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Conducting Respiratory Oscillometry in an Outpatient Setting
Published on: April 8, 2022
Methacholine challenge in young children as evaluated by spirometry and impulse oscillometry.
Johannes Schulze1, Hans-Juergen Smith, Johannes Fuchs
1Department of Allergy, Pulmonology and Cystic Fibrosis Children's Hospital, Goethe-University, Theodor Stern Kai 7, 60590 Frankfurt, Germany. johannes.schulze@kgu.de
Respiratory Medicine
|February 14, 2012
Summary
A short methacholine challenge protocol is feasible in young children. Impulse oscillometry (IOS) detected 70-80% of spirometry responders, with resistance changes preceding FEV1 changes.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Clinical Diagnostics
Background:
- Conventional spirometry for bronchial challenge testing in young children can be difficult due to cooperation dependency.
- The forced oscillation technique (FOT) is a viable alternative in pediatrics, requiring less cooperation.
- FOT, specifically impulse oscillometry (IOS), offers a less invasive method for assessing airway function in children.
Purpose of the Study:
- To evaluate the association between spirometric and impulse oscillometric (IOS) indices during a short methacholine provocation protocol.
- To determine the sensitivity and specificity of IOS parameters in detecting bronchial hyperresponsiveness in children.
- To compare the timing of responses between IOS and spirometry during methacholine challenge.
Main Methods:
- A short methacholine provocation protocol was administered to 48 children (mean age 5.3 years).
- Primary endpoint: methacholine dose causing a 20% decrease in FEV1 (PD(-20)FEV1).
- Changes in respiratory resistance (Rrs5) and reactance (Xrs5) from IOS were compared with FEV1 changes.
Main Results:
- Significant mean reductions in FEV1 (29.8%), increases in Rrs5 (55.3%), and decreases in Xrs5 (0.37 kPa·s·L⁻¹) were observed.
- An Rrs5 increase of 45.2% and Xrs5 decrease of 0.69 kPa·s·L⁻¹ demonstrated optimal sensitivity and specificity for detecting a 20% FEV1 reduction (AUC 0.76 and 0.81, respectively).
- In patients with significant changes, the PD(+40)Rrs5 was found to be lower than PD(-20)FEV1 (0.28 mg vs 0.48 mg, p=0.03).
Conclusions:
- A short methacholine challenge protocol is feasible and effective in young children.
- IOS successfully identified 70-80% of patients who responded to spirometry during the challenge.
- Respiratory resistance (Rrs5) changes detected by IOS often preceded the FEV1 response, suggesting earlier detection of bronchoconstriction.
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