Editing Spirometry (section)

==Testing==
{{unreferenced section|date=November 2019}}
[[File:Spiro solo.jpg|thumb|left|A modern USB PC-based spirometer.]]
[[File:Device for Spirometry or Body Plethysmography 02.jpg|thumb|left|Device for spirometry. The patient places his or her lips around the blue mouthpiece. The teeth go between the nubs and the shield, and the lips go over the shield. A nose clip guarantees that breath will flow only through the mouth.]]
[[File:Body Plethysmography chamber 01.jpg|thumb|left|Screen for spirometry readouts at right. The chamber can also be used for body [[plethysmograph]]y.]]

===Spirometer===
The spirometry test is performed using a device called a [[spirometer]],<ref>{{cite web | title = Spirometry | publisher = Cleveland Clinic | url = https://my.clevelandclinic.org/health/diagnostics/17833-spirometry| access-date = 13 Sep 2020}}</ref> which comes in several different varieties. Most spirometers display the following graphs, called spirograms:
* a ''volume-time curve'', showing volume (litres) along the Y-axis and time (seconds) along the X-axis
* a ''flow-volume loop'', which graphically depicts the rate of airflow on the Y-axis and the total volume [[inhalation|inspired]] or [[exhalation|expired]] on the X-axis

===Procedure===
The basic forced volume vital capacity (FVC) test varies slightly depending on the equipment used. It can be in the form of either closed or open circuit. Regardless of differences in testing procedure providers are recommended to follow the [https://www.thoracic.org/statements/resources/pfet/PFT2.pdf ATS/ERS Standardisation of Spirometry]. The standard procedure ensures an accurate and objectively collected set of data, based on a common reference, to reduce incompatibility of the results when shared across differing medical groups.

The patient is asked to put on soft nose clips to prevent air escape and a breathing sensor in their mouth forming an air tight seal. Guided by a technician, the patient is given step by step instructions to take an abrupt maximum effort inhale, followed by a maximum effort exhale lasting for a target of at least 6 seconds. When assessing possible [[upper airway obstruction]], the technician will direct the patient to make an additional rapid inhalation to complete the round. The timing of the second inhale can vary between persons depending on the length of the proceeding exhale. In some cases each round of test will be proceeded by a period of normal, gentle breathing for additional data.

===Limitations===
Clinically useful results are highly dependent on patient cooperation and effort and must be repeated for a minimum of three times to ensure [[reproducibility]] with a general limit of ten attempts. Given variable rates of effort, the results can only be underestimated given an effort output greater than 100% is not possible.{{Citation needed|reason=Second sentence is making a medical determination so it should be cited to ensure correctness of the underestimated statement. It was also reworded to reduce confusion, but this tag should at minimum serve to notify reader of a potential discrepancy.|date=July 2023}}

Due to the need for patient cooperation and an ability to understand and follow instructions, spirometry can typically only be done in cooperative children when they at least 5 years old<ref>{{cite book |doi=10.1016/B978-0-12-417044-5.00054-8 |chapter=Outcome Measures in Neuromuscular Diseases |title=Neuromuscular Disorders of Infancy, Childhood, and Adolescence |date=2015 |last1=Montes |first1=Jacqueline |last2=Kaufmann |first2=Petra |pages=1078–1089 |isbn=978-0-12-417044-5 }}</ref><ref>{{Cite web |last=Pruthi, M.D. |first=Sandhya |date=January 6, 2022 |title=Asthma: Steps in testing and diagnosis |url=https://www.mayoclinic.org/diseases-conditions/asthma/in-depth/asthma/art-20045198 |access-date=July 14, 2023 |website=[[Mayo Clinic]]}}</ref> or adults without physical or mental impairment preventing effective diagnostic results. In addition, [[General anesthesia]] and various forms of sedation are not compatible with the testing process.

Another limitation is that persons with intermittent or mild asthma can present normal spirometry values between acute exacerbation, reducing spirometry's effectiveness as a diagnostic tool in these circumstances.{{Citation needed|reason=this is making a medical determination so it should be cited to ensure correctness. It was also reworded to reduce confusion, but this tag should at minimum serve to notify reader of a potential discrepancy.|date=July 2023}}

===Supplemental diagnostics===
Spirometry can also be part of a [[bronchial challenge test]], used to determine [[bronchial]] hyperresponsiveness to either rigorous exercise, inhalation of cold/dry air, or with a pharmaceutical agent such as [[methacholine]] or [[histamine]].

