 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 motor response in 50 % of subjects in response to stimulus , and shows similar results for anesthetic potency as the measurements of lipid solubility . 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 . 
