CHICAGO - Cough is the chief complaint for 7% of pediatric office visits, resulting in 16 million visits per year. A thorough history, physical examination and a few readily available diagnostic tests usually lead to a specific diagnosis of the chronic cough, according to Susanna A. McColley, MD, assistant professor of pediatrics, Northwestern University.
Chronic cough is a problem, said McColley, because it is common. It is disturbing to parents, children and others. Although a cough can be nonspecific and sometimes associated with disorders that are self-limiting and minor, chronic cough can also be associated with many serious and life-threatening diseases, she said.
The definition of chronic cough used in the literature, said McColley at the 1999 Spring Session of the American Academy of Pediatrics held here, is cough that occurs daily for three or more weeks. However, there is a broad differential diagnosis of chronic cough, she added.
The most common causes are recurrent viral upper respiratory infections (URIs), asthma and upper airway diseases like rhinitis and sinusitis. She called asthma, gastroesophageal reflux disease (GERD) and postnasal drip "the big three," and said they are most often found to be the cause of chronic cough in adults. Children are also affected by these disorders.
Environmental factors such as tobacco smoke, infection, aspiration disorders and psychogenic cough are common causes. Less common causes are cystic fibrosis (CF), congenital anomalies, immunodeficiency, ciliary dyskinesia and interstitial lung disease.
"Many children will have more than one active diagnosis and often it does take several office visits to get down to the cause of chronic cough," McColley said.
Recurrent URIs may present as chronic cough, especially in infants and young children. History and physical examination will show URI symptoms; each cough begins with upper respiratory symptoms followed by waxing and waning of symptoms, she said.
A careful history will find a child with a cough who can sometimes be cough free for several days at a time. "This is something that definitely gets worse and then gets better and has periods of complete resolution," she said.
Children in day care and in homes with older siblings have a statistically higher risk of developing chronic cough from URIs. The best way to differentiate URIs from other more serious causes of chronic cough, said McColley, is to take a careful history and physical examination.
It is most important in the history to establish if the cough is really chronic, said McColley. The onset should then be looked at to determine if the cough was sudden or insidious, started with an URI or with exposure, or had associated symptoms like ear pain.
A sudden onset is associated with an inhaled foreign body or some kind of acute exposure to a noxious environmental agent. Insidious onset is more commonly associated with things like asthma and chronic sinusitis.
Noting the cough characteristics helps examine its nature. These include determining if the cough is wet or dry; if coughing episodes are single, occur a few at a time, or occur in coughing paroxysms; if the cough has a cycle; and, what time of day or year it occurs.
A wet cough is associated with inflammation. "It makes you think about inflammatory disorders that cause bronchitis such as asthma," she said.
A dry cough is more likely to be caused by an irritant or post nasal drip. "I would say that there is a tremendous overlap between wet and dry and you cannot exclude a diagnosis based only on that, but it is helpful."
Determine the characteristics of the coughs occurrence. Ask the patient if coughing occurs in single episodes, a few at a time, or if there are there paroxysms, she said. Paroxysms are most common in children who have infections - especially in children who have pertussis. However, they can also occur in Mycoplasmainfections and in disorders such as CF, with which there is a lot of mucus in the chest.
"Cough sets off some mucus clearance and you get a paroxysm," she said.
Also note if there is a cycle to the cough and determine if it is circadian, infradian, or ultradian. The time of day the cough occurs is important because nocturnal cough is commonly associated with asthma and sinusitis. Time of week and year is important in a child who has had a cough for more than a year. Determine if there are cough-free intervals, she said.
Some children seem to have no specific triggers; their cough seems random. In many cases, however, viral respiratory infections, allergen exposure or physical activity can provide a clue to the cause of the cough.
McColley recommended looking into a response to prescribed and over-the-counter (OTC) medications. Many people try an OTC remedy before seeing their physician and they sometimes help. "For example, response to an antihistamine gives you a clue into some kind of allergic disorder or nasal problem," she said.
