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Influence of respiratory dead space on lung clearance index in preterm infants

Roland P Neumann1, J Jane Pillow2, Cindy Thamrin3

  • 1Department of Neonatology, University of Basel Children's Hospital, Basel, Switzerland.

Respiratory Physiology & Neurobiology
|January 9, 2016
PubMed

Insights

The lung clearance index (LCI) is affected by dead space to tidal volume ratio (VD/VT) in preterm infants. This VD/VT factor is important for interpreting LCI results in infants with and without bronchopulmonary dysplasia (BPD).

Area of Science:

  • Neonatology
  • Pediatric Pulmonology
  • Respiratory Physiology

Background:

  • The lung clearance index (LCI) is a key outcome in cystic fibrosis trials.
  • LCI utility is debated in preterm infants with bronchopulmonary dysplasia (BPD) due to high dead space to tidal volume ratio (VD/VT).

Purpose of the Study:

  • To investigate the impact of VD/VT on LCI in preterm infants with and without BPD.
  • To determine if VD/VT influences the association between LCI and BPD.

Main Methods:

  • Analysis of multiple breath washout (MBW) data from 455 infants.
  • Estimation of VD using the molar mass signal from an ultrasonic flowmeter (VD,MM).
  • Statistical analysis of LCI, VD,MM/VT, and BPD status.

Main Results:

  • LCI showed a moderate association with VD,MM/VT (r(2)=0.13, p<0.001).
  • No significant association was found between LCI and BPD.
  • Adjusting for VD,MM/VT did not reveal an association between LCI and BPD.

Conclusions:

  • VD/VT is a relevant factor for interpreting LCI in preterm infants.
  • The moderate effect size of VD/VT on LCI suggests other factors may also be involved.
  • LCI may not be directly associated with BPD when VD/VT is considered.

Keywords:
Bronchopulmonary dysplasiaInfantsLung clearance indexRespiratory dead space

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