Continuous monitoring of carbon dioxide (CO ) levels can be achieved by capnography. Our aims were to compare the performance of a sidestream capnograph with a low dead space and sampling rate to a mainstream device and evaluate whether its results correlated with arterial/capillary CO levels in infants with different respiratory disease severities.
End-tidal carbon dioxide (EtCO ) results by sidestream and mainstream capnography would correlate, but the divergence of EtCO and CO results would occur in more severe lung disease.
Prospective cohort study.
Fifty infants with a median (interquartile range) gestational age of 31.1 (27.1-37.4) weeks and birth weight of 1.37 (0.76-2.95) kg.
Concurrent measurements of EtCO in ventilated infants were made using a new Microstream sidestream device and a mainstream capnograph (gold standard). Results from both devices were compared with arterial or capillary CO levels. The ratio of dead space to tidal volume (Vd/Vt) was calculated to assess respiratory disease severity.
The mean difference between the concurrent measurements of EtCO was -0.54 ± 0.67 kPa (95% agreement levels - 1.86 to 0.77 kPa), the correlation between the two was r = .85 (P < .001). Sidestream capnography results correlated better with partial pressure of CO (PCO ) levels in infants with less (Vd/Vt < 0.35; r  = .66, P < .001) rather than more severe (Vd/Vt > 0.35; r  = .33, P = .01) lung disease.
The sidestream capnography performed similarly to the mainstream capnography. The poorer correlation of EtCO to PCO levels in infants with severe respiratory disease should highlight to clinicians increased ventilation-perfusion mismatch.

© 2020 Wiley Periodicals, Inc.