Contemporary N2 and SF6 multiple breath washout in infants and toddlers with cystic fibrosis

Rikke M Sandvik; Per M Gustafsson; Anders Lindblad; Frederik Buchvald; Hanne V Olesen; Jørgen H Olsen; Marianne Skov; Marika N Schmidt; Mette R Thellefsen; Paul D Robinson; Sune Rubak; Tacjana Pressler; Kim G Nielsen

doi:10.1002/ppul.25830

Contemporary N₂ and SF₆ multiple breath washout in infants and toddlers with cystic fibrosis

Pediatr Pulmonol. 2022 Apr;57(4):945-955. doi: 10.1002/ppul.25830. Epub 2022 Jan 25.

Authors

Rikke M Sandvik¹, Per M Gustafsson^{2

3}, Anders Lindblad^{3

4}, Frederik Buchvald¹, Hanne V Olesen⁵, Jørgen H Olsen⁵, Marianne Skov¹, Marika N Schmidt¹, Mette R Thellefsen¹, Paul D Robinson⁶, Sune Rubak⁵, Tacjana Pressler¹, Kim G Nielsen^{1

7}

Affiliations

¹ Danish Paediatric Pulmonary Service, CF Centre Copenhagen, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
² Department of Paediatrics, Central Hospital, Skövde, Sweden.
³ Institute of Clinical Science, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
⁴ Department of Pediatrics, CF Center, Queen Silvia Children's Hospital, Gothenburg, Sweden.
⁵ Department of Paediatrics and Adolescent Medicine, Danish Center of Pediatric Pulmonology and Allergology, Cystic Fibrosis Centre Aarhus, Aarhus University Hospital, Aarhus, Denmark.
⁶ Department of Respiratory Medicine, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
⁷ Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.

PMID: 35029068
DOI: 10.1002/ppul.25830

Abstract

Introduction: Multiple breath washout (MBW) is used for early detection of cystic fibrosis (CF) lung disease, with SF₆ MBW commonly viewed as the reference method. The use of N₂ MBW in infants and toddlers has been questioned for technical and physiological reasons, but a new correction of the N₂ signal has minimized the technical part. The present study aimed to assess the remaining differences and the contributing mechanisms for the differences between SF₆ and N₂ MBW,corrected-such as tidal volume reduction during N₂ washout with pure O₂ .

Method: This was a longitudinal multicenter cohort study. SF₆ MBW and N₂ MBW were performed prospectively at three CF centers in the same visits on 154 test occasions across 62 children with CF (mean age: 22.7 months). Offline analysis using identical algorithms to the commercially available program provided outcomes of N_2,original and N_2,corrected for comparison with SF₆ MBW.

Results: Mean functional residual capacity, FRC_N2,corrected was 14.3% lower than FRC_{N2, original} , and 1.0% different from FRC_SF6 . Lung clearance index, LCI_N2,corrected was 25.2% lower than LCI_N2,original , and 7.3% higher than LCI_SF6 . Mean (SD) tidal volume decreased significantly during N₂ MBW_corrected , compared to SF₆ MBW (-13.1 ml [-30.7; 4.6], p < 0.0001, equal to -12.0% [-25.7; 1.73]), but this tidal volume reduction did not correlate to the differences between LCI_N2,corrected and LCI_SF6 . The absolute differences in LCI increased significantly with higher LCI_SF6 (0.63/LCI_SF6 ) and (0.23/LCI_SF6 ), respectively, for N_2,original and N_2,corrected , but the relative differences were stable across disease severity for N_2,corrected , but not for N_2,original .

Conclusion: Only minor residual differences between FRC_N2,corrected and FRC_SF6 remained to show that the two methods measure gas volumes very similar in this age range. Small differences in LCI were found. Tidal volume reduction during N₂ MBW did not affect differences. The corrected N₂ MBW can now be used with confidence in young children with CF, although not interchangeably with SF₆ .

Keywords: children; functional residual capacity; lung clearance index; lung function; ventilation distribution.

Publication types

Multicenter Study
Research Support, Non-U.S. Gov't

MeSH terms

Breath Tests / methods
Child, Preschool
Cohort Studies
Cystic Fibrosis* / diagnosis
Humans
Infant
Lung
Nitrogen / analysis

Substances

Nitrogen