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ESSENTIALS OF DIAGNOSIS

  • Symptoms temporally related to recent altitude or pressure changes (such as scuba diving).

  • Early recognition and prompt treatment of decompression illness are extremely important.

  • Patient must also be assessed for hypothermia, hypoglycemia, concurrent injuries, and medical conditions.

  • Consultation with diving medicine or hyperbaric oxygen specialist is indicated.

GENERAL CONSIDERATIONS

Dysbarism and decompression illness are physiologic problems that result from altitude changes and the effects of environmental pressure on the gases in the body during underwater descent and ascent. These are most likely to occur when scuba diving is followed closely by travel to high altitudes (ie, air travel, mountain hiking), or when the scuba diver is not adherent to the conservative dive guidelines for dive duration, course, depth, and surface times.

Physics laws describe the mechanisms involved in dysbarism and decompression illness. As a diver descends, the gases in the body compress; gases dissolve in blood and tissues. These gases are in compressible (eg, lungs, gastrointestinal) and noncompressible (eg, sinuses, joints) areas of the body. At low depths, the greatly increased pressure (eg, at 30 meters [100 feet] the pressure is four times greater than at the surface) compresses the respiratory gases into the blood and other tissues. During the ascent, gases in the body expand. This depends on the difference between the atmospheric pressure and the partial pressure of the gas dissolved in the tissues.

Dysbarism results from barotrauma when gas compression or expansion occurs in parts of the body that are noncompressible or have limited compliance. Pulmonary overinflation syndrome is one of the most serious and potentially fatal results of barotrauma. This syndrome is due to an inappropriately rapid ascent causing alveoli rupture and air bubble extravasation into tissue planes or even the cerebral circulation. Barotrauma can also result in pneumomediastinum, pneumothorax, and rupture of the pulmonary vein causing arterial gas embolism. Overpressurization of the bowels (especially if underlying bowel pathology is present) can result in gastric rupture, bowel obstruction or perforation, or pneumoperitoneum. Less serious conditions can also occur, such as mask squeeze, ear squeeze, sinus squeeze, headache, and tooth squeeze.

Decompression illness occurs when the ascent is too rapid and gas bubbles form and cause damage depending on their location (ie, coronary, pulmonary, spinal or cerebral blood vessels, joints, soft tissue). These gas bubbles cause damage due to mechanical disruption of tissue, local inflammatory response, occlusion of blood flow, platelet activation, endothelial dysfunction, and capillary leakage. Decompression illness symptoms depend on the size, number, and location of gas bubbles released (notably nitrogen). Risk of decompression illness depends on the dive details (depth, duration, number of dives, interval surface time between dives, and water conditions) as well as the diver’s age, weight, physical condition, physical exertion, the rate of ascent, and the length of time between the low altitude (scuba dive) and high altitude (air travel or ground ascent). Predisposing factors include obesity, injury, hypoxia, ...

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