OVERVIEW OF ASTHMA
OVERVIEW OF ASTHMA
Common and important questions:
What is asthma?
Why do I have it?
What can I do about it?
Will I always have it?
What is asthma?
Asthma is a condition in which the airways in the lungs overreact to various triggers resulting in narrowing. These narrowings cause obstruction to the flow of air. This happens recurrently and causes one or more of the following symptoms:
Tightness in the chest;
Labored breathing;
Coughing;
Noises in the chest -rattling, or a whistling on expiration (wheezing)
As a result of these symptoms, patients with asthma may not tolerate exertion. The may awaken frequently at night. More severe symptoms may result in requirements for urgent medical care and hospitalizations. For a very few with particularly severe asthma, there is a risk of fatality.
Asthma affects the airways, which begin just below the throat as a single tube called the trachea (see the following picture). In the chest, the trachea is located just in front of the esophagus, the tube that connects the throat with the stomach. The trachea divides into two slightly narrower tubes called the main bronchi (each one is called a bronchus). Each main bronchus then divides into progressively smaller tubes –the smallest are called bronchioles-to carry air to and from microscopic air spaces called alveoli. It is in the alveoli that the important work of the lung occurs, exchanging oxygen in the air for carbon dioxide in the blood.
The airways (trachea, bronchi, bronchioles) are surrounded by a type of muscle, which doesn’t have any voluntary control. This type of muscle is known as smooth muscle (to tell the difference from skeletal muscle, which we control to move parts of our body). The airways are lined with cells that secrete a thin layer of mucus and fluid. This mucus washes the airways to remove any bacteria, dirt or other foreign material that might get into our lungs.
Overreaction, often-called hyper reactivity of the airways can result in bronchospasm, which is a spasm of the bronchial smooth muscle. Or it can cause inflammation, with swelling of the lining of the airway and secretion of excessive thick mucus. Bronchospasm or inflammation can occur alone, but usually happen in some degree of combination. An important part of the evaluation process is to identify the role each of these factors play in your asthma because they respond to different types of medications.
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Each individual patient is different and will respond to an individual trigger differently. But the airway hyper reactivity leading to airway obstruction usually occurs from contact with one of more of the following triggers:
Viral (but not typical bacteria) respiratory infections = common colds;
Inhaled allergens (pollens, dusts, molds, animal danders);
Inhaled irritants (cigarette smoke, wood-burning stoves and fireplaces
strong odors, chemical fumes);
Cold air;
Exercise;
Occasional ingested substances (aspirin, sulfite preservatives, specific foods)
Sometimes these exposures just act as triggers to cause brief symptoms with rapid relief once exposure ends. Unfortunately, the airways may become even more sensitive after even brief exposure to a trigger. Therefore, a different reaction can be seen in the same patient to the same trigger, at different times.
The obstruction of the airways decreases the rate at which air can flow. This may be felt as tightness in the chest or seen as difficulty breathing. The obstruction and inflammation usually causes coughing. If old enough, obstruction to air flow can be measured with pulmonary function testing, which can detect degrees of airway obstruction not yet causing symptoms. Pulmonary function measurements can be made before and after medication to see response. This testing is an extremely valuable tool to evaluate your asthma.
[pic]
The increased mucus in the airways stimulates coughing as the body attempts to clear the airways. The unusually thick mucus id difficult to clear and can cause continued coughing that fairs to clear the airways. General irritability of the airways also causes coughing.
Narrowing of the airway causes noises when enough air passes through them at the right speed. A typical high-pitched whistling-like noise is called wheezing. Rattling is the sound of air moving mucus around. Since some of these noises can be common, it is important to tell whether these noises are more or less concerning. Noises that are heard only when breathing in (inspiration) are usually from the upper respiratory tract. These are usually less concerning and can be caused by many things. Those that are heard best when breathing out (expiration) are more usually transmitted from inside the chest. These are more concerning. While the noise itself is not worrisome, it is generally not normal. Often both are heard, so we try to determine which are more prominent.
