Editing Nitrogen narcosis (section)

== History ==
[[File:The Meyer-Overton correlation.png|thumb|342px|class=skin-invert-image|alt=graph with logarithmic scales showing a close inverse correlation between "Potency of anesthetic drug" and "Olive oil:gas partition coefficient" for 17 different agents|Both Meyer and Overton discovered that the narcotic potency of an anesthetic can generally be predicted from its solubility in oil. Minimum Alveolar Concentration is an inverse indicator of anaesthetic potency.]]
{{See also|Theories of general anesthetic action}}
French researcher [[Victor T. Junod]] was the first to describe symptoms of narcosis in 1834, noting "the functions of the brain are activated, imagination is lively, thoughts have a peculiar charm and, in some persons, symptoms of intoxication are present."{{sfnp|Bennett|Rostain|2003|p=300}}{{r |Junod1834}} Junod suggested that narcosis resulted from pressure causing increased blood flow and hence stimulating nerve centers.{{sfnp|Bennett|Rostain|2003|p=306}} [[Walter Moxon]] (1836–1886), a prominent Victorian [[physician]], hypothesized in 1881 that pressure forced blood to inaccessible parts of the body and the stagnant blood then resulted in emotional changes.{{r |Moxon1881}} The first report of anesthetic potency being related to lipid solubility was published by [[Hans H. Meyer]] in 1899, entitled ''Zur Theorie der Alkoholnarkose''. Two years later a similar theory was published independently by [[Charles Ernest Overton]].{{r |Overton1901}} What became known as the [[Minimum alveolar concentration#Meyer-Overton hypothesis|Meyer-Overton hypothesis]] may be illustrated by a graph comparing narcotic potency with solubility in oil.

In 1939, [[Albert R. Behnke]] and [[O. D. Yarborough]] demonstrated that gases other than nitrogen also could cause narcosis.{{r |Behnke1939}} For an inert gas the narcotic potency was found to be proportional to its lipid solubility. As hydrogen has only 0.55 the solubility of nitrogen, deep diving experiments using [[hydrox (breathing gas)|hydrox]] were conducted by [[Arne Zetterström]] between 1943 and 1945.{{r |Ornhagen1984}} [[Jacques-Yves Cousteau]] in 1953 famously described it as "l'ivresse des grandes profondeurs" or the "rapture of the deep".{{r |Cousteau1953}}

Further research into the possible mechanisms of narcosis by anesthetic action led to the "[[minimum alveolar concentration]]" concept in 1965. This measures the relative concentration of different gases required to prevent [[Reflex|motor response]] in 50% of subjects in response to [[Stimulus (physiology)|stimulus]], and shows similar results for anesthetic potency as the measurements of lipid solubility.{{r |Eger1965}} The (NOAA) Diving Manual was revised to recommend treating oxygen as if it were as narcotic as nitrogen, following research by [[Christian J. Lambertsen]] ''et al.'' in 1977 and 1978,{{r |Lambertsen1978}} but this hypothesis has been challenged by more recent work.<ref name="Vrijdag 2023" /><ref name="Vrijdag et al 2022" /><ref name="Vrijdag et al 2020" />
 
A study on the effects of the environment on inert gas narcosis published by Lafère et al. in 2016 concluded that pressure and gas composition may be the only significant external factors influencing inert gas narcosis. It also found that the onset of narcosis follows a short period of raised alertness during descent, and some of the effects persist for at least 30 minutes after the dive.<ref name="Menduno 2020" /><ref name="Lafere et al 2019" />
As of about 2020, research using [[critical flicker fusion frequency]] (CFFF) and  EEG functional connectivity has shown sensitivity to nitrogen narcosis, but is not sensitive to helium partial pressure, in laboratory trials.<ref name="Vrijdag et al 2020" /><ref name="Vrijdag 2023" /><ref name="Vrijdag et al 2022" />