from Section 3 - Special Topics
Published online by Cambridge University Press: 10 September 2019
The size of the neonatal airway in relation to older children and adults is especially important for understanding its functioning and pathophysiology (Figure 19.1). There are two basic types of airflow through an airway: laminar, or relatively smooth flow, and turbulent, or rough flow. Poiseuille’s law, R ∝ 1/r4 (where R is resistance and r is radius) describes laminar airflow. By this equation, the resistance to airflow increases exponentially (to the fourth power) as the radius decreases. This effect is to the fifth power for turbulent flow, such as with a crying child. Due to this relationship, even minor narrowing of the airway can cause significant increases in resistance in neonates (Figure 19.2).
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