The coughing and mucus production may cause some physicians to diagnose bronchitis. It can be especially confusing, when upper respiratory cold symptoms are present. The term “bronchitis” however means inflamed airways. For a patient that has asthma, the inflamed airway is from asthma, not from an infection of the lower airways. Bronchitis in pediatric patients that don’t have asthma is relatively rare and should only occur every few years. If it occurs more often than that, it should make someone question whether asthma is more likely.
Also in pediatric patients, the cause of infectious bronchitis is almost always either viral or an unusual bacteria called Mycoplasma. Neither of these responds to typical antibiotics. Usually only those patients who are long-term smokers or who have significant immune problems get infectious bronchitis that will respond to typical antibiotics. Consequently, asthma medications are the appropriate treatment for the “bronchitis” of asthma.
If an airway becomes completely obstructed or blocked, the segment of lung beyond the obstruction can collapse. These collapsed segments cast a shadow on chest x-ray (called atelectasis). The rattling sounds or increased shadows on x-ray are often misinterpreted as pneumonia. The inappropriate diagnoses of bronchitis and pneumonia cause much unnecessary use of antibiotics, which are ineffective, both for asthma in general and for most of the infections that can trigger asthma. These are usually viral infections and not bacterial (antibiotics are effective only for bacterial infections).
Asthma is quite variable. Symptoms can range from trivial and infrequent in some, to severe, unrelenting and dangerous in others. Even when severe, however, the airway obstruction is usually fully and completely reversible. This can happen either spontaneously (without medication) or as a result of treatment. Symptoms can be relieved; airway obstruction reversed; and pulmonary function can be made normal.
There are different patterns of asthma. Some people have only intermittent patterns of disease (Intermittent asthma). Usually, these patients only have symptoms when they have colds, but they should have extended periods without any asthma problems even though they are not using medication. This pattern is more commonly seen in young children in whom viral respiratory infections are frequent (average 6-10 per year during the toddler and preschool age group).
Prolonged periods of symptoms occur in some patients with a seasonal allergic pattern of disease. (Seasonal allergic asthma) This may be from grass pollen on the West Coast or mold spores from molds that grow on decaying vegetation in the Midwest. Your doctor may request allergy skin testing, which with knowledge of the surrounding areas allergy patterns can attempt to identify whether the symptoms fit into this pattern of disease.
Some patients have a persistent pattern of disease (Persistent asthma). Although variable in severity, symptoms occur regularly, usually daily or several times per week. These patients do not have extended periods free of chest tightness, labored breathing, exertion intolerance or cough.
Patients with a persistent pattern of disease may additionally have acute exacerbations (asthma attacks) triggered by the same factors that cause symptoms with an intermittent or seasonal pattern of disease. Thus, viral respiratory infections or colds and specific environmental exposures may further increase the severity or frequency of symptoms in these patients.
All patterns of disease are associated with varying degrees of severity ranging from mild to severe. It is your doctor’s job, with your help, to identify the pattern and severity of your disease and provide you with effective intervention measures to rapidly relieve acute symptoms. Also to determine appropriate controller measures for those with extended symptomatic periods (persistent or seasonal allergic).
Why do I have it?
Over 10% of people have asthma. It often runs in families along with allergic rhinitis (hay fever) or atopic dermatitis (eczema). The inheritance pattern of asthma is not well understood in how it passes from parents to children. All we can say is that families with asthma, allergies or eczema are more likely to have children with asthma. Although there appears to be an inherited disposition to develop asthma, the severity varies considerably among patients even in the same family. If asthma is present in both parents, the likelihood of a child having asthma is even greater, but even then not all of the children will have asthma. Even among identical twins, both do not necessarily have asthma, although this is more likely than if they were just siblings or non-identical twins. This supports the belief that there are some additional factors that we do not yet fully understand, in addition to inheritance, that influence the development of asthma.
