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.
Side effects
Although immunoglobulin is frequently used for long periods of time and is generally considered safe, immunoglobulin therapy can have severe adverse effects, both localized and systemic. Subcutaneous administration of immunoglobulin is associated with a lower risk of both systemic and localized risk when compared to intravenous administration (hyaluronidase-assisted subcutaneous administration is associated with a greater frequency of adverse effects than traditional subcutaneous administration but still a lower frequency of adverse effects when compared to intravenous administration). Patients who are receiving immunoglobulin and experience adverse events are sometimes recommended to take acetaminophen and diphenhydramine before their infusions to reduce the rate of adverse effects. Additional premedication may be required in some instances (especially when first getting accustomed to a new dosage), prednisone or another oral steroid.Local side effects of immunoglobulin infusions most frequently include an injection site reaction (reddening of the skin around the injection site), itching, rash, and hives. Less serious systemic side effects to immunoglobulin infusions include an increased heart rate, hyper or hypotension, an increased body temperature, diarrhea, nausea, abdominal pain, vomiting, arthralgia or myalgia, dizziness, headache, fatigue, fever, and pain.Serious side effects of immunoglobulin infusions include chest discomfort or pain, myocardial infarction, tachycardia, hyponatremia, hemolysis, hemolytic anemia, thrombosis, hepatitis, anaphylaxis, backache, aseptic meningitis, acute kidney injury, hypokalemic nephropathy, pulmonary embolism, and transfusion related acute lung injury. There is also a small chance that even given the precautions taken in preparing immunoglobulin preparations, an immunoglobulin infusion may pass a virus to its recipient.