Validation of transcutaneous CO2 measurement in awake children undergoing sleep studies.

Despite the reliance on transcutaneous CO2 measurement (PtcCO2) for continuous alveolar ventilation monitoring in pediatric sleep studies, the agreement between PtcCO2 and arterial CO2 pressure in hemodynamically stable children has not been assessed. To address this gap, we conducted a retrospective study to compare PtcCO2 and arterialized capillary CO2 pressure (PcapCO2) values obtained upon awakening and to identify factors influencing any differences. We retrospectively analysed 335 pediatric records where each patient underwent both earlobe arterialized capillary blood gas measurement and PtcCO2 recording (Sentec ResMed or Radiometer TCM4) prior to sleep on the day of polysomnography while breathing room air. Statistical analysis included Bland-Altman analysis, student's t-test, chi-square test, and univariate and multivariate regression models to determine predictors of the PtcCO2 - PcapCO2 difference (ΔCO2). The median age of the participants was 12.2 years (IQR 8.8-15.3), with 60 % being male. Paired measurements showed a strong positive correlation (r = 0.703; p < 0.0001) between PtcCO2 and PcapCO2. Bland-Altman analysis indicated a ΔCO2 mean bias of -0.59 mmHg, with limits of agreement from -5.56 to +4.38 mmHg. No significant differences in ΔCO2 were found across devices (p = 0.41). In the multivariate regression analysis, mean pH emerged as the sole independent predictor of ΔCO2, with each 0.01-unit pH increase associated with an approximately 0.31 mmHg larger ΔCO2 (β = 0.31; 95 % CI = 0.18, 0.43). These findings suggest that PtcCO2 measurements provide a reliable estimation of PcapCO2 in this population, although temporary differences may arise due to hyperventilation during blood sampling.