Asthma Diagnosis

  • Diagnosis

    Asthma is a chronic respiratory disease that causes difficulty breathing Figure 01. Asthma is caused by inflamed and constricted airways brought on by an allergic reaction or an environmental trigger. It is potentially life-threatening, but is controllable. Asthma often begins in childhood, even as early as infancy; however, it can occur at any age, even among elderly individuals.

    In asthma, the airways become narrowed, thereby trapping air and causing the lungs to become overinflated. The narrowing can occur in varying degrees over a short period of time, causing mild to severe breathing difficulty during an attack.

    Asthma affects more than 15 million people in the U.S., where the disease is responsible for more than 5,000 deaths each year. It is the most common chronic disease of childhood. While asthma can be very disruptive, frustrating, and expensive, if properly controlled, the likelihood of danger and discomfort decreases significantly.

    Asthma attacks can begin suddenly, or they can take days to develop. An asthma attack occurs when the airways undergo changes due to respiratory infection, allergies, irritants, and other environmental triggers.

    The inflammation of asthma causes recurrent episodes of wheezing, breathlessness, tightening of the chest, and coughing. The episodes often occur at night or in the early morning hours.

    Asthma is thought to have two primary stages: hyper-reactivity and the inflammatory response. The first stage, hyper-reactivity (also referred to as hyper-responsiveness), occurs when the smooth muscles in the airways constrict and narrow when exposed to inhaled allergens or other irritants. The airways of someone with asthma do not relax, making breathing difficult. The second stage is the inflammatory response. This reaction causes the airways to swell, fill with fluid, and produce thick, sticky mucus. You then experience wheezing and breathlessness, have difficulty exhaling, and have a cough that produces phlegm.

    Asthma attacks can be mild or severe. If you are having a mild to moderate attack, you may experience a tight sensation in the chest, wheezing, coughing, and difficulty sleeping. After you take asthma medication, the airways usually open up within a few minutes and the symptoms diminish.

    If you are having a severe asthma attack, you will become increasingly breathless, and your neck muscles may become tight. The lack of oxygen will cause your skin to turn bluish, and the skin between your ribs will appear to be sucked in. You may even lose consciousness. Both asthma medication and emergency medical assistance are essential during a severe attack.

    Click to enlarge: Anatomy of the lungs and inflamed airways

    Figure 01. Anatomy of the lungs and inflamed airways

    An asthma attack is usually triggered by something that bothers the lungs. The exact causes of asthma are complex and varied, and it is often difficult to determine precisely what initiates an attack. Genetic susceptibility and environmental triggers are among the factors believed to cause asthma. Intense exercise, especially when performed in cold air, may induce asthma. Asthma usually is worse at night when the airways are cooler, mucus does not clear as effectively, and the metabolism of medications can become altered. Sleep apnea may also be related to the incidence of asthma attacks. Sleep apnea is a disorder that occurs when the body “forgets” to breathe. Breathing ceases for a few seconds (sometimes as much as two minutes, or more) during sleep, but not as a result from an obstruction in the airways. The muscles that control breathing simply don't function correctly.

    Viral infections can be potent triggers. Viral respiratory infections, including the common cold and influenza, can be triggers for a severe asthmatic attack. Viral infections may be the main factor that causes chronic asthma.

    The common cold (rhinovirus) is one of the most common infectious agents associated with asthma attacks, and it can provoke and intensify asthma attacks.

    Allergens can initiate or perpetuate asthma. Airborne pollens, molds, dust, animal dander, and cockroach allergen can trigger asthmatic attacks. The dust mite, a component of house dust, is one of the key causes of asthma symptoms. Dust mites are invisible to the naked eye, and live in bedding, fabric, and carpet. Tobacco and wood smoke, perfume, paint, hair spray, or any other fumes can play a role in triggering asthma attacks. Food allergens or additives also are believed to trigger asthma.

