Asthma is a chronic disorder involving the lung's airways. It is characterized by obstruction and sensitivity of the air passages causing impaired air flow. Fortunately, asthma is treatable. Asthmatics must be treated any time there is an aggravation of baseline symptoms to prevent the possibility of fatal progression. Several classification systems exist based on cause, severity and control to help guide treatment to reduce impairment and prevent exacerbation, according to the National Asthma Education and Prevention Program's 2007 Guidelines for Diagnosis and Management of Asthma.
Classification by Disease Process
Recognizing the presenting disease process leads to appropriate initial management for the patient. Discovering the trigger for asthmatic symptoms reduces exacerbation, and guides treatment recommendations by physicians, thus, the importance of classifying asthma based on its cause. Avoiding triggers, or causes, is the best initial management. One must first identify the trigger. There are many causes of asthma symptoms. Aspirin-induced, tobacco-induced and exercise-induced asthma may be avoidable, while other triggers are unavoidable like cold-air intolerant asthma, upper respiratory-induced and allergen-induced asthma. Still other triggers may be modifiable, but difficult to change like GERD (gastroesophageal reflux disease)-induced asthma whereby symptoms may be less prominent with medications. Occupational and stress-induced asthma are more likely to be avoidable with moderate difficulty. Other lesser-known triggers exist as well.
Classification by Severity of Process
Classifying asthma based on severity helps to guide specific long-term treatment needs for the individual patient. There are four categories used to determine severity. Mild intermittent asthma is defined as symptoms less than two times per week. Typically these patients lack symptoms between exacerbations and do not require daily treatment. A metered dose inhaler is sufficient during infrequent exacerbation of symptoms.
Mild persistent asthma is defined as symptoms that occur more than twice a week, but no more than once in a single day. Those with mild persistent symptoms are usually bothered at night more than twice a month with peak flow greater than 80 percent. Peak flow measures the forced air out of the lungs a person can blow in the first seconds of expiration. Measurements taken when a patient has no symptoms is compared to a measurement taken during symptoms. A high peak flow indicates that the tubes in your lungs are open. A low peak flow indicates that they are closed. Asthmatics should use peak flow to regular monitor their asthma symptoms.
Increased need for rescue inhalers exists in the patient with moderate persistent asthma. Daily use of rescue inhalers with flare-ups more than twice a week identifies this group. The classification of moderate persistent includes a peak flow of less than 80 percent, but greater than 60 percent, according to the American College of Asthma, Allergy and Immunology. Limitation of physical activity is also seen.
Those with severe persistent asthma have daily limitations of activity with symptoms on most days and at night. Severity is indicated by a peak flow of less than 60 percent. Treatment is recommended based on these four classifications. Asthma severity may change over time and so will management.
Classification of Asthma by Control
Classifying disease by control enables physicians and patients to understand management goals for monitoring and adjusting therapy. There are three control processes: well controlled, not well controlled and poorly controlled. Asthmatics with few night time symptoms, no limitations in activities and one exacerbation per year are considered well-controlled. Those that have symptoms up to three times per week and more than two exacerbations of symptoms per year are not considered well-controlled. Poorly-controlled asthmatics have symptoms several times a day with nighttime awakenings of more than four per week, as well as extreme limitation of normal activities such as walking and running. Recommendations for the latter two categories include reevaluation. For poorly controlled asthma, daily corticosteroids are necessary.
References
- National Asthma Education and Prevention Program Report Panel 3: Guidelines for the Diagnosis and Management of Asthma
- Merck Manual: Asthma
- Mayo Clinic: Asthma
- Asthma Initiative of Michigan for Healthy Lungs-Guidelines for the Diagnosis and Treatment of Asthma
- American College of Allergy, Asthma & Immunology: Guidelines for the Diagnosis and Management of Asthma
