Applied respiratory physiology

SummaryRespiratory failure, hypoxia with or without hypercarbia, is common in infants and children. Knowledge of the underlying abnormal physiology facilitates diagnosis and therapy. Isolated hypoxia can result from exposure to reduced oxygen pressure, ventilation/perfusion mismatch, intra- and extrapulmonary shunting, and impaired diffusion. Intra- and extrapulmonary shunting can be distinguished from the other conditions by a poor response to supplementary oxygen.Hypercarbia indicates inadequate alveolar ventilation, which can result from upper or lower airway obstruction, reduced compliance of the respiratory system, or conditions that have an adverse effect on the respiratory pump.