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Guidelines on Diagnosis and Management of Asthma

Contents

Pathogenesis and Definition

Asthma is a chronic inflammatory disease of the airways which causes recurrent episodes of wheezing, chest tightness and coughing. The inflammation which occurs in asthma is caused by many different cells and cellular elements including eosinophils, mast cells, T lymphocytes, macrophages, neutrophils, and epithelial cells. This inflammation is directly correlated to airway hyperresponsivenes. Control of airway inflammation will cause a decrease in hyperresponsiveness.

The four main components of airflow obstruction in asthma are:

  • Acute Bronchoconstriction
    Allergen-induced bronchoconstriction results from IgE dependant mediator release from mast cells. Other causes of bronchoconstriction include aspirin or NSAIDs, exercise, cold air, irritants or stress.
  • Airway Edema
    Increased microvascular permeability due to the release of inflammatory mediators causes increased thickening and swelling of the airway.
  • Chronic Mucus Plug Formation
    In severe asthma, mucus secretion and the formation of inspissated mucus plugs can cause persistent airflow limitation.
  • Airway Remodeling
    Airflow limitation in some patients with asthma may be only partially reversible. This may be related to structural changes in the airway matrix which accompany longstanding airway inflammation.


Types of Asthma

Child-Onset Asthma
When asthma begins in childhood it is frequently associated with atopy, which is the genetic susceptibility to produce IgE to common environmental allergens. Mast cells and other airway cells are sensitized and become activated when they encounter specific antigens. In children with wheezing during a viral infection, allergy or a family history of allergy is the strongest associated factor with recurrent asthma throughout childhood.

Adult-Onset Asthma
Although asthma occurs most commonly in children, it can also occur later in life. Adult-onset asthma can be associated with atopy. However, there can be also other causes of asthma. Some adults develop asthma without IgE antibodies to allergens. These adults often have coexisting sinusitis, nasal polyps and aspirin or NSAID allergies. Occupational exposures to materials like plastic resins, biological enzymes, animal products and wood dusts can also cause asthma.

Initial Assessment of Asthma

In making the diagnosis of asthma the clinician should look for a history of episodic airflow obstruction which is at least partially reversible. Alternative diagnoses should always be excluded. The physician should look for a history of wheezing, recurrent cough, particularly worse at night, recurrent shortness of breath, or recurrent chest tightness. These symptoms may occur or worsen with exercise, viral infection, animals, smoke, pollen, mold, strong emotional expression, menses, and airborne chemicals or dust. Physical exam should include a lung exam for wheezing, examination for nasal polyps or allergic rhinitis and skin exam for atopic dermatitis. Spirometry should be obtained on all patients in whom a diagnosis of asthma is suspected.

Differential Diagnosis of Asthma in Adults and Children

Children Adults
  • Allergic rhinitis and sinusitis
  • Vocal cord dysfunction
  • Vascular rings
  • Laryngotracheomalacia
  • Tumor or enlarged lymph nodes
  • Viral bronchiolitis
  • Cystic Fibrosis
  • Bronchopulmonary dysplasia
  • Aspiration due to gastroesophageal reflux
  • Chronic obstructive pulmonary disease
  • Congestive heart failure
  • Pulmonary Embolism
  • Mechanical obstruction (benign or malignant tumors)
  • Pulmonary infiltration with eosinophilia
  • Cough secondary to drugs (ACE inhibitors)
  • Laryngeal dysfunction

NAEPP Guidelines for Classification of Asthma

The national asthma education and prevention program has developed four different stages of asthma severity - mild intermittent, mild persistent, moderate persistent, and severe persistent asthma. The NAEPP criteria for classification of asthma severity are based on three measures:
  • frequency of symptoms (as measured by beta2 agonist use)
  • frequency of nocturnal symptoms
  • spirometry results
A patient qualifying for two different stages should be classified in the more severe stage. Below is a table outlining the current staging criteria for asthma.

Classification Severity of Symptoms Nightime Symptoms FEV
Mild Intermittent Sx < 2x/wk, otherwise asymptomatic Sx <= 2x/mo > 80%
Mild Persistent Sx > 2x/wk, < 1x/day Sx >= 2x/mo > 80%, variability from 20 to 30%
Moderate Persistent Daily Sx, daily use of a beta2 agonist Sx >= 1x/wk 60% to 80%
Severe Persistent Continual Sx, limited physical activity Frequent < 60%

Monitoring of Treatment of Asthma

With each follow-up visit asthma patients should have the efficacy of their treatment reassessed. The physician should ask about daytime and nocturnal symptoms, quality of life (missed work, decreased activity, or sleep disturbances) and any exacerbations which may have occurred. Patients with moderate to severe persistent asthma should also learn how to monitor their peak expiratory flow rate. This should be done every morning after awakening prior to use of a beta2-agonist. They should also be given a written action plan and be instructed how to use it. The plan is designed to help patients manage asthma exacerbations and adjust their medications.
An example of an Action Plan:

Sample Asthma Action plan

My best peak flow: 40

Green zone peak flow: 40 to 30  (80 to 100% of my best peak flow)
          Action: Take your normal medication

Yellow zone peak flow: 30 to 20  (50 to 80% of my best peak flow)
          Action: Take your quick-relief medication now ( 2 puffs of albuterol )

Red zone peak flow: less than 20  (less than 50% of my best peak flow)
          Action: Take your quick-relief medication now ( 2 puffs of albuterol )
                  Take 40mg of prednisone
                  Call your doctor now!

Factors Exacerbating Asthma

Irritants: Tobacco Smoke

Asthma patients should avoid exposure to environmental smoke. Tobacco smoke is the most important environmental irritant and plays a major role in both childhood and adult asthma. Studies have shown asthma patients exposed to tobacco smoke have decreased pulmonary function and need more medications as compared to asthmatics not exposed to smoke.

Irritants: Air Pollution

Asthma patients should avoid exercise or exertion when pollution levels are high. Increased levels of ozone, sulfur dioxide and nitrous dioxide can cause asthma exacerbations.

Occupational Exposure

It is important to recognize exposures in the workplace which may either cause or exacerbate a patient's asthma symptoms. Substances in the workplace which can cause asthma symptoms include animal products, wood dusts, plastic resin, biological enzymes, and metals. Patients often do not correlate their asthma symptoms with the workplace because symptoms often begin several hours after exposure. Workplace exposure should be considered in a patient whose asthma symptoms improve after several days away from work. Appropriate treatment consists of removal of the offending agent. Asthma symptoms may persist in some patients even after they are no longer exposed.

Inhalant Allergens

Animal Allergens

All warm blooded animals can produce urine, feces, dander and saliva that can cause allergic reaction. If a patient appears to have a sensitivity to animal allergens then the most appropriate measure is removal of the animal. If this is not possible then the animal should be kept out of the patient's room, the patient's bedroom door should be kept closed when possible and the pet should be kept away from any upholstered furniture.

House-dust Mites

House-dust mites usually occur in areas of high humidity or areas where moisture is added to the indoor air. They occur in mattresses, pillows, carpets, upholstery, bed covers and toys. Control measures include allergen impermeable pillow and mattress covers, washing sheets and blankets weekly in hot water, reduction of indoor humidity (if possible) and carpet removal from the bedroom (if possible).

Cockroach allergens

Sensitivity to cockroaches is common in asthmatics who live in the inner city. Measures to control cockroach infestation should be taken in sensitive individuals.

Indoor molds

Indoor fungi are more common in areas of high humidity.

Outdoor Allergens

In some patients worsening of symptoms at certain times of year an correlate with certain types of allergens. Typical patterns include:
  • Trees - Early spring
  • Grasses - Late Spring
  • Weeds - Late summer to autumn
  • Seasonal mold spores - Summer and fall
Patients who are sensitive to these allergens should attempt to stay inside with the windows closed in an air-conditioned environment. They should especially avoid going outside in the afternoon when pollen counts are at their highest.

Other Factors Exacerbating Asthma

Gastroesophageal Reflux

GERD can cause worsening of asthma, especially nocturnal symptoms. Any patient with persistent asthma and heartburn symptoms should be treated for reflux with medical management (either behavioral changes or h2 blockers).

Aspirin Sensitivity

Adult Patients with asthma should be questioned about episodes of bronchospasm associated with ingestion of aspirin or other NSAIDs. If a reaction has occurred patients should be warned about the dangers of a fatal exacerbation with use of these drugs. Patients with severe asthma or nasal polyps should also receive counseling regarding the potential of NSAIDs to cause a fatal exacerbation. Safe alternatives include acetaminophen and salsalate.

Sulfite Sensitivity

Patients with sulfite sensitivity will have asthma symptoms after drinking beer, wine, dried fruits, processed potatoes or shrimp. Patients should be advised to avoid foods containing sulfites.

Beta Blockers

Non-selective beta blockers can cause bronchospasm and exacerbate asthma in susceptible individuals. Even non-selective beta-blocker ophthalmic solutions can have systemic absorption and cause bronchospasm. If use of a beta-blocker is desired then asthma patients should be given a cardio-selective beta blocker

Allergic Rhinitis/Sinusitis

Both allergic rhinitis and sinusitis can cause worsening of asthma symptoms. Patients with persistent asthma and allergic rhinitis should be treated with intranasal corticosteroids. Antihistamines and decongestants may improve AR symptoms but will not improve asthma symptoms like a corticosteroid.