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Clinical Implications of Oscillatory Lung Function during Methacholine Bronchoprovocation Testing of Preschool
Sun Hee Choi1, Youn Ho Sheen2, Mi Ae Kim3
1Department of Pediatrics, Kyung Hee University School of Medicine, Seoul, Republic of Korea.
Insights
Impulse oscillation system (IOS) measurements of airway resistance (Rrs5) and reactance (Xrs5) are repeatable and safe for preschool children during methacholine challenge testing. This method reliably detects bronchial hyperresponsiveness, similar to FEV1.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Allergy and Immunology
Background:
- Bronchoprovocation testing is crucial for diagnosing asthma in children.
- Impulse oscillation system (IOS) offers a non-invasive method to assess respiratory mechanics.
- Evaluating the safety and repeatability of IOS in preschool children is essential for clinical application.
Purpose of the Study:
- To assess the repeatability and safety of measuring IOS parameters (resistance and reactance) and wheezing during methacholine challenge in preschool children.
- To compare the reliability of IOS parameters with traditional lung function measures.
Main Methods:
- Two methacholine challenges were performed on 36 children with asthma.
- Tests were discontinued for significant changes in reactance (Xrs5) or resistance (Rrs5) at 5 Hz, or respiratory distress.
- Repeatability of PC80_Xrs5, PC30_Rrs5, and wheezing (PCw) was evaluated, along with Z-score and SD-index changes.
Main Results:
- PC80_Xrs5 demonstrated the highest repeatability among IOS parameters.
- Significant changes in Rrs5 and Xrs5 were observed from pre- to post-bronchodilator.
- IOS parameter changes correlated with wheezing, and 97.1% of bronchial hyperresponsiveness was detected using Rrs5 or Xrs5 changes.
Conclusions:
- IOS parameters (Xrs5 and Rrs5) show repeatability comparable to FEV1.
- Xrs5 is more reliable than Rrs5 for assessing bronchial hyperresponsiveness.
- Clinicians can safely use IOS by monitoring changes in Rrs5, Xrs5, and Z-scores.
Objective:
To investigate the repeatability and safety of measuring impulse oscillation system (IOS) parameters and the point of wheezing during bronchoprovocation testing of preschool children.
Methods:
Two sets of methacholine challenge were conducted in 36 asthma children. The test was discontinued if there was a significant change in reactance (Xrs5) and resistance (Rrs5) at 5 Hz (Condition 1) or respiratory distress due to airway obstruction (Condition 2). The repeatability of PC80_Xrs5, PC30_Rrs5, and wheezing (PCw) was assessed. The changes in Z-scores and SD-indexes from prebaseline (before testing) to postbaseline (after bronchodilator) were determined.
Results:
For PC30_Rrs5, PC80_Xrs5, and PCw for subjects, PC80_Xrs5 showed the highest repeatability. Fifteen of 70 tests met Condition 2. The changes from pre- and postbaseline values varied significantly for Rrs5 and Xrs5. Excluding subjects with Z-scores higher than 2SD, we were able to detect 97.1% of bronchial hyperresponsiveness during methacholine challenge based on the change in Rrs5 or Xrs5. A change in IOS parameters was associated with wheezing at all frequencies.
Conclusion:
Xrs5 and Rrs5 have repeatability comparable with FEV1, and Xrs5 is more reliable than Rrs5. Clinicians can safely perform a challenge test by measuring the changes in Rrs5, Xrs5, and Z-scores from the prebaseline values.
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