Prevalence and characteristics of Airway Collapse in Non-Specific Pattern of Lung Function

<bold>Introduction:</bold> Non-specific pattern (NSP) of lung function, characterized by inconclusive spirometry results, presents diagnostic dilemmas in respiratory medicine. This study aimed to investigate the prevalence and characteristics of Airway Collapse(AC) in individuals with NSP. <bold>Methods:</bold> This retrospective study included patients diagnosed with NSP. All patients underwent plethysmography with measurement of Forced Expiratory Volume in the first second(FEV1), Forced Vital Capacity(FVC), Forced Expiratory Time(FET), Slow Vital Capacity(SVC), Residual Volume(RV), Functional Residual Capacity(FRC) and Total Lung Capacity(TLC). AC was defined as a difference of more than 100ml between SVC and FVC. <bold>Results:</bold> We included 145 patients of whom, 62.8% were females and 42.8% were obese. Main etiologies of NSP were Sleep Apnea Syndrome(SAS) (32.4%), asthma(17.3%) and Interstitial Lung Disease (14.5%). Mean age(years) was 54.19±15.49 and mean BMI(kg/m2) was 30.92±10.16. Mean values of FEV1%, FVC% and TLC% were 62.55±11.37, 64.17±9.41 and 92.92±11.30, respectively. Among the study population, 49 patients(33.8%) presented AC. These individuals had higher BMI (33.39±9.63 vs 29.66±10.24; p=0.036) and a higher prevalence of SAS(46.93% vs 25%; p=0.007). Additionally, they demonstrated lower FVC%(62.47±9.81 vs 65.93±7.55; p=0.02) and FET (5.22±2.06 vs 6.29±2.43 s; p=0.028) and higher SVC% (79.28±12.15 vs 71.97±12.69; p=0.001). However, no significant difference was found in terms of FEV1, RV, FRC and TLC between patients with AC and the rest of the study population. <bold>Conclusion:</bold> Our study highlights the prevalence of AC among individuals with NSP, particularly in those with SAS and higher BMI.