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.

Prevention of bilirubin encephalopathy.

Prevention of bilirubin encephalopathy is based on the detection of infants at risk of developing a significant hyperbilirubinemia. This task can be accomplished by performing a simple umbilical cord blood test, such as blood group, Rh, Coombs' test and glucose-6-phosphate dehydrogenase, in order to detect hemolytic diseases. In preterm infants, the prevention of hyperbilirubinemia with phototherapy is a relatively simple task, since these infants are cared for in hospital. Early hospital discharge of full-term neonates represents a major concern. The management of neonatal jaundice requires that therapy begins when total serum bilirubin levels are significantly below the levels at which kernicterus is considered an immediate threat. Unfortunately, determination of serum bilirubin is a painful procedure, and is not very accurate since there is a high variability in laboratory measurements. The accuracy and precision of a new transcutaneous bilirubin measurement, comparable to the standard of care laboratory test, makes the daily evaluation of transcutaneous bilirubin measurement a useful tool in distinguishing physiological from nonphysiological hyperbilirubinemia, and determining the bilirubin increment in the first days of life. Full-term neonates who lose a significant amount of weight are especially at risk of significant hyperbilirubinemia and must be treated with ad libitum feeding and intensive phototherapy.

Is breastfeeding really favoring early neonatal jaundice?

OBJECTIVE: The purpose of this study was to evaluate the development of significant hyperbilirubinemia in a large unselected newborn population in a metropolitan area with particular attention to the relationship between type of feeding and incidence of neonatal jaundice in the first week of life. STUDY DESIGN: A population of 2174 infants with gestational age >/=37 weeks was prospectively investigated during the first days of life. Total serum bilirubin determinations were performed on infants with jaundice. The following variables were studied: type of feeding, method of delivery, weight loss after birth in relationship to the type of feeding, and maternal and neonatal risk factors for jaundice. Statistical analyses were performed using the z test for parametric variables and the t test for nonparametric variables. In addition, the multiple logistic regression allows for the estimation of the role of the individual characteristics in the development of hyperbilirubinemia. Data concerning serum bilirubin peak distribution in jaundiced newborns were analyzed using a single and a double Gaussian best fit at least squares. The t test was performed to compare 2 values (high and low) of the serum bilirubin peak in breastfed and supplementary-fed infants with those in bottle-fed infants. RESULTS: The maximal serum bilirubin concentration exceeded 12.9 mg/dL (221 micromol/L) in 112 infants (5.1%). The study demonstrated a statistically significant positive correlation between patients with a total serum bilirubin concentration >12.9 mg/dL (221 micromol/L) and supplementary feeding; oppositely, breastfed neonates did not present a higher frequency of significant hyperbilirubinemia in the first days of life. However, best Gaussian fitting of our data suggests that a small subpopulation of breastfed infants have a higher serum bilirubin peak than do bottle-fed infants. Newborns with significant hyperbilirubinemia underwent a greater weight loss after birth compared with the overall studied population, and infants given mixed feeding lost more weight than breastfed and formula-fed newborns, indicating that formula has been administered in neonates who had a weight loss beyond a predetermined percentage of birth weight. Significant hyperbilirubinemia was also strongly associated with delivery by vacuum extractor, some perinatal complications (cephalohematoma, positive Coombs' test, and blood group systems of A, AB, B, and O [ABO] incompatibility) and Asian origin. Multiple logistic regression analysis shows that supplementary feeding, weight loss percentage, ABO incompatibility, and vacuum extraction significantly increase the risk of jaundice, while only cesarean section decreases the risk. CONCLUSION: The present study confirms the important role of fasting in the pathogenesis of neonatal hyperbilirubinemia, although breastfeeding per se does not seem related to the increased frequency of neonatal jaundice but to the higher bilirubin level in a very small subpopulation of infants with jaundice. In fact, in the breastfed infants, there is a small subpopulation with higher serum bilirubin levels. These infants, when starved and/or dehydrated, could probably be at high risk of bilirubin encephalopathy.

