Is it worthwhile using a transcutaneous bilirubinometer in the nursery?

Transcutaneous bilirubin reliability during and after phototherapy depending on skin color

Measurement of transcutaneous bilirubin (TcB) is a non-invasive, widely used technique to estimate serum bilirubin (SB). However, its reliability in multiethnic populations during and after phototherapy is still controversial even in covered skin. The aim of this study was to determine the reliability of TcB in covered (cTcB) and exposed (eTcB) skin during and after phototherapy in a multiethnic population of term and preterm neonates according to Neomar's neonatal skin color scale. Prospective, observational study comparing SB and TcB. We determined SB when clinically indicated and, at the same time, measured cTcB under a photo-opaque patch and eTcB next to it with a jaundice meter (Dräger JM-105TM). All dyads TcB-SB were compared, both globally and according to skin color. We obtained data from 200 newborns (color1: 44, color2: 111, color3: 41, color4: 4) and compared 296 dyads TcB/SB. Correlation between cTcB and SB is strong during (0.74-0.83) and after (0.79-0.88) phototherapy, both globally and by color group. The SB-cTcB bias depends on gestational age during phototherapy and on skin color following phototherapy. The correlation between eTcB and SB during phototherapy is not strong (0.54), but becomes so 12 h after discontinuing phototherapy (0.78).  Conclusions: Our study supports the reliability of cTcB to assess SB during and after phototherapy, with differences among skin tones after the treatment. The use of cTcB and Neomar's scale during and mainly after phototherapy may help reduce the number of blood samples required. What is Known: • Controversies exist on the reliability of jaundice meters during and after phototherapy in covered skin. Only a few studies have analyzed their accuracy in multiethnic populations, but none has used a validated neonatal skin color scale. What is New: • We verified correlation between serum and transcutaneous bilirubin in covered skin in a multiethnic population depending on skin color based on our own validated neonatal skin color scale during and after phototherapy.

Reliability of transcutaneous bilirubin determination based on skin color determined by a neonatal skin color scale of our own

Measurement of transcutaneous bilirubin (TcB) is widely used to estimate serum bilirubin (SB). However, its reliability depending on skin tone is still controversial. Ethnic classification does not correlate well with skin tone. We aimed to determine the reliability of transcutaneous bilirubin in a multiethnic population based on skin color according to our neonatal skin color scale. We conducted a prospective, observational study comparing SB and TcB among different skin colors. With the blood sample routinely obtained at 48-72 h for the screening of inborn errors of metabolism, we determined SB and TcB with a jaundice meter. We obtained data from 1359 newborns (color 1 337, color 2 750, color 3 249, color 4 23) and analyzed 1549 dyads SB/TcB. Correlation between TcB and serum bilirubin was very good (R² = 0.908-0.956), globally and by color group, with slight differences between darker and lighter skin colors. Bland-Altman plots showed different mean bias depending on skin color. Conclusions: Our study not only supports the reliability of TcB to assess SB regardless of skin color, but also supports the fact that TcB tends to overestimate SB in a higher degree in dark-skinned neonates. This may help reduce the number of blood samples for newborns. What is Known: • Jaundice meters are extensively used to diagnose neonatal hyperbilirubinemia, although controversies exist on their reliability depending on skin color. • Only a few studies have analyzed their accuracy in multiethnic populations, but none has used a validated neonatal skin color scale. What is New: • We verified correlation between serum and transcutaneous bilirubin in a multiethnic population depending on skin color after classifying our neonates into color groups with our own validated neonatal skin color scale.

