Objectives: To study the accuracy of three devices for measuring transcutaneous CO(2) tension in critically ill children.
Methods: A prospective study comparing the values from three transcutaneous CO(2) monitors (SenTec, TOSCA 500, and TINA TCM3) with simultaneous arterial CO(2) (PaCO(2)) and end-tidal CO(2) (EtCO(2)) values. Clinical data were collected from the patients. Influence of core-skin temperature gradient and doses of inotropic drugs was evaluated.
Results: There were 62 samples from 41 critically ill children with ages between 2 and 192 months (median, 18.5 months) and weights between 3.1 and 72 kg (median, 9 kg). The median PaCO(2) was 42.5 mmHg (range, 28-85 mmHg). Transcutaneous CO(2) (PtcCO(2)) values correlated better with PaCO(2) than with EtCO(2). The correlation coefficient between PaCO(2) and PtCO(2) was 0.833 with the TINA TCM3 monitor, 0.931 with the SenTec monitor, and 0.765 with the TOSCA 500 monitor. The mean (SD) differences between the PaCO(2) and PtcCO(2) were 4.5 (3.7) mmHg, 4.3 (3.8) mmHg, and 5.6 (5.1) mmHg, respectively, with the three monitors, and the differences between the PaCO(2) and PtcCO(2) were less than 7.5 mmHg in 77.7%, 81.2%, and 67.7% of the samples. Bland-Altman analysis showed a precision of +/-11.5 mmHg for TINA TCM3 monitor, +/-10.6 mmHg for SenTec monitor, and +/-14.8 mmHg for TOSCA monitor. No influence of core-skin temperature gradient and inotropic index on the differences between PaCO(2) and PtcCO(2) was observed.
Conclusions: The three transcutaneous CO(2) monitors have an acceptable correlation with arterial CO(2) tension and can be useful in critically ill children.