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Assessment of sidestream end-tidal capnography in ventilated infants on the neonatal unit

Research output: Contribution to journalArticle

Emma Williams, Theodore Dassios, Anne Greenough

Original languageEnglish
JournalPediatric Pulmonology
DOIs
Publication statusAccepted/In press - 1 Jan 2020

King's Authors

Abstract

Objectives: Continuous monitoring of carbon dioxide (CO2) 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 CO2 levels in infants with different respiratory disease severities. Working Hypotheses: End-tidal carbon dioxide (EtCO2) results by sidestream and mainstream capnography would correlate, but the divergence of EtCO2 and CO2 results would occur in more severe lung disease. Study Design: Prospective cohort study. Patient-subject Selection: 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. Methodology: Concurrent measurements of EtCO2 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 CO2 levels. The ratio of dead space to tidal volume (Vd/Vt) was calculated to assess respiratory disease severity. Results: The mean difference between the concurrent measurements of EtCO2 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 CO2 (PCO2) levels in infants with less (Vd/Vt < 0.35; r2 =.66, P <.001) rather than more severe (Vd/Vt > 0.35; r2 =.33, P =.01) lung disease. Conclusions: The sidestream capnography performed similarly to the mainstream capnography. The poorer correlation of EtCO2 to PCO2 levels in infants with severe respiratory disease should highlight to clinicians increased ventilation-perfusion mismatch.

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