m (Ngarapihkeun éjahan, replaced: mangrupakeun → mangrupa, rea → réa, ea → éa (5), eo → éo using AWB)
[[Gambar:inhaler_girl.png|thumb|170px|Budak nu boga kasakit asma maké [[inhaler]].]]
'''Asma''' atawa '''bengék'''
<!--The disorder is a chronic [[inflammation|inflammatory]] condition in which the [[lung|airways]] develop increased responsiveness to various stimuli, characterized by [[bronchus|bronchial]] hyper-responsiveness, [[inflammation]], increased [[mucus]] production, and intermittent airway obstruction. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of [[medication|drugs]] and lifestyle changes.
==Signs and symptoms==
An acute exacerbation of asthma is referred to colloquially as an ''asthma attack''. The clinical hallmarks of an attack are shortness of breath ([[dyspnea]]) and [[wheeze|wheezing]], the latter "often being regarded as the ''[[sine qua non]]''."<ref name=McFadden>McFadden ER, Jr. Asthma. In Kasper DL, Fauci AS, Longo DL, et al (eds). ''Harrison's Principles of Internal Medicine'' (16th Edition), pp. 1508-1516. New York: McGraw-Hill;2004.</ref> A cough—sometimes producing clear [[sputum]]—may also be present. The onset is often sudden; there is a "sense of constriction" in the chest, breathing becomes difficult, and wheezing occurs (primarily upon expiration, but can be in both [[Respiration (physiology)|respiratory]] phases).
[[Sign (medicine)|Signs]] of an asthmatic episode are wheezing, rapid breathing ([[tachypnea]]), prolonged expiration, a rapid heart rate ([[tachycardia]]), [[rhonchus|rhonchous]] lung sounds (audible through a [[stethoscope]]), and over-inflation of the chest. During a serious asthma attack, the accessory [[muscle]]s of respiration (sternocleidomastoid and scalene muscles of the neck) may be used, shown as in-drawing of [[biological tissue|tissue]]s between the ribs and above the [[sternum]] and [[clavicle]]s, and the presence of a [[paradoxical pulse]] (a pulse that is weaker during inhalation and stronger during exhalation).<ref name=McFadden>McFadden ER, Jr. Asthma. In Kasper DL, Fauci AS, Longo DL, et al (eds.). ''Harrison's Principles of Internal Medicine'' (16th Edition), pp. 1508-1516. New York: McGraw-Hill;2004.</ref> During very severe attacks, an asthma sufferer can turn blue from lack of oxygen, and can experience [[chest pain]] or even loss of [[consciousness]]. Severe asthma attacks may lead to respiratory arrest and death. Despite the severity of symptoms during an asthmatic episode, between attacks an asthmatic may show few signs of the disease.
In most cases, a physician can [[diagnosis|diagnose]] asthma on the basis of typical findings in a patient's clinical history and examination. Asthma is strongly suspected if a patient suffers from [[eczema]] or other [[allergy|allergic]] conditions—suggesting a general [[atopy|atopic constitution]]—or has a [[Family history (medicine)|family history]] of asthma. While measurement of airway function is possible for adults, most new cases are diagnosed in children who are unable to perform such tests. Diagnosis in children is based on a careful compilation and analysis of the patient's [[medical history]] and subsequent improvement with an inhaled [[bronchodilator]] medication. In adults, diagnosis can be made with a [[peak flow meter]] (which tests airway restriction), looking at both the [[diel|diurnal]] [[Circadian rhythm|variation]] and any reversibility following inhaled [[bronchodilator]] [[Asthma#Rapid relief|medication]].
Testing peak flow at rest (or baseline) and after exercise can be helpful, especially in young asthmatics who may experience only exercise-induced asthma. If the diagnosis is in doubt, a more formal [[spirometry|lung function test]] may be conducted. Once a diagnosis of asthma is made, a patient can use peak flow meter testing to monitor the severity of the disease.
Aspiration, whether '''direct''' due to [[dysphagia]] (swallowing disorder) or '''indirect''' (due to acid reflux), can show similar symptoms to asthma. However, with aspiration, fevers might also indicate [[aspiration pneumonia]]. Direct aspiration (dysphagia) can be diagnosed by performing a Modified Barium Swallow test and treated with feeding therapy by a qualified [[speech therapist]]. If the aspiration is indirect (from acid reflux) then treatment directed at this is indicated.
Only a minority of asthma sufferers have an identifiable [[allergy]] trigger. The majority of these triggers can often be identified from the history; for instance, asthmatics with [[hay fever]] or [[pollen]] allergy will have seasonal symptoms, those with allergies to [[pet]]s may experience an abatement of symptoms when away from home, and those with occupational asthma may improve during leave from work. Occasionally, [[allergy#Diagnosis|allergy tests]] are warranted and, if positive, may help in identifying avoidable symptom triggers.
