Approach to Chronic Cough in Children

Approach to chronic cough in children

Author:

Roni Grad, MD

Section Editor:

George B Mallory, MD

Deputy Editor:

Alison G Hoppin, MD

Contributor Disclosures

All topics are updated as new evidence becomes available and ourpeer review processis complete.

Literature review current through:Nov 2016.|This topic last updated:Jun 29, 2015.

INTRODUCTION—Coughing is an important defensive reflex that protects from aspiration of foreign materials, and enhances clearance of secretions and particulates from the airways. Healthy children may cough on a daily basis; one study documented an average of 11 cough episodes every 24 hours [1]. However, a cough may also be the presenting symptom of a serious underlying pulmonary or extrapulmonary disease. The causes of chronic cough in children are quite different from that of adults, so evaluation and management of children should not be based on adult protocols. Adolescents 15 years and older may be evaluated using guidelines for adults [2]. (See"Evaluation of subacute and chronic cough in adults".)

The differential diagnosis of chronic cough in children includes subacute and chronic infections (eg, bacterial bronchitis, pertussis, mycoplasma, and tuberculosis), foreign body aspiration, and cough-dominant asthma (table 1) [3]. Gastroesophageal reflux, upper airway cough syndrome (formerly known as postnasal drip syndrome), and sinusitis are sometimes implicated because of associations with chronic cough in adults, but their role in causing chronic cough in children is controversial [2]. Warning signs warranting concern include a cough that is unusually severeand/orfrequent, failure to thrive, growth retardation, purulent sputum, exertional dyspnea, hypoxemia, chest pain, or hemoptysis. (See"Causes of chronic cough in children".)

An approach to the diagnosis and management of chronic cough in children is presented here. Approaches to wheezing and stridor in children are presented separately. (See"Approach to wheezing in infants and children"and"Wheezing illnesses other than asthma in children"and"Assessment of stridor in children".)

EPIDEMIOLOGY—Epidemiologic studies of cough in children have been hampered by the variable definitions used for defining chronicity, the presence of other concomitant symptoms (eg, wheezing), the lack of widely accepted objective clinical endpoints to measure cough severity, and the tendency for cough to resolve spontaneously [4,5].

Despite these limitations, chronic cough appears to be common, with an estimated prevalence of 5 to 7 percent in preschoolers, and 12 to 15 percent in older children [6,7]. Cough is more common among boys than girls up to 11 years of age [6], and may be less common in developing countries than in affluent countries [8].

DEFINITION—There is no consensus as to the length of time in the definition of chronic cough in children. The American College of Chest Physicians (ACCP), Thoracic Society of Australia and New Zealand (TSANZ), and many studies have defined chronic cough as one that lasts more than four weeks, because most acute respiratory infections in children resolve within this interval [2,9]. In comparison, guidelines from the British Thoracic Society (BTS) define chronic cough as one that lasts more than eight weeks [10]. However, these guidelines also describe a "prolonged acute cough" as one that lasts at least three weeks and is "relentlessly progressive"; this type of cough may warrant investigation before eight weeks.

PHYSIOLOGY

Pathways—Each cough occurs through the stimulation of a complex reflex arc (figure 1) [3,11]. This is initiated by the irritation of cough receptors that exist not only in the epithelium of the upper and lower respiratory tracts, but also in the pericardium, esophagus, diaphragm, stomach, and external ear [12,13].

Chemical receptors sensitive to acid, heat, andcapsaicin-like compounds trigger the cough reflex via activation of the type 1 vanilloid (capsaicin) receptor [14]. In addition, mechanical cough receptors can be triggered by touch or displacement. The proximal airways (larynx and trachea) are more sensitive to mechanical stimulation, and the distal airways more sensitive to chemical stimulation. Irritation at the bronchiolar and alveolar level does not cause cough.

Impulses from stimulated cough receptors traverse afferent branches of the vagus nerve to a "cough center" in the medulla and nucleus tractus solitarius, which itself is under control by higher cortical centers. The cough center generates an efferent signal that travels down the vagus, phrenic, and spinal motor nerves to expiratory musculature to produce the cough (figure 1) [3,11]. The pelvic sphincter muscles are also stimulated to contract, avoiding urinary incontinence.

The mechanical events of a cough can be divided into three phases [15]:

●Inspiratory phase – Inhalation, which generates the volume necessary for an effective cough.

