Relationship between transcutaneous bilirubin and circulating unbound bilirubin in jaundiced neonates

Skin thickness in preterm neonates: relationship with skin bilirubin and predicted mortality

This study investigates the relationship between the thickness of skin in preterm infants and its link with bilirubin and mortality, as this may help understanding the potential deleterious effects of phototherapy. Observational, prospective cohort study enrolling preterm neonates needing phototherapy and admitted to a neonatal intensive care unit. Transcutaneous bilirubin (TcB) and blood bilirubin were simultaneously measured before the onset of phototherapy, if any. The skin depth was measured by high-frequency point-of-care ultrasound. Mortality risk was estimated using the critical risk index for babies-II. Correlations and multivariate regressions (adjusting for several confounders) were applied to study the relationship between skin depth, TcB, and predicted mortality. One hundred fifty-nine neonates were studied. There was a positive and steady correlation between skin depth and TcB (r = 0.402 (95%CI: 0.206; 0.568), p < 0.001) and inverse correlation between skin depth and predicted mortality (r = -0.503 (95%CI: -0.61; -0.37), p < 0.001) as well as between TcB and predicted mortality (r = -0.303 (95%CI: -0.49; -0.09), p = 0.005). Multivariate analyses showed skin depth to be the strongest risk factors associated with both increasing TcB (β = 198 (59;338), p < 0.001) and decreasing risk of death (β = -24 (-46;2), p = 0.049). Blood bilirubin and gestational age were also associated with TcB and predicted mortality, respectively.   Conclusion: In NICU-admitted preterm infants, thicker skin is associated with higher TcB levels irrespective of gestational age. Greater skin depth is also associated with lower predicted mortality irrespective of blood bilirubin. What is Known: • In preterm infants, phototherapy may improve neuro-developmental outcomes but, particularly in the smallest and sickest ones, may increase mortality. • Mechanisms behind this effect are unclear but could involve the small thickness of preterm skin. This however has never been studied in relationship with bilirubin and mortality. What is New: • In NICU-admitted preterm infants, thicker skin is associated with higher levels of transcutaneous bilirubin, irrespective of gestational age and with lower predicted mortality, irrespective of blood bilirubin. • These data suggest that a thinner skin may contain less bilirubin to be photoisomerised and protect internal tissues less efficiently.

Hyperbilirubinemia and retinopathy of prematurity: a retrospective cohort study

Retinopathy of prematurity (ROP) is a vasoproliferative retinal disease in preterm infants. Oxidative stress plays a key role in the pathogenesis of ROP. Due to its antioxidant effects, bilirubin has been proposed to be protective against ROP. This study explored the association between hyperbilirubinemia and ROP. We analyzed a 10-year cohort from a neonatal intensive care unit in Milan, Italy, including 1606 infants born under 32 weeks and/or < 1500 g. Data from 1606 infants meeting specific inclusion criteria were reviewed. Eighty infants were excluded due to lack of data, 1526 were deemed eligible for analysis, and 1269 had hyperbilirubinemia requiring phototherapy. There was a higher incidence of ROP among infants with hyperbilirubinemia (13.8%) versus those without (7.8%, p<0.01). Infants with any ROP, non-severe or severe ROP, were exposed to hyperbilirubinemia for a significantly higher number of days compared with those without ROP. Each additional day of exposure increases the risk of developing any ROP by 5%, non-severe ROP by 4%, and severe ROP by 6%. However, this correlation was not observed in infants with gestational age less than 27 weeks and/or body weight less than 1000 g.    Conclusion: Our data show that hyperbilirubinemia requiring phototherapy is associated with an increased risk of developing ROP. However, severe hyperbilirubinemia and ROP share many of their risk factors. Therefore, rather than being a risk factor itself, hyperbilirubinemia may be a surrogate for other risk factors for ROP.    Clinical Trial Registration: NCT05806684. What is Known: • The development of retinopathy of prematurity (ROP) is influenced by several critical risk factors, including low gestational age, low birth weight, supplemental oxygen use, and increased oxidative stress. • In vitro, unconjugated bilirubin is an effective scavenger of harmful oxygen species and a reducing agent, highlighting its potential protective role against oxidative stress. What is New: • Hyperbilirubinemia requiring phototherapy was associated with an increased risk of developing ROP, but this association was not observed in the most vulnerable population of extremely preterm infants. • Every additional day of phototherapy for hyperbilirubinemia increases the risk of ROP by 5% for any ROP, 4% for non-severe ROP, and 6% for severe ROP.

