Although cough and wheeze commonly are found in children with serious pulmonary problems, they also are manifestations of acute self-limited illness. The presence of other signs and symptoms is useful in identifying children with an underlying
chronic disorder. Box 244.1 lists signs and symptoms that suggest chronic pulmonary disease.

Generally, the closer to birth that symptoms first appear, the greater the chance is that they are secondary to a congenital malformation or the manifestation of an inherited disease.

Such malformations as tracheoesophageal fistula, laryngeal webs, and vascular rings may present shortly after birth, whereas inherited diseases may present a few months after delivery. Table 244.1 lists inherited lung diseases; the most likely candidate from this list is cystic fibrosis.

Affected children’s histories should include such specific important points as the presence of fever, noisy breathing, snoring, grunting, sputum production, and environmental exposure. If acute infection is present, it usually is accompanied by fever, purulent secretions, and an overall toxic appearance of affected children. Fever accompanied by grunting often represents a pneumonic process with frequent pleural involvement. Often, noisy breathing or snoring during sleep is associated with enlarged adenoids, nasal polyposis, choanal narrowing, nasal foreign body, or Pierre Robin syndrome.

Sputum production varies in children. Generally, children younger than 5 years old are unable to expectorate their sputum; they swallow their secretions after mobilization from the lung. School-aged children begin to expectorate, and attendant physicians should ask about volume, color, viscosity, and odor of the sputum. Often, clear or white secretions are observed in children with asthma, whereas yellow-green sputum is more consistent with a bacterial infection. Blood-tinged mucus can be a sign of tuberculosis, although it can have more benign causes as well. Purulent sputum can be observed with bronchiectasis and lung abscess or can be confused with postnasal drainage from sinusitis. Environmental exposure, with a special emphasis on passive smoke inhalation, should be investigated in all children with chronic or recurrent pulmonary symptoms. Passive smoke exposure may contribute to chronic airway irritation and increase airway reactivity. Other environmental irritants to consider are wood-burning stoves, unvented gas stoves or heaters, pesticides, and airborne allergens (animal dander, molds, pollens).

The physical examination can help to confirm the presence of underlying lung disease, but normal findings in the examination do not exclude the possibility of significant abnormalities. The physical examination should begin with an evaluation of the overall nutritional status of affected children. This assessment, together with analysis of the growth curve, gives a good indication of such children’s recent health. The physical examination should determine the pattern of respiration and adequacy of oxygenation and note specific signs.

First, the rate of respiration should be determined. Respiratory rate decreases with age and is measured best in infants and young children by observing with them in their mother’s arms and with the children’s clothing removed. Rapid rates are observed in the presence of anxiety, fever, exercise, anemia, and metabolic and respiratory disease. Slow rates can be seen with metabolic alkalosis and respiratory acidosis (central nervous system [CNS] depression). An elevated resting respiratory rate should prompt attendant physicians to look for a significant illness because tachypnea in such children is a sensitive indicator of lung disease. The ease of respiration can be determined by
observation. Usually, dyspnea represents obstructive lung disease and is observed readily in children resting in their mother’s lap. Head bobbing in sleeping infants is a sign of dyspnea. The phenomenon probably is explained by use of accessory muscles during respiration. Variously, flaring of the alae nasi, use of accessory muscles of respiration, wheezing, grunting, and retractions are signs of dyspnea and indicators of respiratory disease in affected children.

Assessing adequacy of gas exchange is more difficult. An observer’s ability to detect hypoxia varies, and determining hypoxia is difficult, even for experienced physicians. Most observers cannot detect hypoxia in children until oxygen saturation is 80% or less at sea level. Often, hypercapnia is associated with hypoxemia, and determining it by examination alone also is difficult; generally, an arterial blood gas is required to measure the level of carbon dioxide. Pulse oximeters allow easy noninvasive determination of oxygen saturation even in infants and young children. Although this instrument works well for measuring oxygenation, a comparable device is not readily available for easy, noninvasive measurement of carbon dioxide or acid-base balance.

The head, neck, chest, and extremities should be inspected closely. Commonly, “allergic shiners” under the eyes, nasal mucosal swelling, or a crease across the bridge of the nose is observed in children with allergic disease. Enlarged palatine tonsils are observed in some children with obstructive sleep apnea. The position of the trachea can be determined by palpating the neck. Normally midline, the trachea may be shifted to the right or left in the presence of volume loss in one lung, severe unilateral gas trapping, or a space-occupying lesion. An increase in the anteroposterior diameter of the chest is consistent with severe obstructive lung disease. Auscultation of the chest can reveal crackles, wheezes, or suppression of breath sounds. Clubbing of the extremities is an uncommon finding in children and rarely occurs in asthmatic individuals. If present, an extensive evaluation should be undertaken to rule out chronic liver, heart, and gastrointestinal disease. Clubbing can be familial. When a pulmonary disorder is suspected, however, a search should be made for such diseases as bronchiectasis, cystic fibrosis, immotile cilia syndrome, and disorders causing interstitial fibrosis.

If a serious respiratory disorder is suspected after completion of the history and physical examination, evaluation should proceed on the basis of an age-dependent differential diagnosis.

Cough clears secretions and foreign materials from the lungs. The cough reflex is composed of three parts: the afferent limb, the central cough center, and the efferent limb. The afferent portion of the cough reflex is composed of sensory fibers located in the ciliated epithelium from the pharynx to the small bronchioles. Sensory receptors are responsive to both mechanical and chemical stimuli. Impulses generated from these receptors are transmitted to the brain via the vagus nerve. Such an impulse from the lungs is received in the central cough center, which is located in the upper brainstem and pons and probably is the site of action for pharmacologic cough suppressants. Efferent impulses are initiated by the cough center and are carried by the phrenic, vagus, and spinal motor nerves to the muscles of the larynx, chest, abdominal wall, diaphragm, and pelvic floor. A complex set of muscular contractions results in a cough.

Cough is a symptom of both upper and lower airway illness, and the disease responsible for its presence must be diagnosed carefully. A chronic cough is defined as a persistent cough lasting 3 weeks or longer; Table 244.2 lists characteristics of
chronic cough and their potential associations with disease. Children’s ages are important in developing a differential diagnosis, and Box 244.2 lists potential causes of chronic cough by age group. Some of the more common causes are discussed later.