no DCS, 42.0% failed a grip test, and 31.8% died. Mice that did not express TREK-1 had lower DCS resistance and were more likely to develop neurological symptoms. We conclude that the TREK-1 potassium channel was neuroprotective for DCS.

Authors: Emmanuel Gempp, Jean Morin, Pierre Louge, and Jean Eric Blatteau. A low-grade process of coagulation activation in association with severe neurological decompression sickness (DCS) in divers has been anecdotally observed. The authors aimed to investigate whether measurement of plasma D-dimers and other hemostatic parameters in injured scuba divers were effective as prognostic biomarkers of neurological DCS, and they compared the diagnostic accuracy of a combination of D-dimers test and initial clinical assessment with either one alone.

Authors: Jean-Eric Blatteau, Sandrine Barre, Aurelie Pascual, Olivier Castagna, Jacques H. Abraini, Jean-Jacques Risso, & Nicolas Vallee. Massive bubble formation after diving can lead to decompression sickness (DCS) that can result in central nervous system disorders or even death. Bubbles alter the vascular endothelium and activate blood cells and inflammatory pathways, leading to a systemic pathophysiological process that promotes ischemic damage. Fluoxetine, a well-known antidepressant, is recognized as having anti-inflammatory properties at the systemic level, as well as in the setting of cerebral ischemia. The authors report a beneficial clinical effect associated with fluoxetine in experimental DCS. Ninety- one mice were subjected to a simulated dive at 90 msw for 45 min before rapid decompression.

Authors: O. Castagna, J. E. Blatteau, N. Vallee, B. Schmid, J. Regnard. This study aimed at demonstrating that the neoprene wetsuit provides not only thermal protection. The compression it exerts on the diver’s shell significantly impacts hydromineral homeostasis by restraining the systemic vascular capacity and secondarily increasing urine output on dry land and during scuba diving.

Authors: Stephen R. Thom, Tatyana N. Milovanova, Marina Bogush, Ming Yang, Veena M. Bhopale, Neal W. Pollock, Marko Ljubkovic, Petar Denoble, Dennis Madden, Mislav Lozo, and Zeljko Dujic. The study goal was to evaluate responses in humans following decompression from open-water SCUBA diving with the hypothesis that exertion underwater and use of a breathing mixture containing more oxygen and less nitrogen (enriched air nitrox) would alter annexin V- positive microparticle (MP) production and size changes and neutrophil activation, as well as their relationships to intravascular bubble formation.

Authors: Jean-Eric Blatteau, Alf O. Brubakk, Emmanuel Gempp, Olivier Castagna, Jean-Jacques Risso, Nicolas Vallee. The use of sildenafil, a well-known phosphodiesterase-5 blocker, which acts by potentiating the vasodilatory effect on smooth muscle relaxation, has never been studied in DCS. The purpose of the present study was to evaluate the clinical effects of sildenafil pre-treatment on DCS in a rat model. Sixty-seven rats were subjected to a simulated dive at 90 msw for 45 min before staged decompression.

Authors: Nicolas Vallée, Sandrine Gaillard, André Peinnequin, Jean- Jacques Risso, & Jean-Eric Blatteau. The use of sildenafil, a well-known phosphodiesterase-5 blocker, which acts by potentiating the vasodilatory effect on smooth muscle relaxation, has never been studied in DCS. The purpose of the present study was to evaluate the clinical effects of sildenafil pre-treatment on DCS in a rat model. Sixty-seven rats were subjected to a simulated dive at 90 msw for 45 min before staged decompression.

39 - Relation between cervical and thoracic spinal canal stenosis and the development of spinal cord decompression sickness in recreational scuba divers.

Authors: E Gempp, P Louge, T Lafolie, S Demaistre, M. Hugon, JE. Blatteau. This study investigate the relationship between vertebral degenerative changes resulting in spinal canal, spinal cord lesions, and the devellopment of spinal cord decompression sickness (DCS) in scuba divers.

This document is taken into reference by scientists performing experimentations. The World Medical Association (WMA) serves as a clearinghouse of ethics information resources for its members. The WMA cooperates with academic institutions, global organizations, and individual experts to achieve this goal. The documents it publishes are recognized as the international ethical standard for the topics they address.

Authors: D. J. Harriss, G. Atkinson The ethical standards indicated in this document are also taken into reference by scientists performing experimentations.

Authors: Taiki Miyazawa, Masahiro Horiuchi, Daisuke Ichikawa, Andrew W. Subudhi, Jun Sugawara, & Shigehiko Ogoh. Facial cooling (FC) increases cerebral blood ﬂow (CBF) at rest and during exercise; however, the mechanism of this response remains unclear. The purpose of the present study was to test the author's hypothesis that FC causes facial vasoconstriction that diverts skin blood ﬂow (SkBFface) toward the middle cerebral artery (MCA Vmean) at rest and to a greater extent during exercise.

The documents are classified chronologically from 2011 to 2013. Click on their descriptions to open and download them.