After pulmonary function has been measured, radiological tests, such as a [[chest X-ray]] or [[computed tomography|CT scan]], may be required to exclude the possibility of other lung diseases. In some people, asthma may by triggered by [[gastroesophageal reflux disease]], which can be treated with suitable [[antacid]]s. Very occasionally, specialized tests after inhalation of [[methacholine challenge test|methacholine]] - or, even less commonly, [[histamine]] — may be performed.
*[[Pollution|air pollution]], such as [[ozone]], [[nitrogen dioxide]], and [[sulfur dioxide]], which is thought to be one of the major reasons for the high prevalence of asthma in urban areas;
*various industrial compounds and other chemicals, notably [[sulfites]]; [[chlorine|chlorinated]] swimming pools generate [[chloramine]]s—monochloramine (NH<sub>2</sub>Cl), dichloramine (NHCl<sub>2</sub>) and trichloramine (NCl<sub>3</sub>)—in the air around them, which are known to induce asthma;<ref name=Nemery>Nemery B, Hoet PH, Nowak D. Indoor swimming pools, water chlorination and respiratory health. ''Eur Respir J''. 2002;19(5):790-3. PMID 12030714</ref>
*early childhood [[infection]]s, especially [[virus|viral]] [[URTI|respiratory infections]]. However, persons of any age can have asthma triggered by colds and other respiratory infections even though their normal stimuli might be from another category (e.g. pollen) and absent at the time of infection.
▲*early childhood [[infection]]s, especially [[virus|viral]] [[URTI|respiratory infections]]. However, persons of any age can have asthma triggered by colds and other respiratory infections even though their normal stimuli might be from another category (e.g. pollen) and absent at the time of infection.
*[[exercise]], the effects of which differ somewhat from those of the other triggers; and
*[[stress (medicine)|emotional stress]], which is poorly understood as a trigger.
===The immune response===
When an inhaled antigen becomes trapped in the [[bronchial tubes|airways]], it is [[protease|enzymatically]] degraded into shorter [[peptide]]s by APCs such as [[dendritic cell]]s. APCs express the peptides derived from the antigen on the [[cell membrane|cell surface]], in what is known as the binding groove of the class II [[Major Histocompatibility Complex|major histocompatiblity complex]] (MHC) molecule. Now located on the cell surface, the antigen-MHC complex is presented to [[T cell]]s, which express a [[receptor (biochemistry)|receptor]] that is specific to the MHC II peptide.<ref name=Maddox>Maddox L, Schwartz DA. The Pathophysiology of Asthma. ''Annu. Rev. Med.'' 2002, 53:477-98. PMID 11818486</ref>
Presented with the antigen-MHC II complex, [[T helper cell|T helper 0]] (T<sub>H</sub>0) cells become activated and start to [[differentiation|differentiate]] into either T helper type 1 (T<sub>H</sub>1) or type 2 (T<sub>H</sub>2) cells. The selective differentiation of T<sub>H</sub>0 cells has profound consequences for the immune system: T<sub>H</sub>1 cell production leads to [[cell-mediated immunity]], while the production of predominantly T<sub>H</sub>2 cells provides [[humoral immunity]]. The resulting balance of T<sub>H</sub>1 or T<sub>H</sub>2 cells is a crucial variable in the development of asthma; the dominance of the T<sub>H</sub>2 cell type appears to be necessary for the development of asthma. In one study, [[knockout mouse|mice]] that lacked the ability to create T<sub>H</sub>1 cells displayed an asthma-like [[phenotype]].<ref name=Finotto>Finotto S, Glimcher L. T cell directives for transcriptional regulation in asthma. ''Springer Semin. Immunopathology'' 2004;25(3-4):281-94. PMID 15007632</ref> The variables that decide the fate of T<sub>H</sub>1 vs. T<sub>H</sub>2 cells are not well understood, but depend on many factors, including childhood exposure to infectious agents and the [[cytokine]]s elicited by those agents.
One cytokine secreted by T<sub>H</sub>2 cells—[[interleukin-4|IL-4]]—combined with the action of other cytokines induces synthesis by antigen-stimulated [[B cells]] of [[IgE]], an allergen-specific antibody. [[IgE]] binds allergens and then receptors on [[mast cells]], [[basophil]]s, and [[eosinophil]]s in the airway [[epithelium]]. Subsequent exposure of the same antigen to these cells in the airway [[epithelium]] initiates the acute-phase reaction of asthma. Stimulated [[mast cell]]s in the airway release preformed granules of mediators such as [[histamine]], [[eicosanoids]], and [[cytokines]]. These molecules are responsible for the symptoms of asthma. They affect the [[mucosa]] of the airways, increasing mucosal oedema, and mucus production, [[smooth muscle]] constriction, and recruit other immune cells, thereby exacerbating the reaction.
