Inter-device reproducibility of transcutaneous bilirubin meters.

BACKGROUND: Transcutaneous bilirubinometry is a widely used screening method for neonatal hyperbilirubinemia. Deviation of the transcutaneous bilirubin concentration (TcB) from the total serum bilirubin concentration (TSB) is often ascribed to biological variation between patients, but variations between TcB meters may also have a role. This study aims to provide a systematic evaluation of the inter-device reproducibility of TcB meters. MATERIALS AND METHODS: Thirteen commercially available TcB meters (JM-105 and JM-103) were evaluated in vitro on phantoms that optically mimic neonatal skin. The mimicked TcB was varied within the clinical range (0.5-181.3 µmol/L). RESULTS: Absolute differences between TcB meter outcomes increased with the measured TcB, from a difference of 5.0 µmol/L (TcB = 0.5 µmol/L phantom) up to 65.0 µmol/L (TcB = 181.3 µmol/L phantom). CONCLUSION: The inter-device reproducibility of the examined TcB meters is substantial and exceeds the specified accuracy of the device (±25.5 µmol/L), as well as the clinically used TcB safety margins (>50 µmol/L below phototherapy threshold). Healthcare providers should be well aware of this additional uncertainty in the TcB determination, especially when multiple TcB meters are employed in the same clinic. We strongly advise using a single TcB meter per patient to evaluate the TcB over time. IMPACT: Key message: The inter-device reproducibility of TcB meters is substantial and exceeds the clinically used TcB safety margins. What this study adds to existing literature: The inter-device reproducibility of transcutaneous bilirubin (TcB) meters has not been reported in the existing literature. This in vitro study systematically evaluates this inter-device reproducibility. IMPACT: This study aids in a better interpretation of the measured TcB value from a patient and is of particular importance during patient monitoring when using multiple TcB meters within the same clinical department. We strongly advise using a single TcB meter per patient to evaluate the TcB over time.

How skin anatomy influences transcutaneous bilirubin determinations: an in vitro evaluation.

BACKGROUND: Transcutaneous bilirubinometry is an effective screening method for neonatal hyperbilirubinemia. Current transcutaneous bilirubin (TcB) meters are designed for the "standard" situation of TcB determinations on the forehead or sternum of term newborns. We hypothesize that skin anatomy can considerably influence TcB determinations in non-standard situations-e.g., on preterm newborns or alternative body locations. METHODS: A commercially available TcB meter (JM-105) was evaluated in vitro on phantoms that accurately mimic neonatal skin. We varied the mimicked cutaneous hemoglobin content (0-2.5 g/L), bone depth (0.26-5.26 mm), and skin maturity-related light scattering (1.36-2.27 mm-1) within the clinical range and investigated their influence on the TcB determination. To obtain a reference frame for bone depth at the forehead, magnetic resonance head scans of 46 newborns were evaluated. RESULTS: The TcB meter adequately corrected for mimicked hemoglobin content. However, TcB determinations were influenced considerably by clinically realistic variations in mimicked bone depth and light scattering (deviations up to 72 µmol/L). This greatly exceeds the specified accuracy of the device (±25.5 µmol/L). CONCLUSION: As bone depth and light scattering vary with gestational maturity and body location, caretakers should be cautious when interpreting TcB measurements on premature newborns and non-standard body locations.