Authors: Marco B. Hansen, Tejs Jansen, Michael B. Sifakis, Ole Hyldegaard , Erik C. Jansen. This study evaluated the feasibility and safety of using nitrox 50 as breathing gas during attendance in a hyperbaric chamber. Paper logs were reviewed to analyze nitrogen gas- loading, actual bottom time, total bottom time, and surface interval time. With the Norwegian Diving Tables, nitrogen gas-loading was converted to repetitive group Letters. Symptoms of decompression sickness and health problems related to hyperbaric exposures were registered at weekly staff meetings. The chamber personnel breathed chamber air or Nitrox 50.

8 - Oxygen breathing or recompression during decompression from nitrox dives with a rebreather: effects on intravascular bubble burden and ramifications for decompression profiles

Authors: Jean-Eric Blatteau, Julien Hugon, Emmanuel Gempp, Olivier Castagna, Christophe Peny, Nicolas Vallee. Preventive measures to reduce the risk of decompression sickness can involve several procedures, such as oxygen- breathing during in-water decompression. Theoretical predictions also suggest that brief recompression periods during decompression could be a method for controlling bubble formation. This study aimed to get more precise information about the effects of different experimental ascent profiles (EAPs) on bubble reduction, using pure oxygen or recompression during decompression for nitrox diving.

Authors: Marko Ljubkovic, Jaksa Zanchi, Toni Breskovic, Jasna Marinovic, Mihajlo Lojpur, and Zeljko Dujic Scuba diving leads to tissue gas supersaturation during ascent and venous gas emboli (VGE) formation. VGE crossover to systemic arteries (arterialization), mainly through the patent foramen ovale, has been implicated in various diving-related pathologies. Since recent research has shown that arterializations frequently occur without cardiac septal defects, this study aimed to investigate the mechanisms responsible for these events.

Authors: Dylan Thompson, Alan M. Batterham There has been some discussion of whether it is possible to score highly in one dimension of physical activity behaviour (e.g., moderate-intensity exercise) while scoring poorly in another (e.g., sedentary time). Interestingly, direct empirical observations to support these proposals are lacking. New technologies now capture physical activity thermogenesis on a minute-by-minute basis and over a sustained period. The authors used one of the best available technologies to explore whether individuals can score differently in various physiologically-important physical activity dimensions.

Authors: Virginie Papadopoulou, Robert J. Eckersley, Costantino Balestra, Thodoris D. Karapantsios, Meng-Xing Tang. Bubbles are known to form in the body after scuba dives, even those done well within the decompression model limits. These can sometimes trigger decompression sickness, and the dive protocols should therefore aim to limit bubble formation and growth from hyperbaric decompression. Understanding these processes physiologically has been a challenge for decades, and there are a number of questions still unanswered. The physics and historical background of this ﬁeld of study are presented, and the latest studies and developments are reviewed.

Authors: Sigrid Theunissen, Julie Schumacker, Franc¸ois Guerrero, Frauke Tillmans, Antoine Boutros, Kate Lambrechts, Aleksandra Mazur, Massimo Pieri, Peter Germonpre, & Costantino Balestra The aim of this study is to observe the effects of dark chocolate on endothelial function after a series of successive apnea dives in non-thermoneutral water.

Authors: R. Arieli & A Marmur It is a long-standing hypothesis that the bubbles which evolve as a result of decompression have their origin in stable gas micronuclei. In a previous study (Arieli and Marmur, 2011), the authors used hydrophilic and monolayer-covered hydrophobic smooth silicon wafers to show that nanobubbles formed on a flat hydrophobic surface may be the gas micronuclei responsible for the bubbles that evolve to cause decompression sickness. On decompression, bubbles appeared only on the hydrophobic wafers. The purpose of the present study was to examine the dynamics of bubble evolution.

6 - Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats.

Authors: O. Hyldegaard, D. Kerem, Y. Melamed Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. The authors visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose,spinal white matter, skeletal muscle or tail tendon.

Authors: Sema Yilmaz, Kenan Daglioglu, Dincer Yildizdas, Ibrahim Bayram, Derya Gumurdulu, Sait Polat Current treatment modalities and new therapeutic approaches in acute repiratory distress syndrome primarily focused on the resolution of alveolar edema. These treatments include glucocorticoids, surfactants, inhaled nitric oxide, antioxidants and various anti-inflammatory treatments. Unfortunately, to date, none of these pharmacologic treatments has proven to be effective. The authors hypothesized that helium gas might have a beneficial role in the treatment of ARDS.

Authors: Haim Bitterman This small document provides a review of the Hyperbaric oxygen procedures

Authors: Masaki Fujioka, Daisuke Niino, Masahiro Ito, and Yohjiro Matsuoka Patent Foramen ovale is a well know decease that affects many divers and can lead to decompression accidents. This document is the report of an autopsy that revealed a patent foramen ovale of the heart that resulted in the patient dying of paradoxical air embolization of the coronary and cerebral arteries through a patent foramen ovale because of right-to-left shunting.

