Phototherapy for Jaundice 

Updated: May 01, 2018
Author: Taylor L Sawyer, DO, MEd, FAAP, FACOP; Chief Editor: Dharmendra J Nimavat, MD, FAAP 

Overview

Background

Jaundice refers to the yellow appearance of the skin that occurs with the deposition of bilirubin in the dermal and subcutaneous tissue. Normally in the body, bilirubin is processed through the liver, where it is conjugated to glucuronic acid by the enzyme uridine diphosphate glucuronyl transferase (UGT) 1A1. This conjugated form of bilirubin is then excreted into the bile and removed from the body via the gut. When this excretion process is low following birth, does not work efficiently, or is overwhelmed by the amount of endogenously produced bilirubin, the amount of bilirubin in the body increases, resulting in hyperbilirubinemia and jaundice.

Jaundice occurs in as many as 60% of all normal newborns within the first week of life.[1] Jaundice in the newborn can occur from an underlying pathological condition, such as isoimmune hemolysis or an RBC enzyme deficiency. However, it is more commonly due to the normal physiological inability of the newborn infant to process bilirubin adequately due to the combined effects of increased RBC turnover and a transient deficit in bilirubin conjugation in the liver.[1] This type of nonpathologic jaundice is referred to as physiologic jaundice of the newborn.[2]

In most infants with physiologic jaundice, bilirubin concentrations do not rise to a point that requires treatment. However, in some infants with exaggerated physiologic jaundice, and in many infants with pathologic jaundice, bilirubin in the blood reaches very high concentrations that put the infant at risk for acute and chronic bilirubin encephalopathy (kernicterus). In these cases, treatment aimed at decreasing bilirubin concentration is required in order to avoid kernicterus. Etiologies of hyperbilirubinemia in newborns are provided in the image below.

Causes of hyperbilirubinemia in newborn infants. A Causes of hyperbilirubinemia in newborn infants. Adapted from Maisel MJ. Neonatal Jaundice. Pediatrics in Review. 2006; 27: p. 445.

Effective treatments to decrease bilirubin levels in infants with severe jaundice include phototherapy and exchange transfusion.

The effect of light on jaundice in neonates, and the ability of light to decrease serum bilirubin levels, was first described by Cremer et al in 1958.[3] This observation led to the development of light sources for use in the treatment of infants with hyperbilirubinemia, a treatment now referred to as phototherapy. Since its inception, phototherapy has been effectively used as a relatively inexpensive and noninvasive method of treating neonatal hyperbilirubinemia.[4, 5] The decline in the number or exchange transfusions in recent years is, at least in part, likely a direct reflection of the effectiveness of phototherapy at treating hyperbilirubinemia. In modern neonatal ICUs (NICUs) exchange transfusions are rare and are only used as a rescue therapy to avoid kernicterus in newborns with severe jaundice when phototherapy is inadequate.

At its most basic, phototherapy refers to the use of light to convert bilirubin molecules in the body into water soluble isomers that can be excreted by the body. The absorption of light by normal bilirubin (4Z,15Z-bilirubin) results in the creation of 2 isomeric forms of bilirubin: structural isomers and configurational isomers. The main structural isomer of bilirubin is Z-lumirubin. The main configurational isomer of bilirubin is 4Z,15 E -bilirubin. Configurational isomerization is reversible, and structural isomerization is irreversible. Both the configurational and structural isomers of bilirubin are less lipophilic than normal bilirubin and can be excreted into bile without undergoing glucuronidation in the liver. Some of the configurational isomers of bilirubin, however, revert back to the native form after excretion into bile and can be reabsorbed via enterohepatic circulation in the gut. Structural bilirubin isomers, like Z-lumirubin, can also be excreted in the urine.

The absorptions of light by bilirubin also results in the generation of excited-state bilirubin molecules that react with oxygen to produce colorless oxidation products, or photooxidation products. This process occurs more slowly than configurational or structural isomerization. Photooxidation products are primarily excreted in the urine. The image below provides a schematic of the conversion of normal bilirubin to configurational isomers, structural isomers, and photooxidation products and the respective routes of excretion from the body.

