Performance of capnometry in non-intubated infants in the pediatric intensive care unit

BACKGROUND Assessing the ventilatory status of non-intubated infants in the Pediatric Intensive Care Unit (PICU) is a constant challenge. Methods to evaluate ventilation include arterial blood gas analysis (ABG), which is invasive and intermittent, and transcutaneous carbon dioxide monitoring (PtcCO2), which, while non-invasive, is also intermittent. A method that is non-invasive and continuous would be of great benefit in this population. We hypothesized that non-invasive capnometry via sidestream monitoring of exhaled carbon dioxide (CO2) would provide an acceptable measurement of ventilatory status when compared to ABG or PtcCO2. METHODS Preliminary prospective study of infants less than one year of age admitted to the PICU in a large urban teaching hospital. Infants not intubated and not requiring non-invasive ventilation were eligible. A sidestream CO2 reading was obtained in a convenience sample of 39 patients. A simultaneous ABG was collected in those with an arterial catheter, and a PtcCO2 was obtained in those without. RESULTS Correlation of sidestream CO2 with ABG was excellent (r(2) = 0.907). Sidestream correlated less well with PtcCO2 (r(2) = 0.649). Results were not significantly altered when weight and respiratory rate were added as independent variables. Bland-Altman analysis revealed a bias of -2.7 with a precision of ±6.5 when comparing sidestream CO2 to ABG, and a bias of -1.7 with a precision of ±9.9 when comparing sidestream CO2 to PtcCO2. CONCLUSIONS Performance of sidestream monitoring of exhaled CO2 is acceptable clinical trending to assess the effectiveness of ventilation in non-intubated infants in the PICU.