Without structured exercise, he was able to hold his breath after

Without structured exercise, he was able to hold his breath after initial hyperventilation longer than 2 min for his dives. He never had a professional physical assessment for diving-fitness, a diving accident could not be recalled. During childhood and adolescence he practiced endurance running (half-marathon and marathon distance), during regular visits to the public pool he was able to dive distances greater than 60 m. Apnoea-diving or free breath-hold diving is long practiced, historical proof exists, reaching back longer than 2000 years (wreck,-sponge,-seashell,- or pearldivers) [1]. In the past years, the popularity of this leisuretime-activity

increased, nowadays it is also carried out in professional competitions, including several disciplines regarding speed, depth or distance, and underwater harpoon-fishing 5-FU is still very common [2]. With regular exercise, the diver is able to increase his tolerance level for high CO2 values, and thereby can extend the time under water. By augmenting the TLC at the expense of reducing the RV, the diver can increase the diving depth, as the negative effects of increasing surrounding water pressure can be partially antagonised by this technique. IPI-145 nmr Depending on the diving discipline, record depths of greater than 200 m and diving-time without breathing support exceeding several

minutes can be realised [7]. Three phases in diving can physiologically be distinguished: compression-phase before during descent, the surrounding water pressure increases (about 1 mbar every 10 m); isopression-phase with a constant water pressure acting on the body by having reached the desired depth (although the depth during that phase often varies due to investigation of the underwater-environment), followed by the decompression-phase on ascent with decreasing surrounding water pressure. Each phase involves specific health risks resulting from the pathophysiologic effects on the human

body [8]. Our patient indicated a maximum diving depth of 15 m, which makes a decompression-illness or negative-pressure barotrauma unlikely. However, a positive-pressure barotrauma of the lungs is also possible in lower diving depths. According to the Boyle-Marriott law, the product of pressure and volume is constant (p × V = const.), so with constant temperature, given a defined gas-volume, the relation of pressure and volume is reverse [3]. Therefore, the breathing gas in the lungs, that had been compressed by the surrounding water pressure during the dive, expands again on ascent. A positive-pressure barotrauma can occur, if the air in the lungs can not disperse sufficiently and quick enough due to breathholding on ascent, resulting in an increased positive pressure in the lungs, that can lead to central (mediastinum), or peripheral (pleura) tears causing a pneumomediastinum or pneumothorax with regards to the lung. As a matter of course, all airfilled organs of the human body could potentially be affected by a barotrauma [4].

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