ASTHMA

ASTHMA - Mary Cataletto, MD
BASICS
DESCRIPTION
• Disorder of tracheobronchial tree characterized by mild to severe obstruction to airflow that is at least partially reversible. Symptoms vary, generally episodic or paroxysmal, but may be persistent. Clinical hallmark is wheezing, but cough or chest tightness may be predominant symptom.
• Acute symptoms characterized by narrowing of large and small airways owing to spasm of bronchial smooth muscle, edema, and inflammation of bronchial mucosa, and production of mucus.
• Classification
- Mild intermittent: Day symptoms: /= 2 days/week; Night symptoms: /= 2 nights/month
- Mild Persistent: Day symptoms: >2 days/week, 1/day; Night symptoms: >2 nights/month
- Moderate Persistent: Day symptoms: Daily Night symptoms: >1 night/week
- Severe Persistent: Day symptoms: continuous Night symptoms: >1 night/week
• Occurs in setting in which asthma is likely, and other, rarer conditions have been excluded
• System(s) affected: Pulmonary
• Synonym(s): Bronchial asthma; Reactive airway disease
ALERT
Pregnancy Considerations
• ~50% of asthma patients have no changes, 25% seem to improve, and 25% develop worse symptoms.
• Stress prevention.
• Avoid medications with contraindications.
GENERAL PREVENTION
• Patient and/or family partnership with health care provider
- Patient understanding of medication, inhalers, nebulizers, peak flow meters, triggers
- Monitor symptoms: Peak flow monitoring may also be helpful.
- An asthma action plan may be helpful
• Investigate and control triggering factors (pollutants, exercise, house-dust mites, roaches, molds, animal dander)
• Evaluate and treat comorbidities (GERD, atopy, sinus disease)
• Annual influenza immunization
• Avoid cigarette exposure.
• Avoid aspirin, NSAIDs, -blockers, sulfites, if sensitive.
• Regular follow-up
EPIDEMIOLOGY
• Leading cause of missed school days: 7.5 million per year
• Predominant age
- 50% of cases: Children 10 years
- Young adult (16-40 years), but may occur at any age. Unusual for initial episode to occur in geriatric population
• Predominant sex
- Children 10: Male > Female
- Puberty: Male = Female
- Adult onset: Female > Male
Incidence
• 10 million new cases each year; however, confusion exists owing to lack of uniform definition
• 50% of new cases of asthma occur in children 10 years.
Prevalence
7-19% of children
RISK FACTORS
• Positive family history of asthma or atopy
• Viral lower-respiratory infection during infancy
• Environmental tobacco smoke
• Inner-city dwelling
Genetics
• Search for an asthma gene under way
• Familial association of reactive airway disease, atopic dermatitis, and allergic rhinitis
ASSOCIATED CONDITIONS
• Reflux esophagitis
• Sinusitis
• Atopy

DIAGNOSIS
SIGNS AND SYMPTOMS
• Variation in pattern of symptoms: Paroxysmal, versus constant,
• Abnormal pulmonary function tests may occur without symptoms
- Wheezing
- Cough
- Chest tightness
- Chest pain
- Exercise-induced wheezing or cough
- Prolonged expiration
- Nocturnal attacks
- Pulsus paradoxus
- Tachycardia
- Hypoxia
- Accessory respiratory muscle use
- Flattened diaphragms
- Growth usually normal
History
• Pattern
• Triggers
• Exposures (pets, tobacco smoke)
• Comorbidities
• Severity
• Medications
• Family history of asthma and allergy
Physical Exam
Focus on general appearance; upper, middle, and lower airway; and skin
TESTS
• Pulmonary function tests with methacholine challenge: Reversible airway obstruction (increased airway resistance, decreased airflow rates). If pulmonary function tests are within normal limits and no bronchodilator response is seen, airway challenge with cold air, methacholine, or exercise may be helpful in establishing diagnosis.
• Allergy testing
Lab
• CBC: Peripheral eosinophilia in atopic patients
• Immunoglobulins
- Screen for immunodeficiency (IgA, IgG subclasses) for patients with recurrent infections or severe allergies.
- IgE is elevated in atopic patients and markedly elevated in allergic bronchopulmonary aspergillosis.
• Sweat test in chronic childhood asthmatics to rule out cystic fibrosis
• Arterial blood gases may be helpful in status asthmaticus.
• Antihistamines may alter allergy skin testing.
Imaging
Chest radiograph: Valuable at time of initial diagnosis to rule out other serious intrathoracic pathology, but should not be routine with each exacerbation
• Right middle lobe atelectasis may occur
• Hyperinflation
• Air leak syndromes: Pneumothorax, pneumomediastinum may occur
Diagnostic Procedures/Surgery
• Spirometry: Decreased FEV1
• Bronchoscopy: Rarely indicated
Pathological Findings
• Smooth-muscle hyperplasia
• Mucosal edema
• Thickened basement membrane
• Inflammatory response
• Hyperinflated lungs
• Mucus plugging
DIFFERENTIAL DIAGNOSIS
• Foreign-body aspiration: Always consider, especially with unilateral wheeze.
