Validation of a New Transcutaneous tcPO[sub.2]/tcPCO[sub.2] Sensor with an Optical Oxygen Measurement in Preterm Neonates

Introduction: Traditional transcutaneous oxygen (tcPO[sub.2]) measurements are affected by measurement drift, limiting accuracy and usability. The new potentially drift-free oxygen fluorescence quenching technique has been combined in a single sensor with conventional transcutaneous carbon dioxide (tcPCO[sub.2]) monitoring. This study aimed to validate optical tcPO[sub.2] and conventional tcPCO[sub.2] against arterial blood gas samples in preterm neonates and determine measurement drift. Methods: In this prospective observational study, during regular care, transcutaneous measurements were paired to arterial blood gases from preterm neonates aged 24-31 weeks of gestational age (GA) with an arterial catheter. Samples were included based on stability criteria and stratified for sepsis status. Agreement was assessed using the Bland-Altman analysis. Measurement drift per hour was calculated. Results: Sixty-eight premature neonates were included {median (interquartile range [IQR]) GA of 26 4/7 [25 3/7-27 5/7] weeks}, resulting in 216 stable paired samples. Agreement of stable samples in neonates without sepsis (n = 38) and with suspected sepsis (n = 112) was acceptable for tcPO[sub.2] and good for tcPCO[sub.2]. However, in stable samples of neonates with sepsis (n = 66), tcPO[sub.2] agreement (bias and 95% limits of agreement) was 32.6 (97.0 to 31.8) mm Hg and tcPCO[sub.2] agreement was 4.2 (10.5 to 18.9) mm Hg. The median (IQR) absolute drift values were 0.058 (0.0231-0.1013) mm Hg/h for tcPO[sub.2] and 0.30 (0.11-0.64) mm Hg/h for tcPCO[sub.2]. Conclusion: The accuracy of optical tcPO[sub.2] in premature neonates was acceptable without sepsis, while electrochemically measured tcPCO[sub.2] remained accurate under all circumstances. Measurement drift was negligible for tcPO[sub.2] and highly acceptable for tcPCO[sub.2]. Keywords: Transcutaneous measurements, Transcutaneous oxygen, Transcutaneous carbon dioxide, Sensor, Neonate