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Cough

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Cough
Depiction of cough
Pronunciation
SpecialtyInfectious diseases
Coughing
The sound of a person coughing.
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Acoughis a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles andmicrobes.As a protectivereflex,coughing can be repetitive with thecough reflexfollowing three phases: aninhalation,a forcedexhalationagainst a closedglottis,and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound.[1]

Frequent coughing usually indicates the presence of a disease. Manyvirusesandbacteriabenefit, from an evolutionary perspective, by causing thehostto cough, which helps to spread the disease to new hosts. Irregular coughing is usually caused by arespiratory tract infectionbut can also be triggered bychoking,smoking,air pollution,[1]asthma,gastroesophageal reflux disease,post-nasal drip,chronic bronchitis,lung tumors,heart failureand medications such asangiotensin-converting-enzyme inhibitors (ACE inhibitors)andbeta blockers.[2]

Treatment should target the cause; for example,smoking cessationor discontinuing ACE inhibitors.Cough suppressantssuch ascodeineordextromethorphanare frequently prescribed, but have been demonstrated to have little effect.[citation needed]Other treatment options may target airwayinflammationor maypromote mucus expectoration.As it is a natural protective reflex, suppressing the cough reflex might have damaging effects, especially if the cough is productive (producingphlegm).[3]

Presentation

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Shadowgraphvideos of the outer airflow during a cough, comparing unmasked coughing with several methods of covering one's mouth and nose: coughing into a fist, a cupped hand, a tissue, a "coughcatcher" device, asurgical mask,and anN95 mask

Complications

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The complications of coughing can be classified as eitheracuteorchronic.Acute complications include cough syncope (faintingspells due to decreased blood flow to the brain when coughs are prolonged and forceful),insomnia,cough-inducedvomiting,subconjunctival hemorrhageor "red eye",coughingdefecationand in women with aprolapseduterus,coughurination.Chronic complications are common and include abdominal or pelvichernias,fatiguefracturesof lower ribs andcostochondritis.Chronic or violent coughing can contribute to damage to the pelvic floor and a possiblecystocele.[4]

Differential diagnosis

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A cough in children may be either a normal physiological reflex or due to an underlying cause.[5]In healthy children it may be normal in the absence of any disease to cough ten times a day.[5]The most common cause of an acute or subacute cough is a viralrespiratory tract infection.[5]A healthy adult also coughs 18.8 times a day on average, but in the population with respiratory disease the geometric mean frequency is 275 times a day.[6]In adults with a chronic cough, i.e. a cough longer than 8 weeks, more than 90% of cases are due topost-nasal drip,asthma,eosinophilic bronchitis,andgastroesophageal reflux disease.[5]The causes of chronic cough are similar in children with the addition ofbacterial bronchitis.[5]

Infections

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A cough can be the result of arespiratory tract infectionsuch as thecommon cold,COVID-19,acute bronchitis,pneumonia,pertussis,ortuberculosis.In the vast majority of cases, acute coughs, i.e. coughs shorter than 3 weeks, are due to the common cold.[7]In people with a normal chest X-ray, tuberculosis is a rare finding. Pertussis is increasingly being recognised as a cause of troublesome coughing in adults.

After a respiratory tract infection has cleared, the person may be left with apostinfectious cough.This typically is a dry, non-productive cough that produces nophlegm.Symptoms may include a tightness in the chest, and a tickle in the throat. This cough may often persist for weeks after an illness. The cause of the cough may be inflammation similar to that observed in repetitive stress disorders such ascarpal tunnel syndrome.The repetition of coughing produces inflammation which produces discomfort, which in turn produces more coughing.[8]Postinfectious cough typically does not respond to conventional cough treatments. Medication used for postinfectious coughs may includeipratropium[8]to treat the inflammation, as well as cough suppressants to reduce frequency of the cough until inflammation clears.[9]Inflammation may increase sensitivity to other existing issues such asallergies,and treatment of other causes of coughs (such as use of an air purifier or allergy medicines) may help speed recovery.[10]

