The discovery of nitrous is credited to English scientist Ioseph Priestley, in 1772, although it seems he was not aware of its anaesthetics properties or possible uses. In 1775 he published his discovery in Experiments and Observations on Different Kinds of Air, where he details the production of nitrous oxide, or “nitrous air diminished” as he named it, by heating iron fillings dampened with nitric acid.
Thomas Beddoes and James Watt where responsible in 1794 for the first notable usage of nitrous oxide due to their joint publishing of the volume Considering on the Medicinal Useage and on the New Production of Semi-Factitious Air. The importance of this book is two sided, as it described the innovative device to produce a quantity of “Factitious Airs”, the name given at the time to nitrous oxide, and a new form of “ventilator” used to breathe in the gas, created James Watt. The book also published and highlighted Beddoes theories on the medical uses of nitrous oxide, namely in the treatment of tuberculosis and further respiratory diseases. Watt’s machine was made of three different components:
- A furnace to combust the required materials
- A receptacle with water, through which there processed gas would pass through a curling pipe, to remove the impurities.
- A gas cylinder furnished with a gas-o-meter, thru which the produced gas could be transported into the movable air bags.
The ventilator was a simple mouthpiece connected by a tube to the movable air bags mentioned above.
In 1794, with the machine and the ventilator being constructed and then manufactured, the basis for the clinical trials were set, which started after Beddoes instituted the “New Pneumatic Original Institution for Relieving of many Diseases by the use of Medical Airs” in Bristol. Working with a bigger version of James Watt’s machine, located at its basement, was Humphry Davy. He was responsible for the production of gas, as well as stimulated into testing new gases to treat the patients. This lead to Humphry Davy’s first notable work, the investigation of nitrous oxide, which was subsequently published in his 1800’s book Researches, all about Chemical and also the Modern Philosophical. In this book, Davy’s describes the analgesic consequences of the gas and the possible medical uses in surgical operations. In spite of Humphry Davy’s discoveries, 47 long years would pass before doctors experimented with this gas as a form of anaesthesia.
As an interesting aside, the recreational use was an instant hit among the British wealthiest, as soon as 1799. The then named “laughing gas and fun parties” explored one of the most known effects of nitrous, the euphoric state provoked by the inhaling of the gas.
As for nitrous oxide’s adoption as an anaesthetic, it didn’t happen until 11 December 1844, when the Horace Wells performed a dental extraction, with the patient demonstrating insensitivity to any form of pain or discomfort. Horace Wells continued using this method, during the next weeks, in as much as 12 to 15 patients, and according to his personal reports, the effects of the nitrous oxide only were unsuccessful in a pair of cases. Although these results, indicating the potential of nitrous oxide as an anaesthetic in dental surgeries, were reported as soon as December 1844 to the Boston’s medical society, nitrous oxide adoption did not happen straightway. This is possibly because in the first public showing to the medical community in Boston did not a total success, resulting in an obvious reluctance of his peer in adapting this new methodology, doubting its effectiveness and security of the patient.
As for the usage in hospitals, it was not potent enough for anaesthetic use in any major operations. The more potent sulphuric ether was tested and admitted into use by October 1846 and, later in 1847, so was chloroform. However, it became a common practice using the “gas-ether inhaler”, created by Joseph Thomas Clover in 1876, to start anaesthetic procedures with a minor stream of nitrous oxide, adding gradually the more potent ether or chloroform, in order to increase the anaesthesia. Joseph Thomas Clover’s device was planned to deliver a mixture, controlled by a member of staff, of nitrous oxide and ether. It was used in many medical facilities until the mid-1930s and, although hospitals now use much more advanced anaesthetic devices, many of these machine are still based on Clover’s inhaling device, using nitrous oxide to start the anaesthesia before the usage of an additional, more potent, anaesthetic.