Update on Phototherapy in Jaundiced Neonates.

BACKGROUND: Even relatively low serum bilirubin concentrations can cause neurodevelopmental impairment in extremely low birth weight (EBWL) infants, while sequelae from hyperbilirubinemia in late preterm and term infants are rare and occur only at very high serum bilirubin levels. Phototherapy is the current treatment of choice.

OBJECTIVE: To present an update on the most important issues involved in phototherapy for jaundiced infants.

RESULTS: Light absorption by bilirubin in the skin transforms the native Z,Z-bilirubin to conformational photoisomers Z,E-bilirubin and E,Z-bilirubin and structural photoisomers E,Z-lumirubin and E,E-lumirubin. Formation and excretion of Z,E-bilirubin and E,Z-lumirubin are both important routes of elimination of bilirubin through bile and urine, although the precise contributions of the various photoisomers to the overall elimination of bilirubin are unknown. It appears that the photoisomers of bilirubin are predominantly formed in the plasma, and the rate of formation is affected by the hemoglobin concentration. Phototherapy lights with an emission spectrum of 460-490 nm provide the most efficient bilirubin-reducing light. LEDs should replace fluorescent tubes and halogen spotlights as the preferred light sources. Recent data raise concerns that sick ELBW infants under prolonged phototherapy may have an increased risk of death, though survivors may benefit from reduced rates of neurodevelopmental impairment. Comparison of the efficacy of cycled vs. continuous phototherapy has given divergent results. Changing the infant's position does not increase the efficacy of phototherapy.

CONCLUSION: During the last decade, we have made progress in our understanding of how and where phototherapy works and in its practical applications.