lung and airway disorders
Asthma
Classification of Asthma
Unlike high blood pressure (in which one factor, the blood pressure value, defines the severity of the disorder and the effectiveness of treatment), asthma causes a number of symptoms and testing abnormalities. Also, asthma symptoms typically worsen and improve over time. Doctors evaluate the severity of asthma, and after treatment starts, they monitor how well the person's symptoms are controlled because that information helps doctors determine whether additional drugs are needed. Severity is a measure of how bad a disease is. Asthma severity is usually assessed before treatment is started, because people who have responded well to treatment have few symptoms. Asthma severity is categorized as Intermittent: The person's symptoms occur two days per week or less and do not interfere with activities of daily life Mild persistent: The person's symptoms occur more than twice per week but only slightly limit activities of daily life Moderate persistent: The person's symptoms occur daily and limit some activities of daily life Severe persistent: The person's symptoms occur throughout the day and interfere excessively with activities of daily life It is important to remember that the severity category does not predict how serious an attack a person may have. Even a person who has mild asthma with long periods of no or mild symptoms and normal lung function may have a severe, life-threatening asthma attack. The most severe form of asthma is called status asthmaticus. It is severe, intense, prolonged airway narrowing that is resistant to treatment. In status asthmaticus, the lungs are no longer able to provide the body with adequate oxygen or to remove carbon dioxide adequately. Without oxygen, many organs begin to malfunction. The buildup of carbon dioxide leads to Acidosis , an acidic state of the blood that affects the function of almost every organ. Blood pressure may fall to dangerously low levels. The airways are so narrowed that it is difficult to move air in and out of the lungs. Status asthmaticus may require that an artificial airway be passed through the person’s mouth and throat into the main airway leading to the lungs (the trachea) and that a mechanical ventilator be used to assist breathing. Sometimes breathing can be assisted by a machine without inserting a breathing tube (called noninvasive ventilation). Higher-than-normal doses of several drugs are also needed. Control is the degree to which symptoms, effects on daily life, and risks of severe asthma attacks are minimized by treatment. Asthma control is similar to severity, but it is assessed after treatment has started. The goal is for all people to have well-controlled asthma regardless of disease severity. Control is classified as Well controlled: Symptoms occur twice per week or less often Not well controlled: Symptoms occur more than twice per week but not every day Very poorly controlled: Symptoms occur daily Impairment refers to the limitations symptoms place on daily life. Impairment due to asthma is determined by asking How often symptoms are experienced How often the person awakens at night How often the person uses a short-acting beta-2 agonist for symptom relief How often asthma interferes with normal activity Other factors, such as measures of lung function, responses to standardized questionnaires, and what drugs are used to treat asthma, are also used to determine the severity, control, and impairment of asthma. Risk refers to the likelihood of future asthma attacks, decreases in lung function, and side effects related to the drugs taken to control asthma. Doctors monitor risk with spirometry measurements (which measure lung function) over time as well as factors such as how often the person needs to receive certain oral corticosteroids or to be hospitalized to control asthma symptoms. 