Chapter 376 Chronic or Recurrent Respiratory Symptoms

Cough, wheeze, stridor, and other respiratory tract symptoms occur frequently or persist for long periods in a substantial number of children; others have persistent or recurring lung infiltrates with or without symptoms. Determining the cause of these chronic findings can be difficult because symptoms can be caused by a close succession of unrelated acute respiratory tract infections or by a single pathophysiologic process. Specific and easily performed diagnostic tests do not exist for many acute and chronic respiratory conditions. Pressure from the affected child’s family for a quick remedy because of concern over symptoms related to breathing may complicate diagnostic and therapeutic efforts.

A systematic approach to the diagnosis and treatment of these children consists of assessing whether the symptoms are the manifestation of a minor problem or a life-threatening process; determining the most likely underlying pathogenic mechanism; selecting the simplest effective therapy for the underlying process, which often is only symptomatic therapy; and carefully evaluating the effect of therapy. Failure of this approach to identify the process responsible or to effect improvement signals the need for more extensive and perhaps invasive diagnostic efforts, including bronchoscopy.

Judging the Seriousness of Chronic Respiratory Complaints

Clinical manifestations suggesting that a respiratory tract illness may be life-threatening or associated with the potential for chronic disability are listed in Table 376-1. If none of these findings is detected, the chronic respiratory process is more likely to be benign. Active, well-nourished, and appropriately growing infants who present with intermittent noisy breathing but no other physical or laboratory abnormalities require only symptomatic treatment and parental reassurance. Benign-appearing but persistent symptoms are occasionally the harbinger of a serious lower respiratory tract problem; likewise, occasionally children (those with infection-related asthma) have recurrent life-threatening episodes but few or no symptoms in the intervals. Repeated examinations over an extended period, both when the child appears healthy and when the child is symptomatic, may be helpful in sorting out the severity and chronicity of lung disease.

Recurrent or Persistent Cough

Cough is a reflex response of the lower respiratory tract to stimulation of irritant or cough receptors in the airways’ mucosa. The most common cause in children is reactive airways (asthma). Because cough receptors also reside in the pharynx, paranasal sinuses, stomach, and external auditory canal, the source of a persistent cough may need to be sought beyond the lungs. Specific lower respiratory stimuli include excessive secretions, aspirated foreign material, inhaled dust particles or noxious gases, and an inflammatory response to infectious agents or allergic processes. Some of the conditions responsible for chronic cough are listed in Table 376-2.

Characteristics of cough that can aid in distinguishing its origin are presented in Table 376-3. Additional useful information can include a history of atopic conditions (asthma, eczema, urticaria, allergic rhinitis), a seasonal or environmental variation in frequency or intensity of cough, and a strong family history of atopic conditions, all suggesting an allergic cause; symptoms of malabsorption or family history indicating cystic fibrosis; symptoms related to feeding, suggesting aspiration; a choking episode, suggesting foreign body aspiration; headache or facial edema associated with sinusitis; and a smoking history in older children and adolescents or the presence of a smoker in the house (Table 376-4).

Table 376-3 CHARACTERISTICS OF COUGH AND OTHER CLINICAL FEATURES AND POSSIBLE CAUSES

* This is not an exhaustive list; only the more common respiratory diseases are mentioned.

From Chang AB, Landau LI, Van Asperen PP, et al: Cough in children: definitions and clinical evaluation. Thoracic Society of Australia and New Zealand, Med J Aust 184(8):399–403, 2006.

Table 376-4 CLINICAL CLUES ABOUT COUGH

From Kliegman RM, Greenbaum LA, Lyle PS: Practical strategies in pediatric diagnosis and therapy, ed 2, Philadelphia, 2004, Saunders, p 19.

