Monitoring of carbon dioxide in ventilated neonates: a prospective observational study

Abstract

ObjectiveTo assess the reliability, accuracy and precision of distal end-tidal capnography (detCO2) in neonates compared with transcutaneous (tcCO2) carbon dioxide measurements.DesignObservational, prospective clinical study.SettingNeonatal intensive care unit at Medical University of Vienna.ParticipantsConventionally ventilated neonates with a body weight between 1000 g and 3000 g.InterventionEnd-tidal partial pressure of CO2 was measured in distal position using the separate lumen of a double-lumen endotracheal tube connected to an external side-stream capnometer. Three consecutive detCO2 and tcCO2 values were recorded simultaneously and compared with simultaneous arterialised partial pressure of CO2 (paCO2) measurements in each patient.Main outcome measuresReliability, accuracy and precision of detCO2 and tcCO2 measurements compared with paCO2 in neonates.ResultsTwenty-five neonates were included with a median (range) weight at enrolment of 1410 (1010–2980) g, from which 81 simultaneous measurements of detCO2, tcCO2 and paCO2 were obtained. The mean (SD) of paCO2, detCO2 and tcCO2 was 45.0 (8.6) mmHg, 42.4 (8.4) mmHg and 50.4 (20.4) mmHg, respectively. The intraclass correlation between paCO2 and detCO2 and between paCO2 and tcCO2 reached 0.80 (95% CI 0.71 to 0.87, p<0.001) and 0.59 (95% CI 0.43 to 0.72, p<0.001), respectively. In the Bland-Altman analysis, bias and precision of detCO2 with respect to paCO2 amounted to −2.68 mmHg and 10.62 mmHg (95% CI 8.49 to 14.51), respectively. Bias and precision of tcCO2 with respect to paCO2 amounted to 5.39 mmHg and 17.22 mmHg (95% CI 13.21 to 23.34), respectively.ConclusionDetCO2 had better reliability, accuracy and precision with paCO2 than tcCO2 in ventilated neonates without severe lung diseas.Trial registration numberNCT03758313.