Work

Reversibility in plethysmographic airway and specific airway resistance in children

Year: 2025

Type: article

Abstract: Background Plethysmographic airway resistance ( R aw ) and specific airway resistance (s R aw ) are widely used to assess baseline lung function and bronchodilator reversibility in children unable to perform spirometry. However, no consensus exists on cut-offs for significant reversibility. Methods We conducted a retrospective study on a large cohort of asthmatic children tested during panting without electronic thermal compensation, to determine optimal R aw and s R aw cut-offs for detecting significant forced expiratory volume in 1 s (FEV 1 ) reversibility. A smaller cohort undergoing tidal breathing plethysmography with electronic thermal compensation was also analysed. Results From 2436 tests without thermal compensation, receiver operating characteristic curve analysis identified cut-offs of −34.4% ( R awtot ) and −36.0% (s R awtot ) from baseline to detect significant FEV 1 reversibility, with sensitivities of 70% (95% CI 65–74%) and 72% (95% CI 67–76%) and specificities of 70% (95% CI 68–72%) and 73% (95% CI 71–75%), respectively. Expressing reversibility as a percentage of predicted did not improve accuracy, but required larger cut-offs (−42.6% for R awtot , −56.1% for s R awtot ) and increased the influence of baseline value. In the 106 tests performed using electronic thermal compensation, R awtot/eff and s R awtot/eff cut-offs were lower than that without electronic thermal compensation (−25% of baseline) with sensitivities and specificities ranging from 63% to 70%. Conclusion R awtot and s R awtot reversibility effectively identify FEV 1 reversibility with cut-offs around −35% of the baseline value, showing no added benefit when using larger cut-offs expressed as a percentage of the predicted value. When electronic thermal compensation is applied, it may necessitate lower cut-offs of −25% of the baseline, compared to those determined without it.

Source: ERJ Open Research

DOI: 10.1183/23120541.00727-2025