Mechanism of phototherapy: Blue-green light in the Mechanism of phototherapy: Blue-green light in the range of 460-490 nm is most effective for phototherapy. The absorption of light by the normal bilirubin (4Z,15Z-bilirubin) generates configuration isomers, structural isomers, and photooxidation products. The 2 principal photoisomers formed in humans are shown. Configurational isomerization is reversible and much faster than structural isomerization. Structural isomerization is slow and irreversible. Photooxidation occurs more slowly than both configurational and structural isomerization. Photooxidation products are excreted mainly in urine. Adapted from Maisel MJ, McDonagh AD. Phototherapy for Neonatal Jaundice. N Engl J Med. 2008;358:920-928.

Indications

Prior studies have shown that approximately 5-40 infants per 1,000 in the United States require phototherapy in the newborn nursery, and an equal number require readmission to the hospital for phototherapy after discharge from the nursery.[1] The specific total serum bilirubin concentration at which phototherapy should be initiated varies and depends on several factors, including the total serum bilirubin level, the infants gestational age, age of the infant in hours at the time of testing, and any individual risk factors for hyperbilirubinemia.

Risk factors for the development of severe hyperbilirubinemia and kernicterus include isoimmune hemolytic disease, glucose-6-phosphate deficiency, asphyxia, significant lethargy, temperature instability, sepsis, acidosis, and hypoalbuminemia (< 3g/dL).[6] To aid physicians in the decision on when to initiate phototherapy, the American Academy of Pediatrics Subcommittee on Hyperbilirubinemia developed guidelines on the management of hyperbilirubinemia in newborns 35 or more weeks’ gestation.[6] This guideline includes an algorithm for the management of jaundice in the newborn nursery as well as guidelines for the initiation of phototherapy based on total serum bilirubin levels, gestational age, age of the infant in hours, and individual risk factors.

No evidence-based guidelines are available on the indication for phototherapy in premature infants less than 35 weeks’ gestation. However, several commonly used reference texts provide tables.[7, 8] A commonly used rule of thumb in the NICU is to start phototherapy when the total serum bilirubin level is greater than 5 times the birth weight. Thus, in a 1-kg infant, phototherapy is started at a bilirubin level of 5 mg/dL; in a 2-kg infant, phototherapy is started at a bilirubin level of 10mg/dL and so on.[9]

This article discusses the clinical procedure for providing phototherapy for neonatal jaundice.

Contraindications

Few contraindications to phototherapy are recognized. These include the concomitant use of photosensitizing medications, a diagnosis of congenital erythropoietic porphyria, or a family history of porphyria.[1] Infants with cholestatic jaundice and direct hyperbilirubinemia who are exposed to phototherapy may experience a dark, gray-brown discoloration of the skin, commonly known as ”bronze-baby syndrome.” The etiology of this discoloration is unknown but is possibly due to porphyrin accumulation. The skin discoloration that occurs with bronze-baby syndrome is transient and disappears with the discontinuation of phototherapy.[1] The presence of direct hyperbilirubinemia is not a contraindication to phototherapy.[6]

Technical Considerations

Phototherapy Dose

The effectiveness of phototherapy at converting bilirubin into configurational isomers, structural isomers, and photooxidation products is determined by the dose of phototherapy provided to the infant. The dose of phototherapy depends on several factors, including the spectral wave length of light, the spectral irradiance delivered to the infant’s skin, and the total spectral power (average spectral irradiance delivered across the surface area of the infant). Factors that affect phototherapy are described in the image below.

Factors that affect phototherapy: The 3 factors th Factors that affect phototherapy: The 3 factors that affect the dose of phototherapy include the irradiance of light used, the distance from the light source, and the amount of skin exposed. Standard phototherapy is provided at an irradiance of 8-10 microwatts per square centimeter per nanometer (mW/cm2 per nm). Intensive phototherapy is provided at an irradiance of 30 mW/cm2 per nm or more (430–490 nm). For intensive phototherapy, an auxiliary light source should be placed under the infant. The auxiliary light source could include a fiber-optic pad, a light-emitting diode (LED) mattress, or a bank of special blue fluorescent tubes. Term and near-term infants should receive phototherapy in a bassinet and the light source should be brought as close as possible to the infant, typically within 10-15 cm. However, if halogen or tungsten lights are used, providers should follow the manufacturer recommendation on the distance of the light from the infant to avoid overheating. Preterm infant can be treated in an incubator, but the light rays from the phototherapy device should be perpendicular to the surface of the incubator to minimize light reflectance. Adapted from Maisel MJ, McDonagh AD. Phototherapy for Neonatal Jaundice. N Engl J Med. 2008;358:920-928.

