Transcutaneous bilirubin measurement: a multicenter evaluation of a new device.

OBJECTIVES: The early discharge of neonates from hospitals makes transcutaneous measurement of total bilirubin concentration a useful tool to monitor neonatal jaundice. The objectives of this study were to determine whether 1) transcutaneous bilirubin (TcB) measurement, as performed using BiliCheck (BC), correlates with total serum bilirubin (TSB) levels, measured with standard laboratory methods and with high-pressure liquid chromatography (HPLC-B); 2) infant race, gestational age, postnatal age, or body weight interferes with the measurement of TcB levels in newborn infants; 3) the variability of the TcB measurement is comparable to the variability of TSB measurements; and 4) TcB measurements obtained from the forehead (BCF) and sternum (BCS) generate comparable results. STUDY DESIGN: Newborn infants who were <28 days and >30 weeks' gestational age and who underwent tests for TSB as part of their normal care in 6 different European hospitals were studied. A total of 210 infants were enrolled in the study, 35 at each site. Near simultaneous (within +/- 30 minutes) blood collection for TSB and BCF and BCS measurements were performed. TSB levels were determined by the serum bilirubin method in use at each site, and all HPLC-B determinations were made at the same, independent laboratory. RESULTS: The study group consisted of 140 white, 31 Asian, 14 Hispanic, 9 African, and another 16 newborns of different races. The correlation coefficient (r) between BCF and HPLC-B was 0.890 (95% confidence interval = 0.858-0.915). BCF and BCS generated similar results (r value = 0.890 for BCF and 0.881 for BCS), even if BCS slightly overestimated (mean error = -0.04 mg/dL) and BCF slightly underestimated (mean error = 0.96 mg/dL) in comparison with HPLC-B. Analysis of covariance demonstrated that BC accuracy was independent of race, birth weight, gestational age, and postnatal age of the newborn. Receiver operating characteristic curves were evaluated for BCF and TSB, each compared with HPLC-B. With the use of a cutoff point for HPLC-B of 13 mg/dL (222 micromol/L) and a cutoff of 11 mg/dL on the BCF and TSB, similar sensitivity/specificity (93%/73% for BCF, 95%/76% for TSB) were observed. The use of a cutoff point for HPLC-B of 17 mg/dL (290 micromol/L) and 14 mg/dL (240 micromol/L) for BCF and TSB also produced similar sensitivity/specificity (90%/87% for the BC and 87%/83% for TSB). CONCLUSIONS: Because the correlation coefficient for HPLC-B and BCF is very similar to that found for HPLC-B and laboratory TSB, BC could be used not only as a screening device but also as a reliable substitute of TSB determination. At higher levels of TSB, in which phototherapy and/or exchange transfusion might be considered, BC performed slightly better than the laboratory. The accuracy and precision of the TcB measurement in this study was observed to be comparable to the standard of care laboratory test.

Noninvasive measurement of total serum bilirubin in a multiracial predischarge newborn population to assess the risk of severe hyperbilirubinemia.

