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Asthma

Asthma is the most common chronic disease among children. At least 75 percent of asthmatic patients demonstrate immediate hypersensitivity to common aeroallergens. Asthma triggers include viral infections; environmental pollutants, such as tobacco smoke; certain medications, (aspirin, nonsteroidal anti-inflammatory drugs), and sustained exercise, particularly in cold environments asthma.

Diagnosis

History

Symptoms of episodic complaints of breathing difficulties, seasonal or nighttime cough, prolonged shortness of breath after a respiratory infection,, or

Reversible airways disease does not always represent asthma. Wheezing may persist for weeks after an acute bronchitis episode. Patients with chronic obstructive pulmonary disease.

Asthma Triggers

Sources of inhaled allergens

House dust mites

Animal danders from house pets

Pollen

Fungal spores

Cockroaches

Animal urine from laboratory animals

Infections

Viral respiratory infections

Sinusitis

Gastroesophageal reflux

Sulfites (used as preservatives in food, beer and wine)

Environmental irritants/precipitants

Tobacco smoke

Cold air

Exercise

Particulates from wood stoves

Air pollution

Chemical gases or fumes

Drugs

Aspirin

Nonsteroidal anti-inflammatory drugs

Angiotensin converting enzyme inhibitors

Beta blockers

Physical examination. Hyperventilation, use of accessory muscles of respiration, audible wheezing, and a prolonged expiratory phase are common. Increased nasal secretions or congestion, polyps.

Measurement of lung function. An increase in the forced expiratory volume in one second (FEV1) of 12 percent after treatment with an inhaled beta2 agonist is sufficient to make the diagnosis.

Asthma Classification

Symptoms

Classification

Daytime

Nighttime

Lung function

Mild intermittent

Symptoms occur up to 2 times/week; exacerbations are brief (hours to days), with normal PEFR and no symptoms between exacerbations

Symptoms occur up to 2 times/month

PEFR or FEV1 $80% of predicted; <20% variability in PEFR

Mild persistent

Symptoms occur more than 2 times/week but less than one time/day; exacerbations may affect normal activity

Symptoms occur more than 2 times/month

PEFR or FEV, $80% of predicted; PEFR variability 20-30%

Moderate persistent

Symptoms occur daily; daily need for inhaled short-acting beta2 agonist; exacerbations affect normal activity; exacerbations occur more than 2 times/week and may last for days

Symptoms occur more than one time/week

PEFR or FEV1 >60 but <80% of predicted; PEFR variability >30%

Severe persistent

Symptoms are continual; physical activity is limited; exacerbations are frequent

Symptoms are frequent

PEFR or FEV1 <60% of predicted; PEFR variability >30%

Treatment

Allergen avoidance. Patients should avoid opening windows and using unfiltered window fans. Elimination of allergens from house dust mites.

Long-term control medications

Corticosteroids

Glucocorticoids provide anti-inflammatory effects and reduce bronchial hyperactivity. Inhaled corticosteroids are first-line agents in patients who require daily asthma therapy.

Prednisone, prednisolone or methylprednisolone ( Solu-Medrol), 40 to 60 mg qd; for children.

Cromolyn sodium (Intal, Nasalcrom) and nedocromil sodium (Tilade) are anti-inflammatory

Leukotriene modifiers

Zafirlukast ( Accolate), montelukast ( Zyflo) interfere with the actions of leukotriene inflammatory mediators, preventing bronchoconstriction. Zileuton is a 5-lipoxygenase inhibitor. Zafirlukast is a leukotriene receptor antagonist. Montelukast is similar to zafirlukast but is taken only once per day at night. Zafirlukast must be taken on an empty stomach.

Zafirlukast and zileuton may interfere with the metabolism of warfarin (Coumadin).

Zileuton has been associated with elevated levels of liver enzymes; thus, periodic monitoring of alanine transaminase is required. Zafirlukast (Accolate, 20 mg bid, on an empty stomach), montelukast (Singular, 10 mg PO qhs) and zileuton (Zyflo, 600 mg PO qid) are alternatives for patients.

Long-acting beta2 agonists. If inhaled anti-inflammatory medications do not prevent asthma symptoms, an inhaled long-acting beta2 agonist may be added. Long-acting beta2 agonists relax bronchial smooth muscle. Salmeterol (Serevent, 2 puffs bid), a long-acting beta2 agonist, has a slower onset of action (up to 30 minutes) but a longer duration (at least 12 hours) than short-acting beta2.

Methylxanthines use has declined with the arrival of safer and more effective medications. However, they still have a role in asthma therapy when newer anti-inflammatory medications fail to provide relief. Theophylline produces smooth muscle relaxation resulting in bronchodilation.

Management of acute exacerbations

High-dose, short-acting beta2 agonists delivered by a metered-dose inhaler with a volume spacer or via a nebulizer remain the mainstays of urgent treatment. Nebulized ipratropium bromide