Respiratory mechanics and peripheral airway inflammation and dysfunction in asthma

Abstract

We conclude that respiratory impedance reflects peripheral airway inflammation and ventilation inhomogeneity.

Clinical Application of the Forced Oscillation Technique

“…In addition, high R5-R20 values are physiologically detected in children mainly due to upper airway mechanics (23). In our study, R5-R20 and other pulmonary function values were investigated in 78 patients with asthma (18), and R5-R20, particularly inspiratory measurements, correlated with not only %FEV1 but also the N2 phase III slope of single-breath N2 washout (delta N2). We speculated that R5-R20 had a certain relationship with airway obstruction and ventilator unevenness (Table 1).…”

“…For the purpose of detecting a treatment effect or daily fluctuations, minimal clinically important differences in the FOT parameters should be established. R20 also correlates with FEV1 in asthma, but more weakly than R5 (12,13,18). There was no correlation between R20 and delta N2 in asthma (18), or between R20 and FEV1 in COPD (12).…”

“…R20 also correlates with FEV1 in asthma, but more weakly than R5 (12,13,18). There was no correlation between R20 and delta N2 in asthma (18), or between R20 and FEV1 in COPD (12). There was no difference in R20 among patients with COPD, asthma, and healthy controls (12).…”

“…In patients with asthma, these three parameters were shown to significantly correlate with FEV1 and delta N2, suggesting that those three parameters are other markers of airway obstruction and ventilator unevenness (18) ( Table 1). Although there are some differences in the details, the strongest correlation is generally found between Fres and FEV1 in both asthma and COPD (12,13,18,24). Interestingly, a previous study found hyperbolic relationships between Fres and FEV1 in asthma (24).…”

“…There is no correlation between fractional exhaled nitric oxide (FeNO) and Rrs or Xrs (18,36). However, weak correlations were found between the alveolar nitric oxide concentration (CANO), a marker to reflect peripheral airway or alveolar inflammation, and whole-breath R 5-R 20, X 5, and ALX using IOS (36,37).…”