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

Abstract

Objective: To assess the reliability, accuracy and precision of distal end-tidal capnography (detCO₂) in neonates compared with transcutaneous (tcCO₂) carbon dioxide measurements.

Design: Observational, prospective clinical study.

Setting: Neonatal intensive care unit at Medical University of Vienna.

Participants: Conventionally ventilated neonates with a body weight between 1000 g and 3000 g.

Intervention: End-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 measures: Reliability, accuracy and precision of detCO₂ and tcCO₂ measurements compared with paCO₂ in neonates.

Results: Twenty-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.

Conclusion: DetCO₂ had better reliability, accuracy and precision with paCO₂ than tcCO₂ in ventilated neonates without severe lung diseas.

Trial registration number: NCT03758313.

Keywords: neonatology; technology.