The Correlation Between Impulse Oscillometry System (IOS) And Pulmonary Function Test Used In Diagnosis Of COPD

[Objective] To analysis the relativity of the parameters between impulse oscillmetory system (IOS) and pulmonary function test (PFT) and to study the value of estimating the severity and staging of COPD by IOS.[Methods] IOS and PFT were performed in 325 subjects(including 154 patients with COPD and 171 normal subjects). To avoid IOS results being affected by forced expiratory, we should perform IOS first, then PFT.[Results]1,The correlations between parameters measured by IOS such as respiratory impedance at 5Hz Z5, respiratory resistance at 5Hz R5, difference between respiratory resistance at 5Hz and 20Hz R5-R20, AX, resonant frequency Fres and forced vital capacity FVC%pre, forced vital capacity in one second FEV1%pre, ratio of forced expiratory volume in one second to forced vital capacity FEV1/FVC, maximal ventilatory volume MVV%pre were significantly negative (p<0.05), whereas RV/TLC, Rtot%pre were significantly positive (p <0.05). The correlations between reactance at 5Hz and FVC%pre, FEV1%pre, FEV1/FVC, MVV%pre, were significantly positive (p <0.05), whereas RV/TLC, Rtot%pre were significantly negative (p <0.05).2,The sequence of diagnosis value of parameters measured by IOS for COPD is X5(0.836)>R5(0.831)>R5-R20(0.748)>Fres(0.704).3,There was a significant correlation between the two staging methods derived from H.J.Smith and GOLD (p <0.05).[Conclusions]1,R and X can be used to estimate airway obstruction of COPD patients, also Fres and X5 can be used to reflect respiratory compliance of patients with airway obstructive disease.2,As there was a significant correlation between IOS and PFT in COPD patients, we should consider both IOS and PFT parameters when diagnosis is needed.3,R5 and X were two sensitive parameters which used in estimating peripheral airway obstruction in COPD patients, they be used in diagnosing COPD.