Reactive airway disease

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When coughing is the only complaint of a person who meets the criteria for asthma (bronchial hyperresponsivenessand reversibility), this is termedcough-variant asthma.Atopic cough andeosinophilic bronchitisare related conditions. Atopic cough occurs in individuals with afamily historyofatopy(an allergic condition), abundanteosinophilsin the sputum, but with normal airway function and responsiveness. Eosinophilic bronchitis is characterized byeosinophilsin sputum and inbronchoalveolar lavagefluid without airway hyperresponsiveness or an atopic background.[11]This condition responds to treatment withcorticosteroids.Cough can also worsen in anacute exacerbation of chronic obstructive pulmonary disease.

Asthma is a common cause of chronic cough in adults and children. Coughing may be the only symptom the person has from their asthma, or asthma symptoms may also include wheezing, shortness of breath, and a tight feeling in their chest. Depending on how severe the asthma is, it can be treated with bronchodilators (medicine which causes the airways to open up) or inhaled steroids. Treatment of the asthma should make the cough go away.

Chronic bronchitisis defined clinically as a persistent cough that produces sputum (phlegm) and mucus, for at least three months in two consecutive years. Chronic bronchitis is often the cause of "smoker's cough".The tobacco smoke causes inflammation, secretion of mucus into the airway, and difficulty clearing that mucus out of the airways. Coughing helps clear those secretions out. May be treated by quitting smoking. May also be caused bypneumoconiosisand long-term fume inhalation.

Gastroesophageal reflux

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In people with unexplained cough,gastroesophageal reflux diseaseshould be considered.[5]This occurs when acidic contents of the stomach come back up into the esophagus. Symptoms usually associated withGERDinclude heartburn, sour taste in the mouth, or a feeling of acid reflux in the chest, although, more than half of the people with cough from GERD do not have any other symptoms. An esophageal pH monitor can confirm the diagnosis of GERD. Sometimes GERD can complicate respiratory ailments related to cough, such as asthma or bronchitis. The treatment involves anti-acid medications and lifestyle changes with surgery indicated in cases not manageable with conservative measures.

Air pollution

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Coughing may be caused byair pollutionincludingtobacco smoke,particulate matter, irritant gases, and dampness in a home.[5] The human health effects of poor air quality are far reaching, but principally affect the body's respiratory system and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health status and genetics. People who exercise outdoors on hot, smoggy days, for example, increase their exposure to pollutants in the air.

Foreign body

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Aforeign bodycan sometimes be suspected, for example if the cough started suddenly when the patient was eating. Rarely, sutures left behind inside the airway branches can cause coughing. A cough can be triggered by dryness frommouth breathingor recurrent aspiration of food into thewindpipein people withswallowing difficulties.[12][13]

Drug-induced cough

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Drugs used for treatments other than coughs, such asACE inhibitorswhich are often used to treathigh blood pressure,can sometimes cause cough as a side effect, and stopping their use will stop the cough.[14]Beta blockers similarly cause cough as an adverse event.[2]

Tic cough

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Atic cough,previously called ahabit cough,is one that responds to behavioral or psychiatric therapy after organic causes have been excluded. Absence of the cough during sleep is common, but not diagnostic. A tic cough is thought to be more common in children than in adults.[15] A similar disorder is thesomatic cough syndromepreviously called thepsychogenic cough.

Neurogenic cough

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Some cases of chronic cough may be attributed to a sensory neuropathic disorder.[16]Treatment for neurogenic cough may include the use of certain neuralgia medications. Coughing may occur intic disorderssuch asTourette syndrome,although it should be distinguished from throat-clearing in this disorder.

