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

Transcutaneous bilirubin in predicting hyperbilirubinemia in term neonates

OBJECTIVE

To assess the utility of 24 and 48 hours transcutaneous bilirubin (TcB) index for predicting subsequent significant hyperbilirubinemia in healthy term neonates.

METHODS

TcB indices were obtained for healthy, breastfed, term AGA newborns at 24 +/- 2, 48 +/- 2 and subsequently at intervals of 24 hours. Neonates with illness, on treatment and positive Direct Coomb's test were excluded. Serum bilirubin levels were obtained whenever indicated. Neonates having serum bilirubin > or = 17 mg/dL were considered as significant hyperbilirubinemia. The 24 and 48 hour TcB indices, as risk predictors for such hyperbilirubinemia were determined.

RESULTS

Study included 461 healthy term neonates. The mean birth weight was 2949 (+/- 390) gm and mean gestation of 38.6 (+/- 1.1) weeks. Eight one (17.6%) had significant hyperbilirubinemia. Of 461, 135 (29.3%) had TcB index.

CONCLUSION

The 24 and 48 hour TcB indices are predictive for subsequent significant hyperbilirubinemia and can guide clinician in early discharge of healthy term newborns.

Influence of mutations associated with Gilbert and Crigler-Najjar type II syndromes on the glucuronidation kinetics of bilirubin and other UDP-glucuronosyltransferase 1A substrates

OBJECTIVES

UGT1A1 coding region mutations, including UGT1A1*6 (G71R), UGT1A1*7 (Y486D), UGT1A1*27 (P229Q) and UGT1A1*62 (F83L), have been linked to Gilbert syndrome in Asian populations, whereas homozygosity for UGT1A1*7 is associated with the Crigler-Najjar syndrome type II. This work compared the effects of (a) the individual UGT1A1 mutations on the glucuronidation kinetics bilirubin, beta-estradiol, 4-methylumbelliferone (4MU) and 1-naphthol (1NP), and (b) the Y486 mutation, which occurs in the conserved carboxyl terminal domain of UGT1A enzymes, on 4MU, 1NP and naproxen glucuronidation by UGT1A3, UGT1A6 and UGT1A10.

METHODS

Mutant UGT1A cDNAs were generated by site-directed mutagenesis and the encoded proteins were expressed in HEK293 cells. The glucuronidation kinetics of each substrate with each enzyme were characterized using specific high-performance liquid chromatography (HPLC) methods.

RESULTS

Compared with wild-type UGT1A1, in-vitro clearances for bilirubin, beta-estradiol, 4MU and 1NP glucuronidation by UGT1A1*6 and UGT1A1*27 were reduced by 34-74%, most commonly as a result of a reduction in Vmax. However, the magnitude of the decrease in the in-vitro clearances varied from substrate to substrate with each mutant. The glucuronidation activities of UGT1A1*7 and UGT1A1*62 were reduced by >95%. Introduction of the Y486D mutation essentially abolished UGT1A6 and UGT1A10 activities, and resulted in 60-90% reductions in UGT1A3 in-vitro clearances.

CONCLUSIONS

The glucuronidation of all UGT1A1 substrates is likely to be impaired in subjects carrying the UGT1A1*6 and UGT1A1*62 alleles, although the reduction in metabolic clearance might vary with the substrate. The Y486D mutation appears to greatly reduce most, but not all, UGT1A activities.

A comparison of alternative risk-assessment strategies for predicting significant neonatal hyperbilirubinemia in term and near-term infants

OBJECTIVE

The purpose of this work was to compare the predictive accuracy of alternative risk-assessment strategies used to screen for the risk of significant neonatal hyperbilirubinemia.

PATIENTS AND METHODS

We conducted a prospective cohort study of 823 term and near-term newborns admitted to the well-infant nursery at the Hospital of the University of Pennsylvania. Maternal, infant, and delivery risk factors for significant hyperbilirubinemia were obtained from chart review, structured interviews with parents, and nurse assessments before discharge. Transcutaneous bilirubin measurement was performed daily until discharge and once by a visiting home nurse between 3 and 8 days of life. We used the c statistic to compare the predictive accuracy of 3 risk-assessment strategies for estimating the risk of significant neonatal hyperbilirubinemia, defined as a bilirubin level that at any time after birth exceeded or was within 1 mg/dL (17 micromol/L) of the hour-specific phototherapy treatment threshold recommended by the American Academy of Pediatrics in 2004. The compared strategies included those that use (1) a predischarge bilirubin level (obtained before 52 hours) expressed as a risk zone on an hour-specific bilirubin nomogram, (2) clinical risk factors other than the predischarge bilirubin level, and (3) a combination of the predischarge bilirubin risk zone and additional clinical risk factors.

RESULTS

Forty-eight patients (6%) developed significant neonatal hyperbilirubinemia. The predischarge (<52 hours) bilirubin level expressed as a risk zone on the bilirubin nomogram and a prediction model that combined multiple other clinical risk factors had similar accuracy for predicting significant hyperbilirubinemia. The only clinical risk factor that could be added to the predischarge risk zone to improve overall predictive accuracy was gestational age. The predischarge bilirubin risk zone and gestational age could be used to stratify patients into a large group (n = 523 [70%]) of infants with a very low (0.2%) risk of developing significant hyperbilirubinemia, a small group of infants (n = 127 [17%]) with a low (4%) risk of developing significant hyperbilirubinemia, and an even smaller group of infants (n = 100 [13%]) with a high (42%) risk of developing significant hyperbilirubinemia.

CONCLUSIONS

An infant's risk of developing significant hyperbilirubinemia can be simply and accurately assessed by using just the infant's predischarge bilirubin level and gestational age.

Utility of a new transcutaneous jaundice device with two optical paths in premature infants

BACKGROUND

Hyperbilirubinemia may cause dysfunction of the central nervous system of newborn infants. Recently, a new transcutaneous bilirubin device has been developed, which is not limited by maturity or melanin concentration of the skin. However, there have been few reports limiting the subjects to preterm and very low-birthweight (VLBW) infants.

METHODS

Transcutaneous bilirubin (TcB) and total serum bilirubin (TSB) were measured within 1 h of time lag in 50 premature infants. TcB was measured with the new jaundice device on the forehead. TSB samples were measured by direct colorimetry. The correlation coefficient and regression line were calculated.

RESULTS

The results showed a good correlation between TcB and TSB. However, the correlation tended to be worse with infants whose birthweights were lower than 1000 g, or whose gestational ages at birth were shorter than 28 weeks.

CONCLUSION

TcB and TSB have a close correlation, and TcB tends to be higher than TSB. The Minolta transcutaneous jaundice device could be used as a screening instrument, leading to the avoidance of invasive blood samplings for preterm and VLBW infants. However, in patients whose birthweights are lower than 1000 g or whose gestational ages are shorter than 28 weeks, care must be taken when using the transcutaneous jaundice device because of low reliability in these patients.

Using BiliCheck for preterm neonates in a sub-intensive unit: diagnostic usefulness and suitability

BACKGROUND

BiliCheck (BC), a new transcutaneous bilirubinometer is thought to be lacking in the disadvantages of old devices and could be potentially useful for diagnosing jaundice in preterm babies. Although its accuracy is well known in healthy term babies, there is a lack of knowledge about its usefulness in preterm infants.

AIMS

To investigate BC usefulness in preterm babies and its suitability in a sub-intensive neonatal unit.

STUDY DESIGN

In 340 preterm infants between 30 and 36 weeks of gestational age, transcutaneous and serum bilirubin measurement were performed. Hematocrit, pH, postnatal age, gestational age, and sex were also studied to clarify their influence on BC accuracy. For a subset of 100 neonates transcutaneous measurement, blood collection and serum analysis were timed and costs were considered.

