Obstructive Sleep Apnea severity and lung function

Introduction: Obstructive sleep apnea (OSA) is characterized by excessive narrowing or complete obstruction of supraglottic airway during sleep. Variations in subglottic airway function may also influence supraglottic airway. Previous studies have suggested a protective role of increased air trapping in OSA severity but data are limited. Objective: To determine whether there is a relationship between pulmonary function and OSA severity. Methods: A retrospective analysis of patients who performed a cardiorespiratory polygraphy (CRP) in our hospital in 2015 and 2016 was conducted. Adults diagnosed with OSA who performed pulmonary function tests (PFT) were selected and characterized regarding demographics and pulmonary function. Results: 834 CRP were performed and 374 patients were included with a mean age of 61.7±13.3 years. 61% were male. Mean BMI was 34±6.9 kg/m2. OSA was mild (apnea–hypopnea index [AHI] 5-15) in 42%, severe (AHI > 30) in 35% and moderate (AHI 15-30) in 23%. PFT demonstrated an obstructive pattern in 18.2%, restrictive in 11.8%, nonspecific in 5% and were normal in 65%. Mean FEV1 was 88.1±21.7% of predicted and mean RV was 116.2±27.8% of predicted. FEV1 was negatively correlated with AHI. FEV1 30. FEV1 30. RV > 180% of predicted had an odds ratio of 0.3 for AHI > 15. Conclusion: In our population, a decrease in FEV1 (even among normal values) was associated with an increased risk of severe OSA but this was not true for FEV1 180% of predicted. This points to a possible protective role of air trapping in OSA severity.