0510 ETCO2 Screening for Obesity Hypoventilation Syndrome: A Patient Safety and Quality Improvement Study

Introduction Obesity hypoventilation syndrome (OHS) is a disorder of daytime hypercapnia which worsens during sleep. OHS may be underdiagnosed yet has an insidious progression to significant cardiopulmonary and neurologic morbidities and increased mortality. End-tidal carbon dioxide (ETCO2) monitoring is not routinely obtained in adult patients undergoing in-lab diagnostic polysomnography (PSG), possibly contributing to underdiagnosis. Patients with OHS may be missed without initial screening and consideration for this diagnosis. This quality improvement project sought to estimate the incidental rates of OHS in obese patients and describe their clinical characteristics. Methods Patients presented to our academic sleep center from September – November 2023 for clinically indicated diagnostic PSG. Those with a body-mass index (BMI) greater than 30 kg/m2 underwent ETCO2 monitoring during their PSG. Those with a documented history of opioid use, primary pulmonary or neurologic disease were excluded. Basic demographics and sleep screening questionnaires were obtained. Results Initial data revealed 43 eligible patients. 21% (n=9) of patients met the International Classification of Sleep Disorders (ICSD) Third Edition Text Revision diagnostic criteria for OHS. There was no statistical difference between the OHS group and the non-OHS group in the following categories: Male (77.8% v 76.5%), Age (33.8 v. 33.6), BMI (33.2 v. 33.8), AHI (23.6 v. 22.9), and ESS (12.8 v. 12.3). Of note, ISI scores were significantly different (15.9 v. 16.9, p=0.04). Conclusion Implementing an OHS screening protocol is a quick, feasible way to improve diagnosis of OHS. The incidental discovery of OHS was found to be clinically meaningful. Given the relatively low BMI, this may be an underestimation of OHS prevalence in obese patients. To the authors knowledge, no published improvement projects exist for improving diagnosis of OHS with routine PSG in an outpatient setting. Support (if any)