    There is an association between gastroesophageal reflux disease (GERD) and asthma. Gastroesophageal reflux disease (GERD) causes heartburn when acid from the stomach creeps into the esophagus. The condition is common in many patients with asthma. Some researchers believe that GERD may cause asthma when the acid spill reaches the throat. The irritation this acid causes to the trachea (the tube which brings air in and out of the body) is believed to trigger spasms and narrowing of the airways in the lungs.

    Gastroesophageal reflux often is made worse with the use of oral theophyline, a commonly used bronchodilator medicine that helps stop asthma attacks. Reflux can be made worse because the bronchodilator medicine relaxes the gastroesophageal sphincter, thus allowing even more highly acidic digestive fluids to leak out of the stomach.

    Hormones may be involved in asthma. Some patients whose bodies produce too much thyroid hormone (hyperthyroidism) have persistent asthma. In asthmatic women, asthma frequently gets worse before menstrual periods.

    There is a close association between sinusitis and asthma. Sinusitis is an inflammation or infection of the air pockets on either side of and behind the nose. A reflex from the inflamed sinuses can trigger an asthma attack.

    Typical asthma symptoms include coughing, shortness of breath, a wheezing sound during breathing, and a tight feeling or pain in the chest. If you have asthma, you are likely to experience at least one or more of these symptoms, which may become worse at night.

    In severe cases, asthma attacks can be life-threatening. Your breathing may become shallow as your chest works to exhale sufficient air from the lungs. Without adequate oxygen, your skin will turn a bluish color, and the skin around your rib cage will look sucked in. If untreated, you may start to lose consciousness.

    Asthma symptoms vary in severity. The symptoms can range from an occasional mild attack of breathlessness to persistent wheezing that does not improve with medication. Asthma symptoms can be seasonal, or can be present year-round. They can come on sporadically, or can be continuous.

    Asthma-like wheezing can occur as a result of other serious conditions. Serious lung conditions such as croup, Kartagener's syndrome, and cystic fibrosis; or an obstruction in the trachea, could cause wheezing. Chronic bronchitis and emphysema, the diseases that so often plague smokers, are also associated with wheezing, as is cardiac failure or vocal cord dysfunction. Speak to your doctor about any breathing difficulties you are having, as there are many possible reasons for why you are having trouble.

    Young children are more likely to develop asthma. Asthma often starts during childhood. A child who develops asthma is genetically inclined to have a hypersensitive reaction to environmental allergens (atopy). Individuals with atopy produce antibodies that are directed toward commonly found allergens such as dust mites, pollen, animal proteins, and mold.

    Infants and young children who experience wheezing along with viral respiratory infections or allergies, or who have a family history of allergies are likely to have a type of asthma that will continue through childhood.

    Adult-onset asthma may have a variety of causes. Asthma can develop at any age, although it most often starts during childhood and adolescence. Adults who develop asthma frequently may have coexisting sinusitis, nasal polyps, and sensitivity to aspirin or similar nonsteroidal anti-inflammatory medications.

    Occupational exposure to workplace materials, such as animal products, biological enzymes, plastic resin, wood dusts, and metals may trigger asthma attacks. Individuals exposed to certain irritating materials in occupational settings may experience airway inflammation, bronchial hyper-responsiveness, and clinical signs of asthma.

    While identifying and removing the trigger can reduce asthma symptoms, some individuals continue to suffer from persistent asthma even after they are no longer exposed to the chemical or allergen that is making them sick. Other individuals who develop occupational asthma remain permanently impaired after leaving the job site.

    Asthma frequently runs in families. If both parents have asthma, the probability that their child will have asthma is greater, although not all children will necessarily experience the same degree of severity. In pairs of identical twins, one may have asthma but the other may not, suggesting that inherited genetic factors do not fully account for the development of asthma.

    Your doctor will ask questions to determine the nature and severity of your symptoms, and your risk factors. Your doctor will ask questions about your pattern of symptoms and any family history of asthma or allergies that can support the likelihood that you have asthma. Your doctor will also ask about the frequency and severity of your symptoms, about medications that you take, and about whether or not you are exposed to the kinds of triggers that are known to cause asthma in others, such as viral respiratory infections and allergens or irritants.