BACKGROUND: Jaundice in near-term and term newborns is a frequent diagnosis that may prompt hospital readmission in the first postnatal week. Hyperbilirubinemia, when excessive, can lead to potentially irreversible bilirubin-induced neurotoxicity. Predischarge risk assessment (at 24-72 hours of age) for subsequent excessive hyperbilirubinemia is feasible by a laboratory-based assay of total serum bilirubin (TSB). Hypothesis. Noninvasive, transcutaneous, point-of-care measurement of transcutaneous bilirubin (TcB) predischarge by multiwavelength spectral analysis, using a portable BiliCheck device (SpectRx Inc, Norcross, GA), is clinically equivalent to measurement of TSB in a diverse, multiracial term and near-term newborn population and predictive of subsequent hyperbilirubinemia. METHODOLOGY: We evaluated a hand-held device that uses multiwavelength spectral reflectance analysis to measure TcB (BiliCheck). The study population (490 term and near-term newborns) was racially diverse (59.1% white, 29.5% black, 3.46% Hispanic, 4.48% Asian, and 3.46% other) and was evaluated at 2 separate institutions using multiple (11) devices. The postnatal age ranged from 12 to 98 hours and the ranges of birth weights and gestational ages were 2000 to 5665 g and 35 to 42 weeks, respectively. All transcutaneous evaluations were performed contemporaneously and paired with a heelstick TSB measurement. All TSB assays were performed by high performance liquid chromatography, as well as by diazo dichlorophenyldiazonium tetrafluoroborate techniques. RESULTS: TSB values ranged from .2 to 18.2 mg/dL (mean +/- standard deviation: 7.65 +/- 3.35 mg/dL). The overall correlation of TSB (by high performance liquid chromatography technique) to TcB (by BiliCheck devices) was linear and statistically significant (r =.91; r(2) =.83; TcB =.84; TSB = +.75; standard error of regression line = 1.38; P <.001; n = 490 infants; 1788 samples). Similar regression statistics were evident in subset populations categorized by race (white: r =.91 [n = 289 infants]; black: r =.91 [n = 145 infants]) as well as by gestation (term: r =. 91 [n = 1625 samples]; near-term: r =.89 [n = 163 samples]). Intradevice precision was determined to be.59 mg/dL (2-3 measurements per infant with 1 device; n = 210 infants; 510 samples in a separate subset). Interdevice evaluation of 11 devices determined the precision to be.68 mg/dL (2-4 devices used for measurements per patient). In 23 of 419 of the study population infants who were in the 24- to 72-hour age range, the predischarge TSB values designated them to be at high risk for subsequent excessive hyperbilirubinemia (above the 95th percentile track on the hour-specific bilirubin nomogram). For these infants, the paired BiliCheck TcB values were all above the 75th percentile track (negative predictive value = 100%; positive predictive value = 32. 86%; sensitivity = 100%; specificity = 88.1%; likelihood ratio = 8. 43). CONCLUSIONS: Our data demonstrate the accuracy and reproducibility of the predischarge BiliCheck measurements in term and near-term newborn infants of diverse races and ethnicities. Infants with predischarge BiliCheck values above the 75th percentile of hour-specific TSB values on the bilirubin nomogram may be considered to be at high risk for subsequent excessive hyperbilirubinemia. Further studies are needed to assess the efficacy of this technique in preterm infants, those undergoing phototherapy, and those with TSB values of >/=15 mg/dL (>/=256 micromol/L).

Bilirubin metabolism and kernicterus.

Neonatal jaundice continues to be a common problem. Kernicterus, although rare, continues to be a very real concern in both full-term and preterm infants. The diagnosis of kernicterus requires not only bilirubin staining in a characteristic pattern in the brain but also neuronal damage. With careful pathologic evaluation, kernicterus should be distinguishable from the brain damage associated with asphyxia and hypoxia. Early hospital discharge is a risk factor for the development of kernicterus. Combining the use of traditional phototherapy from above and a fiberoptic blanket from below has improved the effectiveness of phototherapy. Clinical trials with SnMP as an inhibitor of heme oxygenase appear encouraging; no adverse effects were noted, except for mild, occasional photosensitization manifest by erythema in babies receiving phototherapy. One theoretical toxicity of inhibitors of heme oxygenase involves the recent observation that carbon monoxide (CO) is a neurotransmitter in certain regions of the brain, possibly comparable to nitric oxide (NO), and the consequences of such inhibition are unknown. More research is needed to improve our understanding about the entry of bilirubin into the brain, the predilection of bilirubin for certain brain regions, and the cytotoxicity of bilirubin. In the United States, there is currently no generally accepted method to predict hyperbilirubinemia or kernicterus. Brain stem auditory evoked responses and MRI can both be used effectively to monitor the effects of severe hyperbilirubinemia.