Phenotypical Characterization of Obstructive Sleep Apnea in Premature Infants using Polysomnography

Objective: To use objective quantification of polysomnographic (PSG) parameters in premature infants to define the severity and nature of obstructions (partial hypopnea vs. total obstruction), along with the impact on sleep fragmentation and oxygenation patterns.Methods: Retrospective comparison of PSG features in 207 infants (<12 months) referred for sleep disordered breathing. Our study groups included term (> = 37 weeks GA, n = 162) and premature (<37 weeks GA, n = 45) infants. Groups were compared for OSA sleep-stage-specific apnea hypopnea (AHI) indexes (REM and NREM), hypopnea indexes (HI), obstructive apnea indexes (OI) and arousal indexes. Oxygenation was assessed as % of time with SpO2 < 90%, nadir with apneic events and frequency of SpO2 desaturations (>3%) calculated as stage-specific O2 desaturation indexes.Results: Overall, premature infants had greater apnea severity (AHI premature 13.9/h vs. Term 7.9/h, p = 0.018). Additional analyses showed that the primary difference between premature and term infants is seen in the group with partial obstructions (HI index) and severe OSA (OAHI> = 10/h). Premature infants also had greater arousal indexes (premature 13.8/h vs. term 10.5/h, p = 0.003). Although the percentage of time <90% at night and the median SpO2 nadir during apneic events was similar in premature vs. term, O2 desaturation indexes were greater in premature infants (10.3/h in term vs. 18.3/h in prematurity, p = 0.03).Conclusions: Children born premature have an OSA phenotype in infancy characterized by greater severity mostly due to frequent partial obstructions (hypopneas) rather than full obstructions (obstructive apnea). Prematurity is also associated with more intermittent hypoxemia and sleep fragmentation.