RESULTS

Correlation coefficient is 0.795 (p<0.001) and this is not affected by factors previously supposed to be important. Overall sensitivity was 100% and specificity were comprised between 40% and 72%. BC has a tendency to overestimate serum bilirubin, at high values. Considering the whole time for serum bilirubin measurement, transcutaneous bilirubinometry is a faster (p<0.0001), but more expensive technique with a cost of about 5 euro/measurement. Nevertheless, using BC as a screening-device we could safely avoid 58-79% of blood samples, since its positive predictive values is about 21-42%. This would allow to a cost reduction of 1555-2120 euro/year.

CONCLUSIONS

BC has a good reliability in preterm infants although not as good as in healthy term babies. BC is a time-sparing tool and can improve the management of neonatal jaundice in preterm infants; however, its tendency to overestimate suggests its use only for screening purposes.

[Transcutaneous bilirubin measurement in preterm infants]

Transcutaneous bilirubinometry is an effective screening tool for neonatal jaundice in full-term babies. But its accuracy is not shown yet in preterm infants.

METHODOLOGY

We carried out a prospective study in a neonatal intensive care unit. The study included 47 preterm infants. From birth, a transcutaneous bilirubin measurement (BTc) using the BiliCheck was made on the forehead of each newborn every 8 h. Blood sampling for determination of total serum bilirubin (BS) was combined with BTc: 1) if value of BTc was higher than limits values for phototherapy; 2) on the second day of life and 3) 4 hours after cessation of phototherapy.

RESULTS

Mean gestational age was 30 week and mean birth weight was 1419 g. We studied 151 pairs of BTc and BS. Mean values obtained by BTc and BS were respectively 160.6+/-50 mumol/L and 190.6+/-61.4 mumol/L. A significant correlation between BTc and BS was found. But the limits of agreement were very wide. The negative predictive value (NPV) of BTc was above 90% in each group of gestational age.

DISCUSSION

The need for phototherapy cannot be determined by BTc in preterm infants. But the BTc is reliable when its value is under the limits for phototherapy.

CONCLUSION

With a very high incidence of neonatal jaundice (87%) in our cohort, a value of BTc under the limits for phototherapy has a good NPV in preterm infants.

Prediction of severe hyperbilirubinaemia using the Bilicheck transcutaneous bilirubinometer

OBJECTIVES

To determine the sensitivity and specificity of different levels of bilirubin measured by the transcutaneous bilirubinometer Bilicheck on forehead and sternum for predicting severe hyperbilirubinaemia of total serum bilirubin (TSB)>or=300 micromol/L in Malay, Chinese and Indian infants.

DESIGN

A prospective observational study.

SETTING

A tertiary care University hospital.

METHODS

A total of 345 healthy jaundiced term infants were recruited prior to commencement of phototherapy or exchange transfusion. Transcutaneous bilirubin (TcB) level was measured with the Bilicheck from infants' foreheads (TcBh) and sternums (TcBs) within 30 min of serum bilirubin measurement by the diazo method in the hospital laboratory.

RESULTS

The median serum TSB level of these infants was 233.0 micromol/L (range: 108.0-589.0). Ninety-five (27.5%) infants had TSB>or=300 micromol/L. There was good correlation between log10TSB and TcB measured from the forehead (r=0.80, P<0.0001) and the sternum (r=0.86, P<0.0001). At TcBh cut-off of 250 micromol/L, the Bilicheck detected TSB>or=300 micromol/L with a sensitivity of 100% and a specificity of 39.2%, the area under the receiver operative characteristic curve being 0.89 (95% confidence interval 0.85, 0.92). At TcBs cut-off of 200 micromol/L, the Bilicheck detected TSB>or=300 micromol/L with a sensitivity of 100% and a specificity of 33.6%, the area under receiver operative characteristic curve being 0.93 (95% confidence interval 0.90, 0.96).

CONCLUSION

The Bilicheck is not a substitute for measuring serum bilirubin. However, using predetermined TcB cut-off values with reasonable sensitivity and specificity, it is a useful screening tool to identify infants with TSB>or=300 micromol/L requiring blood sampling, hospital admission and treatment.

A systems approach for neonatal hyperbilirubinemia in term and near-term newborns

OBJECTIVE

To propose and implement a family-centered systems approach to manage newborn jaundice for safer outcomes.

DESIGN

Observational study for known adverse outcomes.

SETTING

Semiprivate urban birthing hospital.

PATIENTS/PARTICIPANTS

31,059 well babies discharged as healthy from a cohort of 41,961 live births (1990-2000).

INTERVENTIONS

Incremental implementation of a systems approach that incorporated a hospital policy to (a) authorize nurses to obtain a bilirubin (total serum/transcutaneous) measurement for clinical jaundice, (b) universal predischarge total serum bilirubin (at routine metabolic screening), and (c) targeted follow-up, using the bilirubin nomogram (hour-specific, percentile-based total serum bilirubin/transcutaneous bilirubin).

MAIN OUTCOME MEASURES

Known adverse outcomes assessed for early- and late-onset severe hyperbilirubinemia before, during, and after systems approach implementation.

RESULTS

Adverse outcomes decreased for well babies: exchange transfusion, intensive phototherapy, and readmission. During the study period, there were no "never events" (total serum bilirubin greater than or equal to 30 mg/dl), while "close calls" (total serum bilirubin greater than or equal to 25 mg/dl) were 1 in 15,000 as compared to a reported incidence of 1 in 625.

CONCLUSIONS

Reduced adverse events, significant reduction in close calls, and no never events met family expectations for safer experiences with this approach.

Neurodevelopmental outcome of severe neonatal hemolytic hyperbilirubinemia

We recruited 128 neonates with hyperbilirubinemia over a 5-year period (1995-2000) to study the short- and long-term effects of hemolytic hyperbilirubinemia on the auditory brainstem pathway and neurodevelopmental status. These children were divided into two groups: (1) a hemolytic group (n = 29; ABO incompatibility [n = 19], Rh incompatibility [n = 1], glucose-6-phosphate dehydrogenase deficiency [n = 8] and both ABO incompatibility and glucose-6-phosphate dehydrogenase deficiency [n = 1]) and (2) a nonhemolytic group (n = 99). All received phototherapy. Exchange transfusions were performed for four (13.8%) in the hemolytic group and three (3%) in the nonhemolytic group. The brainstem auditory evoked potential was recorded at a mean age of 3.2 months in the hemolytic group and 3.1 months in the nonhemolytic group. Serial brainstem auditory evoked potential assessments were performed until 2 years of age (3 in the hemolytic group and 18 in the nonhemolytic group). All had regular physical, neurologic, visual, and auditory evaluation until 3 years of age. The rate of exchange transfusion was significantly higher in the hemolytic group than in the nonhemolytic group (P < .05). Brainstem auditory evoked potential abnormalities at the initial assessment occurred in three (10.4%) in the hemolytic group (all related to ABO incompatibility) and nine (9.1%) in the nonhemolytic group. At 2 years, the brainstem auditory evoked potential returned to normal except in three cases with a slightly increased hearing threshold (one [3.5%] in the hemolytic group at 60 dB nHL and two [2%] in the nonhemolytic group at 50 dB nHL]). There were no significant differences in the rate of brainstem auditory evoked potential abnormalities at the initial or subsequent assessments between both groups. All except five cases had a normal neurodevelopmental outcome at 3 years (three [two with ABO incompatibility and one with glucose-6-phosphate dehydrogenase deficiency] in the hemolytic group [10.4%] and two [2%] in the nonhemolytic group). All had mild motor delay and hypotonia, which returned to normal at 3 years. The rate of abnormal neurodevelopmental outcome was higher in the hemolytic group than in the nonhemolytic group, although with no significant difference between both groups (P = .08). All five cases in both groups with abnormal neurodevelopment had a normal brainstem auditory evoked potential at the initial assessment. There was no relationship between the abnormal initial brainstem auditory evoked potential and the final neurodevelopmental outcome. The toxic effect of hyperbilirubinemia on the auditory brainstem pathway and neurodevelopmental status in our cohort was transient. The prognosis of neonatal hemolytic hyperbilirubinemia in our Chinese cohort is excellent, possibly owing to an aggressive early-intervention approach.