The physical examination can provide much information pertaining to the cause of chronic cough. Posterior pharyngeal drainage combined with a nighttime cough suggests chronic upper airway disease such as sinusitis. An overinflated chest suggests chronic airway obstruction, as in asthma or cystic fibrosis. An expiratory wheeze, with or without diminished intensity of breath sounds, strongly suggests asthma or asthmatic bronchitis but may also be consistent with a diagnosis of cystic fibrosis, vascular ring, aspiration of foreign material, or pulmonary hemosiderosis. Careful auscultation during forced expiration may reveal expiratory wheezes that are otherwise undetectable and that are the only indication of underlying reactive airways. Coarse crackles suggest bronchiectasis, including cystic fibrosis, but can also occur with an acute or subacute exacerbation of asthma. Clubbing of the digits is seen in most patients with bronchiectasis but in only a few other respiratory conditions with chronic cough (see Table 376-2). Tracheal deviation suggests foreign body aspiration or a mediastinal mass.

Allowing sufficient examination time to detect a spontaneous cough is important. If a spontaneous cough does not occur, asking the child to take a maximal breath and forcefully exhale repeatedly usually induces a cough reflex. Most children can cough on request by 4-5 yr of age. Children who cough as often as several times a minute with regularity are likely to have a habit (tic) cough (Chapter 22). If the cough is loose, every effort should be made to obtain sputum; many older children can comply. It is sometimes possible to pick up small bits of sputum with a throat swab quickly inserted into the lower pharynx while the child coughs with the tongue protruding. Clear mucoid sputum is most often associated with an allergic reaction or asthmatic bronchitis. Cloudy (purulent) sputum suggests a respiratory tract infection but can also reflect increased cellularity (eosinophilia) due to an asthmatic process. Very purulent sputum is characteristic of bronchiectasis. Malodorous expectorations suggest anaerobic infection of the lungs. In cystic fibrosis, the sputum, even when purulent, is rarely foul smelling.

Laboratory tests can help in the evaluation of a chronic cough. Only sputum specimens containing alveolar macrophages should be interpreted as reflecting lower respiratory tract processes. Sputum eosinophilia suggests asthma, asthmatic bronchitis, or hypersensitivity reactions of the lung, but a polymorphonuclear cell response suggests infection; if sputum is unavailable, the presence of eosinophilia in nasal secretions also suggests atopic disease. If most of the cells in sputum are macrophages, postinfectious hypersensitivity of cough receptors should be suspected. Sputum macrophages can be stained for hemosiderin content, which is diagnostic of pulmonary hemosiderosis (Chapter 400), or for lipid content, which in large amounts suggests, but is not specific for, repeated aspiration. Children whose coughs persist for more than 6 wk should be tested for cystic fibrosis regardless of their race or ethnicity (Chapter 395). Sputum culture is helpful for diagnosis of cystic fibrosis but less so for other conditions because throat flora can contaminate the sample.

Hematologic assessment can reveal anemia that is the result of pulmonary hemosiderosis or eosinophilia that accompanies asthma and other hypersensitivity reactions of the lung. Infiltrates on the chest radiograph suggest cystic fibrosis, bronchiectasis, foreign body, hypersensitivity pneumonitis, or tuberculosis. When asthma-equivalent cough is suggested, a trial of bronchodilator therapy may be diagnostic. If the cough does not respond to initial therapeutic efforts, more-specific diagnostic procedures may be indicated, including an immunologic or allergic evaluation, chest and paranasal sinus imaging, esophagograms, tests for gastroesophageal reflux, special microbiologic studies including rapid viral testing, evaluation of ciliary morphologic features, and bronchoscopy.

Habit cough (“psychogenic cough” or “cough tic”) must be considered in any child with a cough that has lasted for weeks or months, that has been refractory to treatment, and that disappears with sleep or with distraction. Typically the cough is abrupt and loud and has a harsh, honking, or “barking” quality. A disassociation between the intensity of the cough and the child’s affect is typically striking. This cough may be absent if the physician listens outside the examination room, but it will reliably appear immediately on direct attention to the child and the symptom. It typically begins with an upper respiratory infection but then lingers. The child misses many days of school because the cough disrupts the classroom. This disorder accounts for many unnecessary medical procedures and courses of medication. It is treatable with assurance that a pathologic lung condition is absent and that the child should resume full activity, including school. This assurance, together with speech therapy techniques that allow the child to reduce musculoskeletal tension in the neck and chest and that increase the child’s awareness of the initial sensations that trigger cough, has been very successful. Self-hypnosis is another successful therapy, often effective with 1 session. The designation “habit cough” is preferable to “psychogenic cough” because it carries no stigma and because most of these children do not have significant emotional problems. When the cough disappears, it does not re-emerge as another symptom. Nonetheless, other symptoms such as irritable bowel syndrome may be present in the patient or family.

