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# Neonatal Jaundice ## Kernicterus Kernicterus (also called bilirubin encephalopathy) occurs when elevated serum bilirubin levels cause damage to the brain. The exact serum bilirubin level at which damage occurs is unknown. Premature infants are more susceptible to the development of kernicterus a...

# Neonatal Jaundice ## Kernicterus Kernicterus (also called bilirubin encephalopathy) occurs when elevated serum bilirubin levels cause damage to the brain. The exact serum bilirubin level at which damage occurs is unknown. Premature infants are more susceptible to the development of kernicterus at lower serum bilirubin levels because of the immaturity of their blood-brain barrier, causing it to be more permeable to bilirubin than in full term infants. Disease processes, such as acidosis or meningitis, further lessen the competency of the blood-brain barrier. Early signs of kernicterus are divided into three phases. * **Phase I:** Occurs during the first few days of life and is characterized by decreased alertness, hypotonia, and poor feeding. * **Phase II:** The onset and duration of this phase is variable. Hypertonia of the extensor muscles develops. Infants may display opisthotonos (extreme hyperextension or arching of the back) and/or retrocollis (extreme arching of the neck). * **Phase III:** This occurs generally after one week with the recurrence of hypotonia. ## Hyperbilirubinemia-Indications for Phototherapy and Exchange Transfusion Phototherapy is often used to treat hyperbilirubinemia to prevent the need for exchange transfusion. For phototherapy, the infant is placed under special lights (15-20 cm above the infant) that will decrease the bilirubin levels in the blood. Indications include: | Weight | Serum bilirubin level | |---|---| | 500 to 750 g | 5 to 8 mg/dL | | 751 to 1000 g | 6 to 10 mg/dL | | 1001-1250 g | 8 to 10 mg/dL | | 1251-1500 g | 10 to 12 mg dL | Exchange transfusions may be used for hyperbilirubinemia. Blood 15 mg/dL | | 1001-1250 g | 15-18 mg/dL | | 1251-1500 g | 17-20 mg/dL | There are many risks associated with exchange transfusions, including vascular complications, such as emboli or thrombosis, often related to umbilical catheters. Cardiac complications include dysrhythmias and overload, leading to arrest. Clotting disorders may result from over-heparinization (reversed with protamine sulfate). Electrolyte and glucose abnormalities as well as infection may occur. ## Phototherapy Phototherapy is commonly used to treat hyperbilirubinemia and jaundice when the total serum bilirubin (TSB) indicates the infant is at risk. Phototherapy is a treatment in which the infant is placed under special lights that decrease the bilirubin levels in the blood. The lights usually consist of one tungsten halogen lamp or 4-8 white or blue fluorescent lights and a Plexiglas® shield. The infant is placed under these lights with a protective mask covering the eyes to prevent retinal toxicity. The lights should be 15-20 cm above the infant. The lights convert bilirubin into a water-soluble compound that can be excreted by the liver into bile and eventually into the infant's stool. The success of phototherapy is directly related to the quantity of body surface area that is exposed to the lights, so the infant is clad only in a diaper to expose the most skin to the light as possible.