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Page semi-protected Asthma Classification and external resources

Peak flow meters are used to measure one's peak expiratory flow rate ICD-10 	J45 ICD-9 	493 OMIM 	600807 DiseasesDB 	1006 MedlinePlus 	000141 eMedicine 	article/806890 MeSH 	D001249

Asthma (from the Greek άσθμα, ásthma, "panting") is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.[1] Symptoms include wheezing, coughing, chest tightness, and shortness of breath.[2] Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate.[3] Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic).[4]

It is thought to be caused by a combination of genetic and environmental factors.[5] Treatment of acute symptoms is usually with an inhaled short-acting beta-2 agonist (such as salbutamol).[6] Symptoms can be prevented by avoiding triggers, such as allergens[7] and irritants, and by inhaling corticosteroids.[8] Leukotriene antagonists are less effective than corticosteroids and thus less preferred.[9]

Its diagnosis is usually made based on the pattern of symptoms and/or response to therapy over time.[10] The prevalence of asthma has increased significantly since the 1970s. As of 2010, 300 million people were affected worldwide.[11] In 2009 asthma caused 250,000 deaths globally.[12] Despite this, with proper control of asthma with step down therapy, prognosis is generally good.[13] Contents

1 Classification 1.1 Brittle asthma 1.2 Asthma attack 1.3 Status asthmaticus 1.4 Exercise-induced 1.5 Occupational 2 Signs and symptoms 2.1 Gastro-esophageal reflux disease 2.2 Sleep disorders 3 Causes 3.1 Environmental 3.2 Genetic 3.3 Gene–environment interactions 3.4 Exacerbation 3.5 Hygiene hypothesis 3.6 Socioeconomic factors 4 Diagnosis 4.1 Differential diagnosis 5 Prevention 6 Management 6.1 Lifestyle modification 6.2 Medications 6.3 Other 6.4 Complementary medicine 7 Prognosis 8 Epidemiology 8.1 Increasing frequency 8.2 Variability 9 History 10 Notes 11 External links

Classification

Asthma is defined by the Global Initiative for Asthma as "a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. The chronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing particularly at night or in the early morning. These episodes are usually associated with widespread, but variable airflow obstruction within the lung that is often reversible either spontaneously or with treatment".[14] Clinical classification of severity[3] Severity in patients ≥ 12 years of age [15] 	Symptom frequency 	Night time symptoms 	 %FEV1 of predicted 	FEV1 Variability 	Use of short-acting beta2 agonist for symptom control (not for prevention of EIB) Intermittent 	≤2 per week 	≤2 per month 	≥80% 	<20% 	≤2 days per week Mild persistent 	>2 per week but not daily 	3–4 per month 	≥80% 	20–30% 	>2 days/week but not daily Moderate persistent 	Daily 	>1 per week but not nightly 	60–80% 	>30% 	Daily Severe persistent 	Throughout the day 	Frequent (often 7×/week) 	<60% 	>30% 	Several times per day

Asthma is clinically classified according to the frequency of symptoms, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate.[3] Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic), based on whether symptoms are precipitated by allergens (atopic) or not (non-atopic).[4]

While asthma is classified based on severity, at the moment there is no clear method for classifying different subgroups of asthma beyond this system.[16] Finding ways to identify subgroups that respond well to different types of treatments is a current critical goal of asthma research.[16]

Although asthma is a chronic obstructive condition, it is not considered as a part of chronic obstructive pulmonary disease as this term refers specifically to combinations of disease that are irreversible such as bronchiectasis, chronic bronchitis, and emphysema.[15] Unlike these diseases, the airway obstruction in asthma is usually reversible; however, if left untreated, the chronic inflammation from asthma can lead the lungs to become irreversibly obstructed due to airway remodeling.[17] In contrast to emphysema, asthma affects the bronchi, not the alveoli.[18] Brittle asthma Main article: Brittle asthma

Asthma attack
 * 1) Brittle asthma is a term used to describe two types of asthma, distinguishable by recurrent, severe attacks.[19] Type 1 brittle asthma refers to disease with wide peak flow variability, despite intense medication. Type 2 brittle asthma describes background well-controlled asthma, with sudden severe exacerbations.[19]

An acute asthma exacerbation is commonly referred to as an asthma attack. The classic symptoms are shortness of breath, wheezing, and chest tightness.[20] While these are the primary symptoms of asthma,[21] some people present primarily with coughing, and in severe cases, air motion may be significantly impaired such that no wheezing is heard.[19]

Signs which occur during an asthma attack include the use of accessory muscles of respiration (sternocleidomastoid and scalene muscles of the neck), there may be a paradoxical pulse (a pulse that is weaker during inhalation and stronger during exhalation), and over-inflation of the chest.[22] A blue color of the skin and nails may occur from lack of oxygen.[23]

In a mild exacerbation the peak expiratory flow rate (PEFR) is ≥200 L/min or ≥50% of the predicted best.[24] Moderate is defined as between 80 and 200 L/min or 25% and 50% of the predicted best while severe is defined as ≤ 80 L/min or ≤25% of the predicted best.[24] Status asthmaticus Main article: Status asthmaticus

Status asthmaticus is an acute exacerbation of asthma that does not respond to standard treatments of bronchodilators and steroids. Nonselective beta blockers (such as Timolol) have caused fatal status asthmaticus.[25] Exercise-induced
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