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Divers Alert Network: 2008 Technical Diving Conference. The two-day conference, planned for Jan. 18-19, 2008, in Durham, N.C., will feature four half-day workshops. Discussions will include the operational and medical aspects of technical diving. The forum will also address ways to improve effectiveness and safety.
Workshops Overview
PHYSIOLOGY WORKSHOP PLAN
Respiration
Normal respiration and gas exchange at sea level with emphasis on oxygen uptake, CO2 elimination, and ventilatory control. Dependency of CO2 elimination on ventilation. CO2 retention and individual susceptibility. Effects of tidal volume and dead space on alveolar ventilation. Hypo- and hyperventilation. Ventilatory capacity, physical fitness, and respiratory muscle fatigue. Effects of immersion and gas density. Airway collapse and effort independent expiratory flow. Equipment dead space, static lung load, breathing resistance, and work of breathing. Effect of HPNS on respiration. Case reports.
CNS Oxygen Toxicity
Relevant mechanisms of CNS toxicity: free radicals, ventilation, CO2 retention, cerebral blood flow. Risk factors and individual susceptibility. Donald’s WWII studies. Estimating CNS toxicity risk in relation to O2 exposure, review of O2 exposure guidelines, and the O2 clock. O2-CO2 interactions and “Shallow Water Black-Out.? Mixed-gas O2 exposure limits. Recovery from CNS toxicity risk during underwater air breaks. Case reports.
Narcosis and HPNS
Signs and symptoms of nitrogen narcosis; individual susceptibility, accommodation and adaptation to narcosis; effects on narcosis of rate of compression, oxygen and carbon dioxide; onset depths of narcosis; narcotic potencies of N2, He, Ne, Ar, Xe, O2and CO2; oxygen narcosis; recommended depth limits for air diving; mechanism of narcosis; pressure reversal; utility of EAD/END (equivalent air depth/equivalent nitrogen depth). Signs and symptoms of HPNS; individual susceptibility; depth of occurrence; effect on HPNS of compression rate and time at depth; effect of trimix; effect of hydreliox; mechanisms of HPNS; options for reducing HPNS effects given obligatory fast descent rates.
Thermal Mechanisms of heat transfer (radiation, conduction, evaporation, and convection) with application to divers. Physiological temperature control and consequences of heat transfer (work; shivering; regional vasoconstriction; stages of hyperthermia and hypothermia; freezing and non-freezing injury). Respiratory heat transfer (inert gas and density effects). Rewarming and thermal afterdrop (“warm and dead?). Drysuit insulation properties of Ar, He, CO2, air and O2 (is this safe?). Insulation properties of wet undergarments. Tools for thermal modeling. Hotwater suits for shallow in-water decompression stops vs. insulation for dry decompression. (Thermal effects on decompression will be covered in the Decompression Workshop.) Current and new active and passive technologies (power sources, hydrogen thermal batteries, hydrogen catalytic heating, regional rewarming, aerogel garments).