Asthma
Asthma, disorder of the respiratory system in which the passages that enable air to pass into and out of the lungs periodically narrow, causing coughing, wheezing, and shortness of breath. This narrowing is typically temporary and reversible, but in severe attacks, asthma may result in death. Asthma most commonly refers to bronchial asthma, an inflammation of the airways, but the term is also used to refer to cardiac asthma, which develops when fluid builds up in the lungs as a complication of heart failure. This article focuses on bronchial asthma.
Asthma attacks are caused by airway hyperresponsiveness—that is, an overreaction of the bronchi and bronchioles to various environmental and physiological stimuli, known as triggers. The most common causes of asthma attacks are extremely small and lightweight particles transported through the air and inhaled into the lungs. When they enter the airways, these particles, known as environmental triggers, cause an inflammatory response in the airway walls, resulting in an asthma attack.
Physicians typically diagnose asthma by looking for the classic symptoms: episodic problems with breathing that include wheezing, coughing, and shortness of breath. When symptoms alone fail to establish a diagnosis of asthma, doctors may use spirometry, a test that measures airflow. By comparing a patient’s normal airflow, airflow during an attack, and airflow after the application of asthma medication, doctors determine whether the medicine improves the patient’s breathing problems. If asthma medication helps, doctors usually diagnose the condition as asthma.
Identifying the specific trigger of a patient’s asthma is usually more difficult than the initial diagnosis. Triggers may be easily recognizable and consistent; for example, a patient may always develop an asthma attack when using a particular cosmetic or household cleaning product. When the triggers are more difficult to identify, doctors perform a series of allergy skin tests to help determine whether allergy triggers are responsible. Skin tests are not conclusive, however, because patients may have skin reactions to substances that do not necessarily trigger an asthma attack. Doctors may also use spirometry to evaluate a patient’s airflow before and after exposure to common triggers. Triggers that decrease airflow may be responsible for the patient’s asthma.
Although there is no cure for asthma, effective treatment is available for preventing attacks and for controlling and ending attacks soon after they have begun. Asthma medications are taken orally or inhaled in vapor form using a metered-dose inhaler, a hand-held pump that delivers medication directly to the airways. There are two kinds of asthma medications: bronchodilators, which reduce bronchospasm; and anti-inflammatory medications, which reduce airway inflammation.
Asthma attacks are caused by airway hyperresponsiveness—that is, an overreaction of the bronchi and bronchioles to various environmental and physiological stimuli, known as triggers. The most common causes of asthma attacks are extremely small and lightweight particles transported through the air and inhaled into the lungs. When they enter the airways, these particles, known as environmental triggers, cause an inflammatory response in the airway walls, resulting in an asthma attack.
Physicians typically diagnose asthma by looking for the classic symptoms: episodic problems with breathing that include wheezing, coughing, and shortness of breath. When symptoms alone fail to establish a diagnosis of asthma, doctors may use spirometry, a test that measures airflow. By comparing a patient’s normal airflow, airflow during an attack, and airflow after the application of asthma medication, doctors determine whether the medicine improves the patient’s breathing problems. If asthma medication helps, doctors usually diagnose the condition as asthma.
Identifying the specific trigger of a patient’s asthma is usually more difficult than the initial diagnosis. Triggers may be easily recognizable and consistent; for example, a patient may always develop an asthma attack when using a particular cosmetic or household cleaning product. When the triggers are more difficult to identify, doctors perform a series of allergy skin tests to help determine whether allergy triggers are responsible. Skin tests are not conclusive, however, because patients may have skin reactions to substances that do not necessarily trigger an asthma attack. Doctors may also use spirometry to evaluate a patient’s airflow before and after exposure to common triggers. Triggers that decrease airflow may be responsible for the patient’s asthma.
Although there is no cure for asthma, effective treatment is available for preventing attacks and for controlling and ending attacks soon after they have begun. Asthma medications are taken orally or inhaled in vapor form using a metered-dose inhaler, a hand-held pump that delivers medication directly to the airways. There are two kinds of asthma medications: bronchodilators, which reduce bronchospasm; and anti-inflammatory medications, which reduce airway inflammation.
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