Regional differences in bronchial reactivity assessed by respiratory impedance

Small airway dysfunction and bronchial asthma control : the state of the art

“…Small airway function (R5–R20 and X5 ) was comparable between subjects with asymptomatic BHR and healthy controls, whereas asthma patients showed small airway dysfunction as reflected by higher R5–R20 and lower X5 values. Beretta et al used the IOS to gain information concerning the distribution of hyper-reactivity along the bronchial tree during methacholine challenge test [93]. For PD20 < 200 μg, a remarkable frequency dependence was observed, with increase in R5, no change in R20, and decrease in X5, suggesting hyper-responsiveness of the distal airways paralleled by a change in visco-elastic properties of lung parenchyma.…”

Isolated small airway reactivity during bronchoprovocation as a mechanism for respiratory symptoms in WTC dust‐exposed community members

“…Confirmation that the predominant effect of methacholine is a change in peripheral, rather than central, resistance was obtained using a wedged micromanometer into a distal airway [Ohrui et al, ]. Whole lung measurements confirmed the peripheral site of action of methacholine using numerous techniques including air trapping as assessed by spirometry [Chapman et al, ], and peripheral ventilation defects using imaging [Tgavalekos et al, ], and FOT [Pimmel et al, ; King et al, ; Beretta et al, ].…”

“…However, the link between dysfunction in small airways and LRS is by inference since patients are usually asymptomatic at the time that testing is performed in the laboratory. Bronchial provocation testing with methacholine provides an opportunity to study the relationship between onset of LRS and small airway dysfunction since the predominant effect of methacholine has been demonstrated on small as compared with large airways [Pimmel et al, ; Ohrui et al, ; King et al, ; Tgavalekos et al, ; Segal et al, ; Beretta et al, ]. Therefore, the present study uses spirometry and FOT data obtained during routine methacholine challenge testing to evaluate the direct link between development of LRS and simultaneous development of small airway dysfunction.…”

Aberrant small airways function relates to asthma severity in young children

“…Recent reports by Shi et al showed that measures of small airway parameters carried out using IOS, such as the frequency dependence R5-20 and reactance area AX, were better at predicting loss of asthma control in children than spirometric indices [8,12]. An Italian study found an association between small airways dysfunction (by IOS R5, R20 and X5) and the magnitude of the hyperresponsiveness to mch in adults and school-aged children [32].…”