Editing Capnography (section)

=== Emergency medical services ===
Capnography is increasingly being used by [[Emergency medical services|EMS]] personnel to aid in their assessment and treatment of patients in the prehospital environment. These uses include verifying and monitoring the position of an [[endotracheal tube]] or a [[blind insertion airway device]]. A properly positioned tube in the [[trachea]] guards the patient's airway and enables the [[paramedic]] to breathe for the patient. A misplaced tube in the [[esophagus]] can lead to the patient's death if it goes undetected. <ref>{{Cite journal|last1=Katz|first1=Steven|last2=Falk|first2=Jay|date=January 2001|title=Misplaced endotracheal tubes by paramedics in an urban emergency medical services system|url=https://www.annemergmed.com/article/S0196-0644(01)92235-8/fulltext|journal=Ann Emerg Med|language=en|volume=37|issue=1|pages=32–37|doi=10.1067/mem.2001.112098 |pmid=11145768 |url-access=subscription}}</ref>

A study in the March 2005 ''Annals of Emergency Medicine,'' comparing field [[Tracheal intubation|intubations]] that used continuous capnography to confirm intubations versus non-use showed zero unrecognized misplaced intubations in the monitoring group versus 23% misplaced tubes in the unmonitored group.<ref>{{Cite journal|last1=Silvestri|first1=Salvatore|last2=Ralls|first2=George A.|last3=Krauss|first3=Baruch|last4=Thundiyil|first4=Josef|last5=Rothrock|first5=Steven G.|last6=Senn|first6=Amy|last7=Carter|first7=Eric|last8=Falk|first8=Jay|date=May 2005|title=The effectiveness of out-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services system|url=https://pubmed.ncbi.nlm.nih.gov/15855946/|journal=Annals of Emergency Medicine|volume=45|issue=5|pages=497–503|doi=10.1016/j.annemergmed.2004.09.014|issn=1097-6760|pmid=15855946}}</ref> The [[American Heart Association]] (AHA) affirmed the importance of using capnography to verify tube placement in their 2005 [[Cardiopulmonary resuscitation|CPR]] and Emergency Cardiovascular Care Guidelines.<ref>{{Cite journal|last1=Hazinski|first1=Mary Fran|last2=Nadkarni|first2=Vinay M.|last3=Hickey|first3=Robert W.|last4=O'Connor|first4=Robert|last5=Becker|first5=Lance B.|last6=Zaritsky|first6=Arno|date=2005-12-13|title=Major Changes in the 2005 AHA Guidelines for CPR and ECC|journal=Circulation|volume=112|issue=24_supplement|pages=IV–206|doi=10.1161/CIRCULATIONAHA.105.170809|pmid=16314349 |s2cid=934519 |doi-access=free}}</ref>

The AHA also notes in their new guidelines that capnography, which indirectly measures cardiac output, can also be used to monitor the effectiveness of CPR and as an early indication of return of spontaneous circulation (ROSC). Studies have shown that when a person doing CPR tires, the patient's end-tidal {{chem|CO|2}} ('''PETCO2''', the level of carbon dioxide released at the end of expiration) falls, and then rises when a fresh rescuer takes over.  Other studies have shown when a patient experiences return of spontaneous circulation, the first indication is often a sudden rise in the PETCO2 as the rush of circulation washes untransported {{chem|CO|2}} from the tissues. Likewise, a sudden drop in PETCO2 may indicate the patient has lost pulses and CPR may need to be initiated.<ref>{{Cite journal|last1=Long|first1=Brit|last2=Koyfman|first2=Alex|last3=Vivirito|first3=Michael A.|date=December 2017|title=Capnography in the Emergency Department: A Review of Uses, Waveforms, and Limitations|journal=The Journal of Emergency Medicine|volume=53|issue=6|pages=829–842|doi=10.1016/j.jemermed.2017.08.026|issn=0736-4679|pmid=28993038|doi-access=free}}</ref>

Paramedics are also now beginning to monitor the PETCO2 status of nonintubated patients by using a special nasal [[cannula]] that collects the carbon dioxide.  A high PETCO2 reading in a patient with altered mental status or severe difficulty breathing may indicate [[hypoventilation]] and a possible need for the patient to be [[intubated]]. Low PETCO2 readings on patients may indicate [[hyperventilation]].<ref>{{Cite journal| last1= Davis |first1=Daniel |last2=Dunford |first2=James |last3=Ochs |first3=Mel |last4=Park |first4=Kenneth |last5=Hoyt |first5=David |date=April 2004|title= The use of quantitative end-tidal capnometry to avoid inadvertent severe hyperventilation in patients with head injury after paramedic rapid sequence intubation  | journal=J Trauma |language=en |volume=56 |issue=4 |pages=808–814|doi=10.1097/01.TA.0000100217.05066.87 |pmid=15187747 }}</ref>

Capnography, because it provides a breath by breath measurement of a patient's ventilation, can quickly reveal a worsening trend in a patient's condition by providing paramedics with an early warning system into a patient's respiratory status. When compared to oxygenation which is measured by pulse oximetry, there are several disadvantages that capnography can help address to provide a more accurate reflection of cardiovascular integrity. One shortcoming of measuring pulse oximetry alone is that administration of supplemental oxygen (ie. via nasal cannula) can delay desaturation in a patient if they stopped breathing, therefore delaying medical intervention. Capnography provides a rapid way to directly assess ventilation status and indirectly assess cardiac function. Clinical studies are expected to uncover further uses of capnography in [[asthma]], [[congestive heart failure]], [[diabetes]], circulatory shock, [[pulmonary embolus]], [[acidosis]], and other conditions, with potential implications for the prehospital use of capnography.<ref>{{Cite web|title=Experts: Where capnography is headed|url=https://www.ems1.com/ems-products/medical-equipment/airway-management/articles/experts-where-capnography-is-headed-bXd5NUiEucMcXOOg/|access-date=2021-11-16|website=EMS1|date=20 November 2013 |language=en}}</ref>