Chapter 34
Alterations of Pulmonary Function in
Children
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Structure and Function
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Upper airway
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
Conducting airways are present at birth
Airways are smaller in diameter and increase in
size throughout childhood
Lower airways and lung parenchyma
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Major changes
• Loss of mesenchymal tissue, expansion of air spaces,
capillary development, alveolarization, and functional
maturation
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Structure and Function
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Structure and Function
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Surfactant
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Lipid-protein mix
Produced by alveolar type II cells
Surfactant maintains alveolar expansion
• Decreases alveolar surface tension
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Structure and Function
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Surfactant deficiency often in premature infants
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Causes respiratory distress syndrome (RDS; hyaline
membrane disease)
Reflects developmental immaturity
Produced by 20 to 24 weeks of gestation
Secreted into the fetal airways by 30 weeks
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Structure and Function
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Chest wall dynamics
Metabolic characteristics
Immunologic incompetence
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IgG conveyed transplacentally beginning at 20 weeks
of gestation
Breast-feeding allows further transfer of IgG
Babies are able to make IgG, IgM, and IgA
• Levels increase slowly with age
Physiologic control of respiration
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Structure and Function
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Pulmonary Disorders
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Disorders of upper airways
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Acute upper airway obstructions: PATENCY
• Infections, foreign body aspiration, angioedema, and
trauma
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Chronic upper airway obstructions
• Congenital malformations, cartilaginous weakness, vocal
cord paralysis, and subglottic stenosis
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Pulmonary Disorders
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Breathing sounds
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A snoring noise is common for nasopharyngeal
obstructions
 Stridor
• Harsh, vibratory sound caused by turbulent flow through
a partially obstructed airway
• Inspiratory stridor is common with extrathoracic airway
obstructions
• Expiratory stridor is common with intrathoracic airway
obstructions
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Breathing Sounds
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Pulmonary Disorders
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Breathing sounds
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A weak or hoarse voice suggests possible
laryngeal problems
A cough is an indicator of an irritative symptom
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Upper Airway Infections
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Bacterial tracheitis
Retropharyngeal abscess
Tonsillar infections
Peritonsillar abscess
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Croup
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Acute laryngotracheobronchitis
Common in children from 6 months to 5 years
Commonly caused by a virus (parainfluenza,
influenza A, or RSV)
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Causes subglottic edema
Usually occurs after an episode of rhinorrhea,
sore throat, and fever
Causes seal-like barking cough
Self-limiting condition
Severe cases are treated with nebulized
epinephrine
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Spasmodic Croup
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Similar hoarseness, cough, and stridor to
croup
Usually in older children
Demonstrates sudden onset, usually at night,
and with no previous viral illness
Resolves quickly
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Acute Epiglottitis
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Severe, rapidly progressive, life-threatening
infection of the epiglottis and surrounding area
Caused by Haemophilus influenzae type B
(Hib)
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
Manifestations
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
Decreased incidence due to Hib vaccination
High fever, sore throat, inspiratory stridor, and
severe respiratory distress
Treatment
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Emergency airway and antibiotics
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Aspiration of Foreign Bodies
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Foreign body aspiration in children occurs
frequently between ages 1 and 3
Manifestations
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Coughing, choking, gagging, and wheezing
Symptoms depend on foreign body size
Aspirated foreign bodies can be removed by
bronchoscopy
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Other Upper Airway Disorders
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Angioedema
Subglottic stenosis
Laryngomalacia and tracheomalacia
Vocal cord paralysis
Congenital malformation
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Obstructive Sleep Apnea
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Partial or complete upper airway obstruction
during sleep
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Obstructive sleep apnea disrupts normal
ventilation and sleep patterns
The most common cause of childhood
obstructive sleep apnea is adenotonsillar
hypertrophy
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Respiratory Distress Syndrome
(RDS) of the Newborn
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Also called hyaline membrane disease (HMD)
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
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Poor lung structure and lack of adequate
surfactant
Primarily a disease of preterm infants
Causes widespread atelectasis, respiratory
distress, and pulmonary hypertension
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Respiratory Distress Syndrome
(RDS) of the Newborn
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
Pulmonary hypertension causes continued
shunting of blood away from the lungs (ductus
arteriosus)
Prolonged anaerobic metabolism causes
metabolic acidosis
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Respiratory Distress Syndrome
(RDS) of the Newborn
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Symptoms


Tachypnea, expiratory grunting, nasal flaring,
dusky skin
Treatment

Mechanical ventilation, surfactant administration,
glucocorticoid administration to women in preterm
labor
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Bronchopulmonary Dysplasia
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

Chronic disease; result of acute respiratory
disease in the neonatal period
Caused by premature birth, immature lungs,
infections, genetics, etc.
Manifestations


Hypoxemia, hypercapnia, elevated work of breathing,
bronchospasm, mucus plugging, pulmonary
hypertension
Not as common due to availability of exogenous
surfactant and antenatal glucocorticoids
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Respiratory Infections
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Infections: bronchioles, bronchi, alveoli,
interstitium, pleura
Cause and site related to age, seasonal
variables, environmental exposures
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Infants and young children: more viral infections
Environmental factors: presence of siblings,
daycare exposure
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Respiratory Infections
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Bronchiolitis
Pneumonia
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Bacterial pneumonia
Viral pneumonia
Atypical pneumonia
Aspiration pneumonitis
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Respiratory Infections
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Bronchiolitis obliterans
Asthma
Acute respiratory distress syndrome
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Cystic Fibrosis
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Autosomal recessive multisystem disease
Exocrine or mucus-producing glands secrete
abnormally thick mucus due to defective
epithelial ion transport
In lungs, thick secretions obstruct bronchioles
and predispose the lungs to chronic infections
Chronic inflammation leads to hyperplasia of
goblet cells, bronchiectasis, pneumonia,
hypoxia, fibrosis, etc.
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Cystic Fibrosis
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Sudden Infant Death Syndrome
(SIDS)
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Disease of unknown cause
Incidence
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Seasonal variation
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Lower during 1st month of life, increases in 2nd
month, and peaks at 3 to 4 months
More common in male infants
Possible relationship to respiratory infections
Wide range of risk factors
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