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An alternative method to measure the diffusing capacity of the lung for carbon monoxide in infants
Author(s) -
Praca Eduardo L. L.,
Tiller Christina J.,
Kisling Jeffrey A.,
Tepper Robert S.
Publication year - 2018
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.23926
Subject(s) - expiration , medicine , bronchopulmonary dysplasia , carbon monoxide , gas chromatography , lung volumes , dilution , diffusing capacity , chromatography , mass spectrometry , lung , anesthesia , analytical chemistry (journal) , respiratory system , chemistry , lung function , organic chemistry , pregnancy , physics , thermodynamics , biology , catalysis , genetics , gestational age
Background Lung diffusion assessed by the uptake of carbon monoxide (DL CO ) and alveolar volume (V A ) by inert gas dilution are readily assessed in cooperative older subjects; however, obtaining these measurements in infants has been much more difficult. Our laboratory has measured DL CO and V A in sleeping infants using a mass spectrometer, which continuously measures gas concentrations, and demonstrated that infants with bronchopulmonary dysplasia (BPD) have lower DL CO , but no difference in V A compared to full‐term controls. The mass spectrometer is expensive and lacks portability; therefore, we evaluated whether measurement of end‐expiratory alveolar gas concentrations using a gas chromatograph would provide an alternative approach. Methods (1) Using our previously digitized data for infants with BPD and full‐term controls, DL CO and V A were calculated at end‐expiration rather than between 60 and 80% of expired volume, as previously reported. (2) In a new group of infants, DL CO and V A were measured using gas concentrations obtained at end‐expiration with a mass spectrometer and a gas chromatograph. Results (1) Using end‐expiratory concentrations, infants with BPD ( n  = 49) had significantly lower DL CO , but similar V A compared to healthy controls ( n  = 34) (DL CO : 4.2 vs 4.6 mL/min/mmHg, P  = 0.047; V A : 614 vs 608 mL, P  = 0.772). (2) Among newly evaluated infants ( n  = 28), DL CO and V A obtained with a mass spectrometer and a gas chromatograph were highly correlated ( R 2  = 0.94 and 0.99, respectively), and were not significantly different for the two analyzers. Conclusion Measuring DL CO and V A at end‐expiration using a gas chromatograph can provide an effective assessment of gas exchange in sleeping infants.

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