Validation of a neonatal skin color scale

Ethnic classification does not correlate well with skin tone. As there are no neonatal skin color scales, we aimed to create and validate one of our own. After creating the scale and briefly training our staff, we conducted a prospective, observational study to assess reproducibility and correlation of each scale color with the melanin and erythema indexes and transcutaneous bilirubin. The reliability of our color scale was measured using Kappa agreement (and its 95% confidence interval) and the concordance index by comparing inter-observer classification of neonatal skin color. We also calculated inter-rater agreement with the intraclass correlation coefficient (ICC). The Kendall tau-b correlation coefficient was used to test the correlation between our color scale and the Mexameter® MX 18. We obtained data from 258 newborns. Inter-observer agreement on color assignment was 83.2%. Median melanin index was significantly different among the 4 color groups, whereas erythema index and transcutaneous bilirubin were not.Conclusions: Our proposed neonatal skin color scale correlates well with the melanin index at 24 h of life, increasing from colors 1 to 4, and the only chromophore different among our four color groups is melanin. Scale color assignment is reproducible. Therefore, it can be used to classify neonatal skin color. Further research is warranted to assess the clinical relevance of these findings. What is known: • Classifying neonates by skin color is difficult because to date there are no skin color scales available based on real skin tone regardless of ethnicity or country of origin. • Skin color differs among individuals from a given ethnic group and depends, among others, on melanin and hemoglobin. What is new: • We created a neonatal skin color scale based on real skin color. • We conducted a study to validate it, and confirmed a good inter-observer agreement in color assignment as well as a good correlation between each color in the scale and the median melanin level.

Comparison of Transcutaneous and Serum Bilirubin Measurements in Neonates 30 to 34 Weeks' Gestation Before, During, and After Phototherapy

BACKGROUND

The use of noninvasive, transcutaneous bilirubin monitoring (TcB) as a jaundice screen in full-term infants is well established; however, there is a paucity of research evaluating the use of TcB in premature infants.

PURPOSE

To compare agreement and consistency of transcutaneous and serum bilirubin measurements in a multiracial premature infant population ranging from 30 to 34(Equation is included in full-text article.)weeks' gestation before, during, and after phototherapy.

METHODS

Forty-five neonates, 30 to 34(Equation is included in full-text article.)weeks' gestation, were enrolled in this prospective, correlational study over a 12-month period. One set of paired transcutaneous and serum bilirubin measurements, per neonate, was obtained before phototherapy, during therapy, and after phototherapy. Exclusion criteria included neonates with positive direct coombs test or evidence of hemolytic disease, major congenital anomalies, hydrops fetalis, and those not expected to survive.

RESULTS

There was a strong, positive correlation between TcB and total serum monitoring (TSB) measurements obtained pretherapy (r = 0.797, P < .001). A moderate correlation was noted between TcB and TSB measurements obtained during therapy (r = 0.588, P < .001). A strong correlation was noted between TcB and TSB measurements obtained posttherapy (r = 0.869, P < .001). There were no significant differences between paired samples across time (F = 0.891, P = .41, partial η = 0.01). The TSB measurements were consistently lower than TcB pretherapy, during, and posttherapy.

IMPLICATIONS FOR PRACTICE

The TcB measurements provide a reliable estimation, generally within 2 to 3 mg/dL of TSB levels, in premature infants 30 to 34(Equation is included in full-text article.)weeks' gestation.

IMPLICATIONS FOR RESEARCH

Investigation of consumption of time and nursing personnel required to perform TcB testing, compared with TSB testing, is indicated. Cost analyses comparing TcB-driven screening protocols and interval TSB measurements, among premature infants, are indicated. As newer generations of TcB devices are approved for use, additional studies using mixed-race populations of premature infants will be necessary to continue to evaluate the reliability and validity of this screening tool within the everyday neonatal intensive care unit.

Transcutaneous bilirubinometry

Although the modern era of transcutaneous bilirubin monitoring (TcB) began only about 35 years ago, this screening tool is now widely used in newborn nurseries and outpatient clinics, offices, and emergency departments to obtain a rapid and non-invasive estimate of the degree of hyperbilirubinemia. TcB devices have become more sophisticated, and major breakthroughs include the following: (a) ability to report a bilirubin value rather than an index value, (b) enhanced correction for chromophores other than bilirubin, and (c) technologic improvements including interface with electronic medical records. Good agreement with laboratory bilirubin measurement has been demonstrated, and the ability of TcB screening to predict and decrease the incidence of subsequent hyperbilirubinemia has been well-documented. To date, it has not been shown that this screening results in improved long-term outcomes.

Neonatal hyperbilirubinaemia: time for Italian recommendations?

The introduction of effective therapies for hyperbilirubinemia might have led to a general overconfidence among neonatal healthcare providers. National guidelines have been issued in many countries though they hardly stand the challenge of evidence-based medicine. A comparative appraisal shows significant discrepancies among different documents. As new, compelling evidence sheds a different light on bilirubin toxicity, this heterogeneity that borders confusion should be solved by implementing both clinical and basic research on the complex issue of neonatal hyperbilirubinemia.