0675 Nocturnal Oxygen Supplementation With Positive Airway Pressure Therapy For Obesity Hypoventilation Syndrome: Clinical Predictors And Liberation From Oxygen

Introduction Obesity hypoventilation syndrome (OHS) is associated with a high morbidity and mortality. Many patients require nocturnal supplemental oxygen on top of positive airway pressure (PAP) therapy for hypoxemia independent of apneic events. We need to clinically identify patients likely to require nocturnal oxygen supplementation. Follow up is essential as with adequate control of sleep apnea, hypoxia improves and liberation from nocturnal oxygen supplementation may be achievable. Methods Researchers obtained a list of patients with coding diagnosis of OHS, seen at the Jefferson Sleep Center between November 2016 and September 2019. Patients with BMI of ≥ 30 and evidence of hypoventilation were included. Hypoventilation was defined as an elevated CO2 level of ≥ 45 mmHg on blood gas analysis, elevated serum bicarbonate level of ≥ 27 mmol/L or by evidence of nocturnal hypoventilation by AASM criteria on polysomnography. Patients with pulmonary and neuromuscular disorders were excluded Results Out of 189 patients reviewed, 36 met the inclusion and exclusion criteria. Nineteen patients (53%) required nocturnal oxygen supplementation. A higher serum bicarbonate level of 33 mmol/L against 30 mmol/L (p=0.0078) and a lower resting awake SaO2 of 89% versus 95% (p <0.01) were observed in the oxygen supplementation group. In polysomnographic data, the oxygen supplementation group had lower SaO2 nadir of 67% versus 73% (p=0.026) and had a longer time with SaO2 <88% at 238.2 minutes versus 65.5 minutes (p <0.01). Nine out of the 19 patients (47%) underwent nocturnal oximetry on PAP and room air. Of these, 4 patients (44%) were liberated from oxygen. Conclusion Fifty three percent of patients with OHS required nocturnal oxygen supplementation on top of PAP therapy. Higher serum bicarbonate level and lower resting awake SaO2 are potential clinical predictors of nocturnal oxygen supplementation. After nocturnal oximetry on PAP, 44% were successfully liberated from supplemental oxygen. Support