For nitrogen narcosis, under typical cabin pressures of 6,000–8,000 ft, this is generally not a concern unless what condition?

For nitrogen narcosis, under typical cabin pressures of 6,000–8,000 ft, this is generally not a concern unless what condition?

• A. Patient recently surfaced from diving and has residual nitrogen
• B. Patient has a fever
• C. Patient is dehydrated
• D. Patient has a history of asthma

Answer: (A)

Nitrogen narcosis happens when dissolved nitrogen in the body reaches a level high enough to depress brain function, which is a function of the nitrogen partial pressure the person experiences. At cabin altitudes of 6,000–8,000 feet, the ambient pressure is low enough that narcosis is not expected in a person with normal nitrogen loading. The scenario where narcosis becomes a concern is when there is residual nitrogen from a recent dive—the nitrogen that remains dissolved in tissues and blood can continue to influence CNS activity. If a patient has recently surfaced from diving and still carries elevated nitrogen, the stress from cabin pressure changes can allow narcosis-like symptoms to appear even at these lower pressures. The other conditions listed—fever, dehydration, or asthma—do not create the same nitrogen-loading situation or mechanism, so they do not explain why narcosis would be a concern in this setting.

Nitrogen narcosis happens when dissolved nitrogen in the body reaches a level high enough to depress brain function, which is a function of the nitrogen partial pressure the person experiences. At cabin altitudes of 6,000–8,000 feet, the ambient pressure is low enough that narcosis is not expected in a person with normal nitrogen loading. The scenario where narcosis becomes a concern is when there is residual nitrogen from a recent dive—the nitrogen that remains dissolved in tissues and blood can continue to influence CNS activity. If a patient has recently surfaced from diving and still carries elevated nitrogen, the stress from cabin pressure changes can allow narcosis-like symptoms to appear even at these lower pressures. The other conditions listed—fever, dehydration, or asthma—do not create the same nitrogen-loading situation or mechanism, so they do not explain why narcosis would be a concern in this setting.