Changes in mesenteric blood flow response to feeding: conventional versus fiber-optic phototherapy.

OBJECTIVE: To evaluate whether fiberoptic phototherapy influences the postprandial increase in mesenteric blood flow velocity similarly to conventional phototherapy in preterm infants. PATIENTS AND METHODS: With the use of Doppler color ultrasonography, blood flow velocity in the superior mesenteric artery was measured both preprandially and postprandially in 19 preterm infants during and after conventional phototherapy, and in 20 preterm infants during and after fiber-optic phototherapy. The mean arterial blood pressure/mean flow velocity ratio was calculated as an estimate of relative vascular resistance of the superior mesenteric artery. RESULTS: The study shows that conventional phototherapy blunts the postprandial mesenteric blood flow response to feeding in preterm infants. Furthermore, it shows that the postprandial increase in intestinal blood flow is not attenuated when fiber-optic phototherapy is administered, and that such postprandial increase of blood flow is significantly greater than in infants receiving conventional phototherapy. During and after fiber-optic phototherapy, a significant reduction in postprandial relative vascular resistance was found; such reduction was significantly greater than during conventional phototherapy. CONCLUSIONS: Fiber-optic phototherapy is preferable to conventional phototherapy for the treatment of hyperbilirubinemia in preterm infants because it does not affect the physiologic postprandial redistribution of blood flow from the periphery to the gastrointestinal system as does conventional phototherapy.

Current drug treatment options in neonatal hyperbilirubinaemia and the prevention of kernicterus.

Neonatal jaundice is a frequent problem in neonatology, but the advent of phototherapy which has simplified its treatment, it no longer represents a major concern. Early hospital discharge of neonates has now resulted in a re-emergence of kernicterus. Neonatal jaundice is principally the result of a transient deficiency of bilirubin conjugation, of a partial deficiency of hepatic bilirubin uptake and intracellular transport and of an increased enterohepatic circulation of the pigment. The fact that bilirubin production in the neonate is 2 or more times greater than in the adult per kilogram of bodyweight represents the mainstay of this condition. Prevention of kernicterus in full term infants is based on the detection of neonates at risk for developing hyperbilirubinaemia, and can be accomplished with simple tests performed on umbilical cord blood such as blood type, Rh, Coombs' test and glucose-6-phosphate dehydrogenase, in order to detect haemolytic diseases. The daily evaluation of transcutaneous bilirubin measurement gives additional information on the rise of serum bilirubin level, and can help to distinguish physiological from nonphysiological hyperbilirubinaemia. A significant hyperbilirubinaemia is more frequent in infants born before term, and in neonates who do not feed well and lose more than 10% of bodyweight. In preterm infants the typical clinical feature of kernicterus is seen very rarely, and kernicterus is now a very infrequent postmortem observation. Since it is very difficult to distinguish the effects of bilirubin from other potentially toxic factors, it is difficult to give guidelines for the treatment of jaundice in very low birthweight infants other than to keep the serum bilirubin levels to a lower level than in full term infant (e.g. 10 mg/dl lower than in full term babies). The intramuscular administration of a single dose of Sn-mesoporphyrin (6 mumol/kg bodyweight) in healthy term or near-term infants seems to be a promising treatment modality for controlling hyperbilirubinaemia.

Unconjugated and conjugated bilirubin pigments during perinatal development. V. Effect of phototherapy on serum conjugated bilirubin in hyperbilirubinemic neonates.

