Control of breathing in the newborn.

Abstract

Anatomical differences between infants and adults (e.g., fetal hemoglobin, central nervous system maturation) imply that with regard to control of breathing, the newborn infant cannot be considered simply a small adult. Resting breathing of the neonate may be regular or quiet variable. Although breathing patterns are different in rapid eye movement and quiet sleep states, it is not clear whether ventilation is different. Both resting ventilation and CO2 sensitivity increase with postnatal age. The ventilatory response to hypoxia in the neonate is unusual in that there is a transient increase in ventilation at the onset of hypoxia, but this response is not sustained in the steady state. The reasons for this difference from the adult response to hypoxia are uncertain. A possible association between abnormal control of respiration which might predispose to respiratory failure and the occurrence of apneas or periodic breathing has been sought in many studies, but results are inconclusive. It is speculated that respiratory responsiveness to transient changes in chemical stimuli might be important for the long-term well-being of the infant. Furthermore, it is suggested that modelling of respiratory behavior of the neonate may be quite useful because of ethical limits on the experimental protocols that are applicable to the human infant.