Monitoring of end tidal carbon dioxide and transcutaneous carbon dioxide during neonatal transport

Abstract

Objective: To assess the accuracy of measurements of end tidal carbon dioxide (CO₂) during neonatal transport compared with arterial and transcutaneous measurements. Design: Paired end tidal and transcutaneous CO₂ recordings were taken frequently during road transport of 21 ventilated neonates. The first paired CO₂ values were compared with an arterial blood gas. The differences between arterial CO₂ (Paco₂), transcutaneous CO₂ (TcPco₂), and end tidal CO₂ (Petco₂) were analysed. The Bland-Altman method was used to assess bias and repeatability. Results: Petco₂ correlated strongly with Paco₂ and TcPco₂. However, Petco₂ underestimated Paco₂ at a clinically unacceptable level (mean (SD) 1.1 (0.70) kPa) and did not trend reliably over time within individual subjects. The Petco₂ bias was independent of Paco₂ and severity of lung disease. Conclusions: Petco₂ had an unacceptable under-recording bias. TcPco₂ should currently be considered the preferred method of non-invasive CO₂ monitoring for neonatal transport.