A developmental study on types and frequency distribution of short apneas (3 to 15 seconds) in term and preterm infants

Abstract

We measured the frequency distribution and the ventilatory correlates of the various types of apneas 3 to 15 s long during sleep in eight term infants (birth weight 3.65 ± 0.16 kg; gestational age 39.5 ± 0.3 wk) and eight preterm infants (birth weight 2.07 ± 0.18 kg; gestational age 34.3 ± 0.4 wk). Each infant was studied on five to seven occasions from birth to 56 wk of postconceptual age using a modified flow-through system. Sixty-six paired epochs of quiet sleep (1163 min) and rapid eye movement sleep (829 min) were analyzed in term infants and 85 paired epochs of quiet sleep (1553 min) and rapid eye movement sleep (1328 min) in preterm infants. Of the 783 apneas recorded in term infants 82% were central, 1.5% obstructive, 0.5% mixed, and 16% were of the breath-holding type; the corresponding figures for the 4086 apneas recorded in preterm infants were 93, 0.5, 1.0, and 5.5%. This distribution was similar in the two sleep states but term infants had a higher percentage of breath-holding apneas than preterm infants (p < 0.01). In preterm infants the rate of central apneas decreased with postnatal age (p < 0.01); in term infants the rate did not change significantly. The duration of apneas showed a modal distribution for central apneas at about 8 s for both groups during the 1st month of life (p < 0.05). The findings suggest: 1) apneas in the newborn and early infancy are primarily central and are more frequent in preterm than in term infants; 2) the higher rate of apnea in healthy preterm infants is accounted for almost entirely by the higher rate of central apneas; 3) a significant decrease in the rate of apnea occurs during the first 4 months after birth; and 4) preterm infants show longer respiratory pauses in both quiet sleep and rapid eye movement sleep when compared to term infants, and a maturation pattern can be discerned by 3 months of age.