Validation of a New Transcutaneous tcPO₂/tcPCO₂ Sensor with an Optical Oxygen Measurement in Preterm Neonates

Abstract

<b><i>Introduction:</i></b> Traditional transcutaneous oxygen (tcPO<sub>2</sub>) 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</sub>) monitoring. This study aimed to validate optical tcPO<sub>2</sub> and conventional tcPCO<sub>2</sub> against arterial blood gas samples in preterm neonates and determine measurement drift. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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 (<i>n</i> = 38) and with suspected sepsis (<i>n</i> = 112) was acceptable for tcPO<sub>2</sub> and good for tcPCO<sub>2</sub>. However, in stable samples of neonates with sepsis (<i>n</i> = 66), tcPO<sub>2</sub> agreement (bias and 95% limits of agreement) was −32.6 (−97.0 to 31.8) mm Hg and tcPCO<sub>2</sub> 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</sub> and 0.30 (0.11–0.64) mm Hg/h for tcPCO<sub>2</sub>. <b><i>Conclusion:</i></b> The accuracy of optical tcPO<sub>2</sub> in premature neonates was acceptable without sepsis, while electrochemically measured tcPCO<sub>2</sub> remained accurate under all circumstances. Measurement drift was negligible for tcPO<sub>2</sub> and highly acceptable for tcPCO<sub>2</sub>.

Accuracy of a Novel Transcutaneous PCO₂ and PO₂ Sensor with Optical PO₂ Measurement in Neonatal Intensive Care: A Single-Centre Prospective Clinical Trial

“…weeks of GA in a neonatal intensive care unit. The results were very similar to our findings: bias for the transcutaneous-arterial comparison was for PCO 2 0.6 kPa with limits of agreement −1.04 to 2.3 kPa and for PO 2 −2.6 (−8.6; 3.5) kPa, respectively [15]. When comparing our results to other studies with neonates, it is important to consider that we also included critically ill patients.…”

“…Therefore, reliable continuous blood gas trend monitoring is crucial for patients' safety and for guiding respiratory support [12]. However, it has been demonstrated in several studies that accuracy of transcutaneous PCO 2 and PO 2 is dependent on local perfusion [12][13][14][15].…”

European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update

“…Continuous end-tidal CO 2 confirms ongoing correct tube placement as well as showing trends in gas exchange. Transcutaneous oxygen and CO 2 monitoring can give continuous information for trending, but readings can be affected by other conditions such as sepsis [172]. Arterial blood gases are the gold standard, and umbilical or peripheral arterial cannulation is necessary if regular blood gases or if continuous blood pressure monitoring is required.…”

Improving the Clinical Interpretation of Transcutaneous Carbon Dioxide and Oxygen Measurements in the Neonatal Intensive Care Unit

“…Arterial blood gas withdrawal was performed on clinical indication. For data pairing, the exact timing of arterial blood gas withdrawal was identified from the visible disruption of the arterial blood pressure curve [ 11 ]. Data pairs were excluded when recorded after an elapsed site time, within a ten-minute stabilization window following a calibration or during therapeutic hypothermia.…”

“…The difficulty in identifying the cause of inaccuracy often leads to technical blame, which is understandable considering the effects that defective sensor membranes and aging electrolyte solutions can have. However, inaccuracy of transcutaneous blood gas monitoring can, to a large part, be attributed to patient-related factors that affect the diffusion of blood gases in the skin [ 4 , 11 , 12 ]. Determination of factors that affect measurement accuracy could be of considerable value for improving the clinical usability and increasing the use of transcutaneous blood gas monitoring.…”