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The influence of sighing respirations on infant lung function measured using multiple breath washout gas mixing
Damjan Vukcevic1, John B Carlin2, Louise King3
1Data Science, Murdoch Childrens Research Institute, Parkville, Victoria, Australia Department of Mathematics and Statistics, Faculty of Science, University of Melbourne, Parkville, Victoria, Australia.
Insights
Respiratory sighs in infants during multiple breath washout (MBW) testing can be included if they occur during the wash-in phase, improving data yield for lung function studies. Sighs during washout, however, affect measurements and should be excluded.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Infant lung function assessment is crucial for understanding early life origins of chronic lung diseases like asthma.
- Multiple breath washout (MBW) is an adapted technique for infant lung function measurement.
- Respiratory sighs are common in infants and often lead to data exclusion in MBW.
Purpose of the Study:
- To investigate the impact of respiratory sighs during MBW on lung function measurements in infants.
- To determine if MBW data from sighing infants can be salvaged to increase test yield.
Main Methods:
- Analysis of 767 MBW tests from 246 infants (mean age 43 days).
- Comparison of MBW measurements between tests with and without sighs.
- Assessment of sigh timing (wash-in vs. washout phase).
Main Results:
- Sighs during the wash-in phase did not significantly alter standard MBW measurements.
- Sighs during the washout phase were associated with increased lung clearance index magnitude and variability.
- Excluding sighs only during washout could increase acceptable tests by ~10%.
Conclusions:
- MBW data from infant testing cycles with sighs during the wash-in phase are likely valid and can be included.
- Excluding sighs only during the washout phase of MBW is recommended.
- Salvaging MBW data by including wash-in sighs can significantly improve test and individual success rates.
Abstract:
There is substantial interest in studying lung function in infants, to better understand the early life origins of chronic lung diseases such as asthma. Multiple breath washout (MBW) is a technique for measuring lung function that has been adapted for use in infants. Respiratory sighs occur frequently in young infants during natural sleep, and in accordance with current MBW guidelines, result in exclusion of data from a substantial proportion of testing cycles. We assessed how sighs during MBW influenced the measurements obtained using data from 767 tests conducted on 246 infants (50% male; mean age 43 days) as part of a large cohort study. Sighs occurred in 119 (15%) tests. Sighs during the main part of the wash-in phase (before the last 5 breaths) were not associated with differences in standard MBW measurements compared with tests without sighs. In contrast, sighs that occurred during the washout were associated with a small but discernible increase in magnitude and variability. For example, the mean lung clearance index increased by 0.36 (95% CI: 0.11-0.62) and variance increased by a multiplicative factor of 2 (95% CI: 1.6-2.5). The results suggest it is reasonable to include MBW data from testing cycles where a sigh occurs during the wash-in phase, but not during washout, of MBW. By recovering data that would otherwise have been excluded, we estimate a boost of about 10% to the final number of acceptable tests and 6% to the number of individuals successfully tested.
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