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Objective: This study aimed to evaluate the associations between particulate matter (PM), lung function and Impulse Oscillometry System (IOS) parameters in chronic obstructive pulmonary disease (COPD) patients and identity effects between different regions in Beijing, China. Methods: In this retrospective study, we recruited 1348 outpatients who visited hospitals between January 2016 and December 2019. Ambient air pollutant data were obtained from the central monitoring stations nearest the participants' residential addresses. We analyzed the effect of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5) exposure on lung function and IOS parameters using a multiple linear regression model, adjusting for sex, smoking history, education level, age, body mass index (BMI), mean temperature, and relative humidity. Results: The results showed a relationship between PM2.5, lung function and IOS parameters. An increase of 10 µg/m3 in PM2.5 was associated with a decline of 2.083% (95% CI: −3.047 to − 1.103) in forced expiratory volume in one second /predict (FEV1%pred), a decline of 193 ml/s (95% CI: −258 to − 43) in peak expiratory flow (PEF), a decline of 0.932% (95% CI: −1.518 to − 0.342) in maximal mid-expiratory flow (MMEF); an increase of 0.732 Hz (95% CI: 0.313 to 1.148) in resonant frequency (Fres), an increase of 36 kpa/(ml/s) (95% CI: 14 to 57) in impedance at 5 Hz (Z5) and an increase of 31 kpa/(ml/s) (95% CI: 2 to 54) in respiratory impedance at 5 Hz (R5). Compared to patients in the central district, those in the southern district had lower FEV1/FVC, FEV1%pred, PEF, FEF75%, MMEF, X5, and higher Fres, Z5 and R5 (p < 0.05). Conclusion: Short-term exposure to PM2.5 was associated with reductions in lung function indices and an increase in IOS results in patients with COPD. The heavier the PM2.5, the more severe of COPD. [ABSTRACT FROM AUTHOR]

Objective: Bronchodilator responses (BDRs) from impulse oscillometry (IOS) are not interchangeable with those from spirometry. We aimed to identify the characteristics of children with small airway hyperresponsiveness and to determine whether BDR from IOS provides an important supplement to BDR from spirometry. Methods: The records of 592 children with asthma or suspected asthma who underwent spirometric and oscillometric BDRs were retrospectively reviewed. Oscillometric BDR was defined as positive when relative or absolute changes of Rrs5 or Xrs5 were beyond two standard deviations and spirometric BDR as positive when absolute change of forced expiratory volume in one second (FEV1) was ≥12%. Subjects were classified as positive for spirometric BDR only, positive for oscillometric BDR only, positive for both BDRs, or negative for both BDRs. Results: The results indicated that 101 (17.6%) subjects were positive for spirometric BDR only, 49 (8.5%) positive for oscillometric BDR only, 48 (8.3%) positive for both BDRs, and 377 (65.6%) negative for both BDRs. The agreement between spirometric and oscillometric BDRs was poor. Baseline FEV1, Rrs5, and Xrs5 values strongly influenced the BDRs. Subjects positive for oscillometric BDR only were found to be younger than those positive for spirometric BDR only (P < 0.001). Subjects positive for both BDRs were more likely to have asthma, atopic dermatitis, wheezing apart from cold, or decreased baseline lung function relative to those positive in either test (P < 0.001). Conclusions: There was a low concordance between spirometric and oscillometric BDRs. Use of IOS to detect small airway hyperresponsiveness may add more information about a clinical profile of subjects with asthma. [ABSTRACT FROM AUTHOR]