Polydrug abuse associated with nitrous oxide causes death

The case report byHirvioja et al. raises some interesting points [1]. Unfortunately, the title is somewhat misleading because it suggests that it was nitrous oxide alone that caused the death and ignores the likelihood, from the data presented, that the death was probably due to the other substances found in the patient’s blood aswell as the nitrous oxide [1]. As far as I am aware, there is no case in the literature where nitrous oxide alone has caused sudden death during misuse, except when the subject has been asphyxiated because of oxygen lack [2]. I would like to congratulate the authors for not confusing abuse with use, something not always done with enough precision [3]. Indeed, some authors have given the impression that recreational use automatically means abuse [4]. Their paper also highlights the point that pure nitrous oxide abuse is extremely rare and that those who do abuse it do so as part of their polydrug abuse [1, 4]. It is also important to note that although the recreational use of nitrous oxide seems currently to be an increase, the history of the use of nitrous oxide since the late 17th century has been punctuated by cycles of increased and decreased popularity. Furthermore, and in all this time, it has never yet caused the severe problem as foundwith other drugs such asmorphine, heroin, cocaine or the benzodiazepines [4]. However, the statement that ‘Nitrous oxide. . . is used as an anaesthetic. . .. during small dental procedures and labour’ is simply wrong. For these indications, nitrous oxide is used at concentrations well below those that could produce unconsciousness and anaesthesia and while the patient is conscious and fully responsive and definitely not anaesthetized [5].