Asthma Disease

BASICS

DESCRIPTION

A disorder of the tracheobronchial tree characterized by mild to severe obstruction to airflow. Symptoms vary, generally episodic or paroxysmal, may be persistent. The clinical hallmark is wheezing, but cough may be the predominant symptom. Commonly misdiagnosed as recurrent pneumonia or chronic bronchitis.

Acute symptoms are characterized by narrowing of large and small airways due to spasm of bronchial smooth muscle, edema and inflammation of the bronchial mucosa, and production of mucus
Occurs in a setting in which asthma is likely and other, rarer conditions have been excluded
System(s) affected: Pulmonary
Genetics: Search for an asthma gene underway; there is a familial association of reactive airway disease (RAD), ectopic dermatitis, and allergic rhinitis
Incidence/Prevalence in USA:
- 10 million new cases each year, however, there is confusion due to lack of a uniform definition
- 7-19% of children
- A leading cause of missed school days - 7.5 million/year
Predominant age:
- 50% of cases are children under 10
- Young adult (16-40 years); but may occur at any age
Predominant sex:
- Children under 10: Male > Female
- Puberty: Male = Female
- Adult onset: Female > Male

SIGNS AND SYMPTOMS

Variation in pattern of symptoms, paroxysmal, constant, abnormal pulmonary function tests without symptoms

Wheezing
Cough
Periodicity of symptoms
Exercise-induced wheezing or cough
Prolonged expiration
Hyperresonance
Decreased breath sounds
Nocturnal attacks
Pulsus paradoxus
Cyanosis
Tachycardia
Accessory respiratory muscle use
Flattened diaphragms
Nasal polyp; seen in cystic fibrosis and aspirin sensitivity
Clubbing is not seen in asthma
Growth is usually normal

CAUSES

Allergic factors
- Airborne pollens
- Molds
- House dust (mites)
- Animal dander
- Feather pillows
Other factors
- Smoke and other pollutants
- Infections, especially viral
- Aspirin
- Exercise
- Sinusitis
- Gastroesophageal reflux
- Sleep (peak expiratory flow rate [PEFR] lowest at 4 am)
Current research focuses on inflammatory response (including abnormal release of chemical mediators, eosinophil chemotactic factor, neutrophil chemotactic factor, and leukotrienes, etc.)

RISK FACTORS

Positive family history of asthma or atopy
Viral lower respiratory infection during infancy
Environmental tobacco smoke

DIAGNOSIS

LABORATORY

CBC normal
Nasal eosinophils
Immunoglobulins
- Screen for immunodeficiency
- IgE elevated in allergic bronchopulmonary aspergillosis (ABPA)
Sweat test in chronic childhood asthmatics
Arterial blood gases in status asthmaticus

Drugs that may alter lab results: Antihistamines may alter allergy skin testing
Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS

Smooth muscle hyperplasia; mucosal edema; thickened basement membrane; inflammatory response; hyperinflated lungs; mucus plugging; bronchiectasis is not seen except in association with ABPA; increased airway resistance; decreased airflow rates; ventilation-perfusion mismatching

SPECIAL TESTS

Home monitoring of peak flow rates - report if drops below 70% of baseline
Pulmonary function tests - reversible airway obstruction
Allergy testing
PPD
Exercise tolerance testing
Methacholine challenge
Cold air provocation

IMAGING

Chest x-ray (hyperinflation, atelectasis, air leak)

DIAGNOSTIC PROCEDURES

Bronchoscopy: rarely indicated.
Spirometry: decreased FEV1
Chest x-ray: do at least one, but not necessary with each exacerbation

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient
Inpatient for bronchospasm not relieved by beta-agonists and steroids

GENERAL MEASURES

Environmental control of irritants
Education is essential
Appropriate prophylactic management with anti-inflammatories such as inhaled steroids, cromolyn sodium. Role of leukotriene modifiers being defined.
Increase beta-agonists in response to symptoms
Consider hyposensitization
The following are NOT recommended: mist, large volumes of fluid, breathing exercises, IPPB

SURGICAL MEASURES

N/A

ACTIVITY

Early diagnosis and appropriate treatment facilitate unrestricted activity.

DIET

No special diet

PATIENT EDUCATION

American Lung Association, 1740 Broadway, New York, NY 10019, (212)315-8700
Asthma and Allergy Foundation of America, Suite 305, Washington, DC 20036, (800)7-ASTHMA, (800)727-8462

FOLLOW UP

PREVENTION/AVOIDANCE

Co-management is essential
- Understand medication, inhalers, nebulizers, peak flow meters
- Monitor symptoms, peak flows
- Pre-arranged action plan for exacerbations
- Written guidelines
Investigate and control triggering factors (pollutants, exercise, house-dust mite, molds, animal dander) if severe
Annual influenza immunization
Avoid aspirin
Avoid sulfites (food additives)

POSSIBLE COMPLICATIONS

Respiratory failure; mechanical ventilation
Atelectasis in 25% of hospitalized patients
Flaccid paralysis after exacerbation (self-limited)
Death
Air leak syndromes (pneumothorax, etc.)
SIADH
Altered theophylline metabolism
Steroid myopathy

EXPECTED COURSE AND PROGNOSIS

Excellent, with attention to general health and use of medications to control symptoms
Less than 50% of children with asthma "outgrow it"
Mortality risk increases with:
- Greater than 3 emergency room visits/year
- Nocturnal symptoms
- History of ICU admission
- Mechanical ventilation
- Greater than 2 hospitalizations/year
- Steroid dependence (systemic use)
- History of syncope with asthma
- History of noncompliance
Mortality rates are increasing
If responsive to treatment is poor, review diagnosis and compliance prior to adding more potent therapy

MISCELLANEOUS

ASSOCIATED CONDITIONS

Reflux esophagitis
Sinusitis

AGE-RELATED FACTORS

Pediatric: 50% of new cases of asthma occur in children below 10 years
Geriatric: Unusual for initial episode to occur
Others: N/A

PREGNANCY

About 50% of asthma patients have no changes, 25% seem to improve and 25% have worse symptoms
Stress prevention
Avoid medications with contraindications

OTHER NOTES

Antihistamines are not contraindicated in asthma

ABBREVIATIONS

ABPA = allergic bronchopulmonary aspergillosis
PFT = pulmonary function test
RAD = reactive airway disease
PEFR = peak expiratory flow
MDI = metered dose inhaler

Clinical Investigations

ROLE OF HOMOEOPATHY

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