    Your doctor will perform a physical examination focusing on the upper respiratory tract, chest, and skin. Your doctor will look for hyperexpansion of the thorax (particularly in children), hunched-looking shoulders, and chest deformity, as these are physical findings that suggest asthma. Wheezing sounds during normal breathing or a prolonged phase of forced exhalation also may suggest asthma.

    Your doctor will also look for signs of an allergic reaction, such as increased nasal secretion, mucosal swelling, nasal polyps, or allergic skin conditions.

    Lung function tests are usually performed to confirm asthma and to determine its severity. Spirometry is a lung test doctors use to establish whether you have airflow obstruction, and whether it is reversible. Very precise measurements of inhaled and exhaled air are measured when you blow into a device called a spirometer. Spirometry is done periodically to assess obstruction and airway function.

    When asthma is suspected, but previous spirometry measurements were normal or almost normal, doctors can use other methods to diagnose or rule out asthma. These include provoking the bronchial tubes (bronchoprovocation) with methacholine, histamine, or exercise followed by spirometry.

    You can perform tests yourself in your own home to monitor your progress Figure 02. Peak flow meters also are helpful for measuring airflow obstruction. A peak flow meter can help to discover if there is airway narrowing hours, and perhaps even days before asthma symptoms appear. Peak flow meters are inexpensive, simple, and portable tests that you can use to monitor yourself between doctor visits. By keeping records of the measurements, you and your doctor can learn if the particular treatment plan you are using is working well, what makes the asthma worse, and when to add or drop medications. You obtain the measurements by blowing into a tube and reading the corresponding number. Peak flow numbers are color-coded into zones of red (danger), yellow (warning), and green (good), and show you how well your asthma is being controlled.

    Click to enlarge: Peak flow meter

    Figure 02. Peak flow meter

    Know what triggers your asthma. You can help to prevent asthma attacks by avoiding things known to make your asthma worse. Discuss asthma triggers with your doctor and take steps to avoid them. Specific triggers may vary from individual to individual.

    Avoid cigarette smoke. Smoking cigarettes will make asthma symptoms worse, and secondhand smoke may spur an asthma attack. Your doctor can suggest ways to help you stop smoking. Ask family members to stop smoking as well. Do not permit anyone to smoke in your home or around you. Protect children by making sure no one smokes at a children's day care center.

    Reduce your exposure to dust mites. Frequent vacuuming is beneficial, but will not completely remove house dust mites from carpeting or upholstered furniture. When vacuuming, use a dust mask, a double-layered or microfilter vacuum cleaner bag, or a vacuum cleaner with a high efficiency air filtration filter, known as a HEPA filter. Even better, find someone else to do the vacuuming and stay out of the rooms while they are being cleaned.

    Encase your bed mattress and pillows in special allergen-impermeable dust-proof covers. If you don't use dust-proof covers on your pillows, wash your pillows weekly in water hotter than 130°F (54.4°C). Sheets and blankets also should be washed weekly in hot water. Avoid resting on fabric-covered furniture. Having hardwood floors rather than wall-to-wall carpeting may help prevent dust from accumulating. Because high indoor humidity promotes dust mites, try to decrease indoor humidity to less than 50% by using a dehumidifier or a central air-conditioning system. Remove any carpets that are placed on concrete, as mold could grow there easily.

    Protect yourself from animal dander. If you own pets, you can take steps to minimize your exposure to animal dander. If you have a yard or patio, keep furred or feathered pets outside, weather permitting. If animals must live inside, keep them outside the bedroom and make sure the door is closed at all times. Keep pets out of rooms with carpets and fabric-covered furniture. Cover the air vents in the bedroom with a filter.

    Take necessary measures to prevent cockroaches. Many people with asthma are allergic to dried droppings and remains of cockroaches. Poison bait or traps can help control the pests. Food and garbage should not be left exposed, but kept in closed containers. Vigorous and frequent extermination procedures are required to remove cockroaches. If pesticide spray is used, be sure to stay out of the room until the odor is gone.

