TY - JOUR T1 - Accuracy of Transcutaneous Carbon Dioxide Levels in Comparison to Arterial Carbon Dioxide Levels in Critically Ill Children JF - Respiratory Care DO - 10.4187/respcare.06209 SP - respcare.06209 AU - Anoopindar K Bhalla AU - Robinder G Khemani AU - Justin C Hotz AU - Rica P Morzov AU - Christopher JL Newth Y1 - 2018/09/25 UR - http://rc.rcjournal.com/content/early/2018/09/25/respcare.06209.abstract N2 - BACKGROUND: Widespread use of transcutaneous PCO2 (PtcCO2) monitoring is currently limited by concerns many practitioners have regarding accuracy. We compared the accuracy of PtcCO2 with that of PaCO2 measurements in critically ill children, and we investigated whether clinical conditions associated with low cardiac output or increased subcutaneous tissue affect this accuracy.METHODS: We performed a single-center prospective study of critically ill children placed on transcutaneous monitoring.RESULTS: There were 184 children enrolled with paired PaCO2 and PtcCO2 values. Subjects had a median age of 31.8 mo (interquartile range 3.5–123.3 mo). Most children were mechanically ventilated (n = 161, 87.5%), and many had cardiac disease (n = 76, 41.3%). The median PaCO2 was 44 mm Hg (interquartile range 39–51 mm Hg). The mean bias between PaCO2 and PtcCO2 was 0.6 mm Hg with 95% limits of agreement from −13.6 to 14.7 mm Hg. The PtcCO2 and PaCO2 were within ±5 mm Hg in 126 (68.5%) measurements. In multivariable modeling, cyanotic heart disease (odds ratio 3.5, 95% CI 1.2–10, P = .02) and monitor number 2 (odds ratio 3.8 95% CI 1.3–10.5, P = .01) remained associated with PtcCO2 ≥ 5 mm Hg higher than PaCO2. Serum lactate, fluid balance, renal failure, obesity, vasoactive-inotrope score, and acyanotic heart disease were not associated with high or low PtcCO2 values. In 130 children with a second paired PtcCO2 and PaCO2 measurement, predicting the second measured PaCO2 by subtracting the initial observed difference between the PtcCO2 and PaCO2 from the subsequent measured PtcCO2 decreased the mean bias between observed and predicted PaCO2 to 0.2 mm Hg and the 95% limits of agreement to −9.4 to 9.7 mm Hg.CONCLUSIONS: PtcCO2 provides an acceptable estimate of PaCO2 in many critically ill children, including those with clinical conditions that may be associated with low cardiac output or increased subcutaneous tissue, although it does not perform as well in children with cyanotic heart disease. PtcCO2 may be a useful adjunct monitoring method, but it cannot reliably replace PaCO2 measurement. ER -