As complex as it is common, chronic cough in children presents diagnostic and treatment challenges that are complicated by a dearth of solid data and, often, the anxieties of well-meaning parents.
An important defense mechanism for clearing the airway and signaling the presence of an upper respiratory tract infection (URTI), coughing represents the most common reason for pediatrician visits in the United States.1 However, the search for an underlying etiology often proves fruitless, and in other cases multiple etiologies may overlap, making diagnosis and treatment difficult. However, a practical approach focuses on red-flag symptoms that help point the way toward appropriate management strategies regardless of diagnosis.
The cough reflex occurs when inhaled, aspirated, or locally produced objects activate sensory nerves located throughout the airway. These afferent nerves communicate with the brainstem, which signals motor nerves that activate respiratory muscles to produce the characteristic cough response.
Often, coughing is normal. Healthy school-aged children typically cough between 10 and 34 times daily.2 Of concern, however, is chronic cough, which for practical purposes most experts define as cough lasting more than 4 weeks,3 based on the expected duration of acute URTIs, which represent the most common cause of coughing in adults and children. Coughing associated with a typical viral URTI lasts 14 to 21 days.
Because most acute (lasting longer than 3 weeks) and subacute (lasting 3 to 8 weeks) coughs in adults and children signal viral URTIs, they do not demand specific diagnostic evaluation. In otherwise healthy children, these coughs stem from transient situations that are likely to be self-limited.
However, the aftermath of viral respiratory tract infections can include upregulation of cough reflex sensitivity (CRS), which can provoke coughing long after the infection has resolved.
Other conditions associated with increased CRS include asthma, gastroesophageal reflux disease (GERD, albeit weakly), and angiotensin-converting enzyme inhibitor therapy.
When to worry
Children in whom cough reflex hypersensitivity persists beyond 3 weeks may require evaluation. Additionally, all children with cough persisting beyond 8 weeks should be evaluated.
Outside CRS and garden-variety URTIs, other forms of abnormal, persistent coughing in children can be associated with more severe, progressive underlying illnesses and/or structural abnormalities. Such cases require thorough evaluation to ensure that underlying problems are properly identified and, to the extent possible, addressed. The Table lists cough characteristics and associated symptoms that should raise these red flags.
Key questions to ask
Although multiple etiologies can overlap, the following questions1 can help determine the etiology of a particular cough:
· When and how did it begin?
· Is the cough an isolated symptom; if not, what other symptoms exist?
· What is the cough's character or quality? How disruptive is it?
· What triggers the cough?
· At what time(s) does the cough occur?
· Is there a family history of respiratory, allergic, or infectious disease?
· Does the child (or do the parents) smoke? Is there evidence of environmental pollutants in the home?
· What treatments have been tried, and what were their effects?
· What medications, if any, does the child take?
· How old is the child?