Why are children at greater risk for respiratory failure?
Infants and children require more oxygen per kilogram of body weight than adults. Anatomic factors put infants at particularly high risk for respiratory failure. Infants breathe almost exclusively through their noses, so nasal obstruction can cause significant respiratory signs and symptoms. The caliber of infant airways is small, so respiratory resistance is much higher, especially when there is inflammation of the respiratory tree. Alveoli have less collateral ventilation in infants. Thus, obstruction of small, peripheral airways is more likely to lead to atelectasis and hypoxemia. A compliant chest wall facilitates passage through the birth canal but leads to respiratory problems when airway resistance is increased. The diaphragm of infants is weaker and more easily fatigued compared with the diaphragm of older children and adults. Also, the inability of younger children to verbalize their symptoms may cause delayed presentations of significant respiratory problems.