Other

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Cough may also be caused by conditions affecting the lung tissue such asbronchiectasis,cystic fibrosis,interstitial lung diseasesandsarcoidosis.Coughing can also be triggered bybenignormalignant lung tumorsor mediastinal masses. Through irritation of the nerve, diseases of the external auditory canal (wax, for example) can also cause cough. Cardiovascular diseases associated with cough are heart failure, pulmonary infarction and aortic aneurysm. Nocturnal cough is associated with heart failure, as the heart does not compensate for the increased volume shift to the pulmonary circulation, in turn causingpulmonary edemaand resultant cough.[17]Other causes of nocturnal cough includeasthma,post-nasal dripandgastroesophageal reflux disease(GERD).[18]Another cause of cough occurring preferentially insupine positionis recurrent aspiration.[17]

Given its irritant nature to mammal tissues,capsaicinis widely used to determine the cough threshold and as a tussive stimulant in clinical research of cough suppressants. Capsaicin is what makeschili peppersspicy, and might explain why workers in factories with these fruits can develop a cough.

Coughing may also be used for social reasons, and as such is not always involuntary. A voluntary cough, often written as "ahem", can be used to attract attention or express displeasure, as a form ofnonverbal,paralingualmetacommunication.[19][20]

Airway clearance

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Further information:Airway clearance therapy

Coughing, andhuffingare important ways of removing mucus assputumin many conditions such ascystic fibrosis,andchronic bronchitis.

Pathophysiology

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Coughing is viewed as a public health issue.

A cough is a protectivereflexin healthy individuals which is influenced bypsychologicalfactors.[5]The cough reflex is initiated by stimulation of two different classes ofafferent nerves,namely themyelinatedrapidly adapting receptors, and nonmyelinatedC-fiberswith endings in thelung.[21]

Diagnostic approach

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The type of cough may help in the diagnosis. For instance, an inspiratory "whooping" sound on coughing almost doubles the likelihood that the illness ispertussis.

Bloodmay occur in small amounts with severe cough of many causes, but larger amounts suggestsbronchitis,bronchiectasis,tuberculosis,or primarylung cancer.[22]

Furtherworkupmay include labs,x-rays,andspirometry.[5]

Classification

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A cough can be classified by its duration, character, quality, and timing.[5]The duration can be eitheracute(of sudden onset) if it is present less than three weeks,subacuteif it is present between three or eight weeks, andchronicwhen lasting longer than eight weeks.[5]A cough can be non-productive (dry) or productive (whenphlegmis produced that may be coughed up assputum). It may occur only at night (then callednocturnal cough), during both night and day, or just during the day.[5]

A number of characteristic coughs exist. While these have not been found to be diagnostically useful in adults, they are of use in children.[5]A barky cough is part of the common presentation ofcroup.[23]A staccato cough has been classically described withneonatalchlamydialpneumonia.[24]

Treatment

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The treatment of a cough in children is based on the underlying cause. In children half of cases go away without treatment in 10 days and 90% in 25 days.[25]

According to theAmerican Academy of Pediatricsthe use ofcough medicineto relieve cough symptoms is supported by little evidence and thus not recommended for treating cough symptoms in children.[5]There is tentative evidence that the use of honey is better than no treatment ordiphenhydraminein decreasing coughing.[26]It does not alleviate coughing to the same extent asdextromethorphanbut it shortens the cough duration better than placebo andsalbutamol.[26]A trial ofantibioticsorinhaled corticosteroidsmay be tried in children with a chronic cough in an attempt to treatprotracted bacterial bronchitisorasthmarespectively.[5]There is insufficient evidence to recommend treating children who have a cough that is not related to a specific condition with inhaled anti-cholinergics.[27]

Because coughing can spread disease through infectious aerosol droplets, it is recommended to cover one's mouth and nose with the forearm, the inside of the elbow, a tissue or a handkerchief while coughing.[28]

Epidemiology

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A cough is the most common reason for visiting aprimary care physicianin the United States.[5]

Other animals

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A coughing deer hind

Marine mammals such asdolphinsandwhalescannot cough.[29]Someinvertebratessuch asinsectsandspiderscannot cough or sneeze.Alligatorscan cough.[30]Domestic animals and vertebrates such asdogsandcatscan cough, because of diseases, allergies, dust or choking.[31]In particular, cats are known for coughing before spitting up ahairball.[31]

In other domestic animals,horsescan cough because of infections, or due to poor ventilation and dust in enclosed spaces.[32]Kennel coughindogscan result from a viral or bacterial infection.