Early recognition of neonatal hyperbilirubinemia and its emergent management

Hyperbilirubinemia and kernicterus are re-emerging as prominent clinical concerns and have been hypothesized to be secondary to increased breast-feeding rates, early hospital discharges and overall lack of concern for the potential impact of severe hyperbilirubinemia on healthy term newborns. Although the clinical symptoms can be non-specific and vague, they could be early, insidious and heralding signs of acute bilirubin encephalopathy (ABE) or acute stage kernicterus. Because it is highly prevalent, evaluation of a jaundiced neonate requires detailed questions about specific signs, review of birth and postnatal histories, evaluation of predischarge data, and possibly an emergency clinical evaluation of the neurological status of the infant. Medical urgency to evaluate, investigate and monitor such a newborn ensues from the possibility of rapid progression that might lead to permanent sequelae of bilirubin-induced neurologic dysfunction (BIND). Early recognition of the urgency and rapid transition to treatment seem to be the major barriers leading to delay in therapy. However, because there is a well-established and relatively safe treatment for neonatal jaundice, there should be zero tolerance for kernicterus, and BIND prevention has become a national priority in the USA. This paper reviews the clinical signs and epidemiology of ABE and BIND and presents a system-based strategy for preventing their occurrence, focusing particularly on the transition from recognition of clinical jaundice to actual treatment. A novel emergency-room-based protocol is presented as an example of how to expedite and facilitate rapid progression to treatment.

Short- and long-term outcome of severe neonatal nonhemolytic hyperbilirubinemia

We studied the effects of hyperbilirubinemia on brainstem auditory pathways and neurodevelopmental status in 99 full-term neonates with severe nonhemolytic hyperbilirubinemia (total serum bilirubin level = 301 to 500 micromol/L) born between 1995 and 2000. These were divided into three groups: group 1, moderate hyperbilirubinemia (n = 30; mean maximum total serum bilirubin = 320.7 micromol/L or 18.9 mg%); group 2, severe hyperbilirubinemia (n = 63; mean maximum total serum bilirubin = 369.0 micromol/L or 21.7 mg%); and group 3, super hyperbilirubinemia (n = 6; mean maximum total serum bilirubin = 457.2 micromol/L or 26.9 mg%). All received phototherapy, and three neonates also had exchange transfusion. Initial brainstem auditory evoked potentials were recorded in all at the mean age of 3.1 months (range 1-9 months). At initial assessment, only nine neonates (9.1%) had abnormal brainstem auditory evoked potentials. All except two returned to normal at 2 years. These two children had a hearing threshold at 50 nHL. We then compared serial brainstem auditory evoked potentials until 2 years for these nine cases with initial abnormal brainstem auditory evoked potentials, and nine cases with initial normal brainstem auditory evoked potentials were recruited for comparison. All 99 children had regular physical, neurologic, visual, and auditory assessments every 3 to 6 months until the age of 3 years. There was no significant correlation between demographic factors (gender, gestational age, or birthweight), maximum total serum bilirubin, and total serum bilirubin at discharge with an abnormal brainstem auditory evoked potential. There was no significant difference in the rate of brainstem auditory evoked potential abnormalities between the three groups: moderate (10%), severe (7.9%), and super (16.7%). All had normal neurodevelopmental status at 3 years. Only two children had transient mild motor delay and hypotonia, and both had normal brainstem auditory evoked potentials. There was no relationship between the abnormalities of the brainstem auditory evoked potentials and neurodevelopmental status. None of the three children receiving exchange transfusion had abnormal brainstem auditory evoked potentials or neurodevelopmental outcome. With the neurophysiologic and clinical outcomes in our cohort with severe nonhemolytic hyperbilirubinemia, we propose that the toxic effect of hyperbilirubinemia on auditory brainstem pathways might be transient provided that prompt treatment is initiated.

Bilirubin measurement for neonates: comparison of 9 frequently used methods

OBJECTIVE

High blood concentrations of bilirubin are toxic to the brain and may cause kernicterus. Therefore, determination of bilirubin levels is performed for many newborns, and several different methods are available. We compared 9 frequently used methods for bilirubin determination among newborns under routine conditions, to define their sequence of use.

METHODS

In a prospective study, bilirubin concentrations were determined with 9 different methods, ie, 3 skin test devices, 3 nonchemical photometric devices (including 2 blood gas analyzers), and 3 laboratory analyzers.

RESULTS

A total of 124 samples were obtained. All 3 laboratory methods showed very strong correlations with each other, and their means were used as comparison values. To these comparison values, the skin test devices had correlation coefficients between 0.961 and 0.966, and the nonchemical photometric devices between 0.980 and 0.994. Bland-Altman plots demonstrated good agreement with the comparison values for all nonchemical photometric devices. All skin test devices and 1 nonchemical photometric device underestimated bilirubin levels, particularly at high concentrations.

CONCLUSIONS

In the routine care of newborns, the first method for bilirubin testing should be a skin test. If the skin test result exceeds 200 micromol/L and other analytes are to be determined with a nonchemical photometric device, then bilirubin can be included in this analysis and the result trusted up to 250 micromol/L. If the skin test result exceeds 200 micromol/L and only bilirubin concentrations are needed, then a standard laboratory method is the first choice, to avoid repeated blood sampling. Bilirubin concentrations from nonchemical photometric devices that exceed 250 micromol/L should be confirmed with standard laboratory methods.

Management of neonatal hyperbilirubinemia: pediatricians' practices and educational needs

Background

Early detection and treatment of neonatal hyperbilirubinemia is important in the prevention of bilirubin-induced encephalopathy. In this study, we evaluated the New Jersey pediatricians' practices and beliefs regarding the management of neonatal hyperbilirubinemia and their compliance with the recommendations made by the American Academy of Pediatrics (AAP) in 1994.

Methods

A survey questionnaire was mailed to a random sample of 800 pediatricians selected from a list of 1623 New Jersey Fellows of the AAP initially in October 2003 and then in February 2004 for the non-respondents. In addition to the physicians' demographic characteristics, the questionnaire addressed various aspects of neonatal hyperbilirubinemia management including the diagnosis, treatment, and follow up as well as the pediatricians' beliefs regarding the significance of risk factors in the development of severe hyperbilirubinemia.

Results

The adjusted response rate of 49.1% (n = 356) was calculated from the 725 eligible respondents. Overall, the practicing pediatricians reported high utilization (77.9%) of the cephalocaudal progression of jaundice and low utilization (16.1%) of transcutaneous bilirubinometry for the quantification of the severity of jaundice. Most of the respondents (87.4%) identified jaundice as an indicator for serum bilirubin (TSB) testing prior to the neonate's discharge from hospital, whereas post-discharge, only 57.7% felt that a TSB was indicated (P < 0.01). If the neonate's age was under 72 hours, less than one-third of the respondents reported initiation of phototherapy at TSB levels lower than the treatment parameters recommended by the AAP in 1994, whereas if the infant was more than 72 hours old, almost 60% were initiating phototherapy at TSB lower than the 1994 AAP guidelines. Most respondents did not regard neonatal jaundice noted after discharge and gestational ages 37–38 weeks as being significant in the development of severe hyperbilirubinemia. However, the majority did recognize the importance of jaundice presenting within the first 24 hours and Rh/ABO incompatibility.

