Transcutaneous capnometry (tPCO₂) is a non-invasive method for continuous monitoring of ventilation status. In pediatric intensive care patients, it may reduce the need for repeated arterial or arterialized blood sampling. However, the accuracy of tPCO₂ may be influenced by factors such as peripheral perfusion, skin temperature, and vasopressor therapy. This prospective observational study compares transcutaneous carbon dioxide measurements with arterialized or arterial blood gas PaCO₂ values in children with respiratory insufficiency, including a subgroup receiving vasopressor support.