Asthma is a chronic lung disease characterized by inflamed airways that constrict in response to triggers. It can be extrinsic, caused by allergies to things like pollen, or intrinsic, brought on by non-allergic factors like infections or stress. Symptoms include wheezing, coughing, and shortness of breath. Diagnosis involves pulmonary function tests and ruling out other conditions. Treatment focuses on avoiding triggers, using medications to open airways like bronchodilators and preventers like corticosteroids, and mechanical ventilation for severe cases. Complications can include prolonged attacks or respiratory failure.
2. • Asthma is a chronic reactive airway disorder
causing episodic airway obstruction that results
from bronchospasms,
• increased mucus secretion, and mucosal edema.
It is a type of chronic obstructive pulmonary
disease (COPD), a
• long-term pulmonary disease characterized by
increased airflow resistance; other types of COPD
include chronic
• bronchitis and emphysema
3. • Although asthma strikes at any age, about 50% of
patients are younger than age 10; twice as many
boys as girls are
• affected in this age group. One-third of patients
develops asthma between ages 10 and 30, and
the incidence is the
• same in both sexes in this age group. Moreover,
approximately one-third of all patients share the
disease with at least
• one immediate family member
4. • Asthma may result from sensitivity to extrinsic
or intrinsic allergens. Extrinsic, or atopic,
asthma begins in childhood;
• typically, patients are sensitive to specific
external allergens.
5. • AGE ALERT Extrinsic asthma is commonly
accompanied by other hereditary allergies,
such as eczema and
• allergic rhinitis, in childhood populations
6. • Intrinsic, or nonatopic, asthmatics react to
internal, nonallergenic factors; external
substances cannot be implicated in
• patients with intrinsic asthma. Most episodes
occur after a severe respiratory tract infection,
especially in adults.
• However, many asthmatics, especially
children, have both intrinsic and extrinsic
asthma
7. Causes
• Extrinsic allergens include:
• pollen
• animal dander
• house dust or mold
• kapok or feather pillows
• food additives containing sulfites
• other sensitizing substances.
8. Intrinsic allergens include
• irritants
• emotional stress
• fatigue
• endocrine changes
• temperature variations
• humidity variations
• exposure to noxious fumes
• anxiety
• coughing or laughing
• genetic factors
9. Signs and symptoms
Patients with mild asthma
• wheezing due to edema of the airways
• coughing due to stimulation of the cough reflex to
eliminate the lungs of excess mucus and irritants
• histamine-induced production of thick, clear, or yellow
mucus
• dyspnea on exertion due to narrowing of airways and
inability to take in the increased oxygen that is required
for
• exercise
10. Patients with moderate asthma
• respiratory distress at rest due to narrowed
airways and decreased oxygenation to the
tissues
• hyperpnea (abnormal increase in the depth
and rate of respiration) due to the body's
attempt to take in more oxygen
• barrel chest due to air trapping and retention
• diminished breath sounds due to air trapping.
11. Patients with severe asthma
• marked respiratory distress due to failure of
compensatory mechanisms and decreased
oxygenation levels
• marked wheezing due to increased edema and
increased mucus in the lower airways
• absent breath sounds due to severe
bronchoconstriction and edema
• pulsus paradoxus greater than 10 mm Hg
chest wall contractions due to use of accessory
muscles
12. Diagnosis
• Pulmonary function studies reveal signs of
airway obstructive disease, low-normal or
decreased vital capacity, and
• increased total lung and residual capacities.
Pulmonary function may be normal between
attacks. Pa O2 and PaCO2
• usually are decreased, except in severe
asthma, when PaCO2 may be normal or
increased
13. • Serum IgE levels may increase from an allergic reaction.
• Sputum analysis may indicate presence of Curschmann's spirals (casts of airways), Charcot-
Leyden crystals, and
• eosinophils.
• Complete blood count with differential reveals increased eosinophil count.
• Chest X-rays can be used to diagnose or monitor the progress of asthma and may show
hyperinflation with areas of
• atelectasis.
• Arterial blood gas analysis detects hypoxemia (decreased Pa O2; decreased, normal, or
increasing PaCO2) and
• guides treatment.
• Skin testing may identify specific allergens; results read in 1 or 2 days detect an early
reaction, and after 4 or 5
• days reveal a late reaction.
• Bronchial challenge testing evaluates the clinical significance of allergens identified by skin
testing.
• Electrocardiography shows sinus tachycardia during an attack; severe attack may show signs
of cor pulmonale
• (right axis deviation, peaked P wave) that resolve after the attack.
14. Treatment
• prevention, by identifying and avoiding precipitating factors
such as environmental allergens or irritants, which is the best
treatment
• desensitization to specific antigens — helpful if the stimuli
can't be removed entirely — which decreases the
• severity of attacks of asthma with future exposure
• bronchodilators (such as theophylline, aminophylline,
epinephrine, albuterol, metaproterenol, and terbutaline) to
• decrease bronchoconstriction, reduce bronchial airway
edema, and increase pulmonary ventilation
• corticosteroids (such as hydrocortisone and
methylprednisolone) to decrease bronchoconstriction, reduce
bronchial
15. • mast cell stabilizers (cromolyn sodium and nedocromil
sodium), effective in patients with atopic asthma who have
• seasonal disease. When given prophylactically, they block
the acute obstructive effects of antigen exposure by
• inhibiting the degranulation of mast cells, thereby
preventing the release of chemical mediators responsible
for
• anaphylaxis
• low-flow humidified oxygen, which may be needed to treat
dyspnea, cyanosis, and hypoxemia. However, the
• amount delivered should maintain PaO2 between 65 and
85 mm Hg, as determined by arterial blood gas analysis
16. • mechanical ventilation — necessary if the
patient doesn't respond to initial ventilatory
support and drugs, or
• develops respiratory failure
• relaxation exercises such as yoga to help
increase circulation and to help a patient
recover from an asthma attack