●Compression phase – Closure of the larynx combined with contraction of muscles of chest wall, diaphragm, and abdominal wall result in a rapid rise in intrathoracic pressure.

●Expiratory phase – The glottis opens, resulting in high expiratory airflow and the coughing sound. Large airway compression occurs. The high flows dislodge mucus from the airways and allow removal from the tracheobronchial tree.

The specific pattern of the cough depends on the site and type of stimulation. Mechanical laryngeal stimulation results in immediate expiratory stimulation (sometimes termed the expiratory reflex), probably to protect the airway from aspiration; stimulation distal to the larynx causes a more prominent inspiratory phase, presumably to generate the airflow necessary to remove the stimulus.

Ineffective cough—Cough is an important defensive reflex that is required to maintain the health of the lungs. Children who do not cough effectively are at risk for atelectasis, recurrent pneumonia, and chronic airways disease from aspiration and retention of secretions. Many disorders can impair a child's ability to cough effectively, resulting in persistent cough. Children with neuromuscular disease and chest wall deformities may not generate a deep enough inspiratory volume or expiratory flow necessary for effective clearance of secretions due to defective "pump" mechanisms [16]. Children with reduced function of the abdominal wall musculature are particularly at risk for ineffective cough. Children with tracheo-bronchomalacia ("floppy" airways), or with obstructive airways diseases, often do not generate the high flow rates needed for effective clearance of secretions. Individuals with laryngeal disorders, including those with tracheostomies, may not achieve sufficient laryngeal closure to generate the increased intrathoracic pressures necessary for an effective cough [11,12].

DIAGNOSTIC APPROACH—The diagnostic approach outlined in this topic review assumes a definition of chronic cough that has lasted at least four weeks. Some presenting symptoms warrant earlier evaluation (eg, onset after an episode of choking, suggesting foreign body aspiration). One study suggests evaluation and treatment of children by experienced respiratory specialists using a standardized protocol typically led to resolution of the cough within six weeks, suggesting that earlier implementation of a standardized protocol is valuable [17]. The protocol used in this study was similar to that outlined below.

Children with chronic cough should be evaluated with a detailed history, physical examination, chest radiograph, and (if the child is able) spirometry [2,3,5,7]. This evaluation often provides sufficient information to categorize the cough as specific (ie, caused by an underlying disease) or nonspecific (no evidence of an underlying disease).

Further evaluation depends on the provisional diagnosis and the course of the symptoms (algorithm 1).

Specific cough—The causes of specific chronic cough fall into the following general categories (table 2):

●Asthma

●Protracted bacterial bronchitis

●Chronic suppurative lung disease and bronchiectasis

●Airway abnormality (congenital, foreign body, or neoplastic)

●Aspiration

●Chronic or less common infections

●Interstitial lung disease

●Extrapulmonary causes: cardiac abnormalities, ear conditions

The sequence of evaluation for these disorders is informed by the age and presenting features of the child. Identification of the presenting features and cough characteristics is important because many are easily recognizable and strongly suggestive of a specific cause; this is less true in adults. (See"Causes of chronic cough in children".)

Key symptoms and signs—Certain symptoms and signs are highly predictive of a specific cough. These signs or symptoms narrow the diagnostic possibilities and call for further specific testing or referral (algorithm 1) [1,2]:

●Chronic wet cough

●Wheezing or crepitations

●Onset after an episode of choking, or sudden onset while eating or playing

●Abnormal chest radiography or spirometry

●Associated cardiac or neurologic abnormalities

●Failure to thrive, feeding difficulties, or hemoptysis

In particular, the symptom of a chronic wet cough, with or without production of purulent sputum, is always pathologic and warrants investigations for a persistent endobronchial infection (protracted bacterial bronchitis or chronic suppurative lung disease), retained airway foreign body, or immunodeficiency [1] (see"Causes of chronic cough in children", section on 'Specific cough'). Protracted bacterial bronchitis (PBB) is usually diagnosed based on the presence of an isolated chronic wet-moist cough in a child who otherwise appears well, with resolution of the cough after antibiotic treatment, and absence of symptoms, signs, or laboratory evidence suggestive of an alternative cause of the cough. Children with suspected PBB should be treated with antibiotics, usually selected empirically. Treatment withamoxicillin-clavulanatehas been effective in a clinical trial. (See"Causes of chronic cough in children", section on 'Protracted bacterial bronchitis'.)

