Preterm infants at discharge: nap polysomnography versus 24-hour oximetry

This study aimed to determine whether measures of intermittent hypoxia derived from 24-hour oximetry correlate with measures of apnoea derived from modified nap polysomnography undertaken for preterm infants before discharge.

Infants born ≤32 weeks of gestation were recruited from the neonatal intensive care unit and had a modified polysomnography to assess their respiratory stability once they were ≥35 weeks of postmenstrual age. Infants were defined as unstable if they had more than 10 obstructive events per hour or any apnoea of >20 seconds in length. Infants also had a 24-hour oximetry performed during this period. The results of the 24-oximetry desaturation index (DSI) were compared to nap polysomnography results for central and obstructive apnoea indices and correlations tested.

Twenty-four infants completed the study. There were 15 (63%) infants defined as unstable by the modified polysomnography. The 3% DSI and 4% DSI from the 24-hour oximetry were significantly higher in the unstable infants, and values for all infants correlated with the obstructive index and the central apnoea index from the modified polysomnography.

The 3% DSI and 4% DSI values from a 24-hour oximetry study may provide noninvasive measures of respiratory stability in preterm infants ready for discharge.