Detection of carbon dioxide thresholds using low-flow sidestream capnography in ventilated preterm infants.

Monitoring CO₂ levels in preterm infants receiving mechanical ventilation is designed to avoid the harmful consequences of hypocapnia or hypercapnia. Capnography is of questionable accuracy for monitoring PCO₂ in preterm infants. To determine the accuracy of sidestream capnography in ventilated preterm infants by comparing end-tidal carbon dioxide (EtCO₂) values to mixed venous carbon dioxide pressure (PvCO₂) and to transcutaneous carbon dioxide pressure (TcPCO₂). Simultaneous recordings of EtCO₂, TcPCO₂ and PvCO₂ in 37 ventilated preterm infants. The PvCO₂–EtCO₂ gradient was calculated. The Bland–Altman technique and the intra-class correlation coefficient (ICC) were used to assess agreement between methods. The area under the curve (AUC) was calculated. Ninety-nine EtCO₂/PvCO₂ pairs were studied from 37 preterm infants with a mean gestational age of 27.7 ± 1.9 weeks and a mean birth weight of 1,003 ± 331 g. The mean PvCO₂–EtCO₂ gradient was 11.2 ± 8.0 mmHg, and the ICC was 0.28. The mean PvCO₂–TcPCO₂ gradient was 0 ± 7.8 mmHg, and the ICC was 0.78. AUCs for EtCO₂ and TcPCO₂ were similar in detecting high or low PvCO₂. Despite an insufficient correlation between EtCO₂ and PvCO₂, capnography was able to detect low and high CO₂ warning levels with a similar efficacy to that of TcPCO2, and may therefore be of clinical interest. [ABSTRACT FROM AUTHOR]