Asthma secondary prevention

Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org] Phone:617-632-7753; Philip Marcus, M.D., M.P.H. [mailto:pmarcus192@aol.com]

Overview
The most effective treatment for asthma is identifying triggers, such as pets or aspirin, and limiting or eliminating exposure to them. Desensitization to allergens has been shown to be a treatment option for certain patients.

As is common with respiratory disease, smoking is believed to adversely affect asthmatics in several ways, including an increased severity of symptoms, a more rapid decline of lung function, and decreased response to preventive medications. Automobile emissions are considered an even more significant cause and aggravating factor.  Asthmatics who smoke or who live near traffic typically require additional medications to help control their disease. Furthermore, exposure of both non-smokers and smokers to wood smoke, gas stove fumes and second-hand smoke is detrimental, resulting in more severe asthma, more emergency room visits, and more asthma-related hospital admissions. Smoking cessation and avoidance of second-hand smoke is strongly encouraged in asthmatics.

Trigger control
The most effective treatment for asthma is identifying triggers, such as pets or aspirin, and limiting or eliminating exposure to them. Identification of allergen may be possible through skin test or other in vitro tests. Smoking cessation and avoidance of second-hand smoke is strongly encouraged in asthmatics. Since an individual spends majority of his time at home, efforts should be made to keep the home environment should be free from allergens. This can be done by cleaning and dusting the home regularly. If cleaning is not possible, a face mask should be used. Other options such as moving to a higher floor or to a different neighborhood can also be considered.


 * Dust mite which is an intestinal enzyme on fecal particles is a common household allergen. These allergens usually settle on fabrics. Therefore regular washing of beddings in hot water, removing rugs from bedrooms, using impervious covers for mattresses and pillows, avoiding soft toys, putting away clothings in closets minimizes the exposure to dust mites. There are no definitive recommendations for avoiding house dust mite. However, several studies have suggested that the use of acaricides and extensive bedroom-based environmental control programmes may be beneficial.


 * Pets such as cats and dogs are the source for allergens such as dander, urine and saliva. These allergens are usually airborne. Animals, if possible should be removed from home or should be given bath at least twice a week . American Academy of Allergy, Asthma and Immunology Indoor Allergen Committee recommends the use of air filters through out the house with forced air heating, with disposable HEPA filters that are regularly changed or a room air cleaner with a HEPA filter.


 * Cockroaches can produce allergens that trigger asthmatic attack. To control cockroaches, multiple baited traps or poisons, removal of potential food sources (such as refuse and unwashed dishes), and removing reservoirs of cockroach debris and standing water can be done.


 * Indoor molds may occur in homes with high humidity, standing water, or water damage. Keeping the areas dry, removing old wallpaper, cleaning with bleach products, and proper storage of firewood outdoors may help in preventing molds.


 * Pollen is one of the common causes of asthma and is difficult to avoid. However, the exposure can be minimized by closing doors and windows, using air conditioners or high-efficiency particulate air filters in the car and home, wearing a face mask covering the nose and mouth when mowing the lawn or gardening and vacationing elsewhere during pollen season.

Prevention medication
Current treatment protocols recommend prevention medications such as an inhaled corticosteroid, which helps to suppress inflammation and reduces the swelling of the lining of the airways, in anyone who has frequent (greater than twice a week) need of relievers or who has severe symptoms. If symptoms persist, additional preventive drugs are added until the asthma is controlled. With the proper use of prevention drugs, asthmatics can avoid the complications that result from overuse of relief medications.

Asthmatics sometimes stop taking their preventive medication when they feel fine and have no problems breathing. This often results in further attacks, and no long-term improvement.

Preventive agents include the following.
 * Inhaled glucocorticoids are the most widely used of the prevention medications and normally come as inhaler devices (ciclesonide, beclomethasone, budesonide, flunisolide, fluticasone, mometasone, and triamcinolone). Long-term use of corticosteroids can have many side effects including a redistribution of fat, increased appetite, blood glucose problems and weight gain. In particular high doses of steroids may cause osteoporosis. For this reasons inhaled steroids are generally used for prevention, as their smaller doses are targeted to the lungs unlike the higher doses of oral preparations. Nevertheless, patients on high doses of inhaled steroids may still require prophylactic treatment to prevent osteoporosis. Deposition of steroids in the mouth may cause a hoarse voice or oral thrush (due to decreased immunity). This may be minimised by rinsing the mouth with water after inhaler use, as well as by using a spacer which increases the amount of drug that reaches the lungs.
 * Leukotriene modifiers (montelukast, zafirlukast, pranlukast, and zileuton).
 * Mast cell stabilizers (cromoglicate (cromolyn), and nedocromil).
 * Antimuscarinics/anticholinergics (ipratropium, oxitropium, and tiotropium), which have a mixed reliever and preventer effect. (These are rarely used in preventive treatment of asthma, except in patients who do not tolerate beta-2-agonists.)
 * Methylxanthines (theophylline and aminophylline), which are sometimes considered if sufficient control cannot be achieved with inhaled glucocorticoids and long-acting β-agonists alone.
 * Antihistamines, often used to treat allergic symptoms that may underlie the chronic inflammation. In more severe cases, hyposensitization ("allergy shots") may be recommended.
 * Omalizumab, an IgE blocker; this can help patients with severe allergic asthma that does not respond to other drugs. However, it is expensive and must be injected.
 * Methotrexate is occasionally used in some difficult-to-treat patients.
 * If chronic acid indigestion (GERD) contributes to a patient's asthma, it should also be treated, because it may prolong the respiratory problem.

Additionally, the antidepressant tianeptine has shown significant efficacy in children with asthma.