Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (571 page)

   Chronic Cough

Chronic cough is defined as a cough lasting >8 weeks. It is reported by 10–20% of adults and is common in women and obese people. Most patients present with a dry or minimally productive cough. The presence of significant sputum production usually indicates primary lung pathology.

Chest radiograph and spirometry are recommended. Bronchial provocation testing should be performed in patients without a clinically obvious etiology. Bronchoscopy should be undertaken in all patients with chronic cough in whom inhalation of foreign body is suspected. A cough can be dry or productive, depending on whether sputum is coughed up. Dry cough, that is, there is no “phlegm” and is caused by a virus infection, cold, or dry air or air pollutants such as cigarette smoke, smog, and dust. Productive coughs are coughs that produce phlegm and can be associated with tuberculosis, bacterial pneumonia, and bronchitis.

   
PULMONARY DISEASES ASSOCIATED WITH COUGH

INFECTIOUS RESPIRATORY DISEASES

ACUTE BRONCHITIS

   Definitions

Acute bronchitis is a disease caused by infection and inflammation of the bronchial mucosa. Acute bronchitis is caused by respiratory viruses (e.g., influenza virus, parainfluenza virus, rhinovirus, RSV, adenovirus, corona viruses). There is little evidence to implicate bacteria as a significant cause of acute bronchitis, though atypical respiratory bacterial pathogens (
Bordetella pertussis
,
Mycoplasma pneumoniae
,
Chlamydophila pneumoniae
) cause a small proportion of cases.

   Who Should Be Suspected?

   Patients initially present with cold symptoms but progress to cough that persists for more than 5 days. Purulent sputum may be described; purulent sputum alone is not a reliable indication of bacterial infection and should not be used as the sole indication for antibiotic treatment. Cough resolves within 2–3 weeks in most patients.

   Wheezing and bronchospasm develop in some patients.

   Fever and systemic symptoms are unusual in uncomplicated acute bronchitis; these symptoms may suggest pneumonia or influenza.

   Diagnosis

Pertussis should be ruled out for patients with suggestive clinical signs and symptoms. Acute bronchitis is a self-limited viral infection in the vast majority of patients and does not require testing for effective management. Influenza testing might be considered during “flu season” for patients at risk for complicated influenza.

   Radiographic and laboratory testing may be considered in patients if clinical presentation suggests pneumonia (cough, fever, sputum production, and systemic symptoms) or chronic bronchitis (cough and sputum production on most days for at least 3 months during 2 consecutive years).

   There is little evidence that outcome is improved by antibiotic therapy of
M. pneumoniae
or
C. pneumoniae
infection; specific diagnostic testing for these agents is not recommended.

Suggested Reading

Wenzel RP, Fowler AA III. Acute bronchitis.
N Engl J Med.
2006;355:2125–2130.

CROUP (LARYNGOTRACHEITIS)

   Definition