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
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. Diagnos
is
• 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
14. Treatme
nt
• 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
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
