pulmonary disorders
Asthma
Classification of Asthma
Unlike hypertension (eg, in which one parameter [blood pressure] defines the severity of the disorder and the efficacy of treatment), asthma causes a number of clinical and testing abnormalities. Also, unlike most types of hypertension, asthma manifestations typically wax and wane. Thus, monitoring (and studying) asthma requires a consistent terminology and defined benchmarks. The term status asthmaticus describes severe, intense, prolonged bronchospasm that is resistant to treatment. Severity is the intrinsic intensity of the disease process (ie, how bad it is—see table Classification of Asthma Severity* ). Severity can usually be assessed directly only before treatment is started, because patients who have responded well to treatment by definition have few symptoms. Asthma severity is categorized as Intermittent Mild persistent Moderate persistent Severe persistent It is important to remember that the severity category does not predict how serious an exacerbation a patient may have. For example, a patient who has mild asthma with long periods of no or mild symptoms and normal pulmonary function may have a severe, life-threatening exacerbation. Control is the degree to which symptoms, impairments, and risks are minimized by treatment. Control is the parameter assessed in patients receiving treatment. The goal is for all patients to have well-controlled asthma regardless of disease severity. Control is classified as Well controlled Not well controlled Very poorly controlled Severity and control are assessed in terms of patient impairment and risk (see tables Classification of Asthma Severity* and Impairment refers to the frequency and intensity of patients' symptoms and functional limitations (see table Classification of Asthma Severity* ). Impairment is assessed using similar criteria to severity, but differs from severity by its emphasis on symptoms and functional limitations rather than the intrinsic intensity of the disease process. Lung function or physiologic, objective impairment can be measured by spirometry, mainly forced expiratory volume in 1 second (FEV1) and the ratio of FEV1 to forced vital capacity (FVC), which correlate strongly with subjective components of asthma control that includes symptoms and clinical features such as How often symptoms are experienced How often the patient awakens at night How often the patient uses a short-acting beta-2 agonist for symptom relief How often asthma interferes with normal activity Risk refers to the likelihood of future exacerbations or decline in lung function and the risk of adverse drug effects. Risk is assessed by long-term trends in spirometry and clinical features such as Frequency of need for oral corticosteroids Need for hospitalization Need for intensive care unit (ICU) admission Need for intubation 