OBJECTIVE: To determine the effect of phototherapy on serum conjugated bilirubin fractions, an index of bilirubin conjugation, in hyperbilirubinemic neonates. METHOD: Serum was sampled from 21 jaundiced (serum diazo total bilirubin > or = 274 micromol/l), term, otherwise healthy neonates prior to starting phototherapy, and 24 h after the commencement of treatment. Alkaline methanolysis followed by reverse-phase, high-performance liquid chromatography, specific for determination of unconjugated bilirubin and the monoconjugated and diconjugated fractions of total conjugated bilirubin in serum, was used for the analysis. Prephototherapy values were compared to those at 24 h. RESULTS: Serum total bilirubin and total conjugated bilirubin values decreased during the study period, from 220 (211-239) to 177 (157-213) micromol/l (median (25-75% range)) p = 0.001, for the former, and from 1.4 (0.87-1.57) to 0.93 (0.69-1.84) micromol/l, p = 0.005, for the latter. These parameters decreased by a similar percentage (-16.6+/-14.8% and - 14.0+/-23.4%, respectively; p > 0.05). Both monoconjugated and diconjugated bilirubin, calculated as a percentage of total conjugated bilirubin, remained constant over the study period (88.2 (72.2-96.4)% before phototherapy and 92.5 (87.3-96.8)% after 24 h, p > 0.05, for monoconjugated bilirubin, and 11.8 (3.6-27.8)% and 7.5 (3.2-12.7)%, respectively, p > 0.05, for diconjugated bilirubin). CONCLUSIONS: Serum total conjugated bilirubin values decreased in parallel to serum total bilirubin levels during phototherapy, maintaining a constant relationship between these two parameters. The ratios of monoconjugated and diconjugated bilirubin to total conjugated bilirubin remained constant. These findings imply that phototherapy does not alter bilirubin conjugation in hyperbilirubinemic neonates.

The bronze baby syndrome: evidence of increased tissue concentration of copper porphyrins.

A case regarding a newborn infant with severe Rh haemolytic disease, who presented with the bronze baby syndrome and eventually died, is reported. The postmortem examination showed marked extramedullary haematopoiesis in the liver and spleen, heavy hepatic haemosiderosis and mild intralobular cholestasis. The porphyrin content, which was assayed in different tissues, was very high in the liver, suggesting that the increased erythropoiesis seen in Rh haemolytic disease leads to an increased synthesis of porphyrins as by-products of haem synthesis. Phototherapy causes photodestruction, sensitized by bilirubin, of porphyrins (mainly copper porphyrins), yielding brown photoproducts.

Unconjugated and conjugated bilirubin pigments during perinatal development. IV. The influence of breast-feeding on neonatal hyperbilirubinemia.

One thousand four hundred and fifty-four consecutive full-term neonates, delivered over a period extending from February 1, 1991 to January 31, 1992 were prospectively studied during the first days of life to determine if breast-feeding and hyperbilirubinemia were related. Six hundred and five infants were exclusively breast-fed on demand, 623 received both breast- and formula-feeding, and 226 were exclusively formula-fed. Of the 1,454 newborns studied, 70 (4.8%) presented with a bilirubin serum concentration > 12.9 mg/dl (4.62% in the breast-fed group, 5.45% in the group fed with mother's milk with supplements, and 3.54% in the artificial formula group; the differences were not significant). Percent mean weight losses on the 3rd and 5th days were not significantly different. Babies breast-fed on demand seem to have a low incidence of hyperbilirubinemia similar to that found in formula-fed neonates.

Management of neonatal hyperbilirubinaemia and prevention of kernicterus.

Hyperbilirubinaemia remains one of the most common and more important pathological conditions in the newborn. The possibility that the so-called physiological or developmental hyperbilirubinaemia, with relatively low levels of serum bilirubin, could be responsible for bilirubin encephalopathy in the small premature infant is of great concern to the neonatologist; premature newborns are prone to developing hyperbilirubinaemia. Current methodologies for suppressing severe neonatal jaundice include: (a) attempts to stimulate liver conjugating enzymes using drugs such as phenobarbital; (b) attempts to degrade bilirubin with phototherapy; and (c) exchange transfusion. It is too soon to consider tin-protoporphyrin as a drug for the prevention and treatment of neonatal hyperbilirubinaemia. However, if it can be shown that tin-protoporphyrin can serve as a safe and less costly alternate treatment, a considerable improvement in the management of neonatal jaundice would be achieved.

