Noninvasive monitoring of carbon dioxide during mechanical ventilation in older children: End-tidal versus transcutaneous techniques

We prospectively compared the accuracy of end-tidal CO2 (ETco(2)) and trans cutaneous CO2 (TCco(2)) monitoring in older pediatric patients (4 yr or old er) receiving mechanical ventilation for respiratory failure. ETco(2) and T Cco(2) were simultaneously monitored and compared with arterial CO2 (Paco(2 )) values when arterial blood gas analysis was performed. Eighty-two sample sets were compared. The ETco(2) to Paco(2) difference was 6.4 +/- 6.3 mm H g, whereas the TCco(2) to Paco(2) difference was 2.6 +/- 2.0 mmHg (P < 0.00 01). The absolute difference of ETco(2) and Paco(2) was 5 or less in 47 of 82 measurements, whereas the absolute TCco(2) to Paco(2) difference was 5 o r less in 76 of 82 measurements (P < 0.00001). Regression analysis of ETco( 2) and Paco(2) values revealed a correlation coefficient of 0.5418 and an r value of 0.8745. Regression analysis of TCco(2) and Paco(2) values reveale d a correlation coefficient of 1.0160 and an r value of 0.9693. Bland-Altma n analysis revealed a bias of -5.68 with a precision of <plus/minus>6.93 wh en comparing ETco(2) with Paco(2) and a bias of 0.02 with a precision of +/ -3.27 when comparing TCco(2) and Paco(2) (P < 0.00001). TCco(2) monitoring provided an accurate estimation of Paco(2) over a wide range of CO2 values and was superior to ETco(2) monitoring in older pediatric patients with res piratory failure. TCco(2) monitoring may be considered as a useful adjunct to monitoring of ventilation in this patient population.