Elsevier

Early Human Development

Volume 85, Issue 8, August 2009, Pages 537-540
Early Human Development

Skin bilirubin measurement during phototherapy in preterm and term newborn infants

https://doi.org/10.1016/j.earlhumdev.2009.05.010Get rights and content

Abstract

Background

The few existing studies evaluating the reliability of transcutaneous bilirubin monitoring during phototherapy gave controversial results.

Aims

To evaluate the accuracy of transcutaneous bilirubin measurement in a large population of newborn infants, during phototherapy.

Study design and methods

Total serum bilirubin and transcutaneous bilirubin on patched and unpatched skin areas were simultaneously measured in newborn infants undergoing phototherapy. Transcutaneous measurements were performed with a multiwavelength transcutaneous bilirubinometer (Respironics BiliCheck™). The Passing-Bablok regression and the Bland-Altman plot were used to estimate the relationship between serum and transcutaneous bilirubin.

Results

We studied 364 newborn infants with a mean (SD) gestational age of 34.6 (3) weeks and a mean birth weight of 2371 (805) grams. Total serum bilirubin, patched transcutaneous bilirubin and unpatched transcutaneous bilirubin were similar before phototherapy. After 52 (33) hours of phototherapy, the difference between serum bilirubin and patched transcutaneous bilirubin was 0.2 (3.1) mg/dL (not significant) while the difference between serum bilirubin and unpatched transcutaneous bilirubin was 3.2 (3.0) mg/dL (p < 0.001). Statistical analysis showed a good agreement between serum bilirubin and patched transcutaneous bilirubin, while unpatched transcutaneous bilirubin underestimates serum levels. The difference between patched and unpatched values was significantly lower in preterm than in term infants (2.8 mg/dL vs. 3.6 mg/dL; p < 0.001).

Conclusion

BiliCheck can be safely used for the evaluation of bilirubin levels in newborn infants under phototherapy. Its reliability on patched skin of the forehead is high enough to consistently reduce blood draws and to ascertain when to discontinue phototherapy. Because of the individual variance, any clinical decision has to be taken on the basis of the transcutaneous bilirubin trend more than on a single value.

Introduction

Transcutaneous bilirubinometry (TCB), first introduced in neonatal practice by Yamanouchi et al. [1], is an easy, safe and convenient method for the evaluation of the severity of jaundice since no invasive procedure is involved. Several studies have documented its reliability in this respect [1], [2], [3], [4]. In the last years, technological improvements provided new devices for noninvasive bilirubin assay, and transcutaneous bilirubinometry is now becoming widespread diffuse. Among these devices, BiliCheckTM (BC; Respironics, Murrysville, PA, USA) has been reported as very accurate and it constitutes a more useful screening method compared to the visual estimate [5], [6]. In a recent review, the AAP recognized it as a significant improvement over the older devices [7]. Phototherapy is a widely accepted treatment for neonatal indirect hyperbilirubinemia. Phototherapy has been reported to adversely affect the correlation between TCB and blood measurements [8], [9], [10], [11], [12], [13], and available data do not allow clear recommendations about the TCB use during phototherapy [14], [15]. However, it is well known that blanching effect of the light exposure occurs only on exposed areas, while shaded sites remain icteric. This prospective cohort study was designed to evaluate the accuracy of TCB measurement on exposed and not exposed skin areas during phototherapy treatment in newborn infants with the aim to reduce painful blood collection for serum bilirubin.

Section snippets

Materials and methods

The study was performed in the Neonatology Unit of our University Hospital, a tertiary referral centre with approximately 3100 deliveries a year, between June 2006 and May 2008. Although transcutaneous bilirubin measurement is generally considered less accurate in preterm infant [5] we included preterm infants in our study because they usually require phototherapy and serum bilirubin determinations more frequently than full term babies. The institutional review board of our department approved

Results

We studied 364 newborn infants with a mean (SD) gestational age of 34.6 (3) weeks and a mean birth weight of 2371 (805) grams (Table 1). Study population included 69.5% of infants less than 37 weeks of gestation, with a slight prevalence of males (59.3%), almost all Caucasian. The incidence of caesarean section was 75.5%. The mean (SD) age at start of phototherapy was 76 (44) hours of life. TSB (13.6 ±3.8 mg/dL), PTCB (13.3 ± 3.5 mg/dL) and UTCB (13.2 ± 4.1 mg/dL) were not different before

Discussion

Previous studies suggested that transcutaneous measurement of bilirubin is an useful screening device for neonatal hyperbilirubinemia [19], [20]. However, first generation bilirubinometers had several limitation and their accuracy was dependent on gestational age, skin pigments amount and environmental light intensity [21], [22], [23]. A recently developed device, the BiliCheck, with inbuilt algorithms to correct the influence of skin pigments other than bilirubin, is claimed to be more

Ethical statement

The institutional review board of our department approved this study which was considered a non-invasive one, and the parents of all children gave verbal informed consent.

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