Asthma

Objectives

          After review of this module the student should be able to:


 Definition

Asthma is a chronic inflammation of the airways which results in hyperresponsive airways with episodic, reversible airway narrowing.

A list of sources for further information on the pathophysiology of asthma.


 Chief Complaint

Patients with asthma may present with the following complaints:

Patients may report one or more of the following as precipitating an attack:
Past Medical History/Review of Systems

When evaluating a patient for chronic asthma, determine the pattern of symptoms.

Obtain a history of the patientís disease.
Medications

Determine the patientís use of medications.

Family Medical History

Is there a history of allergies or asthma in the patientís family members?


Social History
If peak flow measurements are being recorded at home, request that the patient record them and bring the record to each visit to be noted into the medical record.


 Physical Examination

With the evaluation of the vital signs and general appearance, it should be possible to form an assessment of the severity of an asthma exacerbation. If the patient appears distressed a pusle oximetry reading or arterial blood gas should be obtained and emergent care initiated.
 

  1. HEENT
    1. nasal
      1. Increased nasal secretions or mucosal swelling can be evidence of viral syndromes or upper respiratory infections which can act as precipitants for asthma exacerbations.
      2. The presence of nasal polyps in a patient with asthma should prompt consideration of aspirin sensitivity.
    2. oropharynx
      1. Erythema, edema, or exudate in the oropharynx may indicate upper respiratory infections of bacterial or viral origin
  2. Heart
    1. Tachycardia may indicate respiratory distress or may be present as a side effect of medications.
  3. Chest/Lungs
    1. Visualization
      1. The use of accessory respiratory muscles may be evident during asthma exacerbations with visible contractions of the scalene and or sternocleidomastoid muscles resulting in raised clavicles.  Intercostal, suprasternal, or substernal retractions  during inspiration can be an important clue in patients too young to express a complaint.
      2. With chronic asthma, hyperexpansion of the thorax may develop resulting in a barrel chest with an increased anteroposterior diameter of the chest and decreased respiratory excursion of the chest wall.
      3. An altered level of consciousness may be apparent in severe asthma attacks.
      4. Cyanosis may develop periorally or peripherally in the nailbeds may be present to indicate poor blood oxygenation.
      5. Patients may assume a sitting position and lean slightly forward to maximize air exchange.
    2. auscultation
      1. Wheezing during normal breathing is one of the more common signs of asthma but is not always present in asthma patients.
      2. An expiratory phase that is prolonged compared to the inspiratory phase is characteristic of asthma.
      3. Decreased breath sounds may be an ominous sign in asthma exacerbations, indicating that the patient is no longer moving enough air through air passages to produce wheezing.
  4. Skin
    1. Atopic dermatitis/eczema is associated with asthma in some patients. The connection between allergies and asthma is common enough that the presence of one should prompt consideration of the other.
Testing

1. Pulse Oximetry (Pulse Ox; Sao2) is a noninvasive measurement of peripheral blood oxygenation easily available in most clinical settings. It is faster and less traumatic to obtain than an arterial blood gas but not as accurate. It is commonly used to monitor therapy and determine the degree of severity of an asthma exacerbation.

2. The Peak Expiratory Flow meter is used more for monitoring than diagnosis. Peak flows should be measured at every clinical visit of an asthmatic patient to assess their current state of health and during exacerbations to assess response to therapy. Observing the patient while a peak flow is being measured can identify incorrect use of the peak flow meter and allow an opportunity for education during the clinical visit.

Once a patient is diagnosed with asthma, they should be provided with a peak flow meter and instructed in its use. Patients should be asked to measure their peak flows at home twice daily for a two week period when they feel their asthma is least active. This Ďpersonal bestí is used as a standard by which the patient can determine their lung function and recognize acute changes.

ĎZonesí are assigned to ranges of the patientís peak flow to provide early warning of exacerbations. A plan of action can be written out for the patient to follow depending on which zone their peak flow falls in. Diagrams of peak flow charts, zones, and an example of a written plan of action can be reviewed here.

3. Arterial blood gas measurement is invasive and painful to the patient. It is used to evaluate Pco2 and Po2 during more severe exacerbations of asthma to evaluate possible impending respiratory failure.

4. A Chest Radiograph (CXR) is often unremarkable in asthmatic patients. With chronic untreated disease characteristic changes of hyperexpansion, flattened diaphragms and narrowed mediastinum and cardiac shadow may be present. More often the chest radiograph is ordered to evaluate the patient for concurrent lung disease such as pneumonia or bronchitis. An example of characteristic changes seen with asthma can be reviewed here.

5. Complete blood count is not routinely helpful in evaulation of chronic asthma. Acute attacks triggered by infection may result in an increased white cell count. Patients receiving corticosteroids for treatment of asthma may have an increased white cell count.

6. Patients taking theophylline for their asthma will need a serum theophylline level checked periodically to assess dosing.

7. Spirometry is used both for monitoring and diagnosis of asthma. Full pulmonary function testing or isolated measurements of FEV1 and FVC can illustrate the obstructive and reversible qualities of asthma. An FEV1 or FEV1/FVC values that are lower than expected are indications of obstructive airway disease. The reversibility of asthma can be demonstrated by measurements which show improvement after the administration of a bronchodilator. Significant reversibility is defined as an increase in FEV1 >= 12 and 200 ml after inhaling a short-acting bronchodilator. In some patients a trial of inhaled corticosteroid may be required to demonstrate reversibility.

8. In patients whose asthma is triggered by allergens, allergy testing may be needed to firmly establish the allergens the patient is sensitive to.

9. Gatroesophageal reflux disease can be masked by asthma symptoms and may increase the severity of those symptoms.  Diagnosis and successful treatment of GERD may influence the success of asthma therapy.


Diagnosis
Key Indicators for establishing diagnosis of asthma: 
    a. Wheezing 
    b. History of: 
      - cough, worse particularly at night 
      - recurrent wheeze 
      - recurrent difficulty in breathing 
      - recurrent chest tightness 
    c. Reversible airflow limitation and diurnal variation as measured by PEF meter (AM and early afternoon PEF vary by as much as 20%)
    d. Symptoms occur or worsen in the presence of: 
      - exercise 
      - viral infection 
      - animals with fur or feathers 
      - house-dust mites 
      - mold 
      - smoke 
      - pollen 
      - changes in weather 
      - strong emotional expression 
      - airborne chemicals or dust 
      - menses 
    e. Symptoms occur or worsen at night, awakening the patient 
National Asthma Education and Prevention Program Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma 


Appropriate therapy

Goals of therapy

Appropriate follow-up

Links
National Asthma Education and Prevention Program Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma

American Lung Association - General Asthma Information

American Academy of Allergy, Asthma and Immunology

Lung Information for Health Care Professionals by the National Heart, Lung, and Blood Institute

Lung Information for Patients and the General Public by the National Heart, Lung, and Blood Institute

Asthma Management Handbook 2002 - National Asthma Council, Australia

Asthma Education: Interactive Guidelines - Virtual Hospital, University of Iowa Health Care


D.L. Powell, MD
updated 8/12/05


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