Allergic Asthma Lungs - Managing Your Allergies: Allergies
Content provided by the Faculty of the Harvard Medical School
Allergic asthma (lungs)
Allergic asthma (lungs)
Asthma is an inflammatory disease of the airways, and as such it affects how well — or not — a person can breathe. Asthma can be the result of an allergic reaction, but some people have asthma attacks that are triggered not by allergens but by irritants like smoke or even by exercise. Whatever the cause, anyone who has asthma or who lives with a family member who has asthma knows it can be a debilitating and potentially life-threatening disease.
Asthma is a major public health problem in the United States. And the disease has been on the increase for more than 20 years. The National Heart, Lung, and Blood Institute (NHLBI) estimates that asthma affects around 15 million Americans, of whom nearly 5 million are under age 18.
Asthma attacks can be relatively mild or so severe they leave a person struggling for the very air needed to sustain life. When a healthy person inhales, oxygen-laden air passes easily into the lungs via the branching tubes known as bronchi and bronchioles. The destination of the inhaled air is the grapelike arrangement of small sacs called alveoli and their networks of blood vessels deep in the lung tissue. There, an exchange takes place: Oxygen passes into the bloodstream, and carbon dioxide, a waste product, enters the lungs. As you exhale, the carbon dioxide exits the same way the oxygen-laden air entered.
In asthma, the flow of air through the airways is restricted, and air cannot travel as easily as it should. Sometimes the problem is temporary; at other times it persists, and the airways are permanently damaged in a process called remodeling.
How asthma restricts breathing
 In a normal bronchus (A), muscles are relaxed so that air easily travels through the airway. Asthma causes two problems that can restrict breathing. First, the bronchial muscles contract (B), often in response to an allergen or some other asthma trigger. Second, the bronchial walls, which always have some degree of inflammation in people with asthma, become swollen and filled with excess mucus (C). Some of the cells involved in inflammation of the airways are mast cells and eosinophils, which release chemicals that cause the airways to narrow (D).
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Allergic asthma is the result of what happens during an inflammatory response caused by an allergic reaction. In non-allergic asthma, which is more common in adults, some other, as yet poorly understood, mechanism accounts for the inflammation.
During an allergic reaction, inflammatory chemicals released by both mast cells and eosinophils cause inflammation in the airways. This causes the airway walls to thicken and the muscles in those walls to contract, narrowing the passage. Mucus then begins to fill the narrowed passage, and the airways become obstructed further. Should the muscles start to spasm, this exacerbates the situation. In a severe asthma attack, there’s more of everything — more inflammation, more muscle spasms, more mucus. The combination makes breathing very difficult and produces the distinctive wheezing whistle of asthmatic breathing.
Did you know?Up until puberty, asthma is more common in boys than in girls. After puberty, more women than men have asthma. |
Diagnosing asthma
Your symptoms are the first clue to a diagnosis of asthma. Wheezing, shortness of breath, coughing (especially at night), and a tight sensation in the chest are highly suggestive of asthma. But a conclusive diagnosis is necessary to rule out any other medical possibilities. If your asthma is more than mild, your doctor will want to find out what substances you’re allergic to. As with allergic rhinitis, the diagnostic process is instrumental to the design of the best possible treatment plan for your particular asthma symptoms.
Tell your doctor everything you can about what triggers your asthma attacks:
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Are your attacks related to your medications, including over-the-counter medicines?
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Are your attacks worse at work or at home?
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How often do you need a bronchodilator to relieve an asthma attack?
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How frequently do you awaken at night with symptoms?
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How much school or work time have you lost?
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How many courses of prednisone have you had and when?
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How many emergency department visits and hospitalizations have you had, and when?
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Have you ever needed to have a tube inserted into your windpipe to help you breathe?
Because of the potential for complications during an asthma attack, it’s important to identify what triggers your attacks so you can avoid exposure. However, a lot of things can trigger an asthma attack (see Table 4).
Asthma triggers | |
| Allergens |
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| Irritants |
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| Medications |
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| Medical conditions |
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The doctor will try to determine how well you are breathing with a spirometer. This device measures how much air you can blow out after taking a deep breath, and how quickly you can blow it out. The test helps determine how narrow your airways are. Another device to assess breathing capacity is a peak flow meter. You may be asked to use this hand-held device at home for a week or two. In a similar vein, the doctor may check your breathing with a spirometer during and after exercise. Your doctor may order blood tests to measure the total IgE and circulating eosinophils in your blood. You may have other tests to find out whether you have gastroesophageal reflux disease (GERD), which can bring on an attack, or sinus disease.