Conclusion

The pediatricians' practices regarding the low utilization of laboratory diagnosis for the quantification of jaundice after discharge and underestimation of risk factors that contribute to the development of severe hyperbilirubinemia are associated with initiation of phototherapy at lower than AAP recommended treatment parameters and recognition of neonatal hyperbilirubinemia as an important public health concern.

Transcutaneous bilirubinometry: a noninvasive tool for studying newborn jaundiced rats before and after exposure to light

The homozygous Gunn rat is the most frequently used animal model for the study of neonatal jaundice. We evaluated the applicability of noninvasive transcutaneous bilirubin (TcB) measurements as an index of serum total bilirubin (STB) levels in neonatal rats by comparison to invasive STB measurements. TcB measurements were made during the first 96 h of life with the Model 101 Minolta/Air-Shields Jaundice Meter (JM) and SpectRx BiliCheck System (BC). Measurements with both devices displayed parallel TcB profiles, rapidly rising within 24 h, increasing during the next 6 h, then leveling off after 30 h. Linear regressions for the JM (n = 60) were as follows: STB (mg/dL) = 0.79 (JM) - 0.01 (units, r = 0.95, head); STB (mg/dL) = 0.82 (JM) + 1.51 (units, r = 0.95, upper back); and STB (mg/dL) = 0.74 (JM) + 1.60 (units, r = 0.91, lower back). Mean bias +/- imprecision were as follows: -0.02 +/- 3.99 mg/dL, -0.01 +/- 3.90, and 0.01 +/- 4.28 at the head, upper back, and lower back, respectively. For the BC, only lower back measurements were taken, and the regression was as follows: STB (mg/dL) = 0.77 (BC) + 1.65 mg/dL, (r = 0.93, n = 29) with a mean bias +/- imprecision of -1.08 +/- 3.08 mg/dL. When pups were exposed to light, correlations remained strong but intercepts increased. These results demonstrate that noninvasive TcB measurements correlate highly with STB in the Gunn rat during the first 96 h of life and after exposure to light. We conclude that JM measurements at the head and BC at the lower back reflect STB most reliably and consistently. Thus, in addition to being a useful tool for evaluating jaundice in human neonates, TcB methodology can be used successfully for the noninvasive monitoring of jaundice in neonatal Gunn rats pre- and postlight exposure.

Evaluation of a point-of-care direct spectrophotometric method for measurement of total serum bilirubin in term and near-term neonates

OBJECTIVE

To evaluate point-of-care (POC) measurement of total serum bilirubin (TSB) in the management of neonatal jaundice.

STUDY DESIGN

TSB was measured by a POC direct spectrophotometric bilirubin method (Unistat (U/TSB)) and a standard diazo clinical laboratory method (Olympus AU640E analyzer (diazo/TSB)). Agreement between U/TSB and diazo/TSB was assessed by correlation coefficient and Bland-Altman analysis. Transcutaneous bilirubin (TcB) was measured using JM-103 (JM).

RESULTS

Correlation between U/TSB and diazo/TSB was 0.99 (n = 120). Maximum difference (U/TSB minus diazo/TSB) was -2.9 mg/dl, and 79% were +/-1 mg/dl; the average difference was -0.37+/-0.70 mg/dl and the average absolute difference was 0.60+/-0.52 mg/dl. Median time to determine U/TSB was 5 min. Correlation between U/TSB and JM was 0.92 (n = 113). Maximum difference (U/TSB minus JM) was 6.3 mg/dl, and 45% were +/-1 mg/dl; the average difference was 0.7+/-1.8 mg/dl and the average absolute difference was 1.4+/-1.2 mg/dl.

CONCLUSION

Measurement of TSB using Unistat provides excellent agreement with diazo/TSB and rapid turnaround time. This technique may provide reliable POC confirmation of TcB results that are above a screening cutoff value.

Measurement of transcutaneous hemoglobin concentration by noninvasive white-light spectroscopy in infants

OBJECTIVE

To compare transcutaneously spectroscopically measured hemoglobin values with venous hemoglobin values in infants.

STUDY DESIGN

Prospective study in healthy preterm and term infants who were breathing spontaneously.

RESULTS

Recordings were obtained from 85 stable infants (median gestational age at measurement: 36 weeks [range: 34-43 weeks]; median body weight: 1890 g [range: 1095-4360 g]). The spectroscopic hemoglobin values were corrected for inhomogeneous distribution of hemoglobin in the tissue. The venous and spectroscopic hemoglobin values were then compared by using the Bland-Altman method, which gave an error of <5%.

CONCLUSIONS

This pilot study could illustrate a good relation between the 2 methods for measuring hemoglobin. Larger studies are required to validate the spectroscopic method in those with conditions that affect the skin microcirculation (eg, septicemia).

A controlled, randomized, double-blind trial of prophylaxis against jaundice among breastfed newborns

OBJECTIVES

Neonatal jaundice is a greater problem for infants fed breast milk, compared with formula. This study tested the hypotheses that feeding breastfed newborns beta-glucuronidase inhibitors during the first week after birth would increase fecal bilirubin excretion and would reduce jaundice without affecting breastfeeding deleteriously.

METHODS

Sixty-four breastfed newborns were randomized to 4 groups, ie, control or receiving 6 doses per day (5 mL per dose) of L-aspartic acid, enzymatically hydrolyzed casein (EHC), or whey/casein (W/C) for the first week. L-aspartic acid and EHC inhibit beta-glucuronidase. Transcutaneous bilirubin levels (primary outcome) were measured daily (Jaundice Meter [Minolta/Air Shields, Hatboro, PA] and Bilicheck [Respironics, Pittsburgh, PA]). All stools were collected, and fecal bile pigments, including bilirubin diglucuronide, bilirubin monoglucuronides, and bilirubin, were analyzed with high-performance liquid chromatography. Follow-up assessments included day 7 body weight, day 6/7 prebreastfeeding/postbreastfeeding weights, maternal ratings, and ages at formula introduction and breastfeeding cessation.

RESULTS

The groups were comparable at entry. Overall, the L-aspartic acid, EHC, and W/C groups had significantly lower transcutaneous bilirubin levels than did the control group (75.8%, 69.6%, and 69.2%, respectively, of the control mean, 8.53 mg/dL, at the bilirubin peak on day 4). The L-aspartic acid, EHC, and W/C groups had significantly lower transcutaneous bilirubin levels on days 3 to 7. Fecal bile pigment excretion was greatest in the L-aspartic acid group, significantly greater than control values. There were no significant differences in dosages, follow-up measurements, and maternal ratings.

CONCLUSIONS

Use of minimal aliquots of L-aspartic acid and EHC for beta-glucuronidase inhibition results in increased fecal bilirubin excretion and less jaundice, without disruption of the breastfeeding experience. Decreased jaundice in the W/C group, which lacked a beta-glucuronidase inhibitor, suggests a different mechanism.

Design of a visible-light spectroscopy clinical tissue oximeter

We develop a clinical visible-light spectroscopy (VLS) tissue oximeter. Unlike currently approved near-infrared spectroscopy (NIRS) or pulse oximetry (SpO2%), VLS relies on locally absorbed, shallow-penetrating visible light (475 to 625 nm) for the monitoring of microvascular hemoglobin oxygen saturation (StO2%), allowing incorporation into therapeutic catheters and probes. A range of probes is developed, including noncontact wands, invasive catheters, and penetrating needles with injection ports. Data are collected from: 1. probes, standards, and reference solutions to optimize each component; 2. ex vivo hemoglobin solutions analyzed for StO2% and pO2 during deoxygenation; and 3. human subject skin and mucosal tissue surfaces. Results show that differential VLS allows extraction of features and minimization of scattering effects, in vitro VLS oximetry reproduces the expected sigmoid hemoglobin binding curve, and in vivo VLS spectroscopy of human tissue allows for real-time monitoring (e.g., gastrointestinal mucosal saturation 69+/-4%, n=804; gastrointestinal tumor saturation 45+/-23%, n=14; and p<0.0001), with reproducible values and small standard deviations (SDs) in normal tissues. FDA approved VLS systems began shipping earlier this year. We conclude that VLS is suitable for the real-time collection of spectroscopic and oximetric data from human tissues, and that a VLS oximeter has application to the monitoring of localized subsurface hemoglobin oxygen saturation in the microvascular tissue spaces of human subjects.

