Accuracy and Interpretation of Transcutaneous Carbon Dioxide Monitoring in Critically Ill Children

Abstract

OBJECTIVES: Transcutaneous carbon dioxide (Tcco 2) monitoring can noninvasively assess ventilation by estimating carbon dioxide (CO 2) levels in the blood. We aimed to evaluate the accuracy of Tcco 2 monitoring in critically ill children by comparing it to the partial pressure of arterial carbon dioxide (Paco 2). In addition, we sought to determine the variation between Tcco 2 and Paco 2 acceptable to clinicians to modify patient care and to determine which patient-level factors may affect the accuracy of Tcco 2 measurements. DESIGN: Retrospective observational cohort study. SETTING: Single, quaternary care PICU from July 1, 2012, to August 1, 2020. PATIENTS: Included participants were admitted to the PICU and received noninvasive ventilation support (i.e., continuous or bilevel positive airway pressure), conventional mechanical ventilation, or high-frequency oscillatory or percussive ventilation with Tcco 2 measurements obtained within 15 minutes of Paco 2 measurement. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Three thousand four hundred seven paired arterial blood gas and Tcco 2 measurements were obtained from 264 patients. Bland-Altman analysis revealed a bias of –4.4 mm Hg (95% CI, –27 to 18.3 mm Hg) for Tcco 2 levels against Paco 2 levels on the first measurement pair for each patient, which fell within the acceptable range of ±5 mm Hg stated by surveyed clinicians, albeit with wide limits of agreement. The sensitivity and specificity of Tcco 2 to diagnose hypercarbia were 93% and 71%, respectively. Vasoactive-Infusion Score (VIS), age, and self-identified Black/African American race confounded the relationship between Tcco 2 with Paco 2 but percent fluid overload, weight-for-age, probe location, and severity of illness were not significantly associated with Tcco 2 accuracy. CONCLUSIONS: Tcco 2 monitoring may be a useful adjunct to monitor ventilation in children with respiratory failure, but providers must be aware of the limitations to its accuracy.