Light in the blue region of the spectrum, near 460 nm, is most strongly absorbed by bilirubin. However, only light that penetrates the skin and is absorbed by bilirubin provides the needed photochemical effect. Tissue penetration increases as the wavelength of the light increases. Thus, one must balance the use of a higher wavelength of light, which more readily penetrates tissue, with the use of a wavelength that is more readily absorbed by bilirubin, which may penetrate less deeply. With this in mind, light in the 460-490 nm wavelength is probably the most effective for use during phototherapy.[1]

Spectral irradiance is measured in watts per centimeter, or microwatts per square centimeter per nanometer (mW/cm2 per nm) over a wavelength band. Higher spectral irradiance results in a more rapid decline in the bilirubin levels.[10] Spectral irradiance increases as the distance from the light source to the infant’s skin deceases.[6] Different phototherapy devices deliver significantly different levels of irradiance. The American Academy of Pediatrics defines standard phototherapy as 8-10 mW/cm2 per nm and intensive phototherapy as more than 30 mW/cm2 per nm in the 430-490 nm band.[6]

Spectral power increases as the amount of skin exposed to phototherapy increases. Ways to increase surface area exposure include removal of clothing and increasing the number of lights/lighting devices used to deliver phototherapy. Infants receiving phototherapy should be left only in their diaper, allowing adequate surface area exposure for phototherapy. The use of lights both above and below an infant effectively doubles the area of exposure. Several manufacturers produce fiberoptic pads that can be placed under the infant. The Bili Bassinet (Olympic Medical; Seattle, WA) is one commercial device that provides special blue fluorescent tubes that emit light in the 460-490 nm wavelength, both above and below the infant.

The dose of phototherapy, in mW/cm2 per nm, should be measured during phototherapy using a commercially available radiometer. These devices typically measure the spectral irradiance of phototherapy in the 425-475 or 400-480nm band wavelength. The radiometer used to measure irradiance should be the one recommended by manufacturer of the light source. Due to variance in the strength of phototherapy over the surface of the infant, and because measurements of spectral irradiance can differ greatly depending on where on the infant the measurement is made, taking several measures in different locations on the infant and averaging the values is important.[6]

Complication Prevention

Eye protection should be placed on all infants receiving phototherapy. The need for eye protection is based on animal data that phototherapy may be damaging to the retina.[11] Various commercially available infant eye shields are available for use. In addition to eye shields, many centers also prescribe lubricating eye drops (carboxymethylcellulose sodium) for infant receiving phototherapy. The infant's temperature should be closely monitored while receiving phototherapy. This is especially important in infant under halogen lights because these emit significant amounts of heat and can cause hyperthermia. Unclothed infants in basinets under fluorescent or light-emitting diode (LED) devices are at risk for hypothermia, especially if they are in an area with a low ambient temperature. Premature infants and infants unable to maintain body temperature in a basinet should be placed on a radiant warmer or in an isolette while receiving phototherapy in order to maintain normothermia.

The use of photosensitizing medications should be avoided while infants are receiving phototherapy. Medications used in the newborn period that have been linked to phototoxic reactions include nonsteroidal anti-inflammatory drugs (ibuprofen), diuretics (furosemide, hydrochlorothiazide), and certain antibiotics (doxycycline, tetracycline, ciprofloxacin, ofloxacin, levofloxacin, and sulfonamides). In general, however, photosensitivity from medications are most likely to occur after exposure to light in the UV-A (320- 400 nm) and UV-B (290-302 nm) ranges.[12] Because phototherapy does not produce significant UV-A or UV-B light, phototoxic reactions in infants receiving these medications are rare.[1]

Outcomes

Phototherapy has been safely used for the treatment of neonatal jaundice for over 40 years. Complications from phototherapy are rare and generally mild. The two most notable complications include increased insensible water loss and cutaneous reactions in infants with cholestatic jaundice receiving phototherapy.