Evaluation of a transcutaneous jaundice meter following hospital discharge in term and near-term neonates

OBJECTIVES

To evaluate performance of the Minolta JM-103 Jaundice Meter (JM) as a predictor of total serum bilirubin (TSB) in outpatient neonates during the first week postnatal, and to estimate the number of TSB determinations that might be avoided in clinical use.

STUDY DESIGN

In neonates evaluated posthospital discharge, JM and TSB results were compared using linear regression and a Bland-Altman plot, and predictive indices were calculated for various JM cutoff values. Utilizing the 2004 American Academy of Pediatrics (AAP) guidelines, the ability of JM to predict risk zone status was determined.

RESULTS

Overall correlation between JM and TSB was 0.77 (p<0.001; n=121). When TSB was >17 mg/dl, a cutoff value for JM of 13 mg/dl had a sensitivity of 1.0, and 50% of TSB determinations would be avoided.

CONCLUSIONS

JM may facilitate outpatient management of hyperbilirubinemia by reducing the number of TSB determinations required; however, it does not provide a reliable substitute for laboratory measurement of TSB.

Understanding severe hyperbilirubinemia and preventing kernicterus: Adjuncts in the interpretation of neonatal serum bilirubin

The serum total bilirubin concentration at any point in time represents the amount of bilirubin being produced minus that being excreted. Hyperbilirubinemia develops when bilirubin production exceeds the body's capacity to excrete it, primarily by conjugation. When extreme, hyperbilirubinemia may lead to the development of free bilirubin, that form of bilirubin which may cross the blood-brain barrier and enter and damage the basal nuclei of the brain. This rare, though devastating complication, may result in irreversible bilirubin induced brain damage termed kernicterus. In this paper, adjuncts to the interpretation of the serum total bilirubin are discussed, with the purpose of singling out those few neonates in real danger of bilirubin encephalopathy. Interpretation of the serum total bilirubin should be performed in conjunction with factors unique to the particular infant being evaluated. Understanding the mechanisms and dangers of severe neonatal hyperbilirubinemia should facilitate recognition of an emergency situation and optimize the speed with which bilirubin testing is performed and blood for exchange transfusion prepared. Hyperbilirubinemia is a condition of major importance and a source of concern to all involved in the management of the newborn. Its prevention and management should be based on the recently revised American Academy of Pediatric guidelines, with special attention paid to neonates manifesting risk factors for kernicterus. Close cooperation between the clinical laboratory and the medical team managing the newborn is an essential component in the management of a hyperbilirubinemic baby.

Predictive value of umbilical cord blood bilirubin for postnatal hyperbilirubinaemia

AIM

The study investigated the predictive value of umbilical cord serum (UCS) bilirubin for the postnatal course of bilirubinaemia in healthy term and near-term newborns.

METHODS

Term appropriate-for-gestational-age (AGA; n=1100), small-for-gestational-age (SGA; n=163) and near-term infants (GA 34-36 wk; n=78) were included and separated according to their UCS bilirubin levels, starting from <20 (group 1), 20-<30 (2), 30-40 (3) and >40 (4) micromol/l. The newborns were followed for at least 5 postnatal days, and UCS bilirubin values were correlated with the development of hyperbilirubinaemia and phototherapy (PT) treatment.

RESULTS

A clear relation between UCS bilirubin and the development of hyperbilirubinaemia was found in all three patient populations. None of the 75 AGA patients of group 1 developed postnatal bilirubin values above 300 micromol/l, whereas 0.3, 3.4 and 8.6% of the patients in groups 2-4, respectively, did so. The frequency of PT increased from 0% in group 1 up to 9.6% in group 4. For the prediction of further need of PT using a UCS bilirubin cut-off level of 30 micromol/l, we found a sensitivity of 90% and a negative predictive value of 99.1%, indicating that all patients with UCS bilirubin values below 30 micromol/l (443/1100 or 40.2%) were at a very low risk of developing dangerous hyperbilirubinaemia. Similar results were obtained in SGA children with a sensitivity of 94.1% and a negative predictive value of 98.6%. In comparison to term newborns, we generally found higher bilirubin values in preterms. A total of 6.4% of preterm children developed bilirubin values over 300 micromol/l, compared with 3% of term children, and 47.4% of preterms had to be treated with PT. Predicting the need of PT by using a UCS bilirubin cut-off level of 30 micromol/l revealed a sensitivity of 70.3% and a negative predictive value of 65.6%.

CONCLUSION

These data suggest that UCS bilirubin is useful in predicting the postnatal bilirubin values in term and near-term newborns. We presume that the use of UCS bilirubin values may help detect infants at low risk for postnatal hyperbilirubinaemia and minimize an unnecessary prolongation of hospitalization.

Association of transcutaneous bilirubin testing in hospital with decreased readmission rate for hyperbilirubinemia

BACKGROUND

Newborns are being discharged from hospitals within 1-2 days of birth, before hyperbilirubinemia usually becomes clinically evident. We investigated the use of transcutaneous bilirubin (TcB) before discharge to determine whether it affects the use of laboratory bilirubin testing or decreases the number of neonates readmitted for hyperbilirubinemia within 7 days of initial discharge.

METHODS

We retrospectively searched a clinical laboratory and hospital database to determine the number of births, newborn readmission rates for hyperbilirubinemia, length of stay, and the number of bilirubin measurements in the clinical laboratory ordered for all babies in the newborn unit at the University of Texas Medical Branch from August 2002 to March 2003 (before TcB testing) and from May 2003 to December 2003 (after TcB).

RESULTS

Between August 2002 and December 2003, 8974 newborns (both vaginal and cesarean births) were admitted to the newborn nursery. Babies who did not fit the diagnosis-related group criteria of "normal newborn" were removed, leaving 6933 babies who were included in the study. April was considered a transition month and was not included in the study, leaving 6603 newborns to be included. Of these, 446 (6.8%) required phototherapy for treatment of hyperbilirubinemia before initial discharge. For the 8 months before and 8 months after initiation of TcB testing, the number of laboratory bilirubin measurements ordered per newborn did not change, nor did the mean (SD) length of stay for normal newborns [2.15 (1.1) days vs 2.12 (1.1) days; P = 0.53], nor days of treatment with phototherapy before discharge [2.9 (1.3) days vs 2.9 (1.3) days; P = 0.67]. By contrast, the number of readmissions per 1000 newborns per month for clinically significant hyperbilirubinemia decreased significantly (Wilcoxon rank-sums two-sample test, P = 0.044), from 4.5 (2.4) to 1.8 (1.7) after TcB testing was initiated.

CONCLUSION

Access to TcB testing is associated with a reduction in the hospital readmission rate for hyperbilirubinemia within 7 days of the initial discharge.

Recent advances in the pharmacotherapy for hyperbilirubinaemia in the neonate

Jaundice is a common cause for diagnostic works-up and therapeutic intervention in neonates. This is motivated by the risk for severe neurological sequelae (kernicterus). The mainstays of treatment for the past decades have been exchange transfusion and phototherapy. Exchange transfusion is now becoming rare due to immune prophylaxis in Rhesus-negative women, and treatment of sensitised infants with intravenous immunoglobulin. Several different pharmacological approaches have been studied as far as the treatment of neonatal jaundice. Of these, the focus of attention in recent years has been on the haem oxygenase inhibitors (metal meso- and protoporphyrins). These are effective inhibitors of bilirubin production and have been shown to significantly reduce peak serum bilirubin levels in several clinical trials, both when used prophylactically and therapeutically. However, questions remain regarding long-term safety, as well as the advisability of whole-scale inhibition of bilirubin production. Nevertheless, in selected infants with a high risk of severe jaundice, the use of haem oxygenase inhibitors may be acceptable. Pharmacotherapy in jaundiced infants is fraught with risks, as many drugs may increase the entry of bilirubin into the brain and presumably, the risk for neurotoxicity. Both the displacement of bilirubin from its albumin binding and interference with the function of phosphoglycoprotein in the blood-brain barrier are documented mechanisms in this respect.

