Measurement of Transcutaneous Carbon Dioxide in Low Birthweight Infants During the First Two Weeks of Life

ABSTRACT

With the advent of pulse oximetry, there has been a general decrease in the use of transcutaneous (T_c) blood gas monitoring in intensive care environments. The available data, however, suggest that arterial carbon dioxide pressure (PC₂) levels are best estimated by T_c methods. In this study, we report our experience using routine T_c PCO₂ monitoring in 32 consecutive infants less than 2 weeks of age with birthweights less than 1500 g. A total of 644 simultaneous pairs (T_c PCO₂ versus arterial PCO₂) were obtained. Pairs were categorized according to a 2 × 2 matrix design based on sensor temperature (40° or 43°C) versus site of arterial sampling (umbilical [UAC] or peripheral artery catheter [PAC]). Sampling via the UAC resulted in excellent correlation between sample pairs at both sensor temperatures with similar regressions between groups. Sampling via the PAC, however, yielded poor correlation between sample pairs and a significantly different regression from both UAC groups. Based on these findings, we advocate the use of a sensor temperature of 40°C in very low birthweight infants for tracking T_c PCO₂ values. In addition, we suggest that inaccuracies in PAC sampling may lead to erroneous PCO₂ determinations. We conclude that routine monitoring of T_c PCO₂ is accurate and serves a useful and continuing role in the neonatal intensive care environment.