    Avoid exposure to pollen and outdoor mold. To avoid exposure to pollens from trees, grass, or weeds, and from outdoor molds, try to keep your windows closed during the season when pollen or mold spore counts are high. During allergy season, remain indoors with the windows closed; especially during the morning when pollen and mold spore counts are at their highest.

    Reduce moisture to help eliminate indoor mold. Reduce indoor humidity to less than 50% by using air conditioners or dehumidifiers. Fix all leaks and eliminate any other water sources that are associated with mold growth. Clean moldy surfaces with a product that contains bleach.

    Reduce exposure to other irritants. Try to avoid using wood-burning stoves, fireplaces, and kerosene heaters. Stay away from other irritants, such as perfumes, talcum powder, hair spray, paints, or any other substance that emits noxious fumes.

    Get a yearly influenza (flu) shot to protect yourself against influenza.

  • Prevention and Screening

    Know what triggers your asthma. You can help to prevent asthma attacks by avoiding things known to make your asthma worse. Discuss asthma triggers with your doctor and take steps to avoid them. Specific triggers may vary from individual to individual.

    Avoid cigarette smoke. Smoking cigarettes will make asthma symptoms worse, and secondhand smoke may spur an asthma attack. Your doctor can suggest ways to help you stop smoking. Ask family members to stop smoking as well. Do not permit anyone to smoke in your home or around you. Protect children by making sure no one smokes at a children's day care center.

    Reduce your exposure to dust mites. Frequent vacuuming is beneficial, but will not completely remove house dust mites from carpeting or upholstered furniture. When vacuuming, use a dust mask, a double-layered or microfilter vacuum cleaner bag, or a vacuum cleaner with a high efficiency air filtration filter, known as a HEPA filter. Even better, find someone else to do the vacuuming and stay out of the rooms while they are being cleaned.

    Encase your bed mattress and pillows in special allergen-impermeable dust-proof covers. If you don't use dust-proof covers on your pillows, wash your pillows weekly in water hotter than 130°F (54.4°C). Sheets and blankets also should be washed weekly in hot water. Avoid resting on fabric-covered furniture. Having hardwood floors rather than wall-to-wall carpeting may help prevent dust from accumulating. Because high indoor humidity promotes dust mites, try to decrease indoor humidity to less than 50% by using a dehumidifier or a central air-conditioning system. Remove any carpets that are placed on concrete, as mold could grow there easily.

    Protect yourself from animal dander. If you own pets, you can take steps to minimize your exposure to animal dander. If you have a yard or patio, keep furred or feathered pets outside, weather permitting. If animals must live inside, keep them outside the bedroom and make sure the door is closed at all times. Keep pets out of rooms with carpets and fabric-covered furniture. Cover the air vents in the bedroom with a filter.

    Take necessary measures to prevent cockroaches. Many people with asthma are allergic to dried droppings and remains of cockroaches. Poison bait or traps can help control the pests. Food and garbage should not be left exposed, but kept in closed containers. Vigorous and frequent extermination procedures are required to remove cockroaches. If pesticide spray is used, be sure to stay out of the room until the odor is gone.

    Avoid exposure to pollen and outdoor mold. To avoid exposure to pollens from trees, grass, or weeds, and from outdoor molds, try to keep your windows closed during the season when pollen or mold spore counts are high. During allergy season, remain indoors with the windows closed; especially during the morning when pollen and mold spore counts are at their highest.

    Reduce moisture to help eliminate indoor mold. Reduce indoor humidity to less than 50% by using air conditioners or dehumidifiers. Fix all leaks and eliminate any other water sources that are associated with mold growth. Clean moldy surfaces with a product that contains bleach.

    Reduce exposure to other irritants. Try to avoid using wood-burning stoves, fireplaces, and kerosene heaters. Stay away from other irritants, such as perfumes, talcum powder, hair spray, paints, or any other substance that emits noxious fumes.

    Get a yearly influenza (flu) shot to protect yourself against influenza.

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