Newborn Nursery at LPCH

Frequently Asked Questions About Phototherapy

 

What wavelength of light is used?

What's the difference between "conventional" and "intensive" phototherapy?

Why are the baby's eyes covered?

What are the risks of phototherapy?

Does phototherapy pose any risk to caregivers?

How long is phototherapy usually needed?

How can phototherapy be maximized?

 

 

WHAT WAVELENGTH OF LIGHT IS USED?

Phototherapy lights emit light in the blue-green spectrum (wavelengths 430-490nm).  It is NOT ultraviolet light.

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WHAT'S THE DIFFERENCE BETWEEN "CONVENTIONAL" AND "INTENSIVE" PHOTOTHERAPY?

"Intensive phototherapy" means the irradiance of the light is at least 30µW/cm2 per nm as measured at the baby's skin below the center of the phototherapy lamp.  A hand-held radiometer can be used to measure the spectral irradiance emitted by the light.  Because measurements taken directly under the lights will be higher, measurements should ideally be made at several locations and averaged.  The appropriate radiometer will vary based on the phototherapy system used, so manufacturer recommendations should be followed.

With "Conventional phototherapy" the irradiance of the light is less, but actual numbers vary significantly between different manufacturers.  In general, it is not necessary to rountinely measure irradiance when administering phototherapy, but units should be checked periodically to ensure that the lamps are providing adequate irradiance, according to the manufacturer's guidelines.

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WHY ARE THE BABY'S EYES COVERED?

In adults, prolonged exposure to blue light can cause retinal damage.  Although retinal damage from phototherapy has not been reported, eye covers for newborns are standard prophylaxis.

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WHAT ARE THE RISKS OF PHOTOTHERAPY? 

A rare complication (bronze baby syndrome) occurs in some infants with cholestatic jaundice when treated with phototherapy.  With  exposure to phototherapy lamps, these infants develop a dark, gray-brown discoloration of skin, urine, and serum.  Although the exact etiology is not understood, this effect is thought to be the result of an accumulation of porphyrins and other metabolites.

Another possibility is the development of purpura or bullae in infants with cholestatic jaundice or congenital erythropoietic porphyria.  Because the photosensitivity and blistering can be severe in infants with porphyria, infants who have this diagnosis or a positive family history for this disorder, have an absolute contraindication for phototherapy.

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DOES PHOTOTHERAPY POSE ANY RISK TO CAREGIVERS?

No, although some people who are around blue lights for prolonged periods will feel nauseated.  Yellow plastic placed on the outside of the isolette may mitigate this effect.

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HOW LONG IS PHOTOTHERAPY USUALLY NEEDED?

There are no specific guidelines for when to discontinue phototherapy.  Evidence of hemolysis and age of the infant will impact the duration.  In some cases, phototherapy will only be needed for 24 hours or less, in some cases, it may be required for 5 - 7 days.  The AAP Guidelines suggest that an infant readmitted for hyperbilirubinemia, with a level of 18 mg/dL or more, should have a level of 13 - 14 mg/dL in order to discontinue phototherapy.  In general, serum bilirubin levels should show a significant decrease before the lights are turned off. 

Physical examination for jaundice is not helpful once treatment has started as the yellow color of the skin is temporarily "bleached" by the phototherapy.

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HOW CAN PHOTOTHERAPY BE MAXIMIZED?

The effectiveness of phototherapy is determined largely by the distance between the lamps and the infant, so phototherapy can easily be intensified by bringing the lamps closer to the infant.  Because a closed isolette does not allow the lamps to be moved in close, if there is a concern about the effectiveness of phototherapy, an isolette should not be used.  With the infant in an open bassinet, it is possible to bring the lamps to within 10 cm of the infant.  An undressed term infant with not be overheated with this arrangement, however is is important that halogen spotlights NOT be used.  Halogen lights can get hot, and burns may result if used this way.  Special blue, regular blue, and cool white lights are all acceptable alternatives.

Increasing the skin surface area exposed to phototherapy will also maximize treatment.  Commonly, an overhead phototherapy unit is combined with a bili blanket that can be place under the infant.  Some of these blankets or pads are rather small, so 2 or 3 of these units may be needed to supply more complete coverage from below.  Lining the sides of the bassinet with white blankets or aluminum foil can also increase the effectiveness of phototherapy.

JAbyMD, 5-06

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