Forced Oscillation Technique And Its Association To Airflow Limitation In Copd

Introduction: Forced oscillation technique (FOT) is a non-invasive and rapid technique requiring minimal patient cooperation. It is unclear how FOT parameters are associated with bodyplethysmography variables in patients with different severities of chronic obstructive pulmonary disease. Methods: 173 patients with COPD and 28 patients without COPD presenting at a tertiary institution were enrolled. Within the clinical, laboratorial and functional characterization, the cohort underwent FOT and bodyplethysmography including diffusion capacity at stable state of the disease. Results: Mean age was 66 years, 63% male, BMI 29 kg.m2 . In COPD patients R5, R5-19, AX and X5 were significantly associated with FEV1% pred, FVC, FEV1/FVC, DLCO % pred, and total lung capacity (TLC). GOLD II patients had higher R5-19 (1.2 vs. 1.5 cmH2O/L/s, p<0.05) and AX (26 vs.40 cmH2O/L/s, p<0.05) than GOLD III patients who in turn had higher R5-19 (1.5 vs. 2.8 cmH2O/L/s, p<0.05) and AX (40 vs. 76 cmH2O/L/s, p<0.05) values than GOLD IV patients. R5-19 (mean 1.4 vs. 0.6 cmH2O/L/s, p<0.0001), and AX (mean 34 vs. 14 cmH2O/L/s; p<0.0001) were higher in patients with COPD than in patients with no COPD. X5 (mean, -3.8 vs. -1.8 kPa/L/s, p<0.0001) was lower in patients with COPD than with no COPD. Conclusion: FOT can differentiate across airflow limitation severity according to GOLD stages in COPD.