Phototherapy with halogen spot lights can increase cutaneous blood flow and increase insensible water loss through the skin. This is especially important in premature infants whose skin barrier function is compromised due to immaturity and is more permeable to water. Contemporary studies in premature infants undergoing phototherapy with halogen spot lights have shown transepidermal water loss increases of 20-26%, despite constant temperature and relative humidity.[11, 13] Phototherapy is thought to increases skin blood flow by a mechanism known as photorelaxation.[14] The pathway of this mechanism is not completely understood but is believed to be caused by S-nitrosothiols mediated nitric oxide release.[15]

Due to this increase in insensible water loss, recommendations have been made to increase maintenance fluid by 10 mL/kg/d in premature infants exposed to conventional phototherapy.[15] Additional intravenous fluids are not required in term infants who are maintaining adequate oral intake.[6] Increases in transepidermal water loss in premature infants have not been documented with LED-based phototherapy.[1]

A dark, greyish-brown discoloration of the skin may develop in infants with cholestatic jaundice and direct hyperbilirubinemia exposed to phototherapy. This reaction is commonly referred to as bronzed-baby syndrome. This discoloration of the skin is transient and resolves with cessation of phototherapy.[1] Bolus and purpuric reactions of the skin have also been reported in infants with severe cholestatic jaundice receiving phototherapy. This is thought to be due to sensitization by accumulation of porphyrins.[1]

 

Periprocedural Care

Patient Education & Consent

Patient Instructions

Elements of Informed Consent

According to the American Academy of Pediatrics Clinical Practice Guidelines on the management of hyperbilirubinemia in infants 35 or more weeks’ gestation, all hospitals should provide verbal or written information to parents explaining jaundice, the need to monitor infants for jaundice, and details on how that monitoring should be done.[6] An a example of such a handout is provided by the American Academy of Pediatrics.

Equipment

Several devices can be used to provide phototherapy. These include tungsten-halogen lamps, fluorescent tubes, fiberoptic systems, and gallium nitride LED lights. All these devices are capable of emitting light in the 430-490 nm band at standard spectral irradiance levels of 8-10 mW/cm2 per nm. However, when intensive phototherapy is required either ”special blue” fluorescent tubes or specially designed LED devices should be used because these are the only devices that can reliably provide more than 30 mW/cm2 per nm in the 430-490 nm band.4 16

Halogen-based phototherapy lamps

Halogen-based phototherapy lamps, or spotlights, use a commercially available tungsten- halogen light bulb and direct a strong beam of white/yellow light towards the infant. These devices are typically free-standing on a pole, or available as part of a radiant warmer. Halogen-based spot lights are the most heat producing of all the available phototherapy lights. Care must be taken not to place the devices closer to the infant than recommended by the manufacturer to avoid overheating the infant. Additionally, due to the associated heat output, halogen lights may result in increased insensible water loss in infants receiving phototherapy.

See the image below.

Infant under Ohmeda halogen lamp with eye protecti Infant under Ohmeda halogen lamp with eye protection.

Fluorescent tubes

Fluorescent tubes used to deliver phototherapy have been classified as ”daylight,” ”blue,”’ and ”special blue.” A commercially available daylight tube is the F20T12/D (General Electric, Westinghouse, Sylvania). A commercially available blue florescent tube is the F20T12/B (General Electric, Westinghouse, Sylvania). Special blue fluorescent tubes include those labeled TL52/20W (Philips, Endhoven, The Netherlands) or F20T12/BB (General Electric, Westinghouse, Sylvania).

In prior clinical studies, only the special blue fluorescent tubes were able to reliably emit light at more than 30 mW/cm2 per nm in the 430-490 nm band.[16] Special blue tubes are most effective because they emit light in the blue-green spectrum, which penetrates skin well and is maximally absorbed by bilirubin. Fluorescent tubes are typically housed in a commercially available device which holds 4-8 tubes that are 24 inches. The device is typically attached to a pole and the height of the lighting device can be adjusted up and down. One commercially available device, the Bili Bassinet (Olympic Medical; Seattle, WA), contains special blue fluorescent tubes in a housing both above and below the infant.