Asthma action plan
Treatment is a three-pronged assault, including avoiding your asthma triggers, using preventive medication, and treating asthma attacks with quick-acting medication.
Tobacco avoidance. As well as being life-threatening, smoking can make your life miserable by increasing the inflammation and damage to your airways. This leads to poorer lung function and, in some people, severe COPD in addition to asthma. Even passive exposure to tobacco smoke is harmful. Not only can it trigger an asthma attack, but research shows that just being around tobacco smoke increases a child’s risk of developing allergies and doubles a child’s risk of being hospitalized for asthma.
Exercise. For some people, exercise can bring on an asthma attack. But this doesn’t mean you have to throw in the exercise towel and become a couch potato. You can stay on your toes if you
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warm up before vigorous exercise
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exercise regularly several times a week
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ensure that your day-to-day asthma is under good control with appropriate anti-inflammatory drugs.
Certain asthma medicines may also help:
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cromolyn, nedocromil, or a short-acting beta-agonist taken before exercise
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regular use of a long-acting beta-agonist, taken with an anti-inflammatory drug
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regular use of an antileukotriene.
And remember to
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make sure your asthma is under control before you exercise.
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never exercise when your asthma is bad.
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always carry your short-acting beta-agonist reliever with you.
You need quick-acting medication to treat asthma attacks. If these attacks are other than mild and infrequent, you will need regular treatment with long-acting medications, also known as controllers, to help prevent future attacks and provide long-term control of your condition. The best way to administer either of these two types of asthma medicines is via inhalants that can quickly target the source of distress. Since a fair number of the medications come in inhalant devices such as metered-dose inhalers, an essential aspect of treatment is becoming adept at using the various types of devices.
Asthma medications
Delivering the medicine to where it will do the most good can be tricky for some people.
Delivery devices. There are three types of devices used to deliver inhaled medications:
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Metered-dose inhalers employ a chemical propellant to expel the medication out of a tiny, portable canister. Many people find it difficult to aim and fire these devices so that the medication goes into the airways rather than landing on the back of the throat. A device called a spacer can be attached to the inhaler to help direct the medication where it needs to go — into the airways.
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Dry-powder inhalers are small, portable devices that don’t use propellants to administer the dose.
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Nebulizers are larger devices that spray a liquid mist via a tube or mask that fits over the nose and mouth. Pressurized air or oxygen provides the momentum for the spray.
When you use corticosteroid inhalers, don’t forget to gargle and rinse after each medication to prevent unnecessary systemic absorption of steroids and to reduce the risk of getting a yeast infection, Candida, in the mouth.
Types of medications. There are two types of medications used for asthma — anti-inflammatory medications, which treat the inflamed airways and overproduction of mucus; and bronchodilators, which act by relaxing the constricted muscles within the inflamed airways.
How medications treat asthma
 When you inhale a bronchodilator or controller medication, the drug acts directly on your bronchial tubes (A). (Medications taken as tablets reach your lungs indirectly, through the bloodstream.) Quick relievers act as bronchodilators, relaxing muscles in the bronchial tubes so that the restricted airway passage reopens — often within minutes (B). Controllers may work to relax the bronchial muscles, reduce the cells and molecules involved in inflammation, or both (C).
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Quick-acting (reliever) medications are the short-acting bronchodilators, also referred to as beta-agonists. These include albuterol (Proventil, Ventolin), metaproterenol sulfate (Tornalate), and pirbuterol (Maxair) for relief of asthma. These medicines are much more specific in their action on the airways, have fewer side effects, and are much safer than ephedrine (Primatene Mist) that is available over the counter.
Long-acting (preventive) medications include:
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inhaled corticosteroids: budesonide (Pulmicort), flunisolide (Aerobid), fluticasone (Flovent), triamcinolone (Azmacort)
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long-acting beta-agonists: salmeterol (Serevent), formoterol (Foradil)
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antileukotrienes: montelukast (Singulair), zafirlukast (Accolate), zileuton (Zyflo)
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cromolyn (Intal) and nedocromil (Tilade)
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sustained-release theophylline
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anti-IgE: omalizumab (Xolair).
