S6B-09 SESSION 6B: HFM ROBIN - PART I PSG-BASED PHENOTYPICAL CHARACTERIZATION OF OSA IN ROBIN SEQUENCE INCLUDING AROUSAL AND SLEEP-STAGE SPECIFIC INDICES

Introduction: Robin sequence (RS) is a top cause of obstructive sleep apnea (OSA) in early life. Most studies have focused on understanding anatomic factors leading to OSA and changes in apnea-hypopnea index (AHI) on polysomnography (PSG), but little is known about other PSG features of OSA in RS. The goal of this study was to compare OSA features in newborns with RS vs. infants with OSA using PSG-based determination of arousal responses and sleep-stage specific respiratory indexes. Methods: We included 10 newborns with RS (mean age 1 month) and 20 non-syndromic infants aged 0–2 years (10 non-RS with severe OSA and 10 controls without OSA). We obtained standard OSA severity parameters (OAHI, AHI and RDI) and used raw data to calculate sleep-stage specific indexes (REM vs. NREM) as well as position-specific indexes (supine vs. non-supine). For arousal responses we used respiratory arousal indexes correlated with individual’s AHI. Impact of OSA in gas exchange was assessed by SpO2 values, CO2 values and correlation with AHI. Results: All standard OSA parameters (AHI, OAHI and RDI), gas-exchange values, sleep-stage specific indexes and position-specific indexes showed similar distribution in newborns with RS and in non-RS infants with OSA. AHI correlated strongly with intermittent hypoxemia (O2 desaturation index) in the non-RS group with OSA (R-sq=93%, P <0.01) but only moderately in RS newborns (R-sq=62%, P=0.01). In both OSA groups AHI correlated with sustained hypoxemia (time <90%) (non-RS R-sq=86%, P<0.01; RS R-sq=73%, P<0.01) as well as with nadir SpO2 (non-RS R-sq=84%, P<0.01, RS R-sq=81%, P<0.01). Non-RS infants with OSA exhibited significant correlation between AHI and respiratory arousal indexes (R-sq 72%, p<0.01), however, RS newborns showed no correlation (R-sq 28%, p=0.11), particularly during REM sleep (R-sq 6%, p=0.49). Conclusion: Newborns with RS and OSA seem to have reduced arousal mechanisms to terminate apneic events, particularly during REM sleep. This may be due to young age and the trend of RS babies to have less intermittent hypoxemia, an important arousal trigger in OSA. We believe PSG-based characterization of arousal and sleep-stage specific indexes in RS may contribute to determine the best candidates for surgical correction by identifying individuals with higher risk for severe OSA due to a combination of anatomical factors and reduced arousal mechanisms to terminate apneic events.