A practical approach for the adult asthma patient
By Richard L. Sheldon, MD, FACP, FCCP
(Editor’s note: This is the second of a multi-part series on a practical, structured approach to managing asthma in the adult patient. In the last issue of Asthma Management, we covered the epidemiology, etiology, definition and pathophysiology of asthma.
In this month’s issue, we cover clinical features and differential diagnosis, as well as special tests. In future issues, we will cover disease management procedures, pharmacology, hospital treatment and alternative medicine therapies.)
Clinical features and differential diagnosis
"All that wheezes is not asthma," is an oft-repeated axiom. The diagnosis is usually not difficult and should be entertained when there are episodic symptoms of airflow obstruction that are at least partially reversible.
The differential diagnosis should include chronic obstructive pulmonary disease, recurrent aspiration, congestive heart failure, pulmonary embolism, upper airway obstruction, laryngeal and vocal cord dysfunction, cystic fibrosis, lung involvement of vasculitides, drug-induced cough (ACE inhibitors), industrial bronchitis, carcinoid syndrome, and hysteria.
Most of the diseases making up the differential diagnosis are easily ruled out by a complete history and physical, but complex laboratory and radiographic studies may be required when dealing with some of the more unusual diseases.
In the adult, the most important presenting symptom is intermittent cough. This is usually accompanied by a complaint of recurrent dyspnea and chest tightness (wheezing). The symptoms frequently occur at night, prompting a concern that recumbancy and the clinical situations accompanying recumbancy, such as congestive heart failure and aspiration, are present. Further investigation helps to clarify these issues.
Symptoms tend to present or be made worse with exposure to pollens, tobacco and wood smoke, animals with fur or feathers, molds, dust, chemicals (perfumes, etc.), or industrial pollution (may or may not be job-related). Other inciting historical events include exercise, viral infections, changes in weather, menses, and intense emotional shifts.
The pattern of symptoms is important but may be misleading. Despite a lack of seasonal, diurnal variation, or episodic history, asthma should be high on the diagnostic list in the consideration of undiagnosed cough or wheezing.
Care should be exercised when considering family history of asthma, hay fever, eczema, or other atopic disease since these are not strong indicators of the presence of asthma. Nonetheless, close relatives with allergies, rhinitis, sinusitis, and nasal polyps should be noted.
Injury of the airways by way of pneumonia (especially if recurrent) and exposure to parental smoking as a youth are important pieces of historical data.
Other important historical data include social aspects of patients — where they are employed and, thus, to what substances they are exposed (see table, at below). Home environmental issues (including heating and cooling systems, carpeting, pets, hobbies, and vacation habits) are all important pieces of information.
|Occupational Triggers and At-Risk Workers|
|• Di-isocyanates||Plastics, floor varnishers, spray painters|
|• Anhydride||Plastics, resins|
|• Trimelitic anhydrides||Plastics, epoxy resins|
|• Amines||Photographers, shellac|
|• Wood dust or bark||Carpenters, furniture makers|
|• Metals (nickel & cobalt)||Metal platers and grinders, diamond polishers|
|• Drugs (PCN, psyllium, TCN)||Pharmaceuticals|
|• Enzymes||Pharmaceutical and detergent|
|• Latex||Health care|
|• Plants||Tea and herbal processors|
|• Insects||Farmers, entomologists|
|• Crabs and prawns||Fishermen, processors|
|• Animal urine||Handlers and research labs|
If there is a smoking history present and the patient is a current and active smoker, considerable time should be taken to obtain details of this part of the patient’s life. Extensive questioning by the physician of the patient’s smoking habits will start a process whereby the physician can let the patient know that smoking must immediately stop.
The major physical findings in the asthmatic will occur in the thorax, upper airway, and skin. Since asthma is described in terms that stress the episodic nature of the symptoms, the examiner must be prepared for a normal physical exam, even in a patient with significant disease.
Thorax. Chronic air-trapping will result in a permanently hyper-expanded chest that is seen as an increase in the anterior-posterior diameter. With acute and severe airway obstruction, findings may include the use of accessory muscles. More subtle findings of respiratory muscle distress include abdominal paradox and respiratory alternans.1
Normally, the abdomen moves outward with inspiration and inward with expiration. When the diaphragm fatigues, the opposite occurs causing abdominal paradox. Also, periods may occur when the accessory muscles serve as the main respiratory muscles while the diaphragm rests. Then, the diaphragm resumes its work while the respiratory muscles rest. This is called respiratory alternans. These last two are indicators of a failing respiratory "pump" and should be clues to advanced disease requiring hospitalization.
