Infancy

The infant's thorax is more rounded than that of older children and adults. Also, the chest wall in infancy is thin, with little musculature, and therefore lung and heart sounds are transmitted quite clearly. The bony and cartilaginous rib cage is very soft and pliant. The tip of the xiphoid process is often seen protruding anteriorly immediately beneath the skin at the apex of the costal angle.

Carefully assess respirations and the pattern of breathing. Newborn infants, especially those born prematurely, exhibit irregular breathing characterized by periods of breathing at normal rates (30 to 40 per minute) alternating with "periodic breathing," during which the respiratory rate slows markedly and may even cease for 5 to 10 seconds.

An important tip for the examination of the respiratory status of infants and young children is not to rush to the stethoscope, but to observe the patient carefully as demonstrated in the photograph and the table on the next page. Visual inspection is best done when infants are not crying; thus work with the parents to settle the child. By observing infants for a significant time (perhaps 1 minute), you can note the general appearance, respiratory rate, color, nasal component of breathing, audible breath sounds, and work of breathing, as described on p. 662.

Because infants are obligate nasal breathers, observe their nose as they breathe, looking for nasal flaring. Observe the breathing with the infant's mouth closed or with the infant nursing or sucking on a bottle to assess for nasal patency.

Listen to the sounds of the infant's breathing and note any grunting, audible wheezing, or lack of breath sounds (obstruction).

It is important to evaluate, by observation, two aspects of the infant: audible breath sounds and the work of breathing. These are particularly relevant in as-

Two types of chest wall abnormalities noted in childhood include pectus excavatum, or "funnel chest," and pectus carinatum, or "chicken breast deformity" (see p. 239).

Apnea is defined as cessation of breathing for more than 20 seconds. Apnea is often accompanied by bradycardia and may indicate the presence of a respiratory disease, central nervous system disease, or, rarely, a cardiopulmonary condition. Apnea is a high-risk factor for sudden infant death syndrome (SIDS).

In newborns and young infants, nasal flaring may be due simply to upper respiratory infections with subsequent obstruction of their small nares.

sessing both upper and lower respiratory illness. Studies in countries that have poor access to chest radiographs have found that these signs are at least as useful as auscultation in assessing both the upper and lower respiratory tract.

Examination of the Lungs in Infants—Before You Touch the Child!

Type of Assessment

Specific Observable Pathology

General appearance

Inability to feed or smile Lack of consolability

Respiratory rate

Tachypnea (see p. 662)

Color

Pallor or cyanosis

Nasal component of breathing

Nasal flaring (enlargement of both nasal openings during inspiration)

Audible breath sounds

Grunting (repetitive, short expiratory sound) Wheezing (musical expiratory sound) Stridor (high-pitched, inspiratory noise) Obstruction (lack of breath sounds)

Work of breathing

Nasal flaring (see above) Grunting (see above) Retractions (or chest indrawing): Supraclavicular (soft tissue above clavicles) Intercostal (indrawing of the skin between ribs) Subcostal (just below the costal margin)

In healthy infants, the ribs do not move much during quiet breathing. If the ribs do move, outward movement is produced by descent of the diaphragm. Descent of the diaphragm compresses the abdominal contents, which in turn shifts the lower ribs outward.

Pulmonary disease causes an increase in abdominal breathing in infants, and can result in retractions (chest indrawing), a sign commonly used by the World Health Organization as an indicator of pulmonary disease in infants younger than 2 years of age. Chest indrawing is the inward movement of the ribs (or more precisely, the skin between the ribs) during inspiration. Breath-

Any of the abnormalities listed at the left should raise concern about underlying respiratory pathology.

Lower respiratory infections, defined as infections below the vocal cords, are common in infants, and include bronchiolitis and pneumonia.

Acute stridor is a potentially serious condition; causes include laryngo-tracheo-bronchitis (croup), epiglotti-tis, bacterial tracheitis, foreign body, or a vascular ring.

In infants, abnormal work of breathing, combined with abnormal findings on auscultation, is the best finding for ruling in pneumonia. The best single sign for ruling out pneumonia is the absence of tachypnea.

Asymmetric chest movement may be a clue to a space-occupying lesion, such as pleural effusion, hemothorax, or intrathoracic mass.

ing is predominantly affected by movement of the diaphragm, with little assistance from the thoracic muscles. As mentioned in the table on the previous page, three types of retractions can be noted in infants: supraclavicular, intercostal, and subcostal.

Obstructive respiratory disease in infants can result in Hoover's sign, or paradoxical (seesaw) breathing, in which the abdomen moves outward while the chest moves inward during inspiration. Thoracoabdominal paradox, inward movement of the chest and outward movement of the abdomen during inspiration, is a normal finding in preterm and newborn infants. It continues to persist during active, or REM, sleep even when it is no longer seen during wakefulness or quiet sleep because of the decreased muscle tone of active sleep. As muscle strength increases and chest wall compliance decreases with age and growth, paradox is no longer discernable as a normal finding.

Tactile fremitus can be assessed by palpation. Place your hand on the chest when the infant cries or makes noise. Place your hand or fingertips over each side of the infant's chest and feel for symmetry in the transmitted vibrations. Percussion is not helpful in infants except in extreme instances. The infant's chest is hyperresonant throughout, and it is difficult to detect abnormalities on percussion.

After performing these maneuvers, you are ready for auscultation. Breath sounds are louder and harsher than those in adults because the stethoscope is closer to the origin of the sounds. Also, it is often difficult to distinguish transmitted upper airway sounds from sounds originating in the chest. The table below has some useful hints. Upper airway sounds tend to be loud, transmitted symmetrically throughout the chest, and loudest as you move your stethoscope upward. They are usually inspiratory, coarse sounds. Lower airway sounds are loudest over the site of pathology, are often asymmetric, and often have an expiratory phase.

Children with muscle weakness may be noted to have thoracoabdominal paradox at several years of age.

Because of the excellent transmission of sounds throughout the chest, any abnormalities of tactile fremitus or on percussion suggest severe pathology, such as a large pneumonic consolidation.

Biphasic sounds imply severe obstruction from intrathoracic airway narrowing or severe obstruction from extrathoracic airway narrowing.

Distinguishing Upper Airway From Lower Airway Sounds

Technique

Upper Airway

Lower Airway

Compare sounds from

Same sounds

Often different sounds

nose/stethoscope

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