The possibilities of impulse oscillometry in the diagnosis of the lung function disorders after COVID-19

Abstract

Background. Impulse oscillometry (IOS) is an effort independent method of studying lung mechanics.Aim. To study the diagnostic significance of IOS in assessing lung mechanics after COVID-19.Materials and methods. Spirometry, body plethysmography, diffusion test (DLco), IOS parameters were analyzed in 315 patients (the median age 48 years), the median period from the beginning of COVID-19 to the study was 50 days. Statistical analysis included descriptive statistics, correlation analysis and one-dimensional logistic regression analysis with an assessment of odds ratios.Results. In general group, spirometry and body plethysmography parameters were in normal values, while DLCO was reduced in 61% of patients. Parameters of IOS were analyzed in the general group and between the groups, depending on the value of DLco and total lung capacity (TLC): normal or reduced. In general group, reactance area (AX), hererogeneity of resistance Rrs5–Rrs20, resistance at 5 Hz (Rrs5), reactance at 5 Hz (ΔXrs5) were increased in 29.8%, 17.8%, 6%, 4.8% of patients, respectively, and were statistically significantly higher in the group with reduced TLC, whereas in the group with reduced DLco AX, Rrs5–Rrs20 were statistically significantly higher. Logistic regression analysis showed that patients with Rrs5-Rrs200.07 kPa×sec/l or AX0.32 kPa/l had a 1.99-fold and 2.24-fold increased risk for decrease DLco, respectively, while the risk of decrease in TLC was 2.25-fold (p=0.012) and 3.16-fold (p0.001) higher, respectively.Conclusion. IOS allow to detect both dysfunction of small airways (if AX or Rrs5–Rrs20 are increased) and the risk of restrictive pattern and lung diffusion impairment after COVID-19.