Frequently Recurring or Persistent Stridor

Stridor, a harsh, medium-pitched, inspiratory sound associated with obstruction of the laryngeal area or the extrathoracic trachea, is often accompanied by a croupy cough and hoarse voice. Stridor is most commonly observed in children with croup; foreign bodies and trauma can also cause acute stridor. A few children, however, acquire recurrent stridor or have persistent stridor from the 1st days or weeks of life (Table 376-5). Most congenital anomalies of large airways that produce stridor become symptomatic soon after birth. Increase of stridor when a child is supine suggests laryngomalacia or tracheomalacia. An accompanying history of hoarseness or aphonia suggests involvement of the vocal cords.

Physical examination for recurrent or persistent stridor is usually unrewarding, although changes in its severity and intensity due to changes of body position should be assessed. Anteroposterior and lateral roentgenograms, contrast esophagography, fluoroscopy, CT, and MRI are potentially useful diagnostic tools. In most cases, direct observation by laryngoscopy is necessary for diagnosis. Undistorted views of the larynx are best obtained with fiberoptic laryngoscopy.

Recurrent or Persistent Wheeze

Parents often complain that their child “wheezes,” when, in fact, they are reporting respiratory sounds that are audible without a stethoscope, produce palpable resonance throughout the chest, and occur most prominently in inspiration. Some of these children have stridor, although many have audible sounds when the supraglottic airway is incompletely cleared of feedings or secretions.

True wheezing is a relatively common and particularly troublesome manifestation of obstructive lower respiratory tract disease in children. The site of obstruction may be anywhere from the intrathoracic trachea to the small bronchi or large bronchioles, but the sound is generated by turbulence in larger airways that collapse with forced expiration (Chapter 365). Children younger than 2-3 yr are especially prone to wheezing, because bronchospasm, mucosal edema, and accumulation of excessive secretions have a relatively greater obstructive effect on their smaller airways. In addition, the compliant airways in young children collapse more readily with active expiration. Isolated episodes of acute wheezing, such as can occur with bronchiolitis, are not uncommon, but wheezing that recurs or persists for more than 4 wk suggests other diagnoses (see Table 383-2). Most recurrent or persistent wheezing in children is the result of reactive airways disease. Nonspecific environmental factors such as cigarette smoke may be important contributors.

Frequently recurring or persistent wheezing starting at or soon after birth suggests a variety of other diagnoses, including congenital structural abnormalities involving the lower respiratory tract or tracheobronchomalacia. Wheezing that attends cystic fibrosis is most common in the 1st yr of life. Sudden onset of severe wheezing in a previously healthy child should suggest foreign body aspiration.

Repeated examination may be required to verify a history of wheezing in a child with episodic symptoms and should be directed toward assessing air movement, ventilatory adequacy, and evidence of chronic lung disease, such as fixed overinflation of the chest, growth failure, and digital clubbing. Clubbing suggests chronic lung infection and is rarely prominent in uncomplicated asthma. Tracheal deviation from foreign body aspiration should be sought. It is essential to rule out wheezing secondary to congestive heart failure. Allergic rhinitis, urticaria, eczema, or evidence of ichthyosis vulgaris suggests asthma or asthmatic bronchitis. The nose should be examined for polyps, which can exist with allergic conditions or cystic fibrosis.

