Respiratory pattern at hospital discharge in asymptomatic preterm infants.

Pneumogram (PG) recordings were performed in 87 very low birthweight (VLBW) asymptomatic infants just prior to hospital discharge to determine the relationships between: 1) a prior history of apnea of prematurity (AOP) and cardiorespiratory pattern; and 2) cardiorespiratory pattern at hospital discharge and postconceptional age. Apnea density (A6/D%) and longest apnea were significantly greater in those with (n = 66), versus without (n = 21) a prior history of AOP (P less than 0.05 and P less than 0.01, respectively). Although PG values for the 21 VLBW infants without a prior history of AOP did not differ significantly from those of full-term infants, for the 66 VLBW infants with a prior AOP history A6/D% (P less than 0.01), episodes of periodic breathing (P less than 0.05) and longest apnea (P less than 0.001) were significantly greater compared with full-term infants. Postconceptional age was significantly less in the VLBW infants with A6/D% values above, compared with those within the 95th percentile for normal infants (median age, 36 and 37.5 weeks; P = 0.01). Therefore, respiratory pattern abnormalities in asymptomatic VLBW infants ready for hospital discharge are related to a prior history of AOP and may be significantly higher than in full-term infants at the postconceptional ages at which hospital discharge now tends to occur.