Comparison of Transcutaneous and Blood CO₂ Measurement in Critically Ill Children

This prospective observational study will be conducted in a pediatric intensive care unit to assess agreement between transcutaneous carbon dioxide monitoring and arterialized or arterial blood gas analysis. Consecutive pediatric patients aged 1-18 years with respiratory insufficiency or impaired peripheral perfusion requiring vasopressor support will be included if repeated blood gas sampling is clinically indicated. Paired measurements of tPCO₂ and PaCO₂ will be analyzed using Bland-Altman methods with correction for repeated measures. Subgroup analyses will evaluate the influence of vasopressor therapy on measurement accuracy. Secondary analyses will compare tPO₂ and PaO₂ values. The study aims to define the clinical applicability and limitations of transcutaneous capnometry in critically ill pediatric patients.