Details

Autor(en) / Beteiligte

• Hammer, Jürg
• Eber, Ernst
• Eber, E
• Hammer, J

Titel

The Peculiarities of Infant Respiratory Physiology

Ist Teil von

• Paediatric Pulmonary Function Testing, 2005, Vol.33, p.2-7

Ort / Verlag

Basel, Switzerland: S. Karger AG

Erscheinungsjahr

2005

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• This chapter summarizes the most important developmental changes in respiratory physiology that occur from infancy to adolescence.The first year of life is characterized by major changes in the shape and stiffness of the rib cage. Infants have to adopt a breathing strategy to dynamically elevate their end-expiratory lung volume above that passively determined by the outward recoil of the rib cage and the inward recoil of the lung. This strategy is necessary to maintain an adequate lung volume and to prevent airway closure in the presence of reduced outward recoil of the highly compliant chest wall, which is achieved by three mechanisms: (a) a higher respiratory rate with insufficient time to exhale to the elastic equilibrium volume level, (b) laryngeal adduction during exhalation to increase the resistance to airflow, and (c) maintenance of diaphragmatic muscle tone during expiration. Other important differences relate to the increased compliance of the upper and lower airways which render children susceptible to dynamic airway collapse, especially during vigorous respiration. The elastic recoil of the lung provides little support for the airways to remain open during tidal breathing in infancy, and increases until adolescence due to alveolarization and maturation of elastic fibres. Any decrease in airway diameter results in a dramatic increase in resistance to breathing due to the smaller airway size of infants, since the resistance to airflow is inversely related to the fourth power of the airway radius. The diaphragm acts less efficiently because of the highly compliant chest wall and a more horizontal insertion at the rib cage. It is also poorly equipped to sustain high workloads due to the lower numbers of fatigue-resistant type I muscle fibres in the first year of life. The differences in respiratory physiology between infants and older children and adolescents explain the higher susceptibility of infants to more severe manifestations of respiratory diseases. Knowledge of the developmental changes occurring in the different components of the respiratory system is essential for the correct assessment of respiratory compromise in children.