End-inspiratory molar mass step correction for analysis of infant multiple breath washout tests.
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. © 2016 Wiley Periodicals, Inc.
Telethon Kids Institute, Subiaco, Western Australia, Australia.|Centre for Child Health Research, University of Western Australia, Crawley, Western Australia, Australia.
Rachel E
RE
Foong
Telethon Kids Institute, Subiaco, Western Australia, Australia.|Centre for Child Health Research, University of Western Australia, Crawley, Western Australia, Australia.
Tim
T
Rosenow
Telethon Kids Institute, Subiaco, Western Australia, Australia.|Centre for Child Health Research, University of Western Australia, Crawley, Western Australia, Australia.
Shannon J
SJ
Simpson
Centre for Neonatal Research and Education, University of Western Australia, Perth, Australia; School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Australia.
Benjamin
B
Stöklin
Department of Pediatrics and Child Health, University of Cape Town, Rondebosch, Cape Town, South Africa.
Diane
D
Gray
Centre for Neonatal Research and Education, University of Western Australia, Perth, Australia; School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Australia.
J Jane
JJ
Pillow
Telethon Kids Institute, Subiaco, Western Australia, Australia.|Centre for Child Health Research, University of Western Australia, Crawley, Western Australia, Australia.|Curtin University, Perth, Western Australia, Australia.
Graham L
GL
Hall
Telethon Kids Institute, Subiaco, Western Australia, Australia.|Centre for Child Health Research, University of Western Australia, Crawley, Western Australia, Australia.|Cystic Fibrosis Research and Treatment Centre, University of North Carolina, Chapel Hill, North Carolina.
Kathryn A
KA
Ramsey
D000465:Algorithms; D001944:Breath Tests / Q000379:methods*; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005260:Female; D045268:Flowmeters; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods*; D012189:Retrospective Studies; D012984:Software