The most effective treatment for asthma is identifying triggers, such as pets or aspirin, and limiting or eliminating exposure to them. [[Desensitization]] is commonly attempted, but has not been shown to be effective. As is common with respiratory disease, [[tobacco smoking|smoking]] adversely affects asthmatics in several ways, including an increased severity of symptoms, a more rapid decline of lung function, and decreased response to preventive medications.<ref name=thomson>Thomson NC, Spears M. The influence of smoking on the treatment response in patients with asthma. ''Curr Opin Allergy Clin Immunol''. 2005;5(1):57-63. PMID 15643345</ref> Asthmatics who smoke typically require additional medications to help control their disease. Furthermore, exposure of both nonsmokers and smokers to [[secondhand smoke]] is detrimental, resulting in more severe asthma, more [[emergency room]] visits, and more asthma-related hospital admissions.<ref name=eisner>Eisner MD, Yelin EH, Katz PP, et al. Exposure to indoor combustion and adult asthma outcomes: environmental tobacco smoke, gas stoves, and woodsmoke. ''Thorax''. 2002;57(11):973-8. PMID 12403881</ref> Smoking cessation and avoidance of those who smoke is strongly encouraged in asthmatics.<ref name=epr2>National Asthma Education and Prevention Program. ''Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma''. National Institutes of Health pub no 97-4051. Bethesda, MD, 1997. ([http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf PDF])</ref>
The specific medical treatment recommended to patients with asthma depends on the severity of their illness and the frequency of their symptoms. Specific treatments for asthma are broadly classified as relievers, preventers and emergency treatment. The ''Expert panel report 2: Guidelines for the diagnosis and management of asthma'' (EPR-2)<ref name=epr2>National Asthma Education and Prevention Program. ''Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma''. National Institutes of Health pub no 97-4051. Bethesda, MD, 1997. ([http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf PDF])</ref> of the U.S. National Asthma Education and Prevention Program, and the ''British guideline on the management of asthma'' <ref name=SIGN>British Thoracic Society & Scottish Intercollegiate Guidelines Network (SIGN). ''British Guideline on the Management of Asthma''. Guideline No. 63. Edinburgh:SIGN; 2004. ([http://www.sign.ac.uk/guidelines/fulltext/63/index.html HTML], [http://www.sign.ac.uk/pdf/sign63.pdf Full PDF], [http://www.sign.ac.uk/pdf/qrg63.pdf Summary PDF])</ref> are broadly used and supported by many doctors. Bronchodilators are recommended for short-term relief in all patients. For those who experience occasional attacks, no other medication is needed. For those with mild persistent disease (more than two attacks a week), low-dose inhaled glucocorticoids—or alternatively, an oral leukotriene modifier, a mast-cell stabilizer, or theophylline—may be administered. For those who suffer daily attacks, a higher dose of glucocorticoid in conjunction with a long-acting inhaled β-2 agonist may be prescribed; alternatively, a leukotriene modifier or theophylline may substitute for the β-2 agonist. In severe asthmatics, oral glucocorticoids may be added to these treatments during severe attacks.
[[Image:AsthmaInhaler.jpg|thumb|250px|A typical [[inhaler]], of [[salmeterol|Serevent (salmeterol)]]]]
Symptomatic control of episodes of wheezing and shortness of breath is generally achieved with fast-acting [[bronchodilator]]s. These are typically provided in pocket-sized, metered-dose [[inhaler|inhalers]] (MDIs—see the image to the right). In young sufferers, who may have difficulty with the coordination necessary to use inhalers, or those with a poor ability to hold their breath for 10 seconds after inhaler use (generally the elderly), an [[asthma spacer]] (see top image) is used. The spacer is a plastic cylinder that mixes the medication with air in a simple tube, making it easier for patients to receive a full dose of the drug and allows for the active agent to be dispersed into smaller, more fully inhaled bits. A [[nebulizer]]—which provides a larger, continuous dose—can also be used. Nebulizers work by vaporizing a dose of medication in a saline solution into a steady stream of foggy vapour, which the patient inhales continuously until the full dosage is administered. There is no clear evidence, however, that they are more effective than inhalers used with a spacer. Nebulizers may be helpful to some patients experiencing a severe attack. Such patients may not be able to inhale deeply, so regular inhalers may not deliver medication deeply into the lungs, even on repeated attempts. Since a nebulizer delivers the medication continuously, it is thought that the first few inhalations may relax the airways enough to allow the following inhalations to draw in more medication.
