Asthma The 5 Minute Pediatric Consult


	Asthma

Hakon Hakonarson

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

Characterized by three components:
- Reversible airway obstruction
- Airway inflammation
- Airway hyperresponsiveness to a variety of stimuli

PATHOPHYSIOLOGY AND CAUSES

Immune and inflammatory responses in the airways triggered by inhalation of an array of environmental allergens and/or infectious antigens
Hereditary factors play a role.
Atopy plays a role.
- Ability to make excess IgE in response to antigen is associated with increased airway reactivity.
- Asthma is more common in children who have allergic rhinitis and eczema.
Viral (especially respiratory syncytial virus [RSV]) infections during infancy are associated with the development of asthma.
Exposure to cigarette smoke and other fumes or chemicals is associated with asthma.
IgE response is involved in initiating inflammation and bronchospasm.
Airway is invaded by inflammatory cells (mast cells, basophils, eosinophils, macrophages, neutrophils, B and T lymphocytes).
Inflammatory cells respond to and produce various mediators (cytokines, leukotrienes, lymphokines), augmenting the inflammatory response.
Airway epithelium is disrupted and basal membrane is thickened.
Airway smooth muscle ultimately becomes hyperresponsive, and bronchospasm ensues.
Airway smooth muscle hypertrophy and hyperplasia are characteristic of chronic asthma.

GENETICS

Little is known about why some subjects develop asthma and others do not.
Epidemiologic studies have shown clear evidence for a genetic component in asthma.
Children of asthmatics have higher incidence of asthma:
- 6% to 7% risk if neither parent has asthma
- 20% risk if one parent has asthma
- 60% risk if both parents have asthma
Current evidence supports the environment having a greater influence than genetics.
Atopic asthma tends to run in families.
Several genes are known to be associated with the development of atopy.

EPIDEMIOLOGY

Most common chronic illness in children
Recent increases in asthma prevalence, morbidity, and mortality
Death rate of asthma among children rose over 30% between 1980 and 1987.
Wheezing in children is extremely common in the industrialized world (cumulative prevalence, 30%–60%).
Most episodes occur during viral infections.
Most children outgrow their wheeze by age 6 years.
5% to 7% of all children (30%–40% of those who wheeze) continue to wheeze and asthma develops.
Asthma is more common in boys than in girls up to 10 years, but incidence is equal thereafter.

COMPLICATIONS

Morbidity
- Frequent hospitalizations and absence from school
- Chronic symptoms affect activity level and function.
- Psychologic impact of having a chronic illness
- Chronic recurrent atelectasis may lead to the development of localized bronchiectasis.
Mortality
- Increase in asthma mortality of unknown cause in all age groups in recent years
- Increase in number of life-threatening episodes

PROGNOSIS

With proper therapy and good compliance: excellent

DIFFERENTIAL DIAGNOSIS

INFECTIONS

Pneumonia
Bronchiolitis (RSV)
Chlamydia infection
Laryngotracheobronchitis

MECHANICAL

Obstructive mass
Vascular ring
Foreign body
Vocal cord dysfunction

MISCELLANEOUS

Cystic fibrosis
Bronchopulmonary dysplasia
Pulmonary edema
Gastroesophageal reflux (GER)
Recurrent aspiration
Bronchiolitis obliterans

DATA GATHERING

HISTORY

Inquire about these symptoms:

Coughing
Wheezing
Shortness of breath
Chest tightness

Pattern of Symptoms

Perennial versus seasonal
Continuous versus acute
Duration and frequency of episodes
Diurnal variation/nocturnal symptoms

Do any of the following set off the breathing difficulty?

