Pathophysiologic mechanisms causing sleep apnea and hypoventilation in infants.

Complete absence of chemoreception in the medulla is characterized by sustained hypoventilation. Except for the first months of life, this deficit does not, of itself, cause apnea. Both in infants who lack central chemical drive, as well as those who are only partly deficient, it is necessary to invoke at least one further pathophysiologic event. Various alterations in gas exchange, especially during sleep, which promote hypoxemia can contribute to a positive feedback effect on ventilation. If gas exchange is further impeded by upper-airway obstruction, only a massive arousal response separates the infant from death.