The most compelling finding in the physical examination of the asthmatic is wheezing. This "continuous" near musical sound is caused by narrowing of the bronchi and bronchioles by spasm, airway edema, mucus plugging, or pressure on the airways from the surrounding lung, resulting in fluttering of the airway walls. To be asthmatic wheezing, it should be involuntary, with the normal person being able to produce a wheeze voluntarily with forced expiration. Asthmatic wheezing is usually heard in expiration, but, as the attack worsens, it can be heard throughout the entire respiratory cycle. Ominously, wheezing may dissolve as the attack worsens, so that the chest becomes quiet as the patient in near respiratory collapse struggles to breathe.2
Upper Airway. The asthmatic’s respiratory mucus lining from top to bottom can be viewed as a continuum, with inflammation being the common denominator. An increase in mucosal swelling in the nose along with increased secretions are common. The presence of clear, jelly-like masses starting in the farthest reaches of the nasal passages seen with a otoscope indicate nasal polyps. Use of aspirin, NSAIDs, and tartazine have been implicated as causative factors in their development. In private discussions with fellow clinicians, there is agreement that nasal polyps are seen less often these days. It is suspected that the reason is due to the increased use of nasal steroids and nasal cromolyn.
Skin. Atopic dermatitis and eczema are common problems for the asthmatic.
Pulmonary Function Testing. Part of the basic work-up of the suspected asthmatic should be a measurement of the FVC, FEV1, and FEV1/FVC before and after inhaling a beta-agonist. The response to the inhaled beta-agonist helps to establish the reversibility aspect of asthma. The American Thoracic Society guidelines require an increase of more than 12% and 200 ml in FEV1 to indicate significant reversibility.
Primary care clinics should have access to spirometry for diagnosis and monitoring. Office spirometry for this purpose should be performed using equipment and techniques that conform to American Thoracic Society standards.
Methacholine, Histamine, and Exercise Challenge. The baseline pulmonary function test may be normal in a patient highly suspected of having asthma. In such cases, the patient’s airway can be challenged with methacholine, histamine, or exercise, and then the pulmonary function test is performed again in order to see the effects of the challenge. This test has the potential for being dangerous and therefore should only be done in a lab trained in its use and using tightly controlled protocols. The test should not be done if the patient’s FEV1 is less than 65%.
Allergy Testing. Skin tests and other forms of in-vitro tests should be considered for patients with persistent asthma and who are exposed to perennial indoor allergens.
Bronchoscopy. Within the usual clinical setting, this important diagnostic tool has not been useful in the diagnosis and therapy of asthma. It has proved invaluable in the research setting — tracking the pathophysiology of asthma with bronchoalveolar lavage and studying the effects of medications on many aspects of asthma.
Peak Flow Meters. These hand-held devices are simple to understand and operate. They have become important tools and are used at home for the day-by-day monitoring of airway hyper-responsiveness. Initially, the patient uses the meter over a two- to three-week period to establish his or her "personal best" peak expiratory flow rate (PEFR). Daily monitoring of the PEFR is then compared to his or her personal best. If the daily PEFR stays in the 80% to 100% range of his or her personal best PEFR, then usual dosing of the condition continues or tapering can be advanced. If the PEFR falls to 60% to 80% of his or her personal best, worsening of symptoms will follow and will require an increase in medications. A drop in PEFR to 60% or less requires immediate intervention and perhaps a visit to the physician.
[Editor’s note: Richard L. Sheldon, MD, FACP, FCCP, is a clinical professor of medicine at Loma Linda University, and a staff pulmonologist/intensivist at Beaver Medical Group, in Redlands, CA.
The article was peer reviewed by Felipe A. Rubio, MD, clinical chief of the department of medicine at Kettering Medical Center; and Theodore Shankel, MD, pulmonary and critical care medicine, Beaver Medical Clinic, in Redlands, CA.]
1. Wilkins RL, et al. Clinical Assessment in Respiratory Care. 3rd ed. St. Louis, MO: Mosby-Year Book; 1995.
2. Pasterkamp H, et al. Respiratory sounds: Advances beyond the stethoscope. Am J Respir Crit Care Med 1997; 156:974-984.