Fiberoptic phototherapy

Fiberoptic phototherapy devices deliver light form a high intensity lamp to a fiberoptic blanket. These BiliBlanket devices are typically used in conjunction with overhead halogen, fluorescent, or LED systems. These devices are also commonly used to provide home phototherapy. A disadvantage of using fiberoptic pads is that they cover a fairly small surface area. Therefore, 2-3 pads may be needed to provide effective phototherapy.[16] This is one reason why home phototherapy is reserved only for use in low-risk infants with total bilirubin levels 2-3 mg/dL lower than that recommended for intensive phototherapy.[6] See the image below.

Infant under neoBLUE phototherapy light and lying Infant under neoBLUE phototherapy light and lying on fiberoptic phototherapy blanket.

LED phototherapy systems

LED phototherapy systems, which use gallium nitride LEDs, are the newest devices used to provide phototherapy. Gallium nitride LEDs emit high-intensity light in the blue-green portion of the spectrum within a narrow wavelength (460-485 nm).[17] LEDs offer some advantages to other phototherapy sources. Their narrow wavelength of emission is close to the wavelength at which light is maximally absorbed by bilirubin. Additionally, the spectral quality of the LED device can be customized by the use of varying proportions of blue, blue-green, and green LEDs. Also, LEDs generate less heat than either halogen or fluorescent lamps, and can thus be positioned very close to the skin without significant risk of overheating or burns.

Prior studies have shown that using an array of 600, 3-mm blue LEDs, at a short distance from an infant can achieve an irradiance of more than 200 mW/cm2 per nm.[17] Specially designed LED systems, such as the neoBLUE LED Phototherapy system (Natus Inc; San Carlos, CA), are recommended by the American Academy of Pediatrics for use during intensive phototherapy.[6] See the image below.

neoBLUE light-emitting diode (LED) phototherapy sy neoBLUE light-emitting diode (LED) phototherapy system.

Patient Preparation

Positioning

Infants receiving phototherapy should be placed lying flat on a radiant warmer or in a bassinet. Small or premature infants can remain in an infant incubator during phototherapy. The infant should be naked with the exception of eye protection and a diaper to maximize the surface area of skin exposed to light. The phototherapy device should be placed at the side of the infant’s bed with the light shining on the infant and covering as much surface area as possible.

When fluorescent tubes or LED devices are used, the infant should be placed as close as possible to the light source, typically within 10 cm.[6] This increases the spectral irradiance of the light delivered. Halogen-based devices emit greater amounts of heat than fluorescent or LED devices and therefore need to be positioned at a greater distance from the infant. Providers should follow the manufacturer’s recommendations on how far to position the halogen light source from the infant.

Fiberoptic pads can be positioned directly underneath the infant to provide an additional source of phototherapy. The fiberoptic pads do not emit significant heat. Due to their relatively hard surface, phototherapy pads should be used with caution in extremely low birth weight infants or other infants who are at risk for skin break down from pressure sores.

If phototherapy is provided through the top of an infant, incubator the light source should be kept perpendicular to the surface of the isolette to decrease light reflectance off the plastic, which diminishes the amount of light that reaches the infant inside the isolette. In cases of severe hyperbilirubinemia, white towels or aluminum foil can be placed around the interior of the bassinet to reflect light back on the infant and increase surface area exposure.[6]

Monitoring & Follow-up

Monitoring of serial bilirubin values in infants on phototherapy is important to confirm that the therapy is effective. With intensive phototherapy (>30 mW/cm2 per nm), a decrease in bilirubin concentration by 30-40% can be expected within the first 24 hours.[6] The most significant drop in bilirubin concentration is typically seen within the first 4-6 hours of phototherapy.[6] Thus, bilirubin concentrations are typically checked prior to the start of phototherapy, after 4-6 hours of phototherapy to confirm effectiveness, and then repeated at 12-24 hour intervals until levels are low enough to stop phototherapy. Although no standard is noted for the discontinuation of phototherapy, current guidelines suggest stopping phototherapy on infants 35 or more weeks’ gestation at birth readmitted after their birth hospitalization when the levels of total bilirubin fall below 13-14 mg/dL.[6]

For infants with hemolytic disease, and in those younger than 3-4 days, a ”rebound” bilirubin should be checked within 24 hours after discontinuation of phototherapy.[6] This 24-hour rebound bilirubin check can also be considered in infants 35 or more weeks’ gestation at birth with nonhemolytic jaundice who are readmitted with hyperbilirubinemia.