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Maximal flow at functional residual capacity in asthmatic preschool children
Daphna Vilozni1, Galit Livnat, Fahed Hakim
1a Pediatric Pulmonary Unit, the Bruce Rappaport Faculty of Medicine , Meyer Children's Hospital , Rambam Health Care Campus, Technion-Israel Institute of Technology , Haifa , Israel and.
Insights
Maximal flow at functional residual capacity (V'maxFRC) effectively detects airway obstruction in preschool children with asthma. This method is valuable for young children who struggle with complete exhalation during spirometry tests.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Asthma Research
Background:
- Preschool children often struggle to exhale fully during spirometry, limiting the assessment of airway obstruction.
- Maximal flow at functional residual capacity (V'maxFRC) is a potential parameter for evaluating airflow at low lung volumes, independent of complete exhalation.
- This study investigates V'maxFRC's utility in detecting airway obstruction and dilation in asthmatic preschool children compared to standard spirometry indices.
Purpose of the Study:
- To determine if V'maxFRC can effectively detect airway obstruction or dilation in preschool children with asthma.
- To compare the diagnostic performance of V'maxFRC against established spirometry measures like FEV1 and FEF25-75.
- To assess the response to bronchodilators using V'maxFRC in this age group.
Main Methods:
- The study involved preschool children undergoing either a bronchial provocation test (BPT) or receiving bronchodilators (Post-BD).
- V'maxFRC was measured at the inspiratory capacity point during flow/volume maneuvers.
- Percentage changes in V'maxFRC from baseline were compared with changes in FEV1, FEF25-75, and data from healthy controls.
Main Results:
- During BPT, FEV1, FEF25-75, and V'maxFRC decreased significantly, while FRC increased.
- Following bronchodilator administration, spirometry values for FEV1, FEF25-75, and V'maxFRC showed significant improvements (p < 0.0001).
- A positive bronchodilator response was identified in 48% of children by FEV1, 71% by V'maxFRC, and 71% by FEF25-75.
Conclusions:
- V'maxFRC demonstrates similar efficacy to FEF25-75 and FEV1 in detecting airway obstruction and dilation in young asthmatic children.
- V'maxFRC is a potentially valuable index for preschool children who exhibit premature cessation of exhalation.
- Further research with digitally measured V'maxFRC is recommended across a wider age range and in various health conditions.
Background:
Many preschool children will perform correct peak-flow but will not exhale to residual volume, thus limiting the determination of airways obstruction. The maximal flow measured at function residual capacity (V'maxFRC) is independent of lung empting and could potentially serve as a parameter for describing flow at low lung volumes. The study determines the detection of airway obstruction/dilation in asthmatic preschool children by V'maxFRC, compared to FEV1 and FEF25-75.
Methods:
Children performed bronchial provocation test (BPT; n = 26) or received bronchodilators (Post-BD; n = 31). V'maxFRC was extracted at inspiratory capacity point of flow/volume maneuvers. The %change of V'maxFRC from baseline was compared with changes in various spirometry indices and to values obtained from our previously studied healthy control children.
Results:
FEV1, FEF25-75, and V'maxFRC decreased by 30.9 ± 12.2%, 46.2 ± 10.9%, and 36.6 ± 8.0%, respectively, while FRC increased by 37.0 ± 24.9% at end of the BPT. Post-BD spirometry values increased by 17.1 ± 16.1%, 47.0 ± 42.2, and 45 ± 24%, respectively (p < 0.0001). A positive response to bronchodilators was observed in 15/31 (48%) children by FEV1, in 22/31 (71%) children by V'maxFRC, and in 21/31 children by FEF25-75.
Conclusion:
V'maxFRC detects airway obstruction/dilation in young asthmatic children similar to FEF25-75 and FEV1. V'maxFRC may be a valuable index in preschool children who cease exhalation prematurely. Digitally measured V'maxFRC should confirm the actual values in a wider age range in healthy and disease states.
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