Asthma
Asthma is the most common chronic disease among children. Asthma triggers
include viral infections; environmental pollutants, such as tobacco smoke;
aspirin, nonsteroidal anti-inflammatory drugs, and sustained exercise,
particularly in cold environments.
I. Diagnosis
A. Symptoms of asthma may include
episodic complaints of breathing difficulties, seasonal or nighttime cough,
prolonged shortness of breath after a respiratory infection, or difficulty
sustaining exercise. B. Wheezing does not always represent asthma. Wheezing
may persist for weeks after an acute bronchitis episode. Patients with chronic
obstructive pulmonary disease may have a reversible component superimposed on
their fixed obstruction. Etiologic clues include a personal history of allergic
disease, such as rhinitis or atopic dermatitis, and a family history of allergic
disease.C. The frequency of daytime and nighttime symptoms,
duration of exacerbations and asthma triggers should be assessed. D. Physical examination. Hyperventilation, use of accessory muscles of respiration, audible wheezing, and
a prolonged expiratory phase are common. Increased nasal secretions or
congestion, polyps, and eczema may be present.
E. Measurement of lung function. An
increase in the forced expiratory volume in one second (FEV1) of 12% after
treatment with an inhaled beta2 agonist is sufficient to make the diagnosis of
asthma. A 12% change in peak expiratory flow rate (PEFR) measured on a peak-flow
meter is also diagnostic.
II.Treatment of asthmaA. Beta2 agonists
1. Inhaled short-acting
beta2-adrenergic agonists are the most effective drugs available for treatment
of acute bronchospasm and for prevention of exercise-induced asthma.
Levalbuterol (Xopenex), the R-isomer of racemic albuterol, offers no significant
advantage over racemic albuterol.
2. Salmeterol (Serevent), a
long-acting beta2 agonist, has a relatively slow onset of action and a prolonged
effect. a. Salmeterol should not be used in the treatment of
acute bronchospasm. Patients taking salmeterol should use a short-acting beta2
agonist as needed to control acute symptoms. Twice-daily inhalation of
salmeterol has been effective for maintenance treatment in combination with
inhaled corticosteroids. b. Fluticasone/Salmeterol (Advair Diskus) is a
long-acting beta agonist and corticosteroid combination; dry-powder inhaler
[100, 250 or 500 :g/puff],1
puff q12h. 3. Formoterol (Foradil) is a long-acting beta2 agonist like
salmeterol. It should only be used in patients who already take an inhaled
corticosteroid. Patients taking formoterol should use a short-acting beta2
agonist as needed to control acute symptoms. For maintenance treatment of asthma
in adults and children at least 5 years old, the recommended dosage is 1 puff
bid. 4. Adverse effects of beta2
agonists. Tachycardia, palpitations,
tremor and paradoxical bronchospasm can occur. High doses can cause hypokalemia.
B. Inhaled corticosteroids
1. Regular use of an inhaled
corticosteroid can suppress inflammation, decrease bronchial hyper
responsiveness and decrease symptoms. Inhaled corticosteroids are recommended
for most patients. 2. Adverse
effects. Inhaled corticosteroids are
usually free of toxicity. Dose-dependent slowing of linear growth may occur
within 6-12 weeks in some children. Decreased bone density, glaucoma and
cataract formation have been reported. Churg-Strauss vasculitis has been
reported rarely. Dysphonia and oral candidiasis can occur. The use of a spacer
device and rinsing the mouth after inhalation decreases the incidence of
candidiasis.
C. Leukotriene modifiers
1. Leukotrienes increase production of
mucus and edema of the airway wall, and may cause bronchoconstriction.
Montelukast and zafirlukast are leukotriene receptor antagonists. Zileuton
inhibits synthesis of leukotrienes.
2. Montelukast (Singulair) is modestly
effective for maintenance treatment of intermittent or persistent asthma. It is
taken once daily in the evening. It is less effective than inhaled
corticosteroids, but addition of montelukast may permit a reduction in
corticosteroid dosage. Montelukast added to oral or inhaled corticosteroids can
improve symptoms.
3. Zafirlukast (Accolate) is modestly
effective for maintenance treatment of mild-to-moderate asthma It is less
effective than inhaled corticosteroids. Taking zafirlukast with food markedly
decreases its bioavailability. Theophylline can decrease its effect. Zafirlukast
increases serum concentrations of oral antic agulants and may cause bleeding.
Infrequent adverse effects include mild headache, gastrointestinal disturbances
and increased serum aminotransferase activity. Drug-induced lupus and Churg-Strauss
vasculitis have been reported.
4. Zileuton (Zyflo) is modestly
effective for maintenance treatment, but it is taken four times a day and
patients must be monitored for hepatic toxicity.
D. Cromolyn (Intal) and nedocromil (Tilade)
1. Cromolyn sodium, an inhibitor of
mast cell degranulation, can decrease airway hyper
responsiveness in some
patients with asthma. The drug has no bronchodilating activity and is useful
only for prophylaxis. Cromolyn has virtually no systemic toxicity.
2. Nedocromil has similar effects as
cromolyn. Both cromolyn and nedocromil are much less effective than inhaled
corticosteroids.
E. Theophylline
1. Oral theophylline has a slower
onset of action than inhaled beta2 agonists and has limited usefulness for
treatment of acute symptoms. It can, however, reduce the frequency and severity
of symptoms, especially in nocturnal asthma, and can decrease inhaled
corticosteroid requirements.
2. When theophylline is used alone, serum
concentrations between 8-12 mcg/mL provide a modest improvement is FEV1. Serum
levels of 15-20 mcg/mL are only minimally more effective and are associated with
a higher incidence of cardiovascular adverse events.
F. Oral corticosteroids are the most
effective drugs available for acute exacerbations of asthma unresponsive to
bronchodilators.
1. Oral corticosteroids decrease symptoms and may
prevent an early relapse. Chronic use of oral corticosteroids can cause glucose
intolerance, weight gain, increased blood pressure, osteoporosis, cataracts,
immunosuppressant and decreased growth in children. Alternateday use of
corticosteroids can decrease the incidence of adverse effects, but not of
osteoporosis.
2. P r e d n isone,
prednisolone o r methylprednisolone (Solu-Medrol),
40-60 mg qd; for children, 1-2 mg/kg/day to a maximum of 60 mg/day. Therapy is
continued for 3-10 days. The oral steroid dosage does not need to be tapered
after short-course “burst” therapy if the patient is receiving inhaled steroid
therapy
III. Management of acute
exacerbations A. High-dose, short-acting
beta2 agonists delivered by a metered-dose inhaler with a volume spacer or via a
nebulizer remains the mainstay of urgent treatment.
B. Most patients require therapy with
systemic corticosteroids to resolve symptoms and prevent relapse.
Hospitalization should be considered if the PEFR remains less than 70% of
predicted. Patients with a PEFR less than 50% of predicted who exhibit an
increasing pCO2 level and declining mental status are candidates for intubation. C. Non-invasive ventilation with bilevel
positive airway pressure (BIPAP) may be used to relieve the workof- breathing
while awaiting the effects of acute treatment, provided that consciousness and
the ability to protect the airway have not been compromised
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