Kernicterus: still a concern

The presence of yellow staining and damage to the brain caused by unconjugated bilirubin was first described by Hervieux in 1847. Kernicterus, the technical term used to describe the intense yellow staining in the basal ganglia of the brain, was first used by Schmorl in 1903. Perhaps as many as 60 percent of all babies born each year in the U.S. are diagnosed with clinical jaundice. Kernicterus is a preventable brain injury caused by severe jaundice, yet it remains a threat today. Because of this, anyone caring for newborns must be aware of the risks and treatment for hyperbilirubinemia and the sequelae of this seemingly benign entity.

Towards safer diagnosis in clinical practice - understanding and using diagnostic tests in the neonatal unit more appropriately

The diagnostic process is a complex task that is more often than not done inherently by clinicians. However, it is in fact based around quantitative risk assessment and, as a result, when done intuitively is open to a significant risk of bias. By adopting a more structured and quantitative approach to diagnosis, clinicians might be in a position to make better diagnostic decisions. To achieve this, explicit recognition about the uncertainty surrounding diagnosis and knowledge about the basic properties of diagnostic tests, including disease incidence and predictive values, is necessary, as well as some consideration of newer concepts such as 'action thresholds'. Examples from everyday neonatal practice illustrate the potential clinical risks associated with the inappropriate use and interpretation of diagnostic tests and the potential benefits of approaching diagnosis in a more robust manner. A number of tools are now readily available to help clinicians move towards more 'evidence-based' diagnosis.

Extreme hyperbilirubinaemia in term and near-term infants in Denmark

AIM

To determine the incidence amongst infants born at term or near-term of extreme hyperbilirubinaemia, i.e., with a serum concentration of unconjugated bilirubin exceeding the limit above which an exchange transfusion was indicated according to the authorized guidelines.

METHOD

The investigation period covered 2 y, 1 January 2000 to 31 December 2001, and included all infants born alive at term or near-term in Denmark. All infants with extreme hyperbilirubinaemia admitted to paediatric departments were recorded.

RESULTS

Thirty-two infants developed extreme hyperbilirubinaemia, i.e., an incidence of 25 per 100 000. The maximum total serum bilirubin concentration (TSB) was 492 (385-689) micromol/I (median (range)). The median value of the exchange transfusion limits was 450 micromol/l. Twelve infants had signs and symptoms of central nervous system involvement; 11 had acute bilirubin encephalopathy phase-1 symptoms; and one had phase-2 symptoms. Nineteen infants developed extreme hyperbilirubinaemia during primary admission to the maternity ward or neonatal department; the others after having been discharged. There was no difference in maximum TSB between those infants not discharged from hospital and those infants admitted to hospital from home. Maximum TSB appeared latest amongst those infants admitted from home (p < 0.01), and these more often had signs and symptoms of central nervous system involvement (p < 0.05). Ten infants were of non-Caucasian extraction. Less than half of all Danish mothers receive both verbal and written information after birth on jaundice in the infant.

CONCLUSION

Twenty-five per 100 000 infants born at term or near-term developed extreme hyperbilirubinaemia, the majority of them whilst in hospital. Infants admitted from home more often had signs and symptoms of central system involvement.

In vivo spectroscopy of jaundiced newborn skin reveals more than a bilirubin index

AIM

The aims of this study were to improve the algorithms for calculating a transcutaneous bilirubin index (TcB), to follow the bilirubin concentrations during phototherapy and to evaluate possible changes in skin optical parameters such as pigmentation and erythema during phototherapy.

METHOD

Reflectance measurements were performed on 51 jaundiced newborns, of which 10 were subjected to phototherapy. The measurements were collected with a diode array spectrophotometer with an integrating sphere accessory, and a TcB was calculated from the measured spectra using algorithms based on diffusion theory. The newborns' birthweights were > or = 2000 g and their gestational age was > or = 35.5 wk. They had no substantial illnesses, and no newborns were submitted to the study until their second day. Heel prick blood samples were analysed for total serum bilirubin (Sbr) by the diazo reaction method. Phototherapy equipment was either an overhead lamp or lightbed.

RESULTS

Measurements from the forehead gave the best correlation between TcB and Sbr (r = 0.81, p < 0.05). However, during phototherapy no significant correlation between TcB and Sbr was observed. A correlation (r = 0.45, p < 0.05) was found between phototherapy and melanin index obtained from the patients' back.

CONCLUSIONS

Reflectance spectroscopy is useful in assessing bilirubin concentrations before phototherapy, and can also reveal changes in skin parameters such as pigmentation occurring as a result of phototherapy.

Detection of hyperbilirubinaemia in jaundiced full-term neonates by eye or by bilirubinometer?

The aim of this study was to compare predictions of hyperbilirubinaemia by eye, performed by trained physicians and nurses, with predictions obtained using two commercial bilirubinometers. Jaundice was assessed in 92 white and 48 non-white healthy full-term neonates using three non-invasive methods and by total serum bilirubin as the reference method. Clinical assessment of cephalocaudal progression of jaundice was carried out independently by a physician and by nurses. Simultaneously, the Minolta Airshields JM-102 was applied on the sternum, the BiliCheck on both the forehead and the sternum, and finally, serum bilirubin concentrations were determined. The Minolta JM-102 showed the best performance with r2 = 0.90, an intraclass correlation coefficient (ICC) of 0.93, and a 95% confidence interval (CI) of +/- 4 units (approx. 56 micromol/l). The BiliCheck performed slightly better on the forehead than over the sternum with r2=0.90, an ICC of 0.88, and a CI of +/- 62 microtmol/l. Assessment of jaundice by eye was least accurate with r2 = 0.74, an ICC of 0.67, and a CI of +/- 1.5 zones (corresponding to 75 Lmol/l). Skin pigmentation and ambient light both adversely affected noninvasive bilirubin estimation.

CONCLUSION

All three non-invasive methods are well suited for estimation of serum bilirubin but show large confidence intervals. In healthy term newborns, hyperbilirubinaemia (>250 Lmol/l) can be safely ruled out by eye if jaundice does not reach the abdomen or the extremities (Kramer zones 1 and 2), with < 22 units ( < 230 micromol/l) for the Minolta JM-102, or with a cut-off of 190 microlmol/l for the Bili-Check. If these respective thresholds are exceeded, serum bilirubin concentrations should be measured.

National Institute of Child Health and Human Development (NICHD) conference on kernicterus: a population perspective on prevention of kernicterus

This paper reviews barriers to the prevention of kernicterus. Reports of kernicterus cases persist. We do not know why kernicterus continues to occur or how best to prevent it. We need evidence for key recommendations that make clinical guidelines usable by practitioners caring for newborns, especially for practitioners providing ambulatory care in the first week of life. Data on prevalence and incidence, mortality and morbidity are essential for launching a kernicterus public health campaign. Modeling cost-effectiveness requires data on costs and benefits of alternative strategies for managing hyperbilirubinemia and preventing kernicterus and on parental preferences concerning follow-up in the first days of life. Understanding how existing patterns of care obstruct preventive care involves exploration of the roles of clinicians, health-care organizations, parents, and payers and purchasers of health care. Lastly, discovering how to motivate change in existing practices can provide the guidance needed to prevent kernicterus in the US.

