Editing Capnography (section)

===Anesthesia===
[[File:Capnometry parts together.JPG|thumb|Capnograph]]

During anesthesia, there is interplay between two components: the patient and the anesthesia administration device (which is usually a breathing circuit and a [[ventilator]]). The critical connection between the two components is either an [[tracheal tube|endotracheal tube]] or a mask, and {{chem|CO|2}} is typically monitored at this junction. Capnography directly reflects the elimination of {{chem|CO|2}} by the [[lungs]] to the anesthesia device. Indirectly, it reflects the production of {{chem|CO|2}} by tissues and the circulatory transport of {{chem|CO|2}} to the lungs.<ref>{{Cite journal| last1= Weil |first1=Max |last2=Bisera |first2=Jose |last3=Trevino |first23=Robert |last4=Rackow |first4=Eric |date=October 2016 |title= Cardiac output and end-tidal carbon dioxide  | journal= Crit Care Med |language=en |volume=13 |issue=11 |pages=907–909|doi=10.1097/00003246-198511000-00011 |pmid=3931979 |s2cid=34223367 }}</ref>

When expired {{chem|CO|2}} is related to expired volume rather than time, the area beneath the curve represents the volume of {{chem|CO|2}} in the breath, and thus over the course of a minute, this method can yield the {{chem|CO|2}} per minute elimination, an important measure of metabolism. Sudden changes in {{chem|CO|2}} elimination during lung or heart surgery usually imply important changes in cardiorespiratory function.<ref name="GravensteinJaffeGravenstein2011">{{cite book | editor1 = J. S. Gravenstein | editor2 = Michael B. Jaffe | editor3 = Nikolaus Gravenstein | editor4 = David A. Paulus | date = 17 March 2011 | title = Capnography | edition = 2 | publisher = Cambridge University Press | pages = | isbn = 978-0-521-51478-1 | oclc = 1031490358 | url = https://books.google.com/books?id=9hb6mAEACAAJ}}</ref>

Capnography has been shown to be more effective than clinical judgement alone in the early detection of adverse respiratory events such as [[hypoventilation]], [[oesophagus|esophageal]] intubation and circuit disconnection; thus allowing patient [[injury]] to be prevented. During procedures done under sedation, capnography provides more useful information, e.g. on the frequency and regularity of ventilation, than [[pulse oximetry]].<ref>{{Cite journal|last1=Lightdale|first1=Jenifer R.|last2=Goldmann|first2=Donald A.|last3=Feldman|first3=Henry A.|last4=Newburg|first4=Adrienne R.|last5=DiNardo|first5=James A.|last6=Fox|first6=Victor L.|date=June 2006|title=Microstream capnography improves patient monitoring during moderate sedation: a randomized, controlled trial|url=https://pubmed.ncbi.nlm.nih.gov/16702250/|journal=Pediatrics|volume=117|issue=6|pages=e1170–1178|doi=10.1542/peds.2005-1709|issn=1098-4275|pmid=16702250|s2cid=2857581 }}</ref><ref>{{Cite journal|last1=Burton|first1=John H.|last2=Harrah|first2=John D.|last3=Germann|first3=Carl A.|last4=Dillon|first4=Douglas C.|date=May 2006|title=Does end-tidal carbon dioxide monitoring detect respiratory events prior to current sedation monitoring practices?|url=https://pubmed.ncbi.nlm.nih.gov/16569750/|journal=Academic Emergency Medicine|volume=13|issue=5|pages=500–504|doi=10.1197/j.aem.2005.12.017|issn=1553-2712|pmid=16569750}}</ref>

Capnography provides a rapid and reliable method to detect life-threatening conditions (malposition of [[tracheal tube]]s, unsuspected ventilatory failure, circulatory failure and defective breathing circuits) and to circumvent potentially irreversible patient injury.

Capnography and pulse oximetry together could have helped in the prevention of 93% of avoidable anesthesia mishaps according to an ASA ([[American Society of Anesthesiologists]]) closed claim study.<ref>{{cite journal | doi=10.1097/00000542-198910000-00010 | title=Role of Monitoring Devices in Prevention of Anesthetic Mishaps | year=1989 | last1=Tinker | first1=John H. | last2=Dull | first2=David L. | last3=Caplan | first3=Robert A. | last4=Ward | first4=Richard J. | last5=Cheney | first5=Frederick W. | journal=Anesthesiology | volume=71 | issue=4 | pages=541–546 | pmid=2508510 | doi-access=free }}</ref>