Correlation of end-tidal and arterial carbon-dioxide levels in critically Ill neonates and children.

Abstract

Aim of the Study: End tidal carbon dioxide (EtCO 2 ) monitoring is considered to reflect real-time estimation of partial pressure of carbon dioxide in arterial blood (PaCO 2 ) noninvasively. However, knowledge about its relationship with PaCO 2 in critically ill pediatric and neonatal patients is limited. The primary objective was to evaluate predictive capability of end tidal carbon dioxide monitoring and secondary objective was to determine the influence of severity of lung disease on EtCO 2 and PaCO 2 relationship. Materials and Methods: This was a prospective, nonrandomized, consecutive enrollment study carried out in neonatal and pediatric intensive care units of a tertiary care children hospital. It was conducted in 66 neonates and 35 children receiving mechanical ventilation. Severity of lung disease was estimated by ventilation index and PaO 2 /FiO 2 (P/F) ratio. Simultaneous recording of EtCO 2 and PaCO 2 levels was done and data were analyzed for correlation and agreement. Results: In neonates , 150 EtCO 2 and PaCO 2 pairs were recorded. The mean weight ± SD of patients was 2.1 ± 0.63 kg. PaCO 2 had a positive correlation with EtCO 2 ( r = 0.836, 95% CI = 0.78-0.88). P/F ratio 2 had an excellent correlation with EtCO 2 ( r = 0.914, 95% CI = 0.87 and 0.94). P/F ratio Conclusion: EtCO 2 monitoring displayed a good validity to predict PaCO 2 . Correlation was affected by low P/F ratio ( 2 values.