Deer can cough similarly to humans as a result of respiratory tract infections, such as parasitic bronchitis caused by a species ofDictyocaulus.[33]

References

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  1. ^abChung KF, Pavord ID (April 2008). "Prevalence, pathogenesis, and causes of chronic cough".Lancet.371(9621): 1364–1374.doi:10.1016/S0140-6736(08)60595-4.PMID18424325.S2CID7810980.
  2. ^abGuidelines, Therapeutic (2021).Cough.Therapeutic Guidelines Ltd.
  3. ^Pavord ID, Chung KF (April 2008). "Management of chronic cough".Lancet.371(9621): 1375–1384.doi:10.1016/S0140-6736(08)60596-6.PMID18424326.S2CID30806409.
  4. ^"Cystocele (Prolapsed Bladder) | NIDDK".National Institute of Diabetes and Digestive and Kidney Diseases.Retrieved2017-12-02.
  5. ^abcdefghijklmnopGoldsobel AB, Chipps BE (March 2010). "Cough in the pediatric population".J. Pediatr.156(3): 352–358.e1.doi:10.1016/j.jpeds.2009.12.004.PMID20176183.
  6. ^Nadia, Yousaf; Monteiro, William; Matos, Sergio; Birring, Surinder S.; Pavord, Ian D. (2013)."Cough frequency in health and disease".European Respiratory Journal.41(1): 241–243.doi:10.1183/09031936.00089312.PMID23277523.
  7. ^Dicpinigaitis PV, Colice GL, Goolsby MJ, Rogg GI, Spector SL, Winther B (2009)."Acute cough: a diagnostic and therapeutic challenge".Cough.5:11.doi:10.1186/1745-9974-5-11.PMC2802352.PMID20015366.In the vast majority of cases, acute cough is due to acute viral upper respiratory tract infection (URTI), i.e., the common cold.
  8. ^abBraman SS (January 2006)."Postinfectious cough: ACCP evidence-based clinical practice guidelines".Chest.129(1 Suppl): 138S–146S.doi:10.1378/chest.129.1_suppl.138S.PMID16428703.
  9. ^"Cystic fibrosis - Diagnosis and treatment - Mayo Clinic".www.mayoclinic.org.Retrieved2022-05-24.
  10. ^"UpToDate".www.uptodate.com.Retrieved2022-05-24.
  11. ^Niimi, A (February 2011)."Cough and Asthma".Current Respiratory Medicine Reviews.7(1): 47–54.doi:10.2174/157339811794109327.PMC3182093.PMID22081767.
  12. ^"Cough".Mayo Clinic.Retrieved2022-03-27.
  13. ^"Why You Cough".WebMD.Retrieved2022-03-27.
  14. ^Dicpinigaitis PV (January 2006). "Angiotensin-converting enzyme inhibitor-induced cough: ACCP evidence-based clinical practice guidelines".Chest.129(1 Suppl): 169S–173S.doi:10.1378/chest.129.1_suppl.169S.PMID16428706.
  15. ^Irwin RS, Glomb WB, Chang AB (January 2006)."Habit cough, tic cough, and psychogenic cough in adult and pediatric populations: ACCP evidence-based clinical practice guidelines".Chest.129(1 Suppl): 174S–179S.doi:10.1378/chest.129.1_suppl.174S.PMID16428707.
  16. ^Gibson PG, Ryan NM (August 2011). "Cough pharmacotherapy: current and future status".Expert Opinion on Pharmacotherapy.12(11): 1745–1755.doi:10.1517/14656566.2011.576249.PMID21524236.S2CID24560981.
  17. ^abNCBI » Bookshelf » Clinical Methods » The Pulmonary System » Cough and Sputum ProductionBy Sattar Farzan. Extracted from the book Clinical Methods, 3rd edition The History, Physical, and Laboratory Examinations. Edited by H Kenneth Walker, MD, W Dallas Hall, MD, and J Willis Hurst, MD. Boston: Butterworths; 1990.ISBN0-409-90077-X
