While<unk>  is a well-recognized condition, there is not one universal agreed upon definition. It is defined by the Global Initiative for<unk>  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 hyper-responsiveness 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". There is currently no precise test for the diagnosis, which is typically based on the pattern of symptoms and response to therapy over time.<unk>  may be suspected if there is a history of recurrent wheezing, coughing or difficulty breathing and these symptoms occur or worsen due to exercise, viral infections, allergens or air pollution. Spirometry is then used to confirm the diagnosis. In children under the age of six the diagnosis is more difficult as they are too young for spirometry. Spirometry Spirometry is recommended to aid in diagnosis and management. It is the single best test for<unk> . If the FEV1 measured by this technique improves more than 12% and increases by at least 200 milliliters following administration of a bronchodilator such as salbutamol, this is supportive of the diagnosis. It however may be normal in those with a history of mild<unk> , not currently acting up. As caffeine is a bronchodilator in people with<unk> , the use of caffeine before a lung function test may interfere with the results. Single-breath diffusing capacity can help differentiate<unk>  from COPD. It is reasonable to perform spirometry every one or two years to follow how well a person's<unk>  is controlled. Others The methacholine challenge involves the inhalation of increasing concentrations of a substance that causes airway narrowing in those predisposed. If negative it means that a person does not have<unk> ; if positive, however, it is not specific for the disease. Other supportive evidence includes: a ≥20% difference in peak expiratory flow rate on at least three days in a week for at least two weeks, a ≥20% improvement of peak flow following treatment with either salbutamol, inhaled corticosteroids or prednisone, or a ≥20% decrease in peak flow following exposure to a trigger. Testing peak expiratory flow is more variable than spirometry, however, and thus not recommended for routine diagnosis. It may be useful for daily self-monitoring in those with moderate to severe disease and for checking the effectiveness of new medications. It may also be helpful in guiding treatment in those with acute exacerbations. Classification + Clinical classification (≥ 12 years old) Severity Symptom frequency Night-time symptoms %FEV1 of predicted FEV1 variability SABA use Intermittent ≤2/week ≤2/month ≥80% 2/week 3–4/month ≥80% 20–30% >2 days/week Moderate persistent Daily >1/week 60–80% >30% daily Severe persistent Continuously Frequent (7/week) 30% ≥twice/day<unk>  is clinically classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate.<unk>  may also be classified as atopic (extrinsic) or non-atopic (intrinsic), based on whether symptoms are precipitated by allergens (atopic) or not (non-atopic). While<unk>  is classified based on severity, at the moment there is no clear method for classifying different subgroups of<unk>  beyond this system. Finding ways to identify subgroups that respond well to different types of treatments is a current critical goal of<unk>  research. Although<unk>  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 and emphysema. Unlike these diseases, the airway obstruction in<unk>  is usually reversible; however, if left untreated, the chronic inflammation from<unk>  can lead the lungs to become irreversibly obstructed due to airway remodeling. In contrast to emphysema,<unk>  affects the bronchi, not the alveoli. The combination of<unk>  with a component of irreversible airways obstruction has been termed the<unk> -chronic obstructive disease (COPD) overlap syndrome (ACOS). Compared to other people with "pure"<unk>  or COPD, people with ACOS exhibit increased morbidity, mortality and possibly more comorbidities.