Definition

Asthma is a disorder of the bronchial tubes (the smaller airways in the lungs) characterized by over sensitivity of these airways. During an asthma attack, the muscles that wrap around these bronchial tubes tighten, and there is more sticky mucous secreted. This narrowing and mucous plugging of the bronchi make it more difficult for air to move into and out of the lungs, and cause the wheezing sound and cough that is characteristic of an asthma attack. There are about two million children in the U.S. that have asthma.

Causes

No one really understands why certain children have overly sensitive airways. Sometimes, the tendency toward asthma is inherited, and occasionally it may be secondary to lung damage early in life as in certain premature babies that are born with severe breathing problems. It is not contagious. Often, no real cause for the asthma can be found. However, we do know that certain conditions can set off an episode of asthma in children that have the predisposition:

• Allergy - Most asthmatic children older than 5 years may have symptoms caused by allergy. Usually this is due to something inhaled in the air (e.g. pollen, dust, mold, animal dander). In infants, wheezing can occaisionally be caused by food allergy. Children with asthma often have other allergic problems, such as hayfever or eczema.
  
  
• Infection - Viral upper respiratory infections (colds) are the most common cause of episodes of asthma in children younger than 5. Some children actually seem to be "allergic" to the virus. Some doctors call this type of asthma "bronchitis", "wheezy bronchitis", "asthmatic bronchitis", or "reactive airways disease". Unlike the type of bronchitis found in adults that smoke, antibiotics will not usually help children with wheezing because the cause is not a bacteria, but a virus, allergy, or both.
  
  There is reason to be optimistic: 75% of children with viral-related wheezing will "outgrow" it as their bronchial tubes become larger.
  
  
• Exercise - Many children with allergic asthma can also develop "exercise-induced asthma". This usually starts 5 minutes or so after exercise starts and manifests as cough, chest tightness, and wheezing. It is more likely to happen in cold, dry air or if there are pollutants or allergens (e.g. pollens) in the air.
  
  
• Irritants - Though not a true allergy by medical definitions, some children wheeze when they breathe cigarette smoke, smog, hairspray, insect repellant, paint, etc.
  
  
• Drugs - 25% of children with chronic asthma may have more wheezing if they take aspirin. Acetaminophen (Tylenol) is usually tolerated well.
  
  
• Other - Some children may develop asthma if they have a sinus infection, pneumonia, or emotional upset. Asthma is often worse at night. Occasionally, nothing in particular can be pinpointed as the cause of an asthma exacerbation.

Treatment

Unfortunately, there is no cure for asthma. However, in almost all children, the symptoms can be controlled, and the child can lead a normal life with modern medical therapy.

• Environmental control - Allergens and irritants should be avoided as much as possible. There should be no cigarette smoking in the house of an asthmatic child. The bedroom should be kept dust-free. Don't use a vaporizer, as this can promote mold growth.
  
  
• Medication - There is now availabile a variety of medications to help the asthmatic child. You, your child and your doctor will determine which medicine or combination of medicines is best for your child based on his age, severity of symptoms, frequency of attacks, side effects, and, often, by trial and error.
  
  
  • Bronchodilators - These work by relaxing the muscles that surround the bronchial tubes:
    
    
    • Theophylline - This can be given as a liquid or tablet every six hours or in a long acting tablet or capsule that can be sprinkled on food every 8 to 12 hours.
      
      
    • Adrenergics - These can be given as shots (adrenaline), "breathing treatments" (metaproterenol), pocket-sized inhalers (metaproterenol, albuterol, terbutaline), or orally as liquid or tablets (metaproterenol, albuterol).
      
      
    • Anticholinergics - These have only recently been used for asthma. They must be inhaled.
    
    
  • Cromolyn - This drug must be inhaled. It is not used to treat wheezing, but is used in certain patients to prevent wheezing.
    
    
  • Steroids - Prednisone or other steroid medicines work by reducing the inflamation in the bronchial tubes. Occasional short term use of these drugs will not have significant side effects and can be of great help in stopping severe attacks and preventing hospitalizations. However, if used frequently or over a long period of time there can be severe side effects, so doctors are careful to use these only when necessary. Recently, pocket nebulizers for inhaling steroids have become available that are free of the side effects seen with oral steroids, so these are sometimes used in patients with chronic asthma.
  
  
• Immunotherapy ("Allergy shots")- If your doctor feels that your child's symptoms can't be adequately controlled with medication, he will refer him to an allergist for skin tests and possibly shots to "desensitize" the child. Allergy shots may be of help to some asthmatics whose symptoms are due to allergies, but will not be useful when symptoms are caused by viral infection, exercise, etc.
  
  
• General Health - Good nutrition and physical fitness are as important for children with asthma as they are for everyone. Children should also drink plenty of fluids to keep the bronchial secretions loose. With appropriate medication, nearly all children with asthma can take physical education class and can participate in competitive sports. As a matter of fact, 75 members of the 1984 U.S. Olympic Team had exercised-induced asthma.
  
