0493 Obstructive Sleep Apnea in Idiopathic Pulmonary Fibrosis is Associated with Reduced Arousal Threshold and Preserved Upper Airway Collapsibility

Abstract Introduction An increased prevalence of obstructive sleep apnea (OSA) has been observed among patients with idiopathic pulmonary fibrosis (IPF), fueling speculation of potential interactions between respiratory physiologic changes associated with IPF and the pathogenesis of OSA, including easier arousal by respiratory events. We conducted a matched case-control study to test the hypothesis that individuals with co-morbid IPF and OSA have lower arousal threshold than individuals with OSA alone. Methods We performed a secondary analysis of data collected from participants enrolled in the Role of Obstructive Sleep Apnea in Modulating the Cardio-Pulmonary Responses to Antifibrotics (OSA/IPF), a study of adult subjects with an established diagnosis of IPF on a stable dose of antifibrotic medication (nintedanib or pirfenidone). Participants underwent attended in-lab attended polysomnography (PSG). OSA/IPF participants were matched to historical controls who previously underwent in-lab PSG as part of other OSA research studies. All PSG studies were scored according to American Academy of Sleep Medicine recommendations. OSA endotypes were derived by Phenotyping Using Polysomnography (PUP) analysis and include upper airway collapsibility (Vpassive), arousal threshold (ArTH), loop gain (LG1), and upper airway muscular response (Vcomp). Results Thirteen participants in OSA/IPF (age 71.1±7.8 years, 10 males, BMI 27.7±4.8 kg/m2, AHI3A 29.7±15.2) had acceptable pneumotachygraphy or nasal cannula airflow signals and an AHI3A of at least 10 events/hour, and were age-, sex-, and BMI- matched with 13 historical controls (age 67.5±6.9 years, 10 males, BMI 28.8±5.6 kg/m2), who incidentally had similar OSA severity (AHI3A 27.2±12.5 events/hr, p for difference = 0.687). ArTH was lower in OSA/IPF (108.5±9.1 %Veupnea) compared to controls (140.6±71.3 %Veupnea, p = 0.022). Vpassive was higher in OSA/IPF (95.3±5.4 %Veupnea) than controls (79.5±30.3 %Veupnea, p = 0.016). LG1 was similar across groups (0.65±0.16 versus 0.60±0.23, p = 0.801). Vcomp was higher among OSA/IPF (3.8±12.6 %Veupnea) than controls (-6.6±22.5 %Veupnea), but the difference was not significant (p = 0.064). Conclusion In comparison to OSA in the absence of established cardiopulmonary disease, OSA in the setting of IPF is characterized by easier arousal due to respiratory events and less collapsibility of the upper airway. Support (if any) Boehringer Ingelheim Pharmaceuticals, University of Wisconsin, William S. Middleton Memorial Veterans’ Hospital, T32HL160511.