Comparison of airway resistance in a pediatric versus adult airway

Effects of airway narrowing. Resistance to gas flow is inversely proportional to the fourth power of the radius of the airway lumen, meaning that small decreases in luminal diameter result in large increases in airway resistance. Because infants and children have smaller airways than adults at comparable levels, the same amount of airway narrowing (eg, 1 mm) results in a disproportionate increase in resistance for these patients. This problem is compounded by the fact that the immature respiratory musculature of a pediatric patient is less efficient and therefore more prone to fatigue than that of an adult.