Impact of Protein Binding Capacity and Daily Dosage of a Drug on Total Serum Bilirubin Levels in Susceptible Infants

Hyperbilirubinemia is a common pathological condition in neonates. Free bilirubin can penetrate the blood-brain barrier (BBB), which can lead to bilirubin neurotoxicity. In the context of predicting the risk of bilirubin neurotoxicity, although the specificity and sensitivity of free bilirubin levels are higher than those of total serum bilirubin (TSB), free bilirubin is not widely monitored in clinical practice. The threshold TSB levels at which phototherapy must be administered have been established previously. However, TSB levels are not well correlated with neurodevelopmental outcomes. Currently, TSB levels are commonly used to guide phototherapy for neonatal hyperbilirubinemia. Some clinical drugs can displace bilirubin from its albumin-binding sites, and consequently upregulate plasma bilirubin. Daily dosages play a vital role in regulating bilirubin levels. A drug with both a high protein binding capacity and high daily dosage significantly increases bilirubin levels in infants. Premature or very low birth weight (VLBW) infants are vulnerable to the upregulation of bilirubin levels as they exhibit the lowest reserve albumin levels and consequently the highest bilirubin toxicity index. Because bilirubin is involved in maintaining the balance between pro-oxidant and antioxidant agents, the downregulation of bilirubin levels is not always desirable. This review provides insights into the impact of protein binding capacity and daily dosage of drugs on the bilirubin levels in susceptible infants.

History and current standard of postnatal management in hemolytic disease of the fetus and newborn

Since the discovery of the Rh blood group system in 1940, a greater understanding of hemolytic disease of the fetus and newborn (HDFN) was gained. In the years thereafter, researchers and clinicians came to the current understanding that fetal and neonatal red blood cells (RBC) are hemolyzed by maternal alloantibodies directed against RBC antigens potentially leading to severe disease. Preventative measures, such as Rhesus(D) immunoprophylaxis (RhIG), have greatly decreased the prevalence of Rh(D)-mediated HDFN, although a gap between high-income countries and middle- to low-income countries was created largely due to a lack in availability and high costs of RhIG. Other important developments in the past decades have improved the identification, monitoring, and care of pregnancies, fetuses, and neonates with HDFN. Prenatally, fetal anemia may occur and intrauterine transfusions may be needed. Postnatally, pediatricians should be aware of the (antenatally determined) risk of hemolysis in RBC alloimmunization and should provide treatment for hyperbilirubinemia in the early phase and monitor for anemia in the late phase of the disease. Through this review, we aim to provide an overview of important historic events and to provide hands-on guidelines for the delivery and postnatal management of neonates with HDFN. Secondarily, we aim to describe recent scientific findings and evidence gaps.

CONCLUSION

 Multiple developments have improved the identification, monitoring, and care of pregnancies and neonates with HDFN throughout the centuries. Pediatricians should be aware of the (antenatally determined) risk of hemolysis in RBC alloimmunization and should provide treatment for hyperbilirubinemia in the early phase and monitor for late anemia in the late phase of the disease. Future studies should be set in an international setting and ultimately aim to eradicate HDFN on a global scale.

WHAT IS KNOWN

• Developments have led to a greater understanding of the pathophysiology, an improved serological identification and monitoring of at-risk cases and the current pre- and postnatal treatment.

WHAT IS NEW

• This review provides the pediatrician with hands-on guidelines for the delivery and postnatal management of neonates with HDFN. • Future studies should be set in an international setting with the ultimate aim of eradicating HDFN.

Increased Total Serum Bilirubin Level Post-Ibuprofen Use Is Inversely Correlated with Neonates' Body Weight

Backgrounds: Drugs with the ability to displace bilirubin from albumin-binding sites subsequently leading to an increased bilirubin level may cause hyperbilirubinemia in neonates. Ibuprofen is commonly used to treat patent ductus arteriosus (PDA) in neonates, yet the use of ibuprofen has drawn mixed conclusions. We performed a retrospective study to determine how ibuprofen use influences the total serum bilirubin (TSB) level in neonates of differing birth weight (BW). Materials and methods: Neonates (including premature infants) born at Chang Gung Memorial Hospital, Taiwan during January 2004 to July 2020 were entered into this study. We recorded the phototherapy duration, including the initial day and end day, and determined the average influence of one-day phototherapy on TSB level. The highest monitored TSB level post-ibuprofen use minus the one measured prior to ibuprofen use was considered the TSB change following ibuprofen administration in this study, and the above-mentioned influence of daily phototherapy on the TSB level was used to correlate the results. Neonates with any of the following conditions were excluded: those who received ceftriaxone, those with intraventricular hemorrhage, and those infected with TORCH. Results: The average daily influence of phototherapy on the TSB level of neonates was −0.20 (−0.57~0.05) mg/dL, −0.28 (−0.84~0.13) mg/dL, −0.75 (−1.77~0.10) mg/dL, and −1.60 (−2.70~−0.50) mg/dL in neonates with BWs of <1 kg, 1−1.49 kg, 1.5−2.49 kg, and ≥2.5 kg, respectively, indicating that neonates with a BW ≥ 1.5 kg experienced a greater reduction in TSB level following phototherapy as compared with those with a BW < 1.5 kg. The average TSB increase following ibuprofen use in neonates was 3.38 ± 2.77 mg/dL, 2.04 ± 2.53 mg/dL, and 1.34 ± 2.24 mg/dL in neonates with BWs of <1 kg, 1−1.49 kg, and ≥1.5 kg, respectively, i.e., an elevated TSB change with a decreased neonate BW was noted post-ibuprofen use (p = 0.026, one-way analysis of variance (ANOVA)). Conclusions: As ibuprofen use is correlated with an apparent increase in TSB level in neonates with a lower BW, especially in those with a BW < 1 kg, iv acetaminophen can be an appropriate alternative to ibuprofen for ELBW neonates for the treatment of PDA if they are experiencing severe unconjugated hyperbilirubinemia.

