Description
- respiratory tract infection with wheezing or coughing (with or without sputum)
Incidence/prevalence
- sixth most common diagnosis made during family physician visits
Possible risk factors
- underlying predisposition to bronchial reactivity during viral infection
- immunocompromise
- exposure to persons with respiratory complaints
Associated conditions
- asthma
Causes
- viral infection (most common) in healthy adults
- most commonly isolated viruses in large series
- influenza A and B
- parainfluenza
- respiratory syncytial virus
- coronavirus
- adenovirus
- rhinovirus
- viruses more common than bacteria among elderly patients hospitalized for non-pneumonic lower respiratory tract infection
- nonviral agents (minority of cases) including
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Bordetella pertussis
- Legionella
- Haemophilus influenzae
- Streptococcus pneumoniae
- Moraxella catarrhalis
- noninfectious causes include inhalation of toxic substances such as
- cigarette smoke
- sulfur dioxide
- nitrogen dioxide
- ammonia
Pathogenesis
- bronchial edema and mucus formation leads to sputum production, cough, and symptoms of airway obstruction
Clinical presentation
- patients with acute bronchitis or upper respiratory tract infection (URI) have considerable overlap in symptoms and signs
- symptoms may include
- cough (productive or nonproductive)
- fatigue due to nocturnal cough
- sputum production
- clear or purulent (about 50%)
- sputum color may not be associated with bacterial infection in patients with acute cough and no underlying chronic lung disease
- dyspnea on exertion
- wheezing, rhonchi, or other signs of obstruction
- may have accompanying URI symptoms (for example, fever, sore throat, nasal congestion, runny nose)
Past medical history (PMH)
- ask about history of asthma
Social history (SH)
- ask about smoking or other toxic inhalant exposures
Physical
- General physical
- may have low-grade fever
- practitioner interpretation of common clinical signs (such as fever, tachypnea, and chest signs) may be unreliable in preschool children
- HEENT
- may have rhinitis or pharyngitis
- may have conjunctivitis or otitis media if adenoviral infection
- Neck
- may have lymphadenopathy
- Lungs
- lung examination useful but not diagnostic
- wheezing, rhonchi, prolonged expiratory phase or other obstructive signs may be present but not essential
Making the diagnosis
- no clear diagnostic criteria have been established
- cough in the absence of fever, tachycardia, and tachypnea suggests bronchitis instead of pneumonia, except in elderly patients