• Cystic fibrosis
• Viral respiratory infections (croup, bronchiolitis)
• Epiglottitis
• Bronchopulmonary aspergillosis
• Tuberculosis
• Hyperventilation syndrome
• Habit cough
• Congestive heart failure
• Chronic obstructive pulmonary disease
• Hypersensitivity pneumonitis
• Vascular anomalies
• Mediastinal mass
• Tracheobronchomalacia
• Vocal cord dysfunction
TREATMENT
STABILIZATION
• Relieve bronchospasm: Administer short acting 2 agonist
• Administer supplemental oxygen for severe exacerbation
• IV fluids if necessary
• Oral corticosteroids if exacerbation
- Adult: 60-80 mg/d prednisone
- Pediatric: 1-2 mg/kg/d prednisone (1)
Diet
Avoid foods with preservatives, known allergic triggers and those with sulfites
Activity
• Early diagnosis and appropriate treatment facilitate unrestricted activity.
• Be aware of known triggers
- Allergic factors
 Airborne pollens
 Molds
 House dust (mites)
 Cockroaches
 Animal dander
 Feather pillows
- Other factors
 Tobacco smoke and other pollutants
 Infections, especially viral
 Aspirin
 Exercise
 Cold air
 Sinusitis
 Gastroesophageal reflux
 Sleep (peak expiratory flow rate lowest at 4 am)
• Current research focuses on inflammatory response (including abnormal release of chemical mediators, eosinophil chemotactic factor, neutrophil chemotactic factor, and leukotrienes).
Nursing
Care should be culturally sensitive
SPECIAL THERAPY
IV Fluids
May be necessary if patient is tachypneic, unable to tolerate oral feeds, or is dehydrated.
MEDICATION (DRUGS)
First Line
• Asthmatics should have an action plan for exacerbations. Patients with mild intermittent asthma do not require daily treatment and should keep a short-acting 2 agent available for symptomatic relief. Patients with persistent asthma require daily medication. The drug regimen of choice for patients with persistent asthma includes an inhaled corticosteroid. The preferred regimens are as follows for persistent asthma:
• Mild persistent asthma: Low-dose inhaled corticosteroid
• Moderate persistent asthma: Low-dose inhaled corticosteroid plus a long-acting -agonist. Medium-dose inhaled corticosteroids also can be used.
• Severe persistent asthma: High-dose inhaled corticosteroids plus a long-acting -agonist.
• Alternatives exist in each category.
FOLLOW-UP
DISPOSITION
Admission Criteria
• Respiratory distress
• Complications including pneumonia, pneumothorax, significant atelectasis
• Need for supportive care (e.g., dehydration)
• Poor control of symptoms or poor response to treatment
Discharge Criteria
• Support systems in place
• Patient and family education
• Control of exacerbation
• Stable clinical status
Issues for Referral
• For patients 5 years
- Required for step 3 and 4 care and may be considered for step 2 care. Referral also should be considered when specialized testing or treatment is required, when the diagnosis is in question, and when further education is requested or required.
• For patients 5 years
- Required for step 4 care; should be considered for step 3 care when specialized testing or treatment is required, when the diagnosis is in question, or when additional educational intervention is needed.
PROGNOSIS
• Excellent, with attention to general health and use of medications to control symptoms
• Mortality risk increases with
- >3 emergency room visits per year
- Nocturnal symptoms
- History of ICU admission
- Mechanical ventilation
- >2 hospitalizations per year
- Systemic steroid dependence
- History of syncope with asthma
- History of noncompliance
• Mortality rates are increasing.
• If response to treatment is poor, review diagnosis and compliance prior to adding more potent therapy.
COMPLICATIONS
• Respiratory failure
• Atelectasis: Most common in right middle lobe
• Flaccid paralysis after exacerbation (self-limited and rare)
• Death
• Air-leak syndromes (e.g., pneumothorax)
• Syndrome of inappropriate secretion of antidiuretic hormone (SIADH)
• Altered theophylline metabolism
• Steroid myopathy
• Inhaled steroid safety has been established.
PATIENT MONITORING
• Peak expiratory flow rate at home
• Office spirometry with periodic full pulmonary function tests done in PFT lab
• For ED patients consider
- Oximetry
- Arterial blood gases
- Electrolytes: Frequent albuterol lowers potassium.
- Exhaled nitric oxide
- PEFR or FEV1 measurements
• Written and periodically revised action plan is helpful.
• Periodically drug and device training should be reviewed.
REFERENCES
1. Expert Panel Report. Guidelines for the diagnosis and management of asthma. NHLBI, 2002. NIH Publication 97-4051A.
2. Williams SG, Schmidt DK, et al. Key clinical activities for quality asthma care. Recommendations of the National Asthma Education and Prevention Program, MMWR. 2003;March 28.
ADDITIONAL READING
http://wwww.nhlbi.nih.gov.guidelines/asthma/index/htm
MISCELLANEOUS
See also: Bronchiolitis; Bronchitis, acute; Chronic obstructive pulmonary disease and emphysema; Congestive heart failure; Cystic fibrosis; Epiglottitis; Hypersensitivity pneumonitis; Immunodeficiency diseases; Laryngotracheobronchitis; Tuberculosis