What is Asthma?
Asthma is a chronic respiratory disease that causes the airways in the lungs to become inflamed and restricted. This results in coughing, chest tightening and consistent episodes of persistent wheezing. According to the National Asthma Education and Prevention Program (NAEPP), there are four stages of asthma severity.
Stage One: Mild Intermittent
Mild intermittent asthma attacks usually occur less than twice per week. The attack begins gradually, triggered by an infected or irritated air passageway. The smaller air passageways become inflamed causing a slight case of coughing, also accompanied by light wheezing and shortness of breath. Wheezing is an indication that air flow is constricted. At this stage, the duration of attack can last anywhere from a few minutes to several hours. The measurement of the air amount forced out of the lungs in one second is known as forced expiratory volume. Measuring the forced expiratory volume in stage one asthma will show more than 80 percent of normal lung capacity.
Stage Two: Mild Persistent
Mild persistent asthma attacks occur at least once per week. More extreme than stage one, in stage two the muscles surrounding the airways constrict causing tightness in the chest and shortness of breath. Coughing and wheezing also occur. The measurement of forced expiratory volume in stage two asthma is still greater than 80 percent but may vary by 20 percent.
Stage Three: Moderate Persistent
During a Stage Three attack, the asthma trigger affects the larger passageways in the lungs as the trachea (windpipe) and the bronchi and bronchioles become inflamed and infected. At this stage, the attack is much more severe as the muscles outside these airways constrict causing the passageways to narrow, letting less air through. The airways become swollen with mucous, which causes them to narrow even more. Breathing, at this stage, becomes increasingly difficult causing intensified episodes of coughing and wheezing. The measurement of forced expiratory volume during this stage is usually between 60 to 80 percent.
Stage Four: Severe Persistent
During a stage four attack all symptoms are continuous. Frequent episodes during both the day and night occur continually and can last for more than several days. A severe persistent attack causes the body to produce increased levels of leukotrienes. These substances secrete large quantities of mucous, which obstruct airflow. The airways in a stage four attack swell severely and can close up completely. Breathing is very difficult, and in an attempt to reduce or expel the amount of mucous present, the person experiencing the attack will persistently cough and wheeze. Physical activity at this stage is limited.