Update on nitrous oxide and its use in anesthesia practice.

Nitrous oxide (N2 O) is an anesthetic and analgesic gas with a long history of medical applications. It acts on multiple supraspinal and spinal targets and has utility in a wide range of clinical situations. The relative safety, low incidence, and acuity of adverse effects of N2 O, along with the ability to be administered by trained medical providers with varying clinical backgrounds, as well as self-administered by patients, assure its persistent and expanding role in clinical practice.