  18. ^"C.Chronic Cough".Archived fromthe originalon 2010-10-01.Retrieved2010-10-10.National Lung Health Education Program > C. Chronic Cough] The Snowdrift Pulmonary Foundation, Inc. 2000.ISBN0-9671809-2-9
  19. ^"ahem".Onomatopoeia List.August 10, 2013. Archived fromthe originalon April 4, 2023.RetrievedApril 11,2022.
  20. ^Nänny, Max; Fischer, Olga (1999).Form Miming Meaning: Iconicity in Language and Literature.John Benjamins Publishing.ISBN9789027221797.Retrieved25 July2019.
  21. ^Mazzone, Stuart B.; Undem, Bradley J. (2016-07-01)."Vagal Afferent Innervation of the Airways in Health and Disease".Physiological Reviews.96(3): 975–1024.doi:10.1152/physrev.00039.2015.ISSN0031-9333.PMC4982036.PMID27279650.
  22. ^Noah Lechtzin."Cough in Adults".Merck Manuals.Retrieved2017-04-07.Last full review/revision July 2016
  23. ^Bjornson CL, Johnson DW (July 2007)."Croup in the paediatric emergency department".Paediatr Child Health.12(6): 473–477.doi:10.1093/pch/12.6.473.PMC2528757.PMID19030411.
  24. ^Miller KE (April 2006). "Diagnosis and treatment of Chlamydia trachomatis infection".Am Fam Physician.73(8): 1411–6.PMID16669564.
  25. ^Thompson, M.; Vodicka, T. A.; Blair, P. S.; Buckley, D. I.; Heneghan, C.; Hay, A. D. (11 December 2013)."Duration of symptoms of respiratory tract infections in children: systematic review".BMJ.347(dec11 1): f7027.doi:10.1136/bmj.f7027.PMC3898587.PMID24335668.
  26. ^abOduwole, O; Udoh, EE; Oyo-Ita, A; Meremikwu, MM (10 April 2018)."Honey for acute cough in children".The Cochrane Database of Systematic Reviews.4(12): CD007094.doi:10.1002/14651858.CD007094.pub5.PMC6513626.PMID29633783.
  27. ^Chang, A. B.; McKean, M.; Morris, P. (2004)."Inhaled anti-cholinergics for prolonged non-specific cough in children".The Cochrane Database of Systematic Reviews.2003(1): CD004358.doi:10.1002/14651858.CD004358.pub2.ISSN1469-493X.PMC8823516.PMID14974067.
  28. ^"Coughing and Sneezing".US Centers for Disease Control and Prevention.2020-04-24.Retrieved2020-09-14.
  29. ^Woodard, James C.; Zam, Stephen G.; Caldwell, David K.; Caldwell, Melba C. (29 August 2016)."Some Parasitic Diseases of Dolphins".Pathologia Veterinaria.6(3): 257–272.doi:10.1177/030098586900600307.PMID5817449.S2CID26842976.
  30. ^"Crocodile 'cough' caught on camera in Florida Everglades".WFLA.2023-08-23.Retrieved2024-06-13.
  31. ^ab"Is It Normal for Cats To Cough?".Pet Health Network.Retrieved2018-04-23.
  32. ^"Coughing in horses explained".Your Horse Magazine.Archived fromthe originalon 2020-07-28.Retrieved2018-04-23.
  33. ^Pyziel, Anna M.; Laskowski, Zdzisław; Demiaszkiewicz, Aleksander W.; Höglund, Johan (2017). "Interrelationships ofDictyocaulusspp.In Wild Ruminants with Morphological Description ofDictyocauluscervin. Sp. (Nematoda: Trichostrongyloidea) from Red Deer,Cervus elaphus ".Journal of Parasitology.103(5): 506–518.doi:10.1645/16-75.PMID28585897.S2CID25720548.

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Further reading

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