Infections (upper respiratory, sinusitis)
Allergies to:
- Dust mites
- Animal dander
- Pollen
- Mold
Cold air or weather changes
Exercise (exercise asthma)
Environmental stimulants
- Cigarette smoke
- Strong odors
- Pollutants
Emotional factors
- Laughing
- Crying
- Fear
Drug intake
- Aspirin
- NSAIDs
- b-blockers
- ACE inhibitors
Food additives
Endocrine factors
- Menses
- Pregnancy
- Thyroid dysfunction
Family history of asthma or atopy

Impact of Asthma

Number of hospitalizations/ICU admissions
Number of ER visits/doctor’s office visits
Asthma attack frequency
Number of missed school days
Limitation on activity
Number of courses of systemic steroids needed

Environmental History

Type of home
Location of home (urban, suburban, rural)
Heating system/air conditioning
Fireplace
Carpeting
Stuffed animals
Pets
Exposure to cigarette smoke

PHYSICAL EXAMINATION

Pulmonary examination may be normal when asymptomatic.
Assess work of breathing
- Level of distress
- Intercostal/supraclavicular muscle retractions
Chest shape (i.e., normal vs. barrel-shaped)
Lung auscultation
- Wheezing
- End-expiratory involuntary cough
- Prolonged expiratory phase
- Rhonchi or rales
HEENT examination: Signs of allergies or sinusitis
- Watery or itchy eyes
- Allergic shiners
- Dennie lines
- Nasal congestion
- Boggy nasal turbinates
- Nasal polyps
- Postnasal drip
General examination: Vital signs
- Blood pressure (pulsus paradoxus)
- Respiratory rate (tachypnea)
Skin: Evidence of eczema

Physical Examination Trick

Forced exhalation maneuver to observe for rhonchi or wheezes or for precipitating coughing

LABORATORY AIDS

TESTS

Pulmonary function tests
- Essential for the diagnosis and ongoing care of children with asthma
- Measure the degree of airway obstruction and the response to bronchodilators
- Values obtained can measure absolute degree of airway obstruction.
- Serial values can follow progress of disease and response to treatment.
- Children 4 years old can usually perform airway conductance test.
- Children 6 years old can usually perform spirometry and lung volume tests.
Provocational testing
- Exercise challenge: determines effect of exercise on triggering bronchospasm
- Methacholine challenge: confirms diagnosis of asthma (positive test); useful in cases where history is equivocal and pulmonary function test is normal; measures the degree of airway hyperreactivity
Pressure-volume curves determine lung compliance; useful in selected cases.
Allergy evaluation
- Blood tests (eosinophilic count, IgE level)
- Skin testing (best test for assessing allergen sensitivity)
- RAST testing (not as accurate as skin testing)
- Sputum/nasal examination for presence of eosinophilia
Other studies
- GER evaluation
  - pH probe
  - Milk scan
  - Barium swallow
- Bronchoscopy to rule out:
  - Anatomic malformations
  - Foreign bodies
  - Mucus plugging
  - Vocal cord function
- Assess for aspiration (lipid-laden macrophages)

Imaging

Chest radiograph should be obtained at least once for all children to rule out congenital lung malformations or obvious vascular malformations. Findings can be normal. Common findings are peribronchial thickening, subsegmental atelectasis, and hyperinflation.
Sinus radiography is useful if symptoms suggest sinusitis.
Chest CT should be performed in selected cases: right middle lobe syndrome, bronchiectasis, and anatomical abnormality.

Home Testing

Peak flow meter
- Measures peak flow rate (PEFR)
- Correlates well with FEV₁ of spirometry
- Useful in treating patients with difficult-to-control or labile asthma
- Dips in PEFR precede onset of clinical asthmatic symptoms.
- PEFR should be performed at least once a day.
- PEFR values are divided into three zones:
  - Green: 80% of baseline
  - Yellow: 50 to 80% of baseline
  - Red: 50% of baseline
- Specific PEFR guidelines should be individualized for each patient.

THERAPY

DRUGS

Bronchodilators

Relaxes airway smooth muscle
Three classes described below

b₂-Agonists

Main indication is for relief of acute bronchospasm.
Used PRN in asthmatics who have infrequent symptoms
Used intermittently or routinely in conjunction with antiinflammatory agents in patients with frequent exacerbations or chronic airway obstruction
Used prior to exercise in exercise-induced bronchospasm
Regular use or overuse associated with:
- Worsened control of asthma
- Increased airway hyperresponsiveness
- Increased mortality (highly controversial)
Routes
- Inhaled (most effective): nebulizer
- Metered-dose inhaler (MDI): spinhaler
- Oral (least effective; most side effects)
Preparations: Short-acting (effect lasts 4–6 hours):
- Albuterol (Ventolin, Proventil)
- Terbutaline (Brethaire, Brethsine)
- Metoproterenol (Alupent)
Preparation: Long-acting (lasts up to 12 hours)
- Salmeterol (Serevent)