Glucose-6-phosphate dehydrogenase deficiency: a hidden risk for kernicterus

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, a commonly occurring enzymatic defect, is an important risk factor in the pathogenesis of severe neonatal hyperbilirubinemia. Many of the recently reported cases of kernicterus, even in countries with a low overall incidence of the G-6-PD deficiency such as the United States and Canada, have been found to be enzyme deficient. In many cases the hyperbilirubinemia may be due to acute hemolysis precipitated by exposure to an identifiable chemical trigger, or to infection. In other cases the hemolysis may be mild, the hyperbilirubinemia being due to diminished bilirubin conjugation. An interaction between G-6-PD deficiency and promoter polymorphism for the gene encoding the bilirubin conjugating enzyme, UDP-glucuronosyltranferase 1A1, associated with Gilbert syndrome, has been implicated in the pathogenesis of hyperbilirubinemia. Neonates whose families originated in areas at high risk for G-6-PD deficiency should be vigilantly observed for jaundice. Phototherapy is the mainstay of treatment, with exchange transfusion being performed in those unresponsive to phototherapy. A high degree of physician awareness is essential in the identification and follow-up of these high-risk neonates.

Cost-effectiveness of strategies that are intended to prevent kernicterus in newborn infants

OBJECTIVE

There is concern about an increasing incidence of kernicterus in healthy term neonates in the United States. Although the incidence of kernicterus is unknown, several potential strategies that are intended to prevent kernicterus have been proposed by experts. It is necessary to assess the costs, benefits, and risks of such strategies before widespread policy changes are made. The objective of this study was to determine the direct costs to prevent a case of kernicterus with the following 3 strategies: (1) universal follow-up in the office or at home within 1 to 2 days of early newborn discharge, (2) routine predischarge serum bilirubin with selective follow-up and laboratory testing, and (3) routine predischarge transcutaneous bilirubin with selective follow-up and laboratory testing.

METHODS

We performed an incremental cost-effectiveness analysis of the 3 strategies compared with current practice. We used a decision analytic model and a spreadsheet to estimate the direct costs and outcomes, including the savings resulting from prevented kernicterus, for an annual cohort of 2,800000 healthy term newborns who are eligible for early discharge. We used a modified societal perspective and 2002 US dollars. With each strategy, the test and treatment thresholds for hyperbilirubinemia are lowered compared with current practice.

RESULTS

With the base-case assumptions (current incidence of kernicterus 1:100 000 and a relative risk reduction [RRR] of 0.7 with each strategy), the cost to prevent 1 case of kernicterus was 10,321463 dollars, 5,743905 dollars, and 9,191352 dollars respectively for strategies 1, 2, and 3 listed above. The total annual incremental costs for the cohort were, respectively, 202,300671 dollars, 112,580535 dollars, and 180,150494 dollars. Sensitivity analyses showed that the cost per case is highly dependent on the population incidence of kernicterus and the RRR with each strategy, both of which are currently unknown. In our model, annual cost savings of 46,179465 dollars for the cohort would result with strategy 2, if the incidence of kernicterus is high (1:10,000 births or higher) and the RRR is high (> or =0.7). If the incidence is lower or the RRR is lower, then the cost per case prevented ranged from 4,145676 dollars to as high as 77,650240 dollars.

CONCLUSIONS

Widespread implementation of these strategies is likely to increase health care costs significantly with uncertain benefits. It is premature to implement routine predischarge serum or transcutaneous bilirubin screening on a large scale. However, universal follow-up may have benefits beyond kernicterus prevention, which we did not include in our model. Research is required to determine the epidemiology, risk factors, and causes of kernicterus; to evaluate the effectiveness of strategies intended to prevent kernicterus; and to determine the cost per quality-adjusted life year with any proposed preventive strategy.

Understanding and preventing severe neonatal hyperbilirubinemia: is bilirubin neurotoxity really a concern in the developed world?

Although rare, extreme neonatal hyperbilirubinemia and its dreaded complication, kernicterus, continue to occur. Hyperbilirubinemia develops when bilirubin production exceeds the body's capacity to excrete it, primarily by conjugation. Genetic, environmental, and racial factors affecting the equilibrium between these processes are discussed. Adjuncts to the interpretation of the serum total bilirubin concentration are suggested. Prevention and management of severe hyperbilirubinemia should be based on American Academy of Pediatrics guidelines, with individualization including earlier institution of treatment and delayed discharge from the hospital for neonates with risk factors for kernicterus.

Comparison of skin sites for estimating serum total bilirubin in in-patients and out-patients: chest is superior to brow

OBJECTIVE

[corrected] To compare transcutaneous bilirubin readings from the chest and forehead of inpatient and outpatient infants to investigate whether one site is more accurate for estimating serum bilirubin concentration.

METHODS

In all, 31 infants were followed with serum and transcutaneous bilirubins using BiliChek trade mark at two skin sites.

RESULTS

For inpatients average chest bilirubin was 0.4 mg/dl (7 micromol/l) higher than serum while brow was 0.3 mg/dl (5 micromol/l) lower. For outpatients, skin readings from both sites underestimated serum values. Chest estimates were 0.6 mg/dl (10 micromol/l) lower; brow was 2.1 mg/dl (36 micromol/l) lower (p<0.0001). Correlation coefficients and mean differences between skin and serum values for Hispanic and non-Hispanic infants were similar.

CONCLUSIONS

In our inpatients, chest and brow readings approximated serum values. After discharge, brow readings were lower than serum values by almost 20%, while chest readings were underestimated by 5%. We recommend using the chest for transcutaneous bilirubin estimates.

Diagnosis and management of hyperbilirubinemia in the term neonate: for a safer first week

New data support restructuring the approach toward diagnosis and management of hyperbilirubenia in the term neonate to make it more physician-friendly and gain wider implementation. The authors advocate clear criteria for patient safety, preventive approaches, and timely interventions. Structural changes to facilitate a system-based approach should include predischarge bilirubin management; follow-up bilirubin management; and lactational support and nutritional management. The authors advocate total serum bilirubin screening and a scoring system based on clinical risk factors as predischarge screening strategies; we should screen all babies for hyperbilirubinemia and for targeted follow-up based on an hour-specific total serum bilirubin measured for risk assessment. We should also provide focused universal education emphasizing adequate lactational nutrition, to decrease severe hyperbilirubinemia and thus prevent kernicterus.

Immunizations, neonatal jaundice, and animal-induced injuries

PURPOSE OF REVIEW

Published studies during the past year about three topics important to the pediatric clinician-- immunizations, neonatal jaundice, and animal-induced injuries-are concisely reviewed.

RECENT FINDINGS

Recent updates regarding vaccines including the questionable link with autism, implementation of universal influenza vaccination for young children, the efficacy of pneumococcal vaccine against invasive disease, and new information on pertussis, varicella, hepatitis A, hepatitis B, measles, and rotavirus vaccination are discussed. No association between measles/mumps/rubella vaccine or thimerosal-containing pertussis vaccine and autism is evident. Universal influenza vaccination for children 6 to 23 months of age will be recommended for the 2004-2005 flu season, and this implementation should reduce significant school absenteeism as well as complications seen last year including encephalopathy, seizures, respiratory failure, and pneumonia. Pneumococcal vaccine significantly reduces rates of invasive pneumococcal vaccine in healthy and HIV-infected children, although it does not appear to greatly affect otitis media rates. A reduction in post-vaccine febrile seizures appears to be present since the introduction of acellular pertussis vaccine. Multiple outbreaks in varicella have been reported since the introduction of the varicella vaccine, and a booster vaccination may be necessary in the future. Methods for detecting and preventing severe neonatal hyperbilirubinemia are reviewed, as well as anticipated recommendations from the American Academy of Pediatrics for the detection and management of hyperbilirubinemia. High bilirubin levels in preterm infants may result in hearing dysfunction and developmental impairment. The American Academy of Pediatrics has recommended a higher level of monitoring for newborn jaundice and treatment of hyperbilirubinemia in an effort to prevent kernicterus and sequelae from elevated bilirubin levels, including post-discharge follow-up appointment by day 3 to 5 of age. Dog bites in children with resultant post-traumatic stress disorder, rabies, and salmonellosis from pet reptiles in the home are also addressed. Clinicians need to be aware of the risk for rabies bites, need to recognize that dog bites in children appear to cause post-traumatic stress disorder in more than half of cases, and need to know how to educate patients on how to prevent salmonellosis from pet reptiles and amphibians.