<unk>  exacerbation + Severity of an acute exacerbation Near-fatal High PaCO2, or requiring mechanical ventilation, or both Life-threatening(any one of) Clinical signs Measurements Altered level of consciousness Peak flow 2 2 Cyanosis Silent chest Poor respiratory effort Acute severe(any one of) Peak flow 33–50% Respiratory rate ≥ 25 breaths per minute Heart rate ≥ 110 beats per minute Unable to complete sentences in one breath Moderate Worsening symptoms Peak flow 50–80% best or predicted No features of acute severe<unk>  An acute<unk>  exacerbation is commonly referred to as an<unk>  attack. The classic symptoms are shortness of breath, wheezing, and chest tightness. The wheezing is most often when breathing out. While these are the primary symptoms of<unk> , some people present primarily with coughing, and in severe cases, air motion may be significantly impaired such that no wheezing is heard. In children, chest pain is often present. Signs occurring during an<unk>  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. A blue color of the skin and nails may occur from lack of oxygen. In a mild exacerbation the peak expiratory flow rate (PEFR) is ≥200 L/min, or ≥50% of the predicted best. 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. Acute severe<unk> , previously known as status<unk> ticus, is an acute exacerbation of<unk>  that does not respond to standard treatments of bronchodilators and corticosteroids. Half of cases are due to infections with others caused by allergen, air pollution, or insufficient or inappropriate medication use. Brittle<unk>  is a kind of<unk>  distinguishable by recurrent, severe attacks. Type 1 brittle<unk>  is a disease with wide peak flow variability, despite intense medication. Type 2 brittle<unk>  is background well-controlled<unk>  with sudden severe exacerbations. Exercise-induced Exercise can trigger bronchoconstriction both in people with or without<unk> . It occurs in most people with<unk>  and up to 20% of people without<unk> . Exercise-induced bronchoconstriction is common in professional athletes. The highest rates are among cyclists (up to 45%), swimmers, and cross-country skiers. While it may occur with any weather conditions, it is more common when it is dry and cold. Inhaled beta2-agonists do not appear to improve athletic performance among those without<unk> , however, oral doses may improve endurance and strength. Occupational<unk>  as a result of (or worsened by) workplace exposures is a commonly reported occupational disease. Many cases, however, are not reported or recognized as such. It is estimated that 5–25% of<unk>  cases in adults are work-related. A few hundred different agents have been implicated, with the most common being: isocyanates, grain and wood dust, colophony, soldering flux, latex, animals, and aldehydes. The employment associated with the highest risk of problems include: those who spray paint, bakers and those who process food, nurses, chemical workers, those who work with animals, welders, hairdressers and timber workers. Aspirin-induced<unk>  Aspirin-exacerbated respiratory disease (AERD), also known as aspirin-induced<unk> , affects up to 9% of<unk> tics. AERD consists of<unk> , nasal polyps, sinus disease, and respiratory reactions to aspirin and other NSAID medications (such as ibuprofen and naproxen). People often also develop loss of smell and most experience respiratory reactions to alcohol. Alcohol-induced<unk>  Alcohol may worsen<unk> tic symptoms in up to a third of people. This may be even more common in some ethnic groups such as the Japanese and those with aspirin-induced<unk> . Other studies have found improvement in<unk> tic symptoms from alcohol. Non-atopic<unk>  Non-atopic<unk> , also known as intrinsic or non-allergic, makes up between 10 and 33% of cases. There is negative skin test to common inhalant allergens. Often it starts later in life, and women are more commonly affected than men. Usual treatments may not work as well. The concept that "non-atopic" is synonymous with "non-allergic" is called into question by epidemiological data that the prevalence of<unk>  is closely related to the serum IgE level standardized for age and sex (P<0.0001), indicating that<unk>  is almost always associated with some sort of IgE-related reaction and therefore has an allergic basis, although not all the allergic stimuli that cause<unk>  appear to have been included in the battery of aeroallergens studied (the "missing antigen(s)" hypothesis). For example, an updated systematic review and meta-analysis of population-attributable risk (PAR) of Chlamydia pneumoniae biomarkers in chronic<unk>  found that the PAR for C. pneumoniae-specific IgE was 47%. Infectious<unk>  When queried,<unk>  patients may report that their first<unk>  symptoms began after an acute lower respiratory tract illness. This type of history has been labelled the "infectious<unk> " (IA) syndrome, or as
Asthma
Tracheobronchomalacia
Reactive airway disease
Bronchiolitis
Brittle asthma
Pneumonia
Cardiac asthma
Acute bronchitis