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Published on: February 9, 2022
Tidal changes in respiratory resistance are sensitive indicators of airway obstruction in children
Dorottya Czövek1, Claire Shackleton1, Zoltán Hantos2
1Children's Lung, Environment and Asthma Research Team, University of Queensland, Brisbane, Queensland, Australia Child Health Research Centre, University of Queensland, Brisbane, Queensland, Australia.
Insights
A new lung function measure, tidal changes in resistance (ΔR), accurately detects airway obstruction in young children. This sensitive and specific method is suitable for preschooler lung function testing.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Diagnostic Methods
Background:
- Assessing airway obstruction in preschoolers requires cooperation-light lung function tests.
- Conventional forced oscillation technique (FOT) measurements have limited individual diagnostic power in young children.
Purpose of the Study:
- Identify within-breath respiratory impedance (Zrs) descriptors sensitive to airway obstruction during tidal breathing in children.
- Evaluate the diagnostic utility of novel Zrs measures in pediatric populations.
Main Methods:
- Respiratory impedance (Zrs) was measured using multifrequency FOT and a 10 Hz signal for within-breath analysis.
- Receiver operator characteristic (ROC) analysis assessed Zrs measures in healthy children and those with acute wheeze.
- Cut-off values for airway obstruction were validated in children with recurrent wheeze before and after salbutamol.
Main Results:
- Tidal changes in resistance (ΔR) showed the highest area under the ROC curve (0.95).
- A ΔR cut-off of 1.42 hPa·s/L identified airway obstruction with 92% sensitivity and 89% specificity.
- ΔR effectively distinguished wheezy children from healthy controls and decreased significantly post-salbutamol in wheezy patients.
Conclusions:
- The novel lung function measure, ΔR, demonstrates high sensitivity and specificity for detecting airway obstruction.
- ΔR is a promising tool for lung function testing in young children, requiring minimal cooperation.
Rationale:
Individual assessment of airway obstruction in preschool-age children requires sensitive and specific lung function methods with low demand of cooperation. Although the forced oscillation technique (FOT) is feasible in young children, conventional measurements of respiratory impedance (Zrs) have limited diagnostic power in individuals.
Objective:
To find descriptors of within-breath Zrs that are sensitive indicators of airway obstruction during tidal breathing in children.
Methods:
Zrs was measured with (i) a standard multifrequency FOT (4-26 Hz) to assess the mean values of resistance and reactance for whole breaths and (ii) a 10 Hz signal to track the within-breath changes. Various Zrs measures obtained in healthy children (n=75) and those with acute wheeze (n=31) were investigated with receiver operator characteristic (ROC) analysis. The cut-off values obtained for airway obstruction were then tested in children with recurrent wheeze (n=20) before and after administration of salbutamol.
Results:
The largest area under the ROC curve (0.95) was observed for the tidal changes of resistance between the zero-flow values (ΔR). The ΔR cut-off value of 1.42 hPa s/L detected airway obstruction with sensitivity of 92% and specificity of 89% in children with acute wheeze and distinguished children with recurrent wheeze (16/20 above the cut-off value) from healthy children (22/23 below the cut-off value). Furthermore, ΔR significantly decreased after salbutamol in wheezy children but remained unchanged in healthy children.
Conclusions:
New lung function measure ΔR is able to detect airway obstruction with high sensitivity and specificity and is suitable for use in lung function testing in young children.
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