Background: Lung diffusion assessed by the uptake of carbon monoxide (DLCO) and alveolar volume (VA) 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 DLCO and VA in sleeping infants using a mass spectrometer, which continuously measures gas concentrations, and demonstrated that infants with bronchopulmonary dysplasia (BPD) have lower DLCO, but no difference in VA 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, DLCO and VA were calculated at end-expiration rather than between 60 and 80% of expired volume, as previously reported. (2) In a new group of infants, DLCO and VA 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 DLCO, but similar VA compared to healthy controls (n = 34) (DLCO: 4.2 vs 4.6 mL/min/mmHg, P = 0.047; VA: 614 vs 608 mL, P = 0.772). (2) Among newly evaluated infants (n = 28), DLCO and VA obtained with a mass spectrometer and a gas chromatograph were highly correlated (R2 = 0.94 and 0.99, respectively), and were not significantly different for the two analyzers. Conclusion: Measuring DLCO and VA at end-expiration using a gas chromatograph can provide an effective assessment of gas exchange in sleeping infants.
- gas analyzer
- gas chromatograph
- mass spectrometer
- pulmonary diffusion
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Pulmonary and Respiratory Medicine