Change to Hearing Loss-Related Risks and Screening in Preterm Infants

Hearing loss is one of the most common congenital defects in infancy; it increases speech and language delays and adversely affects academic achievement and socialemotional development. The risk of hearing loss in premature infants is higher than that in normal newborns, and because of the fragility of the auditory nervous system, it is more vulnerable to different risk factors. The hearing screening guidelines in current use were proposed by the American Academy of Pediatrics and updated in 2007, but there are no uniform guidelines for hearing screening in preterm infants. This review focuses on the risk factors related to hearing loss in premature infants, hearing screening strategies, and reasons for failure. The aim is to provide a more comprehensive understanding of hearing development in preterm infants to achieve early detection and early intervention. At the same time, attention should be paid to delayed auditory maturation in preterm infants to avoid excessive intervention. KEY POINTS: · Hearing loss is very common in infancy, especially in premature infants.. · Genetic factors, infection, hyperbilirubinemia, drugs, and noise are the main causes.. · We should pay attention to the delayed hearing maturity of premature infants and avoid excessive intervention..

The effect of different intravenous lipids on free bilirubin levels in premature infants

BACKGROUND

Intravenous lipid emulsions are commonly used as a part of parenteral nutrition in premature infants. The potential bilirubin-displacing effects of high free fatty acid (FFA) levels during lipid infusions are known. Levels of free bilirubin (FB) predict the risk of bilirubin neurotoxicity more accurately than indirect serum bilirubin levels. In the present study, we decided to compare the effect of two different lipid solutions on free bilirubin and free fatty acids levels in premature infants.

METHODS

Infants were grouped into two groups according to intravenous lipid preparations: Infants in Group 1 received lipid emulsion containing olive oil + soybean oil and Group 2 received containing olive oil + soybean oil + fish oil. The blood samples were gained when lipid intake was 3.5 g/kg/day and FFA and FB levels were analyzed.

RESULTS

Serum FFA and FB levels were similar in groups (p = 0.26 and 0.69 respectively). There were significant correlation between serum FFA and FB levels in Group 1 (r = 0.74, p < 0.001) and in Group 2 (r = 0.92, p < 0.001).

CONCLUSION

Both lipid preparations seem to have similar effects on free bilirubin and free fatty acid levels in premature newborns.

Prediction of the need for phototherapy during hospital stay in preterm infants by transcutaneous bilirubinometry

BACKGROUND

Neonatal hyperbilirubinemia is a common condition that frequently requires treatment with phototherapy and less commonly by exchange transfusion, especially in preterm infants. It is important to identify and monitor infants at risk of severe unconjugated hyperbilirubinemia early in the postnatal period to instigate appropriate management plans.

AIMS

To evaluate transcutaneous bilirubinometry (TCB) as a screening tool at 24 and 48 h of age to predict the need for phototherapy during hospital stay in preterm infants.

STUDY DESIGN

A single centre prospective cohort study in a level III perinatal centre.

SUBJECTS

Preterm infants (23⁺⁰ to 36⁺⁶ weeks of gestation) were eligible for enrolment.

OUTCOME MEASURES

Primary outcome was to assess the predictive value of TCB at 24 and 48 h of age for the need of phototherapy during hospital stay.

RESULTS

A total of 338 preterm infants were enrolled. The majority of infants (98.1%) born below 32 weeks of gestation required phototherapy. For infants born at >31 + 6 weeks of gestation, TCB at 24 h of age ≥81 μmol/l had sensitivity 83%, specificity 56%, positive predictive value (PPV) 54.7% and negative predictive value (NPV) 84%. TCB at 48 h of age ≥145 μmol/l had sensitivity 65%, specificity 62%, PPV 24% and NPV 90%.

CONCLUSION

TCB performed poorly at 24 and 48 h of age as a predictor of phototherapy during hospital stay in preterm infants. The negative predictive value of the test at 48 h of age might be helpful for infants born after 31 + 6 weeks of gestation.