Jun 6, 2016 - End-Inspiratory Molar Mass Step Correction for. Analysis of Infant Multiple Breath Washout Tests. Summary. A refined software algorithm was ...
Pediatric Pulmonology 52:10–13 (2017)
Letter to the Editor
End-Inspiratory Molar Mass Step Correction for Analysis of Infant Multiple Breath Washout Tests Summary. A refined software algorithm was recently proposed for the analysis of infant multiple breath washout (MBW) measurements. The proposed algorithm uses the change in end-inspiratory molar mass between the wash-in and wash-out curves (EIMM-step) to define the required step response correction of the MM signal and is assumed to provide an accurate evaluation of complete washout of the tracer gas, in comparison to the current software algorithm which applies the change in end-expiratory molar mass (EEMM)-step. We aimed to evaluate the use of the EIMM-step method in a broad range of infants. We performed retrospective analyses comparing the EIMM- and EEMM-step change methods in MBW data collected from infants with cystic fibrosis (CF), infants born preterm, and healthy infants using an ultrasonic flowmeter. We found that the EIMM-step correction significantly increased LCI and functional residual capacity (FRC) in infants with CF, preterm infants, and healthy infants compared with the EEMM-step method. In addition, more than half the measurements that were technically acceptable and repeatable using the EEMM-step correction in healthy infants were excluded after using the EIMM-step correction. We found a large difference between the EIMM- and EEMM-steps in healthy infants indicating incomplete washout, suggesting the need for a longer washout time with using the EIMM-step analysis method. The data indicates that the EIMM-step analysis method may have the potential to generate false abnormal LCI values in individuals without lung disease. Revised normative data may be required if this method is universally adopted. Pediatr Pulmonol. 2017;52:10–13. ß 2016 Wiley Periodicals, Inc.
To the Editor: Anagnostopoulou et al. proposed a new approach to analyze infant multiple breath washout (MBW) data using the change in end-inspiratory molar mass between the wash-in and wash-out curves (EIMM-step) to define the required step response correction of the MM signal.1 The proposed approach contrasts with the current software algorithm,2 which applies the change in end-expiratory molar mass (EEMM-step). The advantage of the new approach is that the EIMM-step provides a more accurate evaluation of complete washout of the tracer gas as it measures the tracer gas concentration only, unlike EEMMstep, which includes the concentration of the tracer gas, oxygen, and carbon dioxide at the end of expiration. The authors compared the EIMM- and EEMM-step approaches and reported significant increases in the lung clearance index (LCI) and functional residual capacity (FRC) in infants with cystic fibrosis (CF) using the EIMMstep approach compared with the EEMM-step method, while LCI and FRC remained unchanged in the healthy ß 2016 Wiley Periodicals, Inc.
infants. Additionally, some MBW measurements in infants with CF (