Authors: Barbara E. Shykoff & Dan E. Warkander Combined effects on respiratory minute ventilation (VE ) and, thus, on end-tidal carbon dioxide partial pressure of breathing resistance and elevated inspired carbon dioxide had not been determined during heavy exercise. In this Institutional Review Board-approved, dry, sea-level study, 12 subjects in each of three phases exercised to exhaustion at 85% peak oxygen uptake while VE and P ET CO2 were measured. Participants inhaled 0%, 1%, 2%, or 3% CO2 in air, or 0% or 2% CO2 in oxygen, with or without breathing resistance, mimicking the U.S. Navy’s MK 16 rebreather underwater breathing apparatus (UBA).

Authors: A.C.P.K. Siriwardhana, R.G.N. Meegama, and G.M.L.P. Aponsu Sound waves propagate in all direction through air and materials due to diffraction effect. Interference of sound signals generated by several devices could create a noisy state which is harmful for the human being at certain instances in which noise intensity level is beyond 90 dB. The system discussed in this research, facilitates to find noise intensity levels at different places simultaneously and further it identifies and point out the places where the noisy state is harmful for human being. Corresponding calculation by the system is mainly done based on the direct source and reflection effects for the selected area.

Authors: J.C. Rostain, C. Lavoute, J.J. Risso, N. Vallee, M. Weiss Nitrogen narcosis occurs in humans at around 0.4 MPa (4 ATA). Hydrogen narcosis occurs between 2.6 and 3.0 MPa. In rats, nitrogen disturbances occur from 1 MPa and a loss of righting reflex around 4 MPa. Neurochemical studies in striatum of rats with nitrogen at 3 MPa with differential pulse voltammetry have demonstrated a decrease in dopamine (DA) release by neurons originated from the substantia nigra pars compacta (SNc). Such a decrease is found also with compressed argon, which is more narcotic than nitrogen and with the anesthetic gas nitrous oxide. Inversely, compressed helium with its very low narcotic potency induces DA increase. Microdialysis studies in the striatum have indicated that nitrogen also induces a decrease of glutamate concentration. receptors activities in SNc.

Authors: Paul Schaffer and Reginald F. Baugh Acute otitis externa is a common condition involving inflammation of the ear canal. The acute form is caused primarily by bacterial infection, with Pseudomonas aeruginosa and Staphylococcus aureus the most common pathogens. Acute otitis externa presents with the rapid onset ofear canal inflammation, resulting in otalgia, itching, canal edema, canal erythema, and otorrhea, and often occurs following swimming or minor trauma from inappropriate cleaning. Tenderness with movement of the tragus or pinna is a classic finding.

Authors: Ibiam Fa, Obasikene Godwin, Basil Ezeanolue Several agents involving mono or multi-therapy have been used over the years in the treatment of acute otitis externa with varying results. In this study The authors considered the response pattern of acute otitis externa to a tripple regimen of steroid, antibacterial and an anti-fungal medication in our center.

Authors: Dorota Kaczerska, Piotr SiermontowskiOlszansk, Karolina Krefft, Sylwia Małgorzewicz, Katarzyna Van Damme- Ostapowicz Cases of decompression sickness are observed despite the correct application of decompression tables. For this reason, this study investigated factors affecting the safety of diving, with a particular emphasis on diet, which, thus far, has not been taken into account.

Authors: Christian R Gutvik, Tor Arne Johansen, Alf O Brubakk The objective of the work presented in this article is to minimize the time spent decompressing.

Authors: Jacek Kot Clear differences between professional and recreational deep diving are disappearing, at least when taking into account the types of breathing mixtures (oxygen, nitrox, heliox, and trimix) and range of dive parameters (depth and time). Training of recreational deep divers is conducted at depths of 120–150 metres and some divers dive to 180–200 metres using the same diving techniques. Extremely deep recreational divers go to depths of more than 200 metres, at which depths the physical and chemical properties of breathing gases create some physiological restrictions already known from professional deep diving.

Authors: Marc Dalecki, Otmar Bock, and Benjamin Schulze Clear differences between professional and recreational deep diving are disappearing, at least when taking into account the types of breathing mixtures (oxygen, nitrox, heliox, and trimix) and range of dive parameters (depth and time). Training of recreational deep divers is conducted at depths of 120–150 metres and some divers dive to 180–200 metres using the same diving techniques. Extremely deep recreational divers go to depths of more than 200 metres, at which depths the physical and chemical properties of breathing gases create some physiological restrictions already known from professional deep diving.

Authors: David J. Doolette, Wayne A. Gerth Inner ear decompression sickness (DCS) has followed deep breathing gas switches to air (or other nitrogen- oxygen mixtures) during decompression from deep heliox dives. This study investigates the safety of heliox-to-air breathing gas switches at moderate depths.

Authors: Andrea Cortegiani, Grazia Foresta, Giustino Strano, Maria Teresa Strano, Francesca Montalto, Domenico Garbo, and Santi Maurizio Raineri Some cases of decompression illness are known to have occurred among breath-hold (BH) divers also, and they are reported in the medical literature. A male BH diver (57 years old), underwater fishing champion, presented neurological disorders as dizziness, sensory numbness, blurred vision, and left frontoparietal pain after many dives to a 30–35 meters sea water depth with short surface intervals.