Sputum eosinophilia and elevated serum immunoglobulin E (IgE) levels suggest allergic reactions. An FEV₁ (forced expiratory volume in 1sec) increase of 15% in response to bronchodilators confirms reactive airways. Specific microbiologic studies, special imaging studies of the airways and cardiovascular structures, diagnostic studies for cystic fibrosis, and bronchoscopy (Chapter 366) should be considered if the response is unsatisfactory.

Recurrent and Persistent Lung Infiltrates

Radiographic lung infiltrates resulting from acute pneumonia usually resolve within 1-3 wk, but a substantial number of children, particularly infants, fail to completely clear infiltrates within a 4-wk period. These children may be febrile or afebrile and may display a wide range of respiratory symptoms and signs. Persistent or recurring infiltrates present a diagnostic challenge (Table 376-6).

Symptoms associated with chronic lung infiltrates in the 1st several weeks of life (but not related to neonatal respiratory distress syndrome) suggest infection acquired in utero or during descent through the birth canal. Early appearance of chronic infiltrates can also be associated with cystic fibrosis or congenital anomalies that result in aspiration or airway obstruction. A history of recurrent infiltrates, wheezing, and cough may reflect asthma, even in the 1st year of life.

One uncommon but characteristic syndrome appearing in the 1st year of life with recurrent lung infiltrates is pulmonary hemosiderosis related to cow’s milk hypersensitivity or unknown causes. Children with a history of bronchopulmonary dysplasia often have episodes of respiratory distress attended by wheezing and new lung infiltrates. Recurrent pneumonia in a child with frequent otitis media, nasopharyngitis, adenitis, or dermatologic manifestations suggests an immunodeficiency state, complement deficiency, or phagocytic defect (Chapters 118–121). Particular attention must be directed to the possibility that the infiltrates represent lymphocytic interstitial pneumonitis or opportunistic infection associated with HIV infection (Chapter 268). A history of paroxysmal coughing in an infant suggests pertussis syndrome or cystic fibrosis. Persistent infiltrates, especially with loss of volume, in a toddler should suggest foreign body aspiration.

Overinflation and infiltrates suggest cystic fibrosis or chronic asthma. A “silent chest” with infiltrates should arouse suspicion of alveolar proteinosis (Chapter 398), Pneumocystis jiroveci infection (Chapter 236), genetic disorders of surfactant synthesis and secretion causing interstitial pneumonitis, or tumors. Growth should be carefully assessed to determine whether the lung process has had systemic effects, indicating substantial severity and chronicity as in cystic fibrosis or alveolar proteinosis. Cataracts, retinopathy, or microcephaly suggest in utero infection. Chronic rhinorrhea can be associated with atopic disease, cow’s milk intolerance, cystic fibrosis, or congenital syphilis. The absence of tonsils and cervical lymph nodes suggests an immunodeficiency state.

Diagnostic studies should be performed selectively, based on information obtained from history and physical examination and on a thorough understanding of the conditions listed in Table 376-6. Cytologic evaluation of sputum, if available, may be helpful. Chest CT often provides more precise anatomic detail concerning the infiltrate. Bronchoscopy is indicated for detecting foreign bodies, congenital or acquired anomalies of the tracheobronchial tract, and obstruction by endobronchial or extrinsic masses (Chapter 386). Bronchoscopy provides access to secretions that can be studied cytologically and microbiologically. Alveolar lavage fluid is diagnostic for alveolar proteinosis and persistent pulmonary hemosiderosis and can suggest aspiration syndromes. If all appropriate studies have been completed and the condition remains undiagnosed, lung biopsy might yield a definitive diagnosis.

Optimal medical or surgical treatment of chronic lung infiltrates often depends on a specific diagnosis, but chronic conditions may be self-limiting (severe and prolonged viral infections in infants); in these cases, symptomatic therapy can maintain adequate lung function until spontaneous improvement occurs. Helpful measures include inhalation and physical therapy for excessive secretions, antibiotics for bacterial infections, supplementary oxygen for hypoxemia, and maintenance of adequate nutrition. Because the lung of a young child has remarkable recuperative potential, normal lung function may ultimately be achieved with treatment despite the severity of pulmonary insult occurring in infancy or early childhood.

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