nitrous oxide (N2O, NOx) /nī′trəs/ , a colorless, odorless gas, first used as an anesthetic agent in 1844, is the least potent of currently used inhalation anesthetics. It provides analgesia but not complete amnesia or akinesia and is usually supplemented with other drugs. Because high concentrations of nitrous oxide are required, hypoxia is a risk and supplemental oxygen is needed. Nitrous oxide is associated with an increased incidence of nausea and vomiting, environmental pollution, spontaneous abortion in health care workers exposed, and suspected teratogenicity. It has many contraindications to its use. Despite these shortcomings it remains in use in the United States because of its rapid onset and offset, relative lack of cardiac or respiratory depression, and its low cost. It is most often used to supplement other anesthetic agents, especially during an inhalation induction of children. Nitrous oxide remains a commonly administered dental anesthetic.
