An evaluation of a new combined Spo2/PtcCO2 sensor in very low birth weight infants

BACKGROUND: Recently, a new sensor for combined assessment of pulse oximetry oxygen saturation (Spo2) and transcutaneous monitoring of carbon dioxide partial pressure (PtcCO2) has been introduced (TOSCA 500, Radiometer America Inc.). We designed this study to evaluate the usability and reliability of TOSCA in neonates with birth weight ≤1500 g (very low birth weight). METHODS: In a prospective study of 22 newborns, TOSCA was tested, positioning the sensor on the ear pinna with an adhesive attachment clip. Simultaneous monitoring with TOSCA, conventional pulse oximeter (HP; Datex Ohmeda 3740), and a transcutaneous device (TINA TCM3, Radiometer, Copenhagen) was performed for 60 min. PtcCO2 measurement from TOSCA (PtcCO2TOSCA) and TINA (PtcCO2) were compared with Pco2 from blood samples (PCO2EAB) at 1 and 60 min. During the monitoring period, values of PtcCO2TOSCA were compared with PtcCO2, and SatO2 values from TOSCA with those from a pulse oximeter. Corresponding data were compared using Bland-Altman analysis. RESULTS: Bias (precision) at 1 min and at 60 min between PCO2EAB and PtcCO2 values were 3.5 (12.4) mm Hg and 2.8 (10.2), respectively, whereas between PCO2EAB and PtcCO2TOSCA values were 18.3 (30.4) mm Hg and 1.8 (25) mm Hg. Bland-Altman analysis shows a better correspondence PtcCO2/PtcCO2TOSCA between 7 and 15 min. No significant differences were found between Spo2 and SpO2TOSCA. CONCLUSIONS: The TOSCA monitor is safe and easy to apply in very low birth weight newborns. The pulse oximeter measurements may be useful for titrating oxygen therapy. Pco2 measurement with TOSCA is most useful as a trend and independent confirmation of arterial Pco2 is required if an accurate value is needed.