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

Abstract

BackgroundTranscutaneous 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.MethodsA 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.ResultsThe 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).ConclusionAs 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.

A Prospective Comparison of Serum and Transcutaneous Bilirubin in Indian Neonates

“…28 Van Erk et al hypothesized that TcB measurements can be influenced by bone depth, which varies with skin thickness and by the pressure exerted through the transcutaneous bilirubinometer on the skin. 29 In the next future, new insights will come from the very high-resolution skin ultrasound to overcome these problems. This noninvasive and rapid examination is expected to contribute to the evaluation of skin morphology, thickness, and of vessels density before and after phototherapy.…”

Inter-device reproducibility of transcutaneous bilirubin meters

“…To prevent damage to the TcB meters, direct phantom contact was avoided by covering the measurement tip with a transparent, waterproof layer of a stretched Tegaderm TM film dressing (1634W, 3M Healthcare, USA). The thickness of this film was measured by optical coherence tomography to be 44 ± 7 μm (mean ± standard deviation (SD)), 10 , 15 which is comparable to the thickness of the neonatal epidermis. 16 …”

“…This eliminates the uncertainties on sample instability that may arise from inevitable physiological tissue changes during the in vivo comparison of TcB meter performance. 11 , 12 The phantoms were fabricated according to the procedure in our previous work, 10 and the required optical properties were derived from an in vivo study on 60 neonates with varying gestational maturity. 13 …”

“…In our recent work, we demonstrated that TcB determinations are influenced significantly (up to 72 µmol/L) by realistic variations in both bone depth and skin maturity related light scattering. 10 Whereas biological variability is one explanation, another explanation for the variability in the correlation between the TcB and TSB may be the variability between TcB meters themselves. Until now, the inter-device reproducibility between TcB meters has remained unreported.…”

Neonatal wearable device for colorimetry-based real-time detection of jaundice with simultaneous sensing of vitals

“…In the simulation, we used a skin model consisting of five layers: epidermis, dermis, subcutaneous tissue, frontalis muscle, and the skull. The depth from the skin surface to the skull was set to 2.9 mm ( 51 ). The thickness of each layer was set such that the thickness ratio of each layer was equal to that of adult tissues ( 52 ).…”