Chapter 28: Understanding Pulmonary Function in Children

Disorders of the Upper Airways

• Croup is an acute laryngotracheobronchitis primarily caused by the parainfluenza virus, leading to upper trachea swelling and a seal-like barking cough after rhinorrhea, sore throat, and low-grade fever.
• Spasmodic croup occurs in older children with a sudden onset barking cough at night, is fever-free, and has an unidentified cause.
• Acute epiglottitis is a serious airway infection that has decreased due to the Haemophilus influenzae vaccine, with new pathogens like GABHS, Candida, and Staphylococcus aureus emerging as common causes.
• Tonsillar infections often arise from GABHS and may be complicated by tonsillar abscesses.
• Aspiration of foreign bodies can lead to symptoms such as cough, hoarseness, stridor, wheezing, and dyspnea; severity varies with the obstruction's location, and laryngeal or tracheal blockage can be fatal.
• Obstructive sleep apnea syndrome (OSAS) is characterized by intermittent upper airway obstruction during sleep, disrupting normal ventilation and sleep patterns.

Disorders of the Lower Airways

• Respiratory distress syndrome (RDS) typically affects premature infants lacking sufficient surfactant, resulting in atelectasis, shunting, and hypoxemia; prenatal steroids and surfactant therapy are key preventive measures.
• Bronchopulmonary dysplasia (BPD) occurs in infants needing ventilatory support and involves tissue injury, disrupted alveolar development, and may require prolonged oxygen therapy.
• Bronchiolitis, commonly caused by respiratory syncytial virus (RSV), presents with symptoms such as runny nose, wheezing, cough, and tachypnea in infants, particularly those at higher risk, who may receive RSV-specific monoclonal antibodies.
• Viral pneumonia is the most prevalent form of pneumonia in children and often precedes bacterial pneumonia, which leads to significant hospitalization; vaccination with the polyvariant pneumococcal conjugate vaccine helps in prevention.
• Aspiration pneumonitis results from inhalation of foreign substances into the lungs and leads to inflammatory responses.
• Bronchiolitis obliterans is a rare post-inflammatory condition characterized by fibrous tissue obliteration in the bronchioles, resulting in pulmonary impairment.
• Asthma is a chronic inflammatory condition with reversible airflow obstruction, stemming from genetic, allergic, and viral factors, often linked to type I hypersensitivity reactions.
• Acute respiratory distress syndrome (ARDS) arises from lung injury triggering inflammation and alveolar capillary damage, leading to severe hypoxemia and respiratory failure within 24 hours.
• Cystic fibrosis (CF) is an autosomal recessive disorder that thickens airway secretions, causing chronic bacterial infections and long-term lung damage, although survival rates into adulthood are improving.

Sudden Unexpected Infant Death

• Sudden unexpected infant death (SUID) is the primary cause of postnatal death in infants outside the hospital, associated with low birth weight and improper sleeping positions; significant reductions in SUID have followed recommendations for placing infants on their backs during sleep.