Different Kinds of Asthma
Asthma comes in a wide assortment of flavors.
One of the things we've come to realize about asthma is there are significant differences from person to person. Asthma presents itself as a very individualized disease. That's one of the big reasons that a "cure" for asthma is so difficult to pin down.
Modern medicine breaks asthma down into two basic groups based on the causes of an attack, Extrinsic (Allergic or Atopic) and Intrinsic (Nonallergic or Nonatopic) Asthma. Most asthmatics don't fall neatly into either group but somewhere in between, displaying characteristics of both classifications. The leaning toward Extrinsic or to Intrinsic Asthma gives us our distinct flavor or presentation of asthmatic symptoms. Interestingly, falling into one group or the other has little to do with the way an asthmatic is treated for the disease.
Extrinsic (Allergic or Atopic) Asthma is characterized by having asthma attacks that have a known cause. Allergies to dust mites, various pollens, grass/weeds, pet danders, etc. are causes of Extrinsic asthma symptoms. Atopy is the hypersensitivity of the airways to the above Asthma Triggers. Individuals with atopy have a genetic predisposition to produce an excessive amount of IgE antibodies in response to many asthma triggers. In other words, our immune system overreacts to these asthma triggers, in normal individuals the same exposure would not produce symptoms. Its our own immune systems that produce the disease.
Once an Asthma Trigger antigen is introduced into our systems it causes the immune system to release IgE antibodies. These antibodies attach themselves to Mast Cells located in the bronchial walls. IgE antibodies attached to Mast Cells react with the Asthma Trigger antigen and destabilize the cell membranes of the Mast Cells. Mast Cells begin to release chemicals like; histamine, eosinophil chemotactic factor of anaphylaxis (ECF-A), neutrophil chemotactic factors (NCF), leukotrienes, prostaglandins, and platelet-activating factor (PAF). These are the chemical that stimulate the parasympathetic nervous system which causes bronchospasm of the muscles surrounding the airways. These chemicals also allow fluids to escape the capillaries leading to dilation of blood vessels and edema, further restricting air flow.
Asthmatic symptoms from Extrinsic asthma can start within minutes of exposure and/or hours later. The symptoms that start within minutes can resolve within an hour. The late reactions can follow the early one and last much longer.
Intrinsic (Nonallergic or Nonatopic) Asthma has known causes, but the connection between the causes and the symptoms are not clearly understood. There is no antigen/antibody hypersensitivity reaction, IgE levels remain normal.Intrinsic asthma usually starts in adulthood without strong family history of asthma.
Some of the known causes in Intrinsic asthma are:
Infections such as cold and flu viruses are common causes in adults. In children, respiratory syncytial virus (RSV), rhinovirus, and influenza virus are common causes.
Exercise and Cold Air often cause asthma symptoms to occur 5 to 10 minutes after exercise. Cold weather sports like ice skating, hockey, jogging, and cross country skiing are more likely to cause symptoms.
Industrial and Occupational Exposure to Pollutants are known to causes asthma symptoms. Air pollutants including smoke, ozone, noxious gases, sulfur dioxide, nitrous oxide, dust are substances we all may be exposed to. OtherOccupational hazards include isocyanate (found in polyurethane, plastics, varnish, and car spray paints), organic dusts (saw dust from various woods), and tobacco smoke from cigarettes, cigars, pipes, etc.
Food Additives and Preservatives such as food coloring like Tartrazine, bisulfites and metabisulfites (preservatives found in salad bars, some wines, beers, and dry fruit). This group also include drugs including aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs).
Gastroesophageal Reflux (GERD) can stimulate bronchoconstriction. GERD is also associated with Sleep (Nocturnal Asthma). Retained secretions, suppressed cough, lengthened time between medications, and exposure to irritants and allergens in the bedroom also contribute to night time increase in asthma symptoms.
Lastly, Emotional Stress, anxiety, and other psychological factors can make initiate and make asthma symptoms worse.
As stated at the beginning of the article, Extrinsic and Intrinsic Asthma usually exist side by side in most asthmatic. One or the other predominates to some degree to give each of us our distinct and individual flavor of asthma.
This article was written from information obtained in Clinical Manifestations & Assessment of Respiratory Disease, Third Edition, by Terry Des Jardins and George G. Burton, Copyright 1995, Published by Mosby a Times Mirror Company