Thorax and Lungs

Respiratory disorders are common in infancy and childhood and can be acute, life threatening, or chronic. Early screening and detection are essential to being able to refer children for medical treatment. Knowledgeable assessment also assists in monitoring the progress of treatment.

Lungs have two main functions: to supply the body with oxygen and eliminate carbon dioxide and to maintain the body’s acid-base balance. The lungs are paired and symmetric. The right lung has three lobes, and the left lung has two lobes. Air enters the lungs via the trachea and larynx from the mouth or nose. The trachea branches into two major bronchi. The right bronchus is shorter, wider, and angled less sharply to the side than the left.

Fetal lung buds arise in the first lunar month of gestation, along with nasal pits, the trachea, and the larynx. Subsequent budding and branching create the mainstem bronchi pulmonary lobules in the second month. Branching continues into early childhood, although it is less proliferative. By the third month, elementary respiratory-like movements are observed. From the sixth month on, the lobules have developed alveolar ducts, and the ducts have developed alveoli.

As the alveolar sacs develop, the epithelium lining the sacs thins. Pulmonary capillaries press into the walls of the sacs as the lungs are prepared for the exchange of oxygen and carbon dioxide, near the end of the sixth month of gestation. During the final weeks of gestation the lungs secrete surfactants that reduce the surface tension of the alveolar sacs and prevent the alveoli from collapsing and producing atelectasis. At birth, the lungs are fluid filled. This fluid is rapidly dispelled and absorbed as the lungs fill with air.

The newborn infant’s thoracic cage is nearly round. Gradually the transverse diameter increases until the chest assumes the elliptic shape of the adult, at about 6 years of age. The infant’s thoracic cage is also relatively soft, which allows the cage to pull in during labored breathing. Infants have relatively less tissue and cartilage in the trachea and bronchi, which allows these structures to collapse more readily.

Airways tend to grow faster than the vertebral column. In infancy the bifurcation of the trachea is at the level of the third thoracic vertebra. By adulthood the bifurcation is at the level of the fourth thoracic vertebra. Smaller airways in young children and infants tend to narrow more readily from edema and secretions than in older children and adolescents. Shorter distances between structures in the young child also contribute to rapid transmission of organisms and widespread involvement.

Young infants (younger than 6 months) are obligatory nose breathers, and their nasal passages are narrower. Breathing is less rhythmic than in the child. In infants and children younger than 6 or 7 years, respirations are chiefly diaphragmatic or abdominal; in older children and especially females, respirations are chiefly thoracic. The volume of oxygen expired by the infant and the child is greater than that expired by the adult. The volume of air that is inspired increases as the child grows. At the age of 12 years the child has approximately nine times the number of alveoli that were present at birth.

As with heart rate, the respiratory rate in infants and children responds more dramatically than in adults to emotion, illness, and exercise. The rate tends to show greater variability and wider range than in adults.

Ask the parent or child about cough (onset, progress, pattern, secretions), fever, shortness of breath, difficulty breathing, chest pain (or pain at the base of the neck), wheezing, easy fatigability, meningeal signs, abdominal pain, vomiting, sore throat, past respiratory tract infections, frequent colds, family history of respiratory disorders and smoking, history of allergies, immunization status, and type of child care setting (e.g., home, daycare) and environment (e.g., animals, birds, second-hand smoke).

Allow the young child to play with the stethoscope before you perform the assessment. Children often enjoy listening to the sounds in their chests and in their parents’ or the nurse’s chest. Remove the child’s shirt or blouse for best visualization of the chest. Infants and toddlers are often best assessed while held by their parents.

Assessment	Findings
Assess for stridor (high-pitched crowing sound), grunting, hoarseness, snoring, labored breathing, audible wheezing, and cough (Table 15-1).	Clinical Alert
	Stridor, hoarseness, and a barking cough accompany croup syndromes. Inspiratory stridor and expiratory snoring are indicative of epiglottitis.
Precisely describe the sounds and their occurrence.	Audible wheezing can indicate asthma, respiratory syncytial virus, or foreign body aspiration.
	Short, rapid coughs followed by a crowing sound or whoop indicate whooping cough.
	Snoring can indicate enlargement of the adenoids, polyps, or presence of a foreign body.
	A persistent dry cough that later becomes productive, hoarseness, and gasping and grunting respirations are found with congestive heart failure.