Theophylline

Has lost some of its popularity in recent years due to more effective and safer b₂-agonists and the current focus on antiinflammatory therapy
Indications
- Chronic, poorly controlled asthma
- Nocturnal asthma (if no GER)
- Adjunctive therapy with b₂ drugs and steroids in hospitalized patients in selected cases
Route: oral or IV
Serum levels must be routinely monitored
- Therapeutic levels: 5 to 15 mg/mL
- Side effects are seen with increased levels.
- Many factors affect theophylline levels.
  - Increased levels seen with:
    - Erythromycin
    - Ciprofloxacin
  - Cimetidine
    - Viral illnesses
    - Fever
  - Decreased levels seen with:
    - Phenobarbital
    - Phenytoin
    - Rifampin

Anticholinergic Agents

There is little information to support the adjunctive use of anticholinergic drugs in children.

Preparations
- Nebulized atropine
- Ipratropium bromide MDI (Atrovent)

Antiinflammatory Agents

First line of therapy for moderate-to-severe asthma
Three classes described below

Mast-Cell Stabilizers

Preparations
- Short-acting: cromolyn sodium (Intal)
- Long-acting: nedocromil sodium (Tilade)
Decrease bronchial hyperresponsiveness
Effective in both allergic and nonallergic asthma
Used prior to exercise in exercise-induced bronchospasm
No significant side effects
Routes
- Inhaled: nebulizer
- MDI
- Spinhaler

Corticosteroids

Preparations
- Inhaled (dsage individualized to each patient)
  - Beclomethasone (42 mg/puff) (Beclovent, Vanceril)
  - Triamcinolone (100 mg/puff) (Azmacort)
  - Flunisolide (250 mg/puff) (Aerobid)
  - Fluticazone (44; 110; 220 µg/puff) (Flovent)
  - Budesonide (200 µg/puff) (Pulmicort)
- Oral
  - Prednisone 2 mg/kg/d 3 to 5 days; should be tapered if 5 days of therapy required
- Intravenous
  - Solumedrol 1 mg/kg IV q6h until condition improves
Potent antiinflammatory drugs
Inhaled corticosteroids reduce airway inflammation and hyperresponsiveness more than does cromolyn.
Inhibit production and release of cytokines and arachidonic acid—associated metabolites
Enhance b-adrenoceptor responsiveness
Routes
- Inhaled: used for management of chronic asthma
- MDI
- Oral or intravenous (used for management of acute asthma attacks)

Leukotriene Modifiers

First asthma-specific drugs on the market that are effective in preventing asthma
Block the synthesis and/or action of leukotrienes; experience from clinical use is growing
5-Lipoxyenase inhibitors; zileuton. Other inhibitors are in clinical trials.
Leukotriene (LT-1) receptor antagonists; zafir-lukast and montelukast. Other antagonists are in clinical trials.

MISCELLANEOUS DRUGS

Steroid-Sparing Agents

Troleandomycin (Tao)

Macrolide antibiotic
Decreases clearance of corticosteroids, thus prolonging the effects of corticosteroids on the lung
Lower corticosteroid dosing required

Methotrexate

Potent immunosuppressive drug
May have potential role as adjunct to steroid therapy
Needs further investigation in children

Cyclosporine

Has been shown to have steroid-sparing effect in adult population with asthma
Side effects are significant and may limit use.

IV IgG

High-dose therapy under investigation

MgSO₄

Used as a bronchodilator in severe asthma attacks
Few, if any, benefits in most patients with asthma

HELIUM

May improve airflow in severe asthma
Can improve ventilation and potentially oxygenation
Confirmatory studies are not available.

