Chapter 5 Asthma
PATHOPHYSIOLOGY
Asthma, also known as reactive airway disease (RAD), is a disease of the lower airway in which there is airway obstruction, airway inflammation, and airway hyperresponsiveness or spasm of the bronchial smooth muscle, increasing mucus formation. Symptoms usually include wheezing, coughing, shortness of breath, a feeling of tightness in the chest, and fatigue, as well as feeding difficulties in very young children. Clients may have retractions, a prolonged expiratory phase, and decreased breath sounds or poor air movement. An exacerbation of asthma may be precipitated by specific allergens (e.g., pollen, mold, animal dander, dust, or cigarette smoke) or by other factors such as weather changes, respiratory infections, exercise, gastroesophageal reflux, or emotional factors. Although the specific cause of asthma is not known, it is well known that the disease may “run in families,” and genetic investigations are underway.
INCIDENCE
1. Asthma affects over 9 million children under the age of 18 in the United States.
2. Asthma is the number one cause of hospitalization for children under the age of 15, with children under the age of 4 having greater admission rates.
3. Asthma accounts for 25% of school absences caused by chronic illness.
CLINICAL MANIFESTATIONS
1. Clinical evidence of airway obstruction—obstruction may be gradual or acute; severity of acute exacerbations is classified as mild intermittent, mild persistent, moderate persistent, or severe persistent
2. Dyspnea with prolonged expiration
3. Expiratory wheezing, progressing to inspiratory and expiratory wheezing, progressing to inaudibility of breath sounds
4. Grunting respirations in infancy
8. Anxiety, irritability, decreasing level of consciousness
10. Drop in arterial partial pressure of carbon dioxide (PaCO2) initially from hyperventilation; then rise in PaCO2 as obstructive process worsens
