In the technique of inhalation sedation, gaseous agents are absorbed from the lungs into the cardiovascular system. Although any number of inhalation anesthetics may be administered by this route for the production of sedation (see Section VI), only one, nitrous oxide, is used by any appreciable number of health professionals (including, but not limited to, dentists, physicians, and podiatrists). This section is therefore devoted to a discussion of the use of nitrous oxide-oxygen (N₂O-O₂) inhalation sedation.

Inhalation sedation with nitrous oxide (N₂O) and oxygen (O₂) has significant advantages over other techniques of sedation, yet it possesses no disadvantages of importance. This technique is an important part of the armamentarium for the management of fear and anxiety; indeed, the number of health professionals using N₂O-O₂ has risen steadily during the past decade. In the United States it is estimated that approximately 40% of practicing dentists and 90% of all pedodontists currently use N₂O-O₂,¹ and virtually all dental graduates today enter into dental practice proficient in its safe and effective use.² In addition, as of November 2007, 26 states have modified their dental practice acts to permit the registered dental hygienist to administer N₂O-O₂.³ In fields other than dentistry, health professionals are beginning to use this valuable technique of sedation to their patients’ benefit. In anesthesia, N₂O-O₂ has been used for more than 100 years as an important component of most general anesthetics, primarily as a means of permitting other, more potent and potentially dangerous general anesthetics to be used effectively in smaller doses and consequently in a safer manner. In the past 20 years, N₂O-O₂ has been used by emergency medical personnel, both in the hospital and in mobile coronary care units, to decrease or to eliminate pain caused by an acute myocardial infarction.