What Light Type Is Used in Phototherapy for Jaundice?

Different bulbs and colors of light -- usually in the blue-green part of the spectrum -- penetrate skin and help the body clear the excess bilirubin that causes the yellow skin coloration of jaundice.

Jaundice is a condition in which the skin and whites of the eyes turn yellow due to bilirubin accumulation. Bilirubin is a naturally occurring compound when old, worn out red blood cells break up.

The liver normally metabolizes the bilirubin, which is excreted through the bile and the digestive system. This process may be inefficient or slow in a newborn, causing a build-up of bilirubin in the blood (hyperbilirubinemia) and the characteristic yellow coloration of jaundice.

Up to 60% of newborn babies develop jaundice within the first week of life. Some of the babies may have some underlying condition or enzyme deficiency, but transient inefficiency in processing the bilirubin is the cause for jaundice in a majority of the newborns.

Phototherapy is a relatively inexpensive and noninvasive treatment for jaundice in a newborn. The baby’s skin is exposed to certain types of lights at a specific wavelength until the bilirubin level goes down to normal.

Phototherapy has been effectively used for treating jaundice in newborn babies ever since light’s effects on bilirubin was first discovered in 1958. Phototherapy has greatly reduced the need for blood transfusions to treat severe hyperbilirubinemia in infants.

Exposure to light converts bilirubin into two types of water-soluble molecules which bypass the infant liver’s temporarily inefficient bilirubin metabolism. Some of the converted bilirubin molecules are also excreted in urine.

In a second process, the absorption of light causes the bilirubin molecules to react with oxygen allowing excretion through the urine.

Neonatal care units usually follow guidelines published by the American Academy of Pediatrics Subcommittee on Hyperbilirubinemia for phototherapy administration in infants born after 35 or more weeks of gestation.

Serum bilirubin levels measured in milligrams/deciliter usually dictate when doctors start phototherapy for premature babies born earlier than 35 weeks gestation. In these cases, the milligrams/deciliter of bilirubin in the blood is greater than five times the baby’s birth weight.

In addition to the total serum bilirubin levels, initiation of phototherapy also depends on other factors such as:

• Gestational age of the infant
• The infant’s age in hours at the time of testing
• Risk factors for hyperbilirubinemia and kernicterus (brain damage from hyperbilirubinemia)

Risk factors for development of hyperbilirubinemia and kernicterus in an infant include the following:

• Isoimmune hemolytic disease (breakdown of red blood cells due to fetal-maternal blood group incompatibility)
• Glucose-6-phosphate deficiency, which causes red blood cells to break down
• Asphyxia (oxygen deprivation)
• Temperature instability
• Sepsis
• Acidosis (acidic blood)
• Hypoalbuminemia (low albumin levels in the blood)

Phototherapy is not administered in the following situations:

• The baby is given any medication that has photosensitizing effects.
• Congenital erythropoietic porphyria, a rare inherited disorder that causes severe skin photosensitivity.

Following are the kinds of lights used in phototherapy for jaundice:

• Halogen lamps: Halogen lamps produce a warm white/yellow light. Care must be taken with these lights to avoid burns, overheating and dehydration in the baby.
• Fluorescent tubes: Special blue fluorescent tubes produce light in the blue-green spectrum which is highly effective in penetrating the skin and is well absorbed by bilirubin.
• Fiberoptic phototherapy: Fiberoptic phototherapy devices deliver light from a high intensity lamp to a fiberoptic blanket, known as Biliblanket. Biliblankets may be used with halogen, fluorescent or LED lights and are commonly used for home therapy in infants who do not have severe hyperbilirubinemia.
• LED phototherapy systems: LED phototherapy systems, which use gallium nitride LEDs, are the newest devices. These lights emit light at wavelengths that are most effectively absorbed by bilirubin and can be customized by using varying proportions of blue, blue-green and green lights. They generate very little heat and are safe to use relatively closer to the baby’s skin.

Nursing staff trained in neonatal care perform phototherapy for the newborn babies. Following are the steps taken during the procedure:

• Check bilirubin levels to determine need for phototherapy.
• Place the baby flat on a bassinet or a radiant warmer.
• Premature infants can be in an infant incubator.
• The baby is placed naked except for eye protection and a diaper to enable maximum skin exposure.
• Place the phototherapy device next to the baby’s bassinet.
• Switch on the lights and direct them to cover the baby’s entire body.
• Check bilirubin level four to six hours after start of therapy to check if phototherapy is effective.
• Monitor bilirubin levels every 12 to 24- hour intervals until levels are low enough for phototherapy to be stopped.
• Check bilirubin level 24 hours after discontinuation of phototherapy to determine presence of rebound jaundice, particularly in babies with any underlying conditions.

Jaundice improves considerably with 24 hours of intensive phototherapy, commonly with a 30% to 40% drop in bilirubin concentration in blood. Most infants require phototherapy for 24 to 48 hours, but some may require phototherapy for up to a week. Infants with severe hyperbilirubinemia may require blood transfusion if bilirubin levels do not drop significantly.

Phototherapy has been a safe and effective treatment for neonatal jaundice for over 40 years.

Side effects are rare and mild with phototherapy. Two potential complications of phototherapy are:

• Water loss through the skin because of heat from halogen lamps, particularly in premature babies who have immature skin. Water loss can be managed with additional fluid administration to the baby.
• Temporary dark, greyish brown discoloration of the skin in babies with cholecystic jaundice, a condition caused by obstruction in the bile flow. Known as bronzed baby syndrome, this condition goes away with the cessation of phototherapy.