Capnography in newborns under mechanical ventilation and its relationship with the measurement of CO2 in blood samples

Abstract

Introduction: Monitoring the partial pressure of CO2 (PCO2) in newborns who require ventilation would allow avoiding hypocapnia and hypercapnia. The measurement of end-tidal carbon dioxide (ETCO2) is an alternative rarely implemented in this population. Objective: To evaluate the relationship between ETCO2 and PCO2 in newborns. Methods: Cross-sectional study comparing two PCO2 measurement methods, the conventional one by analysis of blood samples and the one estimated by ETCO2. The study included hospitalized newborns that required conventional mechanical ventilation. The ETCO2 was measured with a Tecme GraphNet® neo, a neonatal ventilator with an integrated capnograph, and we obtained the ETCO2–PCO2 gradient. We conducted correlation and Bland-Altman plot analyses to estimate the agreement. Results: A total of 277 samples (ETCO2 / PCO2) from 83 newborns were analyzed. The mean values ​​of ETCO2 and PCO2 were 41.36 mmHg and 42.04 mmHg. There was a positive and significant correlation between ETCO2 and PCO2 in the overall analysis (r = 0.5402; P ETCO2) in 2 of the units, and a negative difference in the third (PCO2 ETCO2) en 2 de las unidades mientras que en la tercera la diferencia fue negativa (PCO2 < ETCO2) Discusión: La correlación entre ETCO y PCO2 es significativa, si bien los valores obtenidos no resultan equivalentes y la diferencia varía entre 0,1 mmHg a 20 mmHg. Asimismo, observamos errores sistemáticos de signo diferente (positivo o negativo) entre las instituciones.

Keywords

• Neonatos
• Ventilación mecánica
• Capnografía
• Monitorización PCO2