SUMMARY

Progress has been made in immunizations, especially immunization for influenza, pneumonia, and pertussis. It is recommended that monitoring for neonatal hyperbilirubinemia be more thorough to prevent the consequences of this condition. Rabies, post-traumatic stress disorder from dog bites, and salmonellosis associated with pet reptiles constitute an important area for patient education.

NICHD Conference on Kernicterus: Research on Prevention of Bilirubin-Induced Brain Injury and Kernicterus: Bench-to-Bedside--Diagnostic Methods and Prevention and Treatment Strategies

In July 2003, the National Institute of Child Health and Human Development (NICHD) organized a consensus conference, where a group of experts were invited to review and discuss the current state of knowledge regarding neonatal hyperbilirubinemia and identify areas in which where future research should be directed. This paper summarizes the presentations addressing the current methodologies for direct and noninvasive assessments of serum total bilirubin concentrations as well as prevention and treatment strategies for the management of neonatal hyperbilirubinemia.

An evidence-based review of important issues concerning neonatal hyperbilirubinemia

This article is adapted from a published evidence report concerning neonatal hyperbilirubinemia with an added section on the risk of blood exchange transfusion (BET). Based on a summary of multiple case reports that spanned more than 30 years, we conclude that kernicterus, although infrequent, has at least 10% mortality and at least 70% long-term morbidity. It is evident that the preponderance of kernicterus cases occurred in infants with a bilirubin level higher than 20 mg/dL. Given the diversity of conclusions on the relationship between peak bilirubin levels and behavioral and neurodevelopmental outcomes, it is apparent that the use of a single total serum bilirubin level to predict long-term outcomes is inadequate and will lead to conflicting results. Evidence for efficacy of treatments for neonatal hyperbilirubinemia was limited. Overall, the 4 qualifying studies showed that phototherapy had an absolute risk-reduction rate of 10% to 17% for prevention of serum bilirubin levels higher than 20 mg/dL in healthy infants with jaundice. There is no evidence to suggest that phototherapy for neonatal hyperbilirubinemia has any long-term adverse neurodevelopmental effects. Transcutaneous measurements of bilirubin have a linear correlation to total serum bilirubin and may be useful as screening devices to detect clinically significant jaundice and decrease the need for serum bilirubin determinations. Based on our review of the risks associated with BETs from 15 studies consisting mainly of infants born before 1970, we conclude that the mortality within 6 hours of BET ranged from 3 per 1000 to 4 per 1000 exchanged infants who were term and without serious hemolytic diseases. Regardless of the definitions and rates of BET-associated morbidity and the various pre-exchange clinical states of the exchanged infants, in many cases the morbidity was minor (eg, postexchange anemia). Based on the results from the most recent study to report BET morbidity, the overall risk of permanent sequelae in 25 sick infants who survived BET was from 5% to 10%.

Transcutaneous bilirubinometry in very low birthweight infants

AIM

To evaluate whether transcutaneous bilirubinometry (TcB) would be a reliable and efficient screening technique for hyperbilirubinaemia in very low birthweight (VLBW, < or =1500 g) infants in an intensive care unit setting.

METHODS

TcB measurements (Minolta Airshield Jaundice Meter JM-102, Osaka, Japan) were obtained immediately before or within 10 min following routine blood sampling for plasma bilirubin concentration measurements in 124 VLBW infants not receiving phototherapy. The relationship between the two techniques was analysed by linear regression analysis. A plasma bilirubin > or =150 micromol/l was defined as hyperbilirubinaemia. The sensitivity and specificity of possible TcB cut-off readings to detect hyperbilirubinaemia was evaluated.

RESULTS

There was a significant correlation between the measurements of both techniques (p < 0.0001, r = 0.68). In the present study, a TcB cut-off reading of 14 would have reduced the need for plasma bilirubin measurements by 26% without missing true hyperbilirubinaemia.

CONCLUSION

The data suggest that TcB will improve VLBW infant care in an intensive care unit setting by reducing the need for invasive bilirubin concentration measurements.

Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation

Jaundice occurs in most newborn infants. Most jaundice is benign, but because of the potential toxicity of bilirubin, newborn infants must be monitored to identify those who might develop severe hyperbilirubinemia and, in rare cases, acute bilirubin encephalopathy or kernicterus. The focus of this guideline is to reduce the incidence of severe hyperbilirubinemia and bilirubin encephalopathy while minimizing the risks of unintended harm such as maternal anxiety, decreased breastfeeding, and unnecessary costs or treatment. Although kernicterus should almost always be preventable, cases continue to occur. These guidelines provide a framework for the prevention and management of hyperbilirubinemia in newborn infants of 35 or more weeks of gestation. In every infant, we recommend that clinicians 1) promote and support successful breastfeeding; 2) perform a systematic assessment before discharge for the risk of severe hyperbilirubinemia; 3) provide early and focused follow-up based on the risk assessment; and 4) when indicated, treat newborns with phototherapy or exchange transfusion to prevent the development of severe hyperbilirubinemia and, possibly, bilirubin encephalopathy (kernicterus).

Neonatal jaundice: physiologic variation or pathologic process

Neonatal hyperbilirubinemia and jaundice affect approximately 60% of the 4 million newborns in the United States each year. Jaundice results from bilirubin deposition in the skin and mucous membranes, becoming clinically visible at a serum bilirubin level of 5 to 7 mg/dL. At a higher but undefined level, bilirubin may deposit in the brain where it can cause transient dysfunction or permanent neurologic impairment.

Transcutaneous bilirubin measurements and serum total bilirubin levels in indigenous African infants

OBJECTIVE

The objective of this study was to determine whether transcutaneous bilirubin (TcB) measurements correlate with serum total bilirubin (STB) levels in indigenous, darkly pigmented African newborns with varying degrees of skin pigmentation, some of which had developed kernicterus.

METHODS

Jaundiced infants who were < or =2 weeks of age and admitted to Baptist Medical Center-Eku (Eku; n = 29) and Jos University Teaching Hospital (Jos; n = 98) in Nigeria were studied. TcB measurements using the BiliChek were made simultaneously with blood sampling for STB measurements by spectrophotometry before phototherapy.

RESULTS

Using linear regression analysis, we found that measurements of TcB correlated well with those of STB with r values of.90 and.88 for Eku and Jos, respectively. Mean bias and imprecision of TcB measurements as compared with STB measurements for the total population was 0.5 +/- 7.6 mg/dL using the method of Bland and Altman. At STB > or 12 mg/dL, correlation (r =.84) and bias and imprecision (-1.2 +/- 8.6 mg/dL) of measurements were only slightly poorer. Furthermore, when infants were grouped by degree of skin pigmentation, correlations of TcB and STB measurements remained strong.

CONCLUSIONS

From these results, we can conclude that TcB measurements are a useful and reliable index for estimating STB levels in pigmented neonates, including those with hyperbilirubinemia and kernicterus. In the absence of reliable STB measurements, the relatively simple and noninvasive TcB measurements can be an important adjunct in directing phototherapy and exchange transfusions, thereby preventing bilirubin-induced morbidity and mortality in low-technology clinical environments.