The limited clinical pharmacology of nitrous oxide

Despite more than a century of clinical use, there is a bare minimum of precise information on the pharmacology of nitrous oxide. This is probably the consequence of (1) weakness of general effect which makes results difficult to measure and provides unstable conditions for study, (2) inadequate number of studies of nitrous oxide without accompanying depressant drugs, and (3) failure of many reports to provide data. Nitrous oxide now has been proved to he analgetic and, at least to some degree, anesthetic. It does not depend upon hypoxia for this effect. Serious neurological sequelae coincident to use of the agent are due to asphyxia. Clinical use of such a weak agent gives rise to interesting problems of pharmacologic concept. There is question as to whether weakness of the drug and its lack of tOXicity are separate phenomena or different ways of expressing the same thing. The use of supplemental drugswith nitrous oxide brings up "polypharmacy versus purism" as an approach to anesthetic depression and gives information suggesting that other agents add to toxicity as well as "potency." Exposure of patients to surgical procedures during very "light" anesthesia has been suggested as cause for shock and perhaps other sequelae. Current usage fails to support this concept. Nitrous oxide remai118 a useful clinical anesthetic agent and knowledge has increased, even with few precise pharmacologic studies, and the scope of clinical usefulness has been enlarged thereby.