Elsevier

Respiratory Medicine

Volume 101, Issue 5, May 2007, Pages 995-1000
Respiratory Medicine

The utility of the forced oscillation technique in assessing bronchodilator responsiveness in patients with asthma

https://doi.org/10.1016/j.rmed.2006.09.001Get rights and content
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Summary

Objective: To address the utility of the forced oscillation technique (FOT) in assessing bronchodilator responsiveness compared with forced expiratory volume in 1 s (FEV1).

Methods: This is a retrospective analysis of consecutive 126 patients with a clinical history of asthma without any other lung diseases at a pulmonary function testing laboratory. The following measurements were obtained three times each, before and after two doses of pirbuterol 0.2 mg inhalation: the respiratory resistance at 5 Hz (Rrs5), the mean respiratory resistance between 5 and 20 Hz (Rrs5–20), and the mean respiratory conductance (Grs5–20) by FOT and the FEV1 by spirometer. These measurements were transformed into dimensionless subject-specific effect-size “d-scores” by dividing them by the estimated pooled within-subject standard deviation.

Results: Descriptive statistics for each value were the following [mean baseline value (±sd), Δ value (pre- minus post value), and d-score (P value compared to FEV1)]: Grs5–20 (L s−1 kPa−1) [1.79±0.53, Δ=+0.39, d=2.64 (P<0.001)], Rrs5–20 (kPa L−1 s) [0.60±0.16L, Δ=−0.10, d=2.56 (P=0.001)], Rrs5 (kPa L−1 s) [0.78±0.25, Δ=−0.16, d=2.52 (P<0.001)], and FEV1 (L) [1.90±0.64, Δ=−0.20, d=1.83]. The higher d-score of Grs5–20, Rrs5–20 and Rrs5 compared to FEV1 indicates that these are better indicators for bronchodilator response than FEV1. The percentages of subjects exhibiting change in the expected direction after bronchodilator were not significantly different between each value: Rrs5 (85.7%), Rrs5–20 (83.3%), Grs5–20 (83.3%), and FEV1 (83.3%) [P>0.05].

Conclusions: Several forced oscillation measures, namely Grs5–20, Rrs5–20 and Rrs5, are more accurate and sensitive for detecting bronchodilator response than FEV1 in patients with asthma.

Keywords

Airway obstruction
Asthma
Bronchodilator
Forced oscillation
Impulse oscillometry system (IOS)

Abbreviation

FOT
forced oscillometry technique
IOS
impulse oscillometry system
Rrs5 and Rrs20
the respiratory resistance at 5 and 20 Hz
respectively (R5 and R20)
Rrs5–20
the mean respiratory resistance between 5 and 20 Hz
Rrs
Grs5–20
the total respiratory conductance
the reciprocal of Rrs5–20
Grs
FEV1
forced expiratory volume in 1 s
PEF
peak expiratory flow
GEE analysis
generalized estimating equation analysis
COPD
chronic obstructive pulmonary disease
ATS
American Thoracic Society
ERS
European Respiratory Society

Cited by (0)

The abstract of this article was presented at the American College of Chest Physicians 2004 Seattle: Yaegashi M, Akerman MJ, Yamalanchili VAK, Kaza V, Weedon J, Heurich AE. “The Utility of Forced Oscillation Technique (FOT) to Assess Bronchodilator Responsiveness in Patients with Asthma” Chest 2004; 126S (4): 796. All abbreviations of FOT measurements were based on the ones used in the recommendation from ERS task force.