Asthma treatment during pregnancy
Pregnancy raises concerns for mom’s well-being and the safety of the fetus. In general, though, pregnancy does not appear to either increase or decrease the likelihood of asthma attacks. Nor does pregnancy seem to increase the risk for serious asthma complications. However, pregnancy does bring about certain changes that asthmatic pregnant women should be aware of. In particular, changes in lung volume during pregnancy could lead to greater difficulty with breathing for women who have acute asthma.
As soon as you find that you are pregnant, review your asthma medications with your doctor. Furthermore, because the greatest risk to the baby from most drugs is in the first trimester, it’s a good idea to review your medicines if you are planning a pregnancy. It goes without saying that any medications you take during pregnancy should belong to a category of drugs that has been deemed safe. This means that, whenever possible, your drugs should be in category A or B for safety.
Cracking the pregnancy drug codeTo be licensed by the FDA, all drugs must undergo rigorous testing in animals and people. But no medicine is completely risk free. The FDA has devised categories of drug safety for pregnancy. These categories are A, B, C, D, and X, with A meaning human studies show no risk and X meaning the drug should never be taken during pregnancy. The in-between categories of B and C don’t necessarily mean the drug is unsafe, rather that post-licensing human studies may not have been done or perhaps there is some problem found in animals but not proven for humans. Human studies of category D drugs show some risk for humans, but the potential benefit of the treatment outweighs the risk. Bear in mind that it’s only when a drug has been licensed and is being taken by a very large number of patients that problems become obvious; or vice versa, what may have been suspect disappears. So it’s not that unusual for a drug to be recategorized after it’s been around for a while. |
Throughout pregnancy, inhaled medications are preferable to oral ones because of less fetal exposure. And older medications may be advisable if for no other reason than there is more information available about their safety. For example, there’s no human pregnancy information available yet about the leukotriene modifiers. And although inhaled corticosteroids appear to be safe, only budesonide is a category B drug, a status it acquired in 2004. Of the antihistamines, the first-generation chlorpheniramine has long been considered the safest because it has been around the longest, similarly the decongestant pseudoephedrine. Of the second-generation antihistamines, loratadine and cetirizine are in category B.
If you are pregnant, it is important to keep your asthma under control throughout your pregnancy. Bad asthma control is far more dangerous to you and your baby than your asthma medication, because uncontrolled asthma reduces the amount of oxygen in your blood. This can result in less oxygen in the fetal blood, which is potentially very dangerous to the fetus. Do everything possible to avoid your asthma triggers. Smokers, for instance, should quit smoking.
Asthma and aging
While asthma usually appears first in childhood, it can also develop for the first time late in life. Diagnosing and treating late-onset asthma presents the allergist with some puzzles to solve. Other causes of the symptoms have to be ruled out, which may not be so straightforward as it is with young people. First, do the symptoms signify a heart condition? Or are they symptoms of another respiratory disease?
One condition that has very similar symptoms and is more often seen in seniors is COPD. Unlike mild to moderate asthma, where the situation in the airways is reversible and lung function can be improved, COPD patients have irreversible airway obstruction, most often caused by smoking, and their lungs are permanently damaged. To complicate matters, some people have both asthma and COPD.
Another wrinkle regarding late-onset asthma is that whereas most children with asthma also have allergies, this is not true of adults with asthma. However, the inflammation in the airways is very similar, whether or not it is caused by allergies. This means the treatments are the same, with one big difference — allergen avoidance isn’t an option because allergens can’t be identified!
Drawing up a treatment plan for seniors can be somewhat challenging because side effects of medications tend to increase with age. Studies have shown that long-term use of inhaled corticosteroids at higher doses can modestly increase a senior’s chance of developing glaucoma. In addition, because seniors tend to be on medications for other conditions, there’s more likelihood of unwanted reactions between drugs. But late-onset asthma is not a picture of gloom and doom. If you work with a good allergist or pulmonologist, your asthma symptoms can be successfully controlled — as they are in younger people.
| Last updated: | August 21, 2006 |
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| Reviewed By: | Faculty of Harvard Medical School |
Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.
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