Evaluation of a transcutaneous carbon dioxide monitor in patients with acute respiratory failure

BACKGROUND: Non-invasive measurement of oxygenation is a routine procedure in clinical practice, but transcutaneous monitoring of PCO(2) (PtCO(2)) is used much less than expected. METHODS: The aim of our study was to analyze the value of a commercially available combined SpO(2)/PtCO(2) monitor (TOSCA-Linde Medical System, Basel, Switzerland) in adult non-invasive ventilated patients with acute respiratory failure. Eighty critically ill adult patients, requiring arterial blood sample gas analyses, underwent SpO(2) and PtCO(2) measurements (10 min after the probe was attached to an earlobe) simultaneously with arterial blood sampling. The level of agreement between PaCO(2) - PtCO(2) and SaO(2) - SpO(2) was assessed by Bland-Altman analyses. RESULTS: Both, SaO(2) from blood gas analysis and SpO(2) from the transcutaneous monitor, and PaCO(2) and PtCO(2) were equally useful. No measurements were outside of the acceptable clinical range of agreement of +/- 7.5 mmHg. CONCLUSIONS: The accuracy of estimation of the TOSCA transcutaneous electrode (compared with the gold standard blood sample gas analysis) was generally good. Moreover, TOSCA presents the advantage of the possibility of continuous non-invasive measurement. The level of agreement of the two methods of measurement allows us to state that the TOSCA sensor is useful in routine monitoring of adults admitted to an intermediate respiratory unit and undergoing non-invasive ventilation.