To assess the reversibility of a particular condition, a [[bronchodilator]] can be administered before performing another round of tests for comparison. This is commonly referred to as a ''reversibility test'', or a ''[[post bronchodilator test]]'' (Post BD), and is an important part in diagnosing asthma versus COPD.

Other complementary lung functions tests include [[plethysmography]] and [[nitrogen washout]].

===Indications===
Spirometry is indicated for the following reasons:
* to diagnose or manage asthma<ref name="AAAAIfive">{{cite web |author1 = American Academy of Allergy, Asthma, and Immunology |author1-link = American Academy of Allergy, Asthma, and Immunology |title = Five Things Physicians and Patients Should Question |publisher = [[American Academy of Allergy, Asthma, and Immunology]] |work = Choosing Wisely: an initiative of the [[ABIM Foundation]] |url = http://choosingwisely.org/wp-content/uploads/2012/04/5things_12_factsheet_AAAAI.pdf |access-date = 14 August 2012}}</ref><ref name="NIHasthmaguide">{{cite book|title=Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma|year=2007|publisher=National Institutes of Health|url=http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf|edition=NIH Publication Number 08-5846}}</ref><ref name="globalstrategy">{{cite journal | last1 = Bateman | first1 = E. D. | last2 = Hurd | first2 = S. S. | last3 = Barnes | first3 = P. J. | last4 = Bousquet | first4 = J. | last5 = Drazen | first5 = J. M. | last6 = Fitzgerald | first6 = M. | last7 = Gibson | first7 = P. | last8 = Ohta | first8 = K. | last9 = O'Byrne | first9 = P. | last10 = Pedersen | first10 = S. E. | last11 = Pizzichini | first11 = E. | last12 = Sullivan | first12 = S. D. | last13 = Wenzel | first13 = S. E. | last14 = Zar | first14 = H. J. | title = Global strategy for asthma management and prevention: GINA executive summary | journal = European Respiratory Journal | volume = 31 | issue = 1 | pages = 143–178 | year = 2008 | pmid = 18166595 | doi = 10.1183/09031936.00138707 | s2cid = 206960094 | doi-access = free }}</ref>
* to detect respiratory disease in patients presenting with symptoms of breathlessness, and to distinguish respiratory from [[cardiac disease]] as the cause<ref name="essentialspirometry">{{Cite journal | last1 = Pierce | first1 = R. | title = Spirometry: An essential clinical measurement | journal = Australian Family Physician | volume = 34 | issue = 7 | pages = 535–539 | year = 2005 | pmid = 15999163}}</ref>
* to measure bronchial responsiveness in patients suspected of having asthma<ref name="essentialspirometry"/>
* to diagnose and differentiate between [[obstructive lung disease]] and [[restrictive lung disease]]<ref name="essentialspirometry"/>
* to follow the [[natural history of disease]] in respiratory conditions<ref name="essentialspirometry"/>
* to assess of impairment from [[occupational asthma]]<ref name="essentialspirometry"/>
* to identify those at risk from pulmonary [[barotrauma]] while [[scuba diving]]<ref name="essentialspirometry"/>
* to conduct pre-operative risk assessment before anaesthesia or [[cardiothoracic surgery]]<ref name="essentialspirometry"/>
* to measure response to treatment of conditions which spirometry detects<ref name="essentialspirometry"/>
* to diagnose the [[vocal cord dysfunction]].

===Contraindications===
Forced expiratory maneuvers may aggravate some medical conditions.<ref>{{cite book|last1=Clark|first1=Margaret Varnell|title=Asthma: A Clinician's Guide |url=https://archive.org/details/asthmaclinicians00clar|url-access=limited|date=2010|publisher=Jones & Bartlett Learning|location=Burlington, Ma.|isbn=978-0763778545|page=[https://archive.org/details/asthmaclinicians00clar/page/n62 46]|edition=ist}}</ref> Spirometry should not be performed when the individual presents with:
* [[Hemoptysis]] of unknown origin
* [[Pneumothorax]]
* Unstable cardiovascular status ([[angina]], recent [[myocardial infarction]], etc.)
* Thoracic, abdominal, or cerebral [[aneurysms]]
* [[Cataracts]] or recent eye surgery
* Recent thoracic or abdominal surgery
* [[Nausea]], [[vomiting]], or acute illness
* Recent or current viral infection
* Undiagnosed [[hypertension]]