The condition is generally asymptomatic, with detection relying on differential diagnosis of high quality radiographs and by excluding other causes. There is a tendency to assume that bone necrosis is caused by evolved gas bubbles that did not necessarily cause acute symptoms, but there is no direct evidence for any clear etiology. It is probably important to understand that existing decompression schedules have been defined and refined experimentally based on symptoms, rather than on preventing bubbles per se or by maintaining and applying good epidemiological health surveillance. It provides a comprehensive discussion of the topic. Diving Medicine Resource is designed as an information resource for doctors.
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Control Administratively limiting depth has been the most common control for nitrogen narcosis. However, it is limited to a shallower depth than air diving because of oxygen's own toxicity at pressures of more than one atmosphere. The rate of compression must be kept slow to avoid symptoms of High Pressure Nervous Syndrome, such as nausea, fine tremors, and incoordination that can begin to appear at about 500 fsw. Dives deeper than 1000 fsw have been made using a tri-mix of nitrogen, helium, and oxygen. The substitution of helium for nitrogen changes the rates of gas exchange and the decompression schedule, but does not remove the bubble hazard.