Nonspecific cough—If symptoms suggesting specific cough are absent and the chest radiograph and spirometry are normal, a presumptive diagnosis of nonspecific cough should be made (algorithm 1). If the cough is troublesome, the possibility of asthma should be considered and pursued with an empiric trial of bronchodilators and other asthma medications. (See"Causes of chronic cough in children", section on 'Asthma'.)

If there is no response, the child should be considered to have a nonspecific cough, and the medication should be stopped. The child and parents should be reassured and the patient observed over time for possible emergence of specific symptoms.

HISTORY—The diagnostic approach outlined above requires a detailed history, which should focus on the following key elements:

Age and circumstances at onset—Neonatal onset of coughing should prompt consideration of congenital malformations (eg, tracheobronchomalacia), conditions predisposing to aspiration (eg, tracheoesophageal fistula, laryngeal cleft, or a neurological disorder), or chronic pulmonary infections (eg, cystic fibrosis or ciliary dyskinesia). (See"Congenital anomalies of the intrathoracic airways and tracheoesophageal fistula"and"Cystic fibrosis: Clinical manifestations and diagnosis".)

A cough that begins suddenly while playing or eating, especially in the toddler age range, should raise suspicion of an aspirated foreign body in the airway. The physician should specifically ask about a history of choking, because this may have occurred weeks before and the family may not voluntarily recall the information. Even if there is no history of choking, a foreign body remains a diagnostic possibility. (See"Airway foreign bodies in children".)

An episode of severe pneumonia can damage the airways, making the child vulnerable to chronic cough. More rarely, severe pneumonia may cause frank bronchiectasis. A psychogenic or habitual cough also often begins after an upper respiratory infection.

Nature of the cough—Chronic paroxysmal cough triggered by exercise, cold air, sleep, or allergens is often seen in patients with asthma. Barking or brassy cough suggests a process in the trachea or more proximal airways, such as airway malacia or vascular compression, laryngotracheobronchitis, spasmodic croup, or foreign body. Staccato cough in young infants can be the result of infection with Chlamydia trachomatis. Cough that is honking ("Canadian Goose-like") and disappears at night suggests a psychogenic or habitual cough.

A chronic productive (or "wet-moist") cough suggests a suppurative process, and may require further investigation to exclude bronchiectasis, cystic fibrosis, active infection, immune deficiency, or congenital malformation. In a study of children presenting with chronic cough, a wet-moist quality to the cough was the most useful clinical marker of predicting a specific etiology (sensitivity of 96 percent, although specificity was only 26 percent) [18]. Specific causes of chronic wet-moist cough include bacterial bronchitis (40 percent of young children with wet cough in one series), bronchiectasis, asthma-like conditions, and aspiration disorders [19]. (See'Specific cough'above.)

Acute or subacute paroxysmal cough suggests infection with pertussis or parapertussis; this characteristic cough can be retriggered by subsequent upper respiratory illness. An inspiratory "whoop", when present, is an important diagnostic clue. The diagnosis can be difficult to ascertain, as cultures are typically negative after the fourth week of illness, and convalescent-phase serology can be difficult to interpret unless acute-phase titers were also obtained. (See"Pertussis infection in infants and children: Clinical features and diagnosis", section on 'Clinical features'.)

Timing and triggers—The timing and triggers associated with cough can help guide diagnosis. Cough due to asthma typically occurs following exposure to characteristic asthma triggers (ie, allergens, smoke, exercise, cold air, or viral infection), and typically worsens during sleep. Cough associated with nasal problems typically is worst during changes of position, while cough due to bronchiectasis typically is worst and most productive early in the day.

Cough that is triggered during swallowing is suggestive of aspiration, either primary or due to tracheoesophageal fistula or laryngeal abnormalities. Cough in the first hour after meals, or which is worse while supine, may reflect gastroesophageal reflux. Psychogenic cough is present during the day, disappears at night, and is typically worst and most disruptive during school classes. (See"Congenital anomalies of the larynx"and"Clinical manifestations and diagnosis of gastroesophageal reflux disease in children and adolescents".)

