Applied Evidence

Neonatal hyperbilirubinemia: An evidence-based approach

Author and Disclosure Information

 

References

Phototherapy: What kind of light, when to initiate

The initial management of hyperbilirubinemia is phototherapy. Light directed at the skin converts bilirubin to lumirubin—a compound that unlike bilirubin does not require conjugation in the liver and can be directly excreted in the urine or bile.8

No professional society currently recommends the use of TcB for the diagnosis of hyperbilirubinemia in infants <35 weeks’ gestation.

Light in the blue-green spectrum (460-490 nm) is most effective. Generally, phototherapy is more effective the closer the light is to the infant and the greater the surface area of skin the infant has exposed. There are many different types of lights used to provide phototherapy including fluorescent, halogen, light emitting diode (LED), and fiber optic lights, which are commonly used in home biliblankets.8 Fluorescent and halogen lights are the conventional methods, but newer LED systems are equally effective in terms of rate of decline of serum bilirubin levels, duration of phototherapy required, and need for exchange transfusion. Fiber optic lights work as well as other lights in preterm infants but are less effective in term infants. Using 2 fiber optic lights in term infants can increase efficacy to the level of a single conventional or LED source.32

Phototherapy thresholds. The AAP phototherapy curve (see Figure 3 at http://pediatrics.aappublications.org/content/114/1/297) is commonly used to determine phototherapy thresholds for infants with hyperbilirubinemia. This nomogram applies TSB level and age in hours to a “low,” “medium,” or “high” risk curve that is determined by the presence of neurotoxicity risk factors and gestational age. Infants on the “medium” and “high” risk curves have lower thresholds for initiation of phototherapy.9 The majority of infants born at gestational age ≥38 weeks being cared for in a newborn nursery will be assigned to a low risk curve on the AAP phototherapy nomogram, as many of the neurotoxicity risk factors that elevate risk would also be reasons for infants to be in an intensive care unit.

Online calculators and apps based on the AAP phototherapy nomogram, such as BiliTool (bilitool.org), offer recommendations for phototherapy thresholds and may suggest a time interval at which to repeat bilirubin testing if phototherapy is not indicated.

The additional work-up for infants requiring phototherapy often includes neonatal blood type, direct Coombs test, complete blood count and smear, and conjugated bilirubin level.9 Besser et al,33 however, found that 88% of infants requiring phototherapy had normal laboratory results. They also found that those infants with lab abnormalities often started phototherapy before 48 hours of age and did not have an appropriate decrease in bilirubin after initiation of phototherapy.

Continue to: Timing

Pages

Next Article: