Information AboutAsthma |
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| asthma | |
| diseasesasthma | |
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-->Zhao J, Takamura M, Yamaoka A, Odajima Y, Iikura Y. Altered eosinophil levels as a result of viral infection in asthma exacerbation in childhood. ''J Pediatr Allergy Immunol''. 2002 Feb;13(1):47–50. PMID 12000498 This airway narrowing causes Symptom s such as Wheezing , Shortness Of Breath , chest tightness, and Cough ing. The airway constriction responds to Bronchodilators . Between episodes, most patients feel well but can have mild symptoms and they may remain short of breath after exercise for longer periods of time than the unaffected individual. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of Drugs and environmental changes. Public attention in the Developed World has recently focused on asthma because of its rapidly increasing Prevalence , affecting up to one in four urban children.Lilly CM. Diversity of asthma: Evolving concepts of pathophysiology and lessons from genetics. ''J Allergy Clin Immunol''. 2005;115 (4 Suppl):S526-31. PMID 15806035 HISTORY The word 'asthma' is derived from the Greek ''aazein'', meaning "sharp breath." The word first appears in Homer's '' Iliad '';Marketos SG, Ballas CN. Bronchial asthma in the medical literature of Greek antiquity. ''J Asthma''. 1982;19(4):263-9. PMID 6757243 Hippocrates was the first to use it in reference to the medical condition, in 450 BC. Hippocrates thought that the spasms associated with asthma were more likely to occur in tailors, anglers, and metalworkers. Six centuries later, Galen wrote much about asthma, noting that it was caused by partial or complete bronchial obstruction. In 1190 AD, Moses Maimonides , an influential medieval Rabbi , philosopher, and physician, wrote a treatise on asthma, describing its prevention, diagnosis, and treatment.Rosner F. Moses Maimonides' treatise on asthma. ''Thorax''. 1981;36:245–251. PMID 7025335 In the 17th century, Bernardino Ramazzini noted a connection between asthma and Organic dust. The use of Bronchodilator s started in 1901, but it was not until the 1960s that the inflammatory component of asthma was recognized, and Anti-inflammatory medications were added to the regimens. SIGNS AND SYMPTOMS In some individuals asthma is characterized by chronic respiratory impairment. In others it is an intermittent illness marked by episodic symptoms that may result from a number of triggering events, including upper respiratory infection, stress, airborne allergens, air pollutants (such as smoke or traffic fumes), or exercise. Some or all of the following symptoms may be present in those with asthma: dyspnea, wheezing, stridor, coughing, an inability for physical exertion. Some asthmatics that have severe shortness of breath and tightening of the lungs never wheeze or have stridor and their symptoms may be confused with a COPD -type disease. An acute exacerbation of asthma is referred to as an ''asthma attack''. The clinical hallmarks of an attack are shortness of breath ( Dyspnea ) and either Wheezing or Stridor .1 Although the former is "often regarded as the '' Sine Qua Non '' of asthma, some patients present primarily with Cough ing, and in the late stages of an attack, air motion may be so impaired that no wheezing may be heard. When present the cough may sometimes produce clear Sputum . The onset may be sudden, with a sense of constriction in the chest, breathing becomes difficult, and wheezing occurs (primarily upon expiration, but can be in both Respiratory phases). An asthma attack may spread the mold to others through the air. Signs of an asthmatic episode include Wheezing , rapid breathing ( Tachypnea ), prolonged expiration, a rapid heart rate ( Tachycardia ), 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 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). During very severe attacks, an asthma sufferer can Turn Blue from lack of oxygen, and can experience Chest Pain or even loss of Consciousness . Just before loss of consciousness, there is a chance that the patient will feel numbness in the limbs and palms may start to sweat. Feet may become icy cold. Severe asthma attacks, which may not be responsive to standard treatments ('' Status Asthmaticus ''), are life-threatening and 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.2 DIAGNOSIS Asthma is defined simply as reversible airway obstruction. Reversibility occurs either spontaneously or with treatment. The basic measurement is Peak Flow Rates and the following diagnostic criteria are used by the British Thoracic Society :3
In many cases, a physician can 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 Allergic conditions—suggesting a general Atopic Constitution —or has a 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 diurnal Variation and any reversibility following inhaled Bronchodilator 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 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. In the Emergency Department doctors may use a Capnography PMID 16187465 which measures the amount of exhaled Carbon Dioxide along with Pulse Oximetry which shows the amount of oxygen dissolved in the blood, to determine the severity of an asthma attack as well as the response to treatment. Differential diagnosis Before diagnosing someone as asthmatic, Alternative Possibilities should be considered. A clinician taking a history should check whether the patient is using any known bronchoconstrictors (substances that cause narrowing of the airways, e.g., certain Anti-inflammatory agents or Beta-blockers ). Chronic Obstructive Pulmonary Disease , which closely resembles asthma, is correlated with more exposure to cigarette smoke, an older patient, less symptom reversibility after bronchodilator administration (as measured by Spirometry ), and decreased likelihood of family history of Atopy . Pulmonary 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. A majority of children who are asthma sufferers have an identifiable Allergy trigger. Specifically, in a 2004 study, 71% had positive test results for more than 1 allergen, and 42% had positive test results for more than 3 allergens.4 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 Tests are warranted and, if positive, may help in identifying avoidable symptom triggers. After a Pulmonary Function Test has been carried out, radiological tests, such as a Chest X-ray or CT Scan , may be required to exclude the possibility of other lung diseases. In some people, asthma may be triggered by Gastroesophageal Reflux Disease , which can be treated with suitable Antacid s. Very occasionally, specialized tests after inhalation of Methacholine — or, even less commonly, Histamine — may be performed. Asthma is categorized by the United States National Heart, Lung And Blood Institute as falling into one of four categories: mild intermittent, mild persistent, moderate persistent and severe persistent. The diagnosis of "severe persistent asthma" occurs when symptoms are continual with frequent exacerbations and frequent nighttime symptoms, result in limited physical activity and when lung function as measured by PEV or FEV1 tests is less than 60% predicted with PEF variability greater than 30%. There is no cure for asthma. Doctors have only found ways to prevent attacks and relieve the symptoms such as tightness of the chest and trouble breathing. PATHOPHYSIOLOGY Bronchoconstriction During an asthma episode, inflamed Airways react to environmental triggers such as smoke, dust, or pollen. The airways narrow and produce excess Mucus , making it difficult to breathe. In essence, asthma is the result of an Immune Response in the Bronchial airways.Maddox L, Schwartz DA. The Pathophysiology of Asthma. ''Annu. Rev. Med.'' 2002, 53:477-98. PMID 11818486 The airways of asthmatics are " Hypersensitive " to certain triggers, also known as ''stimuli'' (see below). In response to exposure to these triggers, the Bronchi (large airways) contract into Spasm (an "asthma attack"). Inflammation soon follows, leading to a further narrowing of the airways and excessive Mucus production, which leads to coughing and other breathing difficulties. Stimuli There are many different categories of stimuli:
Bronchial inflammation The mechanisms behind allergic asthma—i.e., asthma resulting from an Immune Response to inhaled Allergen s—are the best understood of the causal factors. In both asthmatics and non-asthmatics, inhaled allergens that find their way to the inner Airways are Ingested by a type of cell known as Antigen Presenting Cell s, or APCs. APCs then "present" pieces of the allergen to other Immune System cells. In most people, these other immune cells ( TH0 Cells ) "check" and usually ignore the allergen molecules. In asthmatics, however, these cells Transform into a different type of cell (TH2), for reasons that are not well understood. The resultant TH2 cells activate an important arm of the immune system, known as the Humoral Immune System . The humoral immune system produces Antibodies against the inhaled allergen. Later, when an asthmatic inhales the same allergen, these antibodies "recognize" it and activate a Humoral Response . Inflammation results: chemicals are produced that cause the airways to constrict and release more mucus, and the cell-mediated arm of the immune system is activated. The inflammatory response is responsible for the clinical manifestations of an asthma attack. The following section describes this complex series of events in more detail. Pathogenesis The fundamental problem in asthma appears to be give clues as to the Pathogenesis : the incidence of asthma seems to be increasing worldwide, and asthma is now very much more common in affluent countries. In 1968 Andor Szentivanyi first described ''The Beta Adrenergic Theory of Asthma''; in which blockage of the Beta-2 receptors of pulmonary smooth muscle cells causes asthma.5 Szentivanyi's Beta Adrenergic Theory is a citation classicLockey, Richard, In lasting tribute: Andor Szentivanyi, MD. ''J. Allergy and Clinical Immunology'', January, 2006 and has been cited more times than any other article in the history of the Journal of Allergy. In 1995 Szentivanyi and colleagues demonstrated that IgE blocks beta-2 receptors.6 - Part of Abstracts from: 7 Since overproduction of IgE is central to all atopic diseases, this was a watershed moment in the world of allergy.8 | |||||||||||||||||||||||||||||||||||||
| A Study Conducted By The National Jewish Medical And Research Center Concluded That Overweight And Obesity Are Associated With A Dose-dependent Increase In The Odds Of Incident Asthma In Men And Women, Suggesting Asthma Incidence Could Be Reduced By Interventions Targeting Overweight And Obesity Journal | American Journal of Respiratory and Critical Care Medicine volume=175 pages=661-666 year=2007 |
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