Many asthmatics, like those who suffer from other chronic disorders, use alternative treatments; surveys show that roughly 50% of asthma patients use some form of unconventional therapy.<ref name=blanc>Blanc PD, Trupin L, Earnest G, et al. Alternative therapies among adults with a reported diagnosis of asthma or rhinosinusitis: data from a population-based survey. ''Chest''. 2001;120(5):1461-7. PMID 11713120</ref><sup>,</sup><ref name=shenfield>Shenfield G, Lim E, Allen H. Survey of the use of complementary medicines and therapies in children with asthma. ''J Paediatr Child Health''. 2002;38(3):252-7. PMID 12047692</ref> There are little data to support the effectiveness of most of these therapies. A [[Cochrane Collaboration|Cochrane]] [[Evidence-based medicine|systematic review]] of acupuncture for asthma found no evidence of efficacy.<ref name=mccartney>McCarney RW, Brinkhaus B, Lasserson TJ, et al. Acupuncture for chronic asthma. ''Cochrane Database Syst Rev''. 2004;(1):CD000008. PMID 14973944</ref> A similar review of [[air ionizer]]s found no evidence that they improve asthma symptoms or benefit lung function; this applied equally to positive and negative ion generators.<ref name=blackhall>Blackhall K, Appleton S, Cates CJ. Ionisers for chronic asthma. ''Cochrane Database Syst Rev.'' 2003;(3):CD002986 PMID 12917939</ref> A study of "manual therapies" for asthma, including [[osteopathic]], [[chiropractic]], [[physiotherapy|physiotherapeutic]] and [[respiratory therapy|respiratory therapeutic]] maneuvers, found no evidence to support their use in treating asthma;<ref name=hondras>Hondras MA, Linde K, Jones AP. Manual therapy for asthma. ''Cochrane Database Syst Rev''. 2005;(2):CD001002. PMID 15846609</ref> these manoeuvres include various osteopathic and chiropractic techniques to "increase movement in the rib cage and the spine to try and improve the working of the lungs and circulation"; chest tapping, shaking, vibration, and the use of "postures to help shift and cough up phlegm." On the other hand, one [[meta-analysis]] found that [[homeopathy]] has a potentially mild benefit in reducing symptom intensity;<ref name=reilly>Reilly D, Taylor MA, Beattie NG, et al. Is evidence for homoeopathy reproducible? ''Lancet.'' 1994;344(8937):1601-6. PMID 7983994</ref> however, the number of patients involved in the analysis was small, and subsequent studies have not supported this finding.<ref name=white>White A, Slade P, Hunt C, et al. Individualised homeopathy as an adjunct in the treatment of childhood asthma: a randomised placebo controlled trial. ''Thorax.'' 2003;58(4):317-21. PMID 12668794</ref> Several small trials have suggested some benefit from various [[yoga]] practices, ranging from integrated yoga programs<ref name=nagendra>Nagendra HR, Nagarathna R. An integrated approach of yoga therapy for bronchial asthma: a 3-54-month prospective study. ''J Asthma.'' 1986;23(3):123-37. PMID 3745111</ref>—"yogasanas, Pranayama, [[meditation]], and kriyas"—to ''sahaja'' yoga<ref name=manocha>Manocha R, Marks GB, Kenchington P, et al. Sahaja yoga in the management of moderate to severe asthma: a randomised controlled trial. ''Thorax.'' 2002;57(2):110-5. PMID 11828038</ref>, a form of meditation. A randomized, controlled trial of just 39 patients suggested that the [[Buteyko method]] may moderately reduce the need for beta-agonists among asthmatics, but found no objective improvement in lung function.<ref name=bowler>Bowler SD, Green A, Mitchell CA. Buteyko breathing techniques in asthma: a blinded randomised controlled trial. ''Med J Aust''. 1998;169(11-12):575-8. PMID 9887897</ref>
See also ''[[Complementary and alternative medicine]]''.
* [http://www.nlm.nih.gov/medlineplus/asthma.html MedLinePlus: Asthma] – a U.S. National Library of Medicine page.
* [http://www.nhlbi.nih.gov/health/public/lung/index.htm#asthma National Heart, Lung, and Blood Institute — Asthma] – U.S. NHLBI Information for Patients and the Public page.
* [http://www.nhlbi.nih.gov/health/prof/lung/index.htm#asthma National Heart, Lung, and Blood Institute — Asthma] – U.S. NHLBI Information for
* [http://www.aaaai.org American Academy of Allergy, Asthma, and Immunology] – a U.S. organization of medical professionals with a special interest in
* [http://www.atsdr.cdc.gov/HEC/CSEM/asthma/ Case Studies in Environmental Medicine (CSEM) Environmental Triggers of Asthma] – a page from the Agency for Toxic Substances and
* [http://www.seattlechildrens.org/child_health_safety/resources/health/diseases_conditions/allergies_asthma_immune.asp Children's Hospital & Regional Medical Center — Allergies, Asthma & Immune System] – A
* [http://www.housedustmite.org.uk HouseDustMite-org-uk : House Dust Mite and Asthma]