The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

Correlation of End Tidal Carbon Dioxide and Arterial Carbon Dixode in Mechanically Premature Infants



John Emberger BS RRT, Robert Locke DO, Michael Western AS RRT, Departments of Respiratory Care and Neonatology, Christiana Care Health System, Newark, DE

Background: Non-invasive end-tidal CO2 (ETCO2) monitoring to trend PaCO2 in mechanically ventilated premature infants offers many potential advantages. Published data is lacking concerning the accuracy of ETCO2 measurements in premature infants receiving mechanical ventilation. This study evaluated the correlation of ETCO2 to PaCO2 in a cohort of premature mechanically ventilated premature infants.

Methods: 24 arterial blood gas results were correlated to PaCO2 measurements in 10 premature infants receiving mechanical ventilation. Infants weight ranged from 1400 to 2500 grams. Cuffless endotracheal tubes size ranged from 2.5 to 3.5 mm. ETCO2 adapter (CO2SMO Plus, Novametrix Medical Systems, Wallingford CT) adds < 0.5 ml dead-space. Univariate linear regression was used to establish correlation coefficients.

Results: PaCO2 ranged from 17.7 to 55 torr. ETCO2 ranged from 16 to 52 torr. The individual mean ±+ SD gradient between PaCO2 and ETCO2 was 1.29 ± 1.06 torr. Correlation between PaCO2 and ETCO2 was statistically and clinically significant (r2=0.9918, p< 0.01). See figure below.

Conclusions: In this population of premature infants, ETCO2 correlated very closely to PaCO2. ETCO2 monitoring may be an accurate non-invasive method of trending PaCO2 in this population. ETCO2 monitoring may be a safe, non-invasive method for reducing the number of blood gas measurements as well as providing real-time PaCO2 information to the clinician in mechanically ventilated premature infants.

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