In vivo clearance of natural and modified surfactant.

The loss of radiolabelled phosphatidylcholine associated with surfactants and lipid extracts of surfactants from different species sources was measured following tracheal injection into the lungs of adult and 3 day old rabbits. Clearance was more rapid from the lungs of adult than 3 day old rabbits. The percent labelled phosphatidylcholine cleared per 24 h did not change independently of dose injected indicating that clearance and catabolic pathways were not saturable in either group of rabbits. Different species sources or lipid extraction of natural surfactants did not alter clearance rates very much in the 3 day old rabbits. Small differences in clearance rates were identified by comparing rabbit surfactant with calf surfactant or Surfactant-TA in the adult rabbits. These results indicate that the lungs of developing and adult rabbits can clear large doses of surfactants from multiple sources at rates comparable to the species common natural surfactant.

Unconjugated bilirubin and the bile from light exposed Gunn rats inhibit intestinal water and electrolyte absorption.

Jaundiced babies undergoing phototherapy often develop diarrhoea. The cause of it is still uncertain. Increasing evidence supports a role of a secretory mechanism for the diarrhoea. We therefore studied the effects of bile from congenitally jaundiced rats undergoing phototherapy and of unconjugated bilirubin on rat small intestine in vivo and in vitro. Results suggest that: (1) the bile from homozygous Gunn rats under phototherapy has an anti-absorptive effect when tested in the perfused jejunum of normal Wistar rats; (2) unconjugated bilirubin has a dose dependent secretory effect on the intestinal transport of water and electrolytes, when tested in the same system. Alteration of cyclic AMP or cyclic GMP, known intracellular mediators of secretion, was not observed. We conclude that free bilirubin is an intestinal secretagogue acting by an as yet unknown mechanism, that may mediate the secretory type of diarrhoea in jaundiced neonates undergoing phototherapy.

Efficacy and safety of the "integral" phototherapy for neonatal hyperbilirubinemia. Results of a follow-up at 6 years of age.

One hundred and ten full-term newborns were treated with integral phototherapy (IP) in the first week of life for hyperbilirubinemia (peak bilirubin concentration, 19.5 +/- 2.8 mg/dl). IP was provided by an apparatus which irradiated the infants over the entire skin surface with four visible blue light lamps placed around the body at a mean distance of only 20 cm. The irradiance of the lamps at the skin surface was 0.350 mW/sq cm, in the wavelength range between 425 and 475 nm. The IP resulted in a 48-hour bilirubin decline rate of 0.163 mg/dl/h. After a mean exposure of 78 +/- 32 h, the mean plasma bilirubin level was 8.4 +/- 0.8 mg/dl. One hundred and ten comparable nonjaundiced infants were studied as controls. At 6 years of age, both groups of subjects were called for a follow-up concerning growth, visual, and hearing functions, and neuro-developmental status. The follow-up was completed in 81 children of the IP group (73.6%) and in 89 of the controls (80.6%). There were no significant differences in the studied parameters between the two groups. The study concludes that IP appears to be an effective and safe treatment for jaundiced infants. IP employs less radiant energy from the lamp source than the traditional apparatus, but delivers this energy to a larger skin surface area.

Sites of action of light during phototherapy.

In order to investigate the main sites of action of phototherapy in the treatment of neonatal jaundice we studied (a) the in vivo and in vitro relationship between the hematocrit and the effectiveness of phototherapy, and (b) the effect of varying the skin area exposed to light. The results show that the hematocrit does not influence in vivo the efficacy of phototherapy, while they confirm that the total skin surface exposed to light is important in determining the effectiveness of light treatment. The authors have also studied the possible action of phototherapy on bilirubin solutions placed into the postmortem brain or the stomach. The results suggest that blue light does not penetrate strongly enough to photomodify the exposed pigment.

