Editing Nitrous oxide (section)

===Medical===
{{Main|Nitrous oxide (medication)}}
[[File:N2O Medical Tanks.jpg|thumb|right|upright|Medical-grade {{chem|N|2|O}} tanks used in [[dentistry]]]]

Nitrous oxide has been used in dentistry and surgery, as an anaesthetic and analgesic, since 1844.<ref name="Drug discovery">{{cite book|url=https://books.google.com/books?id=mYQxRY9umjcC |author=Sneader W |title=Drug Discovery –A History |chapter=Systematic Medicine |pages=74–87 |date=2005 |publisher=John Wiley and Sons |isbn=978-0-471-89980-8}}</ref> In the early days, the gas was administered through simple inhalers consisting of a breathing bag made of rubber cloth.<ref name="use in dentistry">{{cite journal|author=Miller AH |title=Technical Development of Gas Anesthesia |journal=Anesthesiology |volume=2 |issue=4 |pages=398–409 |year=1941 |doi=10.1097/00000542-194107000-00004|s2cid=71117361 |doi-access=free }}</ref> Today, the gas is administered in hospitals by means of an automated [[relative analgesia machine]], with an [[anaesthetic vaporiser]] and a [[medical ventilator]], that delivers a precisely dosed and breath-actuated flow of [[nitrous oxide and oxygen|nitrous oxide mixed with oxygen]] in a 2:1 ratio.

Nitrous oxide is a weak [[general anaesthetic]], and so is generally not used alone in general anaesthesia, but used as a carrier gas (mixed with oxygen) for more powerful general anaesthetic drugs such as [[sevoflurane]] or [[desflurane]]. It has a [[minimum alveolar concentration]] of 105% and a [[blood/gas partition coefficient]] of 0.46. The use of nitrous oxide in anaesthesia can increase the risk of postoperative nausea and vomiting.<ref>{{Cite journal|last1=Divatia|first1=Jigeeshu V.|last2=Vaidya|first2=Jayant S.|last3=Badwe|first3=Rajendra A.|last4=Hawaldar|first4=Rohini W.|title=Omission of Nitrous Oxide during Anesthesia Reduces the Incidence of Postoperative Nausea and Vomiting|journal=Anesthesiology|volume=85|issue=5|pages=1055–1062|doi=10.1097/00000542-199611000-00014|pmid=8916823|year=1996|s2cid=41549796|doi-access=free}}</ref><ref>{{Cite journal|last=Hartung|first=John|title=Twenty-Four of Twenty-Seven Studies Show a Greater Incidence of Emesis Associated with Nitrous Oxide than with Alternative Anesthetics|journal=Anesthesia & Analgesia|volume=83|issue=1|pages=114–116|doi=10.1213/00000539-199607000-00020|year=1996}}</ref><ref>{{Cite journal|last1=Tramèr|first1=M.|last2=Moore|first2=A.|last3=McQuay|first3=H.|date=February 1996|title=Omitting nitrous oxide in general anaesthesia: meta-analysis of intraoperative awareness and postoperative emesis in randomized controlled trials|journal=British Journal of Anaesthesia|volume=76|issue=2|pages=186–193|pmid=8777095|doi=10.1093/bja/76.2.186|doi-access=free}}</ref>

Dentists use a simpler machine which only delivers an {{chem|N|2|O}}/{{chem|O|2}} mixture for the patient to inhale while conscious but must still be a recognised purpose designed dedicated relative analgesic flowmeter with a minimum 30% of oxygen at all times and a maximum upper limit of 70% nitrous oxide. The patient is kept conscious throughout the procedure, and retains adequate mental faculties to respond to questions and instructions from the dentist.<ref>{{Cite journal|last=Council on Clinical Affairs|date=2013|title=Guideline on use of nitrous oxide for pediatric dental patients|url=http://www.aapd.org/media/policies_guidelines/g_nitrous.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.aapd.org/media/policies_guidelines/g_nitrous.pdf |archive-date=2022-10-09 |url-status=live|journal=Reference Manual V37|volume=6|pages=206–210}}</ref>

Inhalation of nitrous oxide is used frequently to relieve pain associated with [[childbirth]], [[Physical trauma|trauma]], [[dentistry|oral surgery]] and [[acute coronary syndrome]] (including heart attacks). Its use during labour has been shown to be a safe and effective aid for birthing women.<ref>{{cite web |last=Copeland |first=Claudia |url=http://www.pregnancy.org/article/nitrous-oxide-analgesia-child-birth |title=Nitrous Oxide Analgesia for Childbirth |website=Pregnancy.org  |archive-url=https://web.archive.org/web/20110525080809/http://www.pregnancy.org/article/nitrous-oxide-analgesia-child-birth |archive-date=25 May 2011 }}</ref> Its use for acute coronary syndrome is of unknown benefit.<ref name="AHA10">{{cite journal|author=O'Connor RE |title=Part 10: acute coronary syndromes: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care |journal=Circulation |volume=122 |issue=18 Suppl 3 |pages=S787–817 |year=2010 |pmid=20956226 |doi=10.1161/CIRCULATIONAHA.110.971028 |author2=Brady W |author3=Brooks SC |last4=Diercks |first4=D. |last5=Egan |first5=J. |last6=Ghaemmaghami |first6=C. |last7=Menon |first7=V. |last8=O'Neil |first8=B. J. |last9=Travers |first9=A. H. |last10=Yannopoulos |doi-access=free }}</ref>

In Canada and the UK, [[Nitrous oxide (medication)|Entonox]] and Nitronox are used commonly by ambulance crews (including unregistered practitioners) as rapid and highly effective analgesic gas.

Fifty percent nitrous oxide can be considered for use by trained non-professional first aid responders in prehospital settings, given the relative ease and safety of administering 50% nitrous oxide as an analgesic. The rapid reversibility of its effect would also prevent it from precluding diagnosis.<ref>{{Cite journal|last1=Faddy|first1=S. C.|last2=Garlick|first2=S. R.|date=2005-12-01|title=A systematic review of the safety of analgesia with 50% nitrous oxide: can lay responders use analgesic gases in the prehospital setting?|journal=Emergency Medicine Journal|volume=22|issue=12|pages=901–908|doi=10.1136/emj.2004.020891|pmc=1726638|pmid=16299211}}</ref>