Respiratory events in preterm infants prior to discharge: with and without clinically concerning apnoea.

PURPOSE: This study aimed to determine the characteristics of respiratory events in preterm infants with clinically concerning apnoea at or beyond 35 weeks postmenstrual age and to compare these findings with a group of preterm infants ready for discharge, without clinically concerning apnoea.
METHODS: Infants born at <32 weeks of gestation and who underwent nap polysomnography at or beyond 35 weeks corrected age prior to discharge were included. Cases were preterm infants with clinically concerning apnoea, and control infants were preterm infants asymptomatic for apnoea. Infants with upper airway obstruction, congenital malformations or apnoea associated with sepsis were excluded. Studies were retrospectively reviewed for length, type and frequency of apnoea. The relationship between sleep state and changes in oxygen saturation was compared between groups. Peri-natal and demographic data were also compared.
RESULTS: Data were complete for 16 case and 18 control infants. Gestational age was similar at birth and at time of study, but cases had a lower birth weight (p = 0.04) and higher weight at study (p = 0.04). There were no group differences in the mean duration, type or numbers of apnoea. The duration of the longest apnoea was greater in case infants (17.4 s vs. 12.3 s, p = 0.02). Lowest oxygen saturation (p < 0.05) and average minimum oxygen saturation (p < 0.05) were lower in case infants.
CONCLUSIONS: Preterm infants with clinically concerning apnoea have similar amounts and types of apnoea but lower oxygen saturation after apnoea compared with controls. The use of oxygen saturation monitoring is more useful than respiratory monitoring alone in recognising these events.