Effect of carnitine on lipid metabolism in the newborn. I. Carnitine supplementation during total parenteral nutrition in the first 48 hours of life.

The effect of carnitine administration on neonatal lipid metabolism was studied during endovenous loading with Intralipid (1 g/kg body weight over a 4-hour period). During a 6-hour period the plasma level of triglycerides, glycerol, free fatty acids (FFA), beta-hydroxybutyrate (beta-OHB), and acetoacetate were monitored in a group of newborns infused with carnitine and compared with a control group infused only with Intralipid. Carnitine administration caused an increased plasma concentration of ketone bodies, probably consequent to an increased rate of FFA mitochondrial beta-oxidation. An increased plasma level of glycerol and FFA was also observed, whereas the triglyceride plasma levels were not different between the two groups. Carnitine administration in the neonatal period seems to act by increasing ketogenesis and lipolysis.

Inhibitory effects of bilirubin and photobilirubin on neonatal and adult T lymphocytes and granulocytes.

The lymphoproliferative response to phytohemagglutinin of lymphocytes and spontaneous motility, chemotaxis and phagocytic activity of granulocytes were studied in the newborn and adult blood in the presence of bilirubin and photobilirubin. All of these activities were inhibited to the same extent by these substances. In addition, a significant difference between newborn and adult values was found. In conclusion, the authors suggest that phototherapy does not decrease bilirubin cellular toxicity.

Phototherapy-induced covalent binding of bilirubin to serum albumin.

Bilirubin displays a detectable fluorescence emission only when it is complexed with serum albumin, whereas free bilirubin has a very low fluorescence yield. Actually, nearly complete disappearance of bilirubin emission was obtained when the unirradiated human serum albumin-bilirubin complex was precipitated with acetone to extract the pigment; complete removal of protein-bound bilirubin (as monitored by fluorescence spectroscopy) was achieved by repeating the acetone extraction after incubation of the complex in the phosphate buffer, pH 7.4, containing 7 M guanidinium chloride; the latter compound causes on extensive unfolding of protein molecules. On the other hand, in the case of irradiated solutions, even after denaturation of the protein with 7 M guanidinium chloride, a detectable amount of bilirubin-type fluorescent material was found to be associated with albumin. This finding clearly shows that bilirubin and/or some photoproduct underwent in part a photoinduced covalent binding with human serum albumin. Fragmentation of the bovine albumin polypeptide chain according to the procedure detailed in the experimental section yielded only one peptide-containing material fluorescent in the 530 nm region. This fact underlines the selective nature of the photobinding reaction. The amino acid composition of the isolated peptide is shown in Table 2; the composition is closely similar with that found for peptide 187-397 of native bovine serum albumin. In the case of the jaundiced babies who were subjected to phototherapy, we were able to demonstrate that only after 7 to 9 hr of exposure to light a detectable amount of bilirubin-type fluorescent material was present even at the end of the serum treatment with acetone and guanidinium chloride (see Fig. 1; Table 1). Fractional precipitation of the serum proteins by addition of controlled amounts of ammonium sulphate showed that the fluorescent material was present only in the albumin fraction. The photoadduct disappeared about 15 to 20 days after the phototherapy had been discontinued. This period of time represents the natural turnover period of human serum albumin.

Effect of infused hypothalamic phospholipids on the maturation of foetal rabbit lungs.

The effect of hypothalamic phospholipids on the maturation of foetal lung was investigated in a series of experiments in rabbits. Sixteen pregnant does were injected with hypothalamic phospholipids (2 mg day-1 kg-1) from day 21 of gestation. A second group of 16 does was injected with saline, and served as controls. The foetuses were delivered at gestational ages between 27 and 28 days by means of caesarean section under intravenous pentothal anaesthesia. Foetuses born from treated mothers were more active, breathed better, and their lungs expanded to a greater extent compared with the foetuses born to control mothers. In the animals of treated mothers there was, on electron microscopy, evidence of accelerated maturation of alveolar epithelial cells.