Respiratory Disorders

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CHAPTER 20 Respiratory Disorders

Respiratory disorders, or lung diseases, are disorders such as asthma, chronic obstructive pulmonary disease (COPD), and allergic rhinitis. Lung disease can affect people of all ages and both sexes. Lung disease is the fourth leading cause of death in the United States.

1. Asthma is a chronic, inflammatory lung disease.

2. In people with asthma, the air passages within the lungs are constantly swollen, which restricts the amount of air that can pass through the trachea.

3. Those with asthma have recurrent breathing problems and a tendency to cough and wheeze.

4. According to the American Lung Association, approximately 20 million Americans have asthma, which causes about 5000 deaths each year.

5. There is no cure for asthma, but many medications and lifestyle changes help manage the condition.

6. According to a 2002 National Health Interview Survey, asthma has been diagnosed in nine million children, from newborns to 18-year-olds, in the United States.

a. Asthma rates in children younger than 5 years of age have increased more than 160% between 1980 and 1994.

b. One study found a strong correlation between obesity and asthma but no similar relationship between obesity and allergies. Some researchers believe this is the result of increased physical exertion of the lungs in obese individuals.

B. Classifications

1. There are various classifications of asthma. These conditions cause airway obstruction and inflammation that is partly reversible by medication. The symptoms are usually similar; however, the main difference is their cause.

a. Allergic (extrinsic) asthma

(1) An allergic reaction triggers allergic asthma, which is an immune system response that causes the airway to become inflamed.

(2) Inhaled allergens, such as dust mites, mold spores, pollen, and pet dander, may trigger allergic asthma.

(3) It is the most common form of asthma, affecting more than 50% of asthma sufferers.

b. Nonallergic (intrinsic) asthma

(1) Nonallergic asthma is not related to allergies and does not involve the immune system.

(2) Instead, the disease is triggered by factors like anxiety, stress, exercise, cold air, dry air, smoke, hyperventilation, viruses, and other irritants.

c. Exercise-induced asthma

(1) When the airway becomes constricted during vigorous physical activity, the condition is known as exercise-induced asthma.

d. Cough-variant asthma

(1) Cough-variant asthma is a chronic, persistent cough without shortness of breath.

e. Occupational asthma

(1) Occupational asthma occurs as a result of a particular environment.

C. Pathophysiology

1. Because asthma is an inflammatory process, several cells (mostly immune system–mediated cells) have been identified as playing a role in the disease process (Figure 20-1).

2. There are three major parts of the immune system response

(1) The antibody or immunoglobulin (Ig)E is responsible for carrying out the body’s allergic reaction (shortness of breath, inflammation, closing of airways).

b. Inflammatory cells

(1) The major inflammatory cells involved in asthma are mast cells and eosinophils.

(2) Mast cells, which can be found in the lungs, mediate the inflammatory response that is triggered by IgE.

(3) The inflammatory eosinophil cells are closely associated with all types of asthma and can be found in various parts of the lungs and respiratory system.

(4) Activation of these inflammatory cells causes a release of inflammatory mediators.

c. Inflammatory mediators

(1) The mediators that are often involved in asthma are histamine, leukotrienes, prostaglandins, and cytokines.

3. The whole inflammatory process contributes to airway restriction and bronchospasms.

a. Airway restriction and bronchospasms are produced by the tightening of the muscles that surround the respiratory system. This tightening is achieved by the binding of catecholamines, such as epinephrine or norepinephrine, to beta-2 receptors in the lungs and airway.

D. Signs and symptoms

1. Asthma symptoms may appear at any time in life. Individuals who develop asthma as adults have adult-onset asthma. This condition may develop as late as age 50 or older. Unlike children, who usually experience intermittent symptoms, individuals with adult-onset asthma are more likely to experience persistent symptoms. The cause of adult-onset asthma is unknown. However, some evidence suggests that allergy and asthma may be genetically determined. In addition, obesity, which has both genetic and environmental influences, appears to significantly increase the risk of developing asthma in adulthood. The following symptoms may occur in any age group, unless otherwise noted.

a. Bronchospasm (abnormal contraction of the bronchi, which obstructs the airway), coughing (constant or intermittent)

b. Wheezing or whistling sounds when exhaling

c. Shortness of breath or rapid breathing

d. Chest tightness or pain and fatigue

e. Infants may have trouble feeding and may grunt during suckling.

a. Spirometry is a noninvasive way to evaluate the air capacity of the lungs.

b. In a spirometry test, a person breathes into a mouthpiece that is connected to an instrument called a spirometer.

c. The spirometer records the amount and the rate of air that is breathed in and out over a specified time.

1. Short-term relief: bronchodilation

a. Beta-2 adrenoceptor agonists

(1) Mechanism of action

(a) Relaxes bronchial smooth muscle by activating beta-2 receptors

(b) Increases cyclic adenosine monophosphate (cAMP) levels and subsequent relaxation of smooth muscle and bronchodilation

(2) Indications

(a) Relieve bronchospasm alone or in combination

(3) Warnings/Precautions

(a) Hyperthyroidism

(b) Cardiovascular disease

(c) Arrhythmias

(d) Diabetes mellitus

(4) Adverse effects

(a) Fine tremor

(b) Tachycardia

(c) Hypokalemia

(6) Long-acting: NOT for acute attacks

(a) Salmeterol (Serevent)

(b) Formoterol (Foradil)

(c) Combination products: more likely to be prescribed (preferred) due to anti-inflammatory (corticosteroid) component for control of symptoms

(i) Fluticasone/salmeterol (Advair Diskus)

(ii) Budesonide/formoterol (Symbicort)

2. Long-term control: anti-inflammatory medications (asthma “controllers”)

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