Apnoea in the newborn infant.

Clinical apnoea in infants is defined as a pause in breathing of more than 20 s duration or a briefer pause associated with bradycardia. Such events are uncommon in term infants and usually are due to some precipitating factor. They occur more commonly in preterm infants and there is an exponential increase in incidence with decreasing gestational age at birth. Although insults such as infection or hypoxia can accentuate the problem, the major factor appears to be immaturity. Studies of brain-stem maturity using auditory evoked responses indicate that infants with immature responses have a higher incidence of apnoea. Brain-stem immaturity has also been implicated in histopathological studies of infants dying from Sudden Infant Death Syndrome (SIDS). In preterm infants, upper airway obstruction occurs commonly at the end of longer events and some infants have a predominantly obstructive pattern. These latter infants are often neurologically abnormal and have had prolonged endotracheal intubation. Both of there factors could be associated with disordered control of upper airway patency. This notion is supported by the finding of upper airway instability during nasal occlusion in these infants. A link with SIDS is uncertain, although preterm infants with chronic pulmonary insufficiency, usually following a prolonged intubation, are said to be at particularly high risk of dying suddenly and unexpectedly during infancy.