Correlation of Transcutaneous pCO₂ and Capillary pCO₂ in Newborn Patients Depending on Gestational Age: A Secondary...

Transcutaneous monitoring of CO₂ partial pressure (tcpCO₂) provides continuous information about the CO₂ partial pressure in the blood (pCO₂). However, the deviation of tcpCO₂ from pCO₂ is variable. Our aim was to assess whether this deviation depends on gestational age in the first postnatal week.

Single-center secondary data cohort study at a Tertiary Care NICU. 116 neonates undergoing tcpCO₂ monitoring were included. A linear mixed-effects model was used to analyze the difference between tcpCO₂ and capillary pCO₂ (ΔpCO₂) in the first postnatal week.

926 simultaneous measurements were included. The evaluation of the linear mixed-effects model revealed a significant effect of gestational age on ΔpCO₂. Median [interquartile 1; interquartile 3] ΔpCO₂ was significantly higher for extremely preterm infants (< 28 weeks) with 7.6 [2.4; 13.9] mmHg compared to 3.1 [-1.0; 6.4] mmHg for very preterm (28-31 + 6 weeks), 0.6 [-4.6; 4.7] mmHg for late preterm (32-36 + 6 weeks) and -0.5 [-4.8; 4.7] mmHg for term infants (≥ 37 weeks). There were no significant differences in ΔpCO₂ between patients born at 23 to 25 compared to 26 and 27 completed weeks of gestation. In multivariable analysis, gestational age, early-onset bacterial infection and capillary pCO₂ were independently associated with ΔpCO₂, whereas birth weight was not.

The gestational age has a significant directed effect on the accuracy of transcutaneous CO₂ monitoring in preterm neonates and can-together with other known influence factors-be used to improve the non-invasive pCO₂ estimation.