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ESSENTIALS OF DIAGNOSIS

ESSENTIALS OF DIAGNOSIS

  • Early recognition of symptoms temporally related to recent altitude or pressure changes (eg, scuba diving, and aviation). Prompt treatment of decompression illness is extremely important for optimal outcome.

  • Patients 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 result from altitude changes and effects of environmental pressure on the gases in the body. These are most likely to occur when scuba diving is followed closely by rapid ascent, travel to high altitudes (eg, 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.

Physic laws describe the mechanisms involved in dysbarism and decompression illness. As a diver descends, the gases in the body compress and dissolve throughout areas of the body that are both compressible (lungs, GI tract) and noncompressible (sinuses, joints). As the diver descends further, there is increased pressure on the body’s gases and increasing amounts dissolve into the bloodstream and tissues (eg, at 30 meters [100 feet], the pressure is four times greater than at the surface). During the subsequent ascent, these dissolved gases expand within the body, which can cause dysbarism and decompression illness. The gas compression and expansion depend 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 the vital organs or 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 pressure change is too rapid from higher pressure to lower pressure (eg, ascent is too rapid while scuba diving, aviation pressurization drops too fast). The result is that gas bubbles form and cause damage on their location (eg, coronary, pulmonary, spinal, or cerebral blood vessels, joints, soft tissues). 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 released gas bubbles (notably nitrogen). Risk of decompression illness in scuba diving depends on multiple factors: the dive details (depth, duration, number of dives, interval ...

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