Print

Story and heritage

The history of nitrous oxide 

Inhaled nitrous oxide has been used in pain relief and anaesthesia for more than 150 years. It was first used medically in 1844, when the American dentist Horace Wells had a wisdom tooth extracted. This inhalation method became popular in the USA during the 1860s and was introduced into Europe, in 1867, by Quincy Coulton. He was one of the most fervent advocates of the positive effects of nitrous oxide in dentistry.

High concentrations of nitrous oxide 

In the late 1800s, nitrous oxide was used alone, without any supplementary air or oxygen. It is therefore quite possible that reported effects of nitrous oxide were to some degree caused by hypoxia (shortage of oxygen). In the latter part of the century, it was found that the gas mixture should comprise at least 21% oxygen by volume in order to avoid risks and side effects associated with the inhalation of a hypoxic mixture. 

Pain control in the delivery suite 

In 1881, nitrous oxide was introduced for pain relief in childbirth. Then in 1911, the American anaesthetist, Arthur Ernest Guedel, described an analgesic technique where patients themselves were allowed to control the administration of a mixture of nitrous oxide and air during childbirth and minor surgery.

First medical use of a gas mixture 

In 1961, Michael Tunstall et al. described for the first time the medical use of a pre mixed gas consisting of 50% nitrous oxide and 50% oxygen as an analgesic during childbirth (1). It was found that it was possible to store a homogeneous gas mixture containing up to about 75% nitrous oxide at a pressure of 132 bar, at ambient temperature. This led to the premixed gas patent – and to the ENTONOX product introduced by BOC Medical. 

Ideal for short-term pain relief 

Today, ENTONOX, in addition to its use in childbirth, is also established for emergency medical use in pre-hospital care. Other uses that continue to generate interest are in connection with a variety of painful procedures such as colonoscopy, pin removal, cannulation and phlebotomy. 

(1) Tunstall ME. Obstectric analgesia. The Lancet 1961; 2:964.

Up