REVIEW ARTICLE
Forced Oscillation Technique and Childhood Asthma

https://doi.org/10.2332/allergolint.12-RAI-0440Get rights and content
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ABSTRACT

Most infants and preschool children are not able to voluntarily perform the physiological maneuvers required to complete the pulmonary function tests that are used in adults and older children. Recently, commercial devices using forced oscillation technique (FOT) suitable for young children have become available. In devices with FOT, an oscillation pressure wave is generated by a loud speaker, is applied to the respiratory system, usually at the mouth, and the resulting pressure-flow relationship is analyzed in terms of impedance (Zrs). Zrs encompasses both resistance (Rrs) and reactance (Xrs). Rrs is calculated from pressure and flow signals, and is a measure of central and peripheral airway caliber. Xrs is derived from the pressure in the phase with volume and is related to compliance (Crs) and inertance (Irs). These parameters individually indicate the condition of the small and large airways in each patient and indirectly suggest the presence of airway inflammation. It is agreed that the clinical diagnostic capacity of FOT is comparable to that of spirometry. One of the advantages of FOT is that minimal cooperation of the patient is needed and no respiratory maneuvers are required. The use of FOT should be considered in patients in whom spirometry or other pulmonary function tests cannot be performed or in cases where the results of other tests appear to be unreliable. In addition, this approach is effective in assessing bronchial hyperresponsiveness. Considering these qualities, FOT is a useful method to study pulmonary function in preschool children with asthma.

KEY WORDS

asthma
forced oscillation technique
impulse oscillometry
preschool children
pulmonary function test

ABBREVIATIONS

BHR
bronchial hyperresponsiveness
FOT
forced oscillation techniques
IOS
impulse oscillometry
MEFV
maximal forced expiratory flow-volume
Zrs
impedance
Rrs
resistance
Xrs
reactance
Crs
compliance
Irs
inertance
FRC
functional residual capacity
Rint
interrupter resistance
sRaw
specific airway resistance
Vpleth
plethysmographic volume
TGV
thoracic gas volume
eNO
exhaled nitric oxide
tcPO2
transcutaneous oxygen tension
FVC
forced vital capacity
FEV1
forced expiratory volume in one second
MMF
maximal midexpiratory flow
PEF
peak flow
V50
maximal expiratory flow at 50% vital capacity
V25/HT
maximal expiratory flow at 25% vital capacity per height
Dmin
minimal dose of methacholine
St
speed of bronchoconstriction in response to methacholine
PC20
provocation concentration producing a 20% fall in FEV1
ATS
American Thoracic Society
ERS
European Respiratory Society

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Review Series: Non-Invasive Monitoring of Airway Inflammation in Asthma