Associated symptoms—A history of dyspnea or hemoptysis should trigger a search for an underlying lung disease. Hemoptysis should also raise concerns of bronchiectasis, cavitary lung disease (tuberculosis or bacterial abscesses), heart failure, hemosiderosis, neoplasm, foreign bodies, vascular lesions, endobronchial lesions, catamenial bleeding, and clotting disorders [20]. (See"Hemoptysis in children".)

Cough, with or without symptoms of pancreatic insufficiency, recurrent endobronchial infection,and/orfailure to thrive should raise suspicion of cystic fibrosis. Cough associated with persistent fever,and/orfailure to thrive, or weight loss should raise suspicion of chronic infection and immune deficiency. Children with neurologic impairment or seizures frequently have chronic aspiration. Rarely, children with an abnormality of the central nervous system such as Chiari type 1 malformation present with chronic cough due to swallowing dysfunction, usually in association with headache [21]. (See"Cystic fibrosis: Clinical manifestations and diagnosis"and"Approach to the child with recurrent infections".)

Anaphylactic reactions to food can include cough but are unlikely to present with recurrent cough in the absence of other symptoms of anaphylaxis. (See"Food-induced anaphylaxis", section on 'Signs and symptoms'.)

Past medical history—The past medical history should include an account of the pregnancy, labor, and delivery, as well as the neonatal course. Low birth weightand/orpremature neonates are at risk for developing atopic sensitization and asthma. In addition, prematurity and neonatal respiratory distress syndrome are precursors for bronchopulmonary dysplasia, which may cause persistent respiratory symptoms in children and adolescents. (See"Risk factors for asthma", section on 'Pre- and perinatal factors'and"Pathogenesis and clinical features of bronchopulmonary dysplasia".)

The past medical history should also include questions related to eczema and pulmonary infections. In preschool children, a history of infantile eczema is often associated with inhalant allergy [22]. Coughing episodes diagnosed as pneumonia may or may not have been related to other pulmonary processes, as discussed below.

Recurrent right middle lobe atelectasis or infiltrates are common in children with asthma and other processes that cause increased mucus production, due to relatively poor collateral ventilation in the right middle lobe. This is frequently mistaken for pneumonia. A history of recurrent or unresolving pneumonia in one lobe or segment of the lung may also be caused by obstruction or anatomic abnormality in that airway. (See"Congenital anomalies of the intrathoracic airways and tracheoesophageal fistula".)

In children with chronic cough and a history of recurrent pneumonias involving multiple lobes, considerations include cystic fibrosis, immune deficiency, aspiration (swallowing dysfunction, gastroesophageal reflux, tracheoesophageal fistula), primary ciliary dyskinesia and autoimmune disease. Severe infection caused by pertussis or adenovirus has been associated with the subsequent development of bronchiectasis, bronchiolitis obliterans, and chronic lung disease. If the child is known to be immunodeficient, atypicaland/orchronic infections of the sinusesand/orlungs should be suspected. (See"Approach to the child with recurrent infections".)

Family history—Family history of atopy or asthma increases the risk in offspring, and suggests a diagnosis of either allergic rhinitis or asthma in the child with chronic cough [22,23]. Family history of cystic fibrosis or primary ciliary dyskinesia should raise suspicion for these disorders. A careful history should be obtained for current illness in family members or close contacts; such individuals with cough, weight loss, and night sweats should arouse suspicion of tuberculosis. In some cases, the possibility of HIV transmission from mother to child should be assessed.

Social history and environmental exposures—Passive or active exposure to smoke from tobacco [22], marijuana, cocaine or other chemical irritants can result in chronic cough. Indoors, damp homes are associated with chronic respiratory complaints [24]. In addition, wood-burning stoves cause indoor air pollution and can predispose children to respiratory infections [25]. Gas stoves are also associated with respiratory symptoms in children [26]. These environmental exposures are important exacerbating factors for chronic cough in some children but are not necessarily the sole causative factors [27]. (See"Secondhand smoke exposure: Effects in children"and"Cocaine: Acute intoxication".)

Residence in the inner cities of the United States is associated with exposure to cockroaches and mice, which are common allergens in these environments [28,29]. Outdoor air pollution in inner cities is also associated with chronic cough [30-32]. Indoor air pollution due to the use of biomass fuels (wood and crop residues and animal dung) is common in developing countries; this may predispose children to respiratory infections [33].