Asthma commonly begins early in childhood, even in infancy. But it can begin at any time even among the elderly. In many cases, asthma runs in families; sometimes it does not. Sometimes is goes away with time; sometimes it does not. We do not know what causes asthma to start nor can we predict exactly who will lose it over time. We do know that people with asthma can be provided with the means to control the disease and prevent symptoms that interfere with daily living. Rather than ask, “Why do I have asthma?” it may be better to ask “How can I control my asthma so I may have as little interference as possible from daily life?”
What can I do about it?
Asthma can be controlled! What’s more, those who have asthma can control it. In other words, the physician’s role is to help the patient and family learn how, and provide the tools so that it can be managed at home.
Since asthma varies greatly in pattern of symptoms and severity, the treatment plan needs to be individualized. This will be done in a systematic manner. Goals of therapy must be realistically attainable and explicitly defined by you and your physician. The plan for reaching these goals must be understood. Once the measures needed for control of asthma are identified, they can be placed in the hands of the patient with appropriate instructions to use. Parental supervision is needed for young children, but progressive responsibility for self-management is given with advancing maturity.
Treatment may consist of medication, environment changes, and life-style modifications. The more the patient or family understands the disease and its treatment, the better the outcome is likely to be. The patient and family need to be an active partner in making decisions about treatment. Be aware of superstitions and misinformation regarding asthma. More than almost any other medical problem, asthma is associated with a wide diversity of medical and non-medical opinion. Both the physician and the patient need to exercise judgment. Four common sense measures to remember are:
Ineffective measures should not be continued.
Effective measures should be continued as long as they are needed unless risk
exceeds benefit.
Treatment should not be worse than the problem being treated.
Treatment should be the simplest that is adequate.
You must also understand why measures are used so that you can take an active part in learning what measures are required and when they should be used. Learn the names of your medications (some have more than one, such as Proventil which is the same as albuterol). Watch closely and don’t discount your observations. Discuss your observations and concerns with your doctor. Ask questions. Answering your questions is part of the physician’s job in providing you with the skills to manage your (or your child’s) asthma. The final goal is for you, not the physician, to be treating the asthma. After all, you are there when it occurs. Your physician will try to determine the most appropriate therapeutic measures. But even the best plans are not worth much until they are put into use.
Will I always have asthma?
Asthma has a variable course. Many children with asthma see it improve or appear to go away as they get older. This can happen any time in childhood or adolescence. If asthma is Intermittent in type, triggered mainly by viral respiratory infections, there is an excellent likelihood that asthma will be much less of a problem as the child gets older. Sometimes the nature of the asthma changes with age. A young child may have asthma initially only with viral infections. As the child ages, it usually occurs less with colds (because older children get fewer viral infections than younger children), but inhalant allergy may become an important contributor to the asthma. Asthma may persist into adult life, or return later in adult life after a remission.
Approximately half of children with Intermittent asthma have little or no problem after adolescence. There appears to be no way to predict who will “outgrow” their asthma and who will not. This does not relate to severity however. Very severe asthma often goes away, and mild asthma may persist. Even when asthmatic symptoms cease to be a problem for a while, there is no assurance that asthma will not return later in life. We should therefore, not talk about “growing out of asthma” in children but should instead refer to extended periods of remission when asthma becomes quiescent. Asthma that persists into adult life, returns in an adult or begins later in life, is much less likely to go into remission. Waxing and waning of severity may occur. Additionally, we know that better control of asthma reduces the sensitivity of the airway and gives the best chance of remission.
Whatever the course, asthma is virtually always controllable with acceptable safe measures. Repeated evaluations of asthma should assess whether the disease is still active and continues to need treatment. Withholding treatment in the hopes that asthma will go away by itself is often self-defeating. While it may indeed occur, there can be quite a bit of avoidable suffering and disability in the meanwhile.
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