EDUCATION/ENVIRONMENTAL CONTROL

First step in managing asthma is to educate the patient and his or her family about avoiding known triggers.
Avoid airborne irritants (tobacco smoke, wood stoves, noxious fumes).
Minimize dust-mite exposure
- Remove carpets (if possible) or use 3% tannic acid solution or benzyl benzoate for cleaning.
- Use plastic (vinyl) coverings on mattresses and box springs.
- Wash pillows, blankets, and sheets in hot water.
Avoid molds by decreasing relative humidity to 50%.
Remove pets (if necessary).

IMMUNOTHERAPY

Efficacy in asthma is controversial.
Use only in selected cases if medical management and environmental control measures are ineffective.

Duration of Therapy

Depends on severity of the patient’s asthma
Bronchodilators
- Should be PRN (if able)
- In URI-triggered flares: 7 to 14 days
- Monitor PEFR
Antiinflammatory agents
- Use every day.
- May be weaned in many patients as asthma comes under long-standing control

DIET

Avoid foods or food additives (if truly allergic).
Food-induced asthma is uncommon.

POSSIBLE CONFLICTS WITH OTHER TREATMENTS

Theophylline kinetics are altered by many drugs.
Use of theophylline can worsen GER.

FOLLOW-UP

WHEN TO EXPECT IMPROVEMENT

In acute asthma attacks, with appropriate therapy, improvement is usually seen within 24 to 48 hours.
In chronic asthma, control of symptoms can usually be obtained within 1 month.

SIGNS THAT MAY INDICATE PROBLEMS

Decrease in PEFR
Increasing use of inhaled bronchodilators
Subject not improving on enhanced home therapy

PITFALLS

Not recognizing that asthma can manifest as chronic cough
“Recurrent pneumonias” many times are actually virus-triggered asthma attacks with coughing and subsegmental atelectasis on chest radiography.
Pulmonary function testing is effort-dependent.
Suboptimal effort may result in artificially decreased pulmonary function values, overestimating the amount of bronchospasm present.

COMMON QUESTIONS AND ANSWERS

Q: Will my child outgrow his or her asthma?
A: Family history and allergies affect the ultimate outcome. Wheezing during the first 3 years of life is extremely common, with 40% to 50% of all children wheezing at some time. Many of these children do not develop asthma and “outgrow” their illness by school age. Some patients develop asthma again as young adults.

Q: Can my child become dependent on asthma medications?
A: Children do not become “dependent” on these medications as they would with narcotic agents. Daily asthma medications are required to maintain airway patency and to control airway inflammation.

Q: Will my child be on medications for the rest of his or her life?
A: This depends on the severity of the asthma. The types, doses, and frequency of asthma medications will change over a patient’s lifetime.

Q: Do inhaled steroids affect patient growth?
A: There is no convincing evidence of long-term growth suppression or bone demineralization in school-aged children receiving up to 400 mg/d of inhaled steroids. Further studies are in progress.

ICD-9-CM 493.01

BIBLIOGRAPHY

Bloomberg GR, Strunk RC. Crisis in asthma care. Pediatr Clin North Am 1992;39:1225–1241.

Hakonarson H, Grunstein MM. Management of childhood asthma. In: Barnes P, Grunstein MM, Leff A, Woolcock A, eds. Asthma, vol. 2. New York: Raven Press, 1997:1847–1868.

Hill M, Szefler SJ. Asthma pathogenesis and the implications for therapy in children. Pediatr Clin North Am 1992;39:1205–1224.

Koenig P. A step-wise approach to the changing drug therapy of asthma. Pediatr Ann 1992;21:565–571.

Morgan WJ, Martinez FD. Risk factors for developing wheezing and asthma in children. Pediatr Clin North Am 1992;39:1185–1203.

National Asthma Education and Prevention Program. Expert Panel Report 2: Guidelines for the diagnosis and management of asthma. Washington, DC: US Government Printing Office, February 1997 (NIH-NHLBI publication).

Reid MJ. Complicating features of asthma. Pediatr Clin North Am 1992;39:1327–1341.

Richards W. Asthma, allergies, and school. Pediatr Ann 1992;21:575–585.

Shapiro GG. Childhood asthma: update. Pediatr Rev 1992;13:403–412.

Workshop on Early Childhood Asthma. What are the questions? Am J Respir Crit Care Med 1995;151:S1–S42.

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