Neonatal hyperbilirubinemia (usually seen as jaundice) is a usually mild condition in newborns affecting up to 50% of neonates. Elevated bilirubin levels cause the skin and other tissues to look yellowish on inspection. Furthermore, high levels of bilirubin can cause bilirubin toxicity, then acute bilirubin encephalopathy and ultimately kernicterus--irreparable brain damage. Acute bilirubin encephalopathy and kernicterus are characterized by athetoid cerebral palsy--leading to involuntary, purposeless movements-- as well as auditory dysfunction, dental problems, and mental handicaps.
Mechanism of Action
Phototherapy lowers the concentration of bilirubin by enabling it to be more easily excreted. Blue light (430 to 490nm) matches the absorption spectrum of bilirubin and drives a photoreaction, transforming bilirubin into water-soluble products which can be excreted in urine and bile. A baby is typically exposed continuously over the course of one or more days. Efficacy depends on irradiance (light intensity); the American Academy of Pediatrics (AAP) intensive phototherapy standard is 30 μW/cm2/nm. Any light source that can provide the required color and power can be used, even filtered sunlight.
Current Use in High-Resource Settings
LED-based systems have become increasingly popular in high-resource settings for their intensive irradiance and low maintenance requirements. If phototherapy fails, exchange blood transfusions are used as a last resort. In the US fewer than 1% of neonatal hyperbilirubinemia patients require more than phototherapy.
Application in Low-Resource Settings
In resource limited settings, fluorescent devices are commonly used and are often locally produced. However, the commonly used fluorescent bulbs need frequent replacement. In practice such devices often have burnt out bulbs, or have bulbs that have been replaced with low irradiance white light which will only function at a fraction the prescribed effectiveness. Low cost LED units offer 10 year bulb lives while meeting the AAP intensive phototherapy standards. More radically, ultra low cost treatments under development include blue filters for use under direct sunlight.