PHOTO-THERAPY

PHOTO-THERAPY

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

 "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

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.

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.

some people who are around blue lights for prolonged periods will feel nauseated.  Yellow plastic placed on the outside of the isolate may mitigate this effect.  

 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. 

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.

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