A comprehensive review of systems is also helpful in chronic cough diagnosis. Many children present with a history of chronic cough as their chief complaint, but they have wheezing. "This makes you think of asthma or asthma mimickers, things that cause intrathoracic airways obstruction," she said.
Association with meals is important, particularly in infants. A cough occurring during feeding is associated with aspiration disorders and one occurring after is associated with GERD.
Ear, nose, or throat irritation can be associated with cough, said McColley. Determine if the child has any voice change, stridor, or hemoptysis.
Digestive problems and bowel movements should be evaluated for possible CF in the patient with chronic cough, because weight change or irregular growth patterns could be associated with more serious types of disorders, like CF.
A growth assessment should be conducted during the physical examination to look at current percentiles and patterns over time. "A loss in percentiles is worrisome," McColley said. Also note if the child is generally vigorous or not and look for evidence of respiratory distress.
The ear, nose, and throat examination is one of the most important parts of the physical examination in children with chronic cough. "You want to look for evidence of allergic disease, like inflammation of the nose," she said.
The middle and external ear are also important to evaluate. "One of my favorite pieces of pulmonary trivia is that a retained foreign body in the ear canal can cause chronic cough through stimulation of a branch of the facial nerve called Arnold's nerve," said McColley. "I have found one case of a child who had a small bead in the external ear canal and when it was removed the cough did go away."
Diaphragm position can be found by careful chest percussion. Most of the time it can be performed in infants and children, but those around 2 years of age will usually not let enough percussion be performed.
"Chest percussion is a very useful and underutilized physical examination maneuver in children," she said.
McColley suggested a careful cardiac examination to rule out causes of congenital heart disease that cause pulmonary over circulation and can present as chronic cough.
In children presenting with chronic cough, the history should be reviewed carefully when determining strategy. "Laboratory testing is not necessarily a situation of `more is better,' " she said.
In almost all cases, said McColley, a chest radiograph is indicated to rule out certain types of anomalies that can be associated with chronic cough. A sweat test should always be considered in the evaluation. It is a accurate test when performed appropriately.
Pulmonary function testing (PFT) is useful for looking at airway function and the general size of the lung. This can generally be achieved in children who are at least 5 years old. While many literature references suggest PFT for children 7 to 8 years age, McColley said a pulmonary function laboratory that tests many children can perform reasonable PFTs on 3-year-olds, and in "probably 50% of 4-year-olds, and almost all 5-year-olds who are developmentally normal." PFT is likely underused because of access problems, but most laboratories will allow you to refer patients to the laboratory without a subspecialty diagnostic referral, she explained.
Studies other than these, said McColley, should only be performed according to the history, physical and response to therapy.
For management of chronic cough, cough suppressants have limited indications, said McColley. The important thing about a cough suppressant, said McColley, is that it should be used acutely not chronically. Acute viral cough, especially for sleep, may be an indication.
However, the efficacy of most over-the-counter and prescribed cough suppressants is very poor, and these are contraindicated in asthma or pertussis because they decrease secretion removal, she said.
"When we see a patient with a cough we want to know what is causing it and that it is not serious. The patient just wants the cough to go away. So to give a cough suppressant is tempting."
In some situations codeine, which works on central receptors, is efficacious. "However, I think that should be prescribed rarely because most of these coughs are going to be self-limited," she said.
Patients need to be counseled and should understand that even with appropriate therapy, the most common diagnoses take time to improve. "Most chronic cough has an inflammatory component that resolves slowly, even with appropriate therapy," she said.
Patients need to understand, said McColley, that even with the best treatment their cough could still last for one or two weeks. "I think that gives them some piece of mind when they are listening to their child cough at night."
For more information:
- McColley SA. Chronic cough (ARS). Session S305. Presented at the American Academy of Pediatrics 1999 Spring Session. April 17-20. Chicago.
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