  As much as possible, avoid exposure to cold and flu viruses and pay attention to careful handwashing to help lessen the number of respiratory infections that might trigger an asthmatic episode. If your child has severe asthma, your doctor may recommend a yearly "flu" shot.

When should I call the doctor's office?

Asthma severity can range from the patient who has only a nagging cough without wheezes, to a life threatening emergency. Fortunately, in most children, asthma is mild and easily controlled with medication. However, if your child has mild symptoms that do not clear in a few days with his usual medication, please call us. Likewise, if he seems to be having difficulty breathing and is not relieved after his medication is started, call us right away. It's always better to start asthma therapy "too early" rather than too late. If you are unsure about whether to give a particular medicine, how much to give, or whether your child needs to see the doctor, please call us. When you bring your child to see the doctor for asthma, either bring his medicines with you, or write down the names and dosages.

For additional information, you may write to:

Asthma and Allergy Foundation of America
1302 18th St., NW, Suite 103
Washington, D.C. 20032

American Lung Association
909 12th Street
Sacramento, CA 95814

Medical Sciences Bulletin Contents

Role of Vitamin C in Asthma Unclear

Reprinted from the November 1994 issue of Medical Sciences Bulletin , published by Pharmaceutical Information Associates, Ltd.

Unconventional therapy, which includes the use of vitamins and minerals, is on the rise in the United States. The $3 billion per year that Americans pay for vitamins indirectly increases health care costs, yet vitamin therapy has no clearly defined cost effectiveness. Great controversy surrounds the use of daily recommended doses or megadoses to combat disease and enhance health and immunity. Leonard Bielory and Rinki Gandhi, physicians at the New Jersey Medical School, Newark, have reviewed the medical literature to assess one aspect of vitamin use: vitamin C in the treatment of asthma.

Asthma, an episodic disease in which air passages narrow as a secondary response to the hyperresponsiveness of the tracheobronchial tree, is either extrinsic or intrinsic. In its extrinsic, or allergic form, mucosal hyperresponsiveness triggers atopy, rhinitis, sinusitis, elevated serum Immunoglobulin E (IgE) levels, nasal polyps, and increased bronchial responsiveness to methacholine-, histamine-, or cold air-provocation. The intrinsic, or idiosyncratic form occurs in the absence of these stimuli. Antigen-antibody interaction probably occurs on the surface of pulmonary mast cells, causing degranulation of those cells and the release of major basic protein, superoxide radicals, and eosinophilic cationic protein into the air passages. Ciliary function stops, mucosal integrity is disrupted, and cells exfoliate, resulting in obstruction and bronchoconstriction.

As long ago as 1803, an association was observed between vitamin C (ascorbic acid) deficiency and convulsive asthma in patients with scurvy. Found predominantly in citrus fruit, potatoes, and green vegetables, vitamin C -- a water-soluble vitamin -- is a reducing agent. In 1953, an Irish study concluded that vitamin-C deficiency was related to asthma; during acute asthma, vitamin-C excretion was reduced. During the 1970s, one study demonstrated low levels of vitamin C in asthmatics, but no significant difference in levels among different grades of asthma. Vitamin C levels were not related to atopy or the duration of asthma. More recent studies have shown that 500 mg vitamin C exerts antibronchospastic action, with significant changes in one-second forced expiratory volume (FEV1) and forced vital capacity (FVC). One double- blind randomized study reported a decrease in the frequency and severity of acute asthma; however, since the study was conducted during the rainy season, the results may stem from vitamin C's action in preventing infection. FEV1 increased with increased dietary vitamin-C intake in one large-scale study of 2526 healthy and asthmatic adults. Methacholine- induced bronchospasm decreased after vitamin-C intake, possibly because vitamin C interferes with metabolism of arachidonic acid, a mediator of asthma.

Studies of histamine-induced bronchoconstriction have not demonstrated a clear effect for vitamin C. Five hundred milligrams vitamin C was found to be ineffective against ragweed antigen. Among 10 asthmatic children in an uncontrolled study, vitamin C produced an insignificant decrease in total IgE, restoration of normal chemotaxis in 2 patients, and normal lymphocytic transformation in 4 patients. A single-blind study of 16 asthmatic children showed that when 1 g ascorbic acid was administered each day, polymorphonuclear leukocyte motility improved significantly.

The reviewers concluded that the medical literature does not support a definite indication for the treatment of asthma and allergy with vitamin C. However, chronic use of vitamin C may have effects that could not be measured in the short-term studies they examined. Further studies are therefore required to define the effects of vitamin C in asthma and to determine its cost-effectiveness. (Bielory L et al. Annals of Allergy. 1994; 73: 89-95.)