Nitrous oxide as a single gas was first used as a medical analgesic in 1844 by American dentist Horace Wells, growing in popularity in the late 1800s. Negative side effects were found from the hypoxia caused by a lack of oxygen, and the requirement to have at least 21% oxygen content in the gas was discovered (the same percentage as in air).
In 1911, the anaesthetist Arthur Ernest Guedel first described the use of self-administration of a nitrous oxide and oxygen mix.
It was not until 1961 that the first paper was published by Michael Tunstall et al. describing the administration of a pre-mixed 50:50 nitrous oxide and oxygen mix, which led to the commercialisation of the product.
The gas is made of a mixture of fifty percent nitrous oxide (N<sub>2</sub>O or laughing gas) and fifty percent oxygen (O<sub>2</sub>).<ref... Read More