Asthma Definition and Characteristics

Study Notes

Asthma is a heterogeneous disease characterized by chronic airway inflammation and variable respiratory symptoms.
Symptoms include wheeze, shortness of breath, chest tightness, and cough, which vary over time and intensity.
Asthma is defined by a history of these symptoms, along with variable expiratory airflow limitation.

Airway hyperreactivity, resulting in airway narrowing as a reaction to irritants.
Inflammation and airway remodeling, including eosinophilic inflammation.

T2-type asthma: allergic and late onset eosinophilic asthma, exercise-induced asthma, and childhood or early adulthood onset.
Non-T2 type asthma: obesity associated asthma, smooth muscle mediated paucigranulocytic asthma, and smoking related neutrophilic asthma.

Objective examination: usually normal, with wheezing (also common in respiratory infections, COPD, upper airway dysfunction, and heart failure)
Anamnesis: symptoms change over time and intensity, worsen at night or when waking up, and can be provoked by exercise, laughter, allergens, or cold air
Tests: spirometry, challenge test, and exercise challenge test

Mild asthma: can be controlled with treatment in step 1 or 2
Moderate asthma: can be controlled with treatment in step 3
Severe asthma: can be controlled with treatment in step 4 or 5, or remains uncontrolled

Step 1: for symptoms less than twice a month
Step 1/2 track 1 or step 2 track 2: for symptoms less than 4-5 days a week
Step 3: for symptoms most days, or waking with asthma once a week or more
Step 4: for daily symptoms or waking with asthma once a week or more, and low lung function
Non-pharmacological treatment includes avoidance of smoke, allergens, and occupational factors, as well as physical activity, breathing techniques, weight reduction, and stress reduction.