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Distribution of ventilation in young children with cystic fibrosis
Insights
The multiple breath nitrogen washout test revealed higher ventilation distribution abnormalities in children with cystic fibrosis (CF). This test shows promise for CF research but faces challenges in young children.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Cystic Fibrosis (CF) affects lung ventilation distribution.
- Assessing ventilation in young children is challenging.
Purpose of the Study:
- To evaluate the feasibility and findings of the multiple breath nitrogen washout (MBNW) test in young children with and without CF.
- To determine if MBNW can detect ventilation abnormalities in pediatric CF patients.
Main Methods:
- The multiple breath nitrogen washout (MBNW) test was administered to 24 children with CF and 58 controls (ages 3.9-6.8 years).
- Moment analysis of the MBNW curve was used to derive first and second moment ratios.
- Test completion success rates and variability were assessed.
Main Results:
- Only 49% of children completed the MBNW test satisfactorily; success correlated with age.
- Children with CF exhibited significantly higher first and second moment ratios than controls.
- Higher moment ratios were observed in CF subjects with more severe symptoms.
- The first moment ratio demonstrated lower variability and better reproducibility.
Conclusions:
- Moment analysis of the MBNW test can identify ventilation distribution abnormalities in young children with CF.
- The test is feasible in approximately 50% of children aged 4-6 years.
- Test complexity and high failure rates in younger children may limit its use to specialized research settings.
Abstract:
We attempted to measure the distribution of ventilation in 24 children who had cystic fibrosis (CF) and 58 control subjects (ages 3.9-6.8 years) using the multiple breath nitrogen washout (MBNW) test. Moment analysis was performed on the MBNW curve, and the first and second moment ratios were derived. Only 40 (49%) of the children were able to complete the test satisfactorily and success was related to age (P less than 0.01). Children who had CF had higher moment ratios, both first and second, than did controls (P less than 0.001); also, CF subjects who had more severe symptoms had higher moment ratios than did those who had minimal symptoms (P less than 0.005). The first moment ratio had a lower coefficient of variation than did the second (14% vs 31%) and, in 8 children who performed the test in duplicate, it also had a lower index of intrasubject variability (6.4% vs 15.1%). Both ratios were lower than those described in older children and in adults, which is consistent with the more rapid washout seen in this age group. Although moment analysis of the MBNW curve can be performed in approximately 50% of children 4 to 6-years-old, the complexity of the test, the apparatus, and the analysis and the high failure rate in children under the age of 6 are likely to restrict its use to research studies in specialized pediatric respiratory laboratories.