In the rare event of misdiagnosis when another condition is causing the symptoms, the initial management – ascending closer to the surface – is still essential. Prevention
The most straightforward way to avoid nitrogen narcosis is for a diver to limit the depth of dives. The other main preventive measure is properly informed selection/choice of which gas to use for the particular dive under consideration. Since narcosis becomes more severe as depth increases, a diver keeping to shallower depths can avoid serious narcosis. Most recreational dive schools will only certify entry level divers to depths of 18 to 20 m (60 to 70 ft), and at these depths narcosis does not present a significant risk. Further training is normally required for certification up to 30 m (100 ft) on air, and this training should include a discussion of narcosis, its effects, and management. Some diver training agencies offer specialized training to prepare recreational divers to go to depths of 40 m (130 ft), often consisting of further theory and some practice in deep dives under close supervision. Scuba organizations that train for diving beyond recreational depths, may forbid diving with gases that cause too much narcosis at depth in the average diver (such as the typical widely used nitrox mixtures suitable for most recreational diving), and strongly encourage the use of other breathing gas mixes containing helium in place of some or all of the nitrogen in air – such as trimix and heliox – because helium has no narcotic effect.
Thus narcosis while diving in open water rarely develops into a serious problem as long as the divers are aware of its symptoms, and are able to ascend to manage it. Diving much beyond 40 m (130 ft) is generally considered outside the scope of recreational diving. In order to dive at greater depths, as narcosis and oxygen toxicity become critical risk factors, specialist training is required in the use of various helium-containing gas mixtures such as trimix or heliox. These mixtures prevent narcosis by replacing some or all of the inert fraction of the breathing gas with non-narcotic helium. Classification
Narcosis results from breathing gases under elevated pressure, and may be classified by the principal gas involved. The noble gases, except helium and probably neon, as well as nitrogen, oxygen and hydrogen cause a decrement in mental function, but their effect on psychomotor function (processes affecting the coordination of sensory or cognitive processes and motor activity) varies widely. The effect of carbon dioxide is a consistent diminution of mental and psychomotor function. The noble gases argon, krypton, and xenon are more narcotic than nitrogen at a given pressure, and xenon has so much anesthetic activity that it is a usable anesthetic at 80% concentration and normal atmospheric pressure. Xenon has historically been too expensive to be used very much in practice, but it has been successfully used for surgical operations, and xenon anesthesia systems are still being proposed and designed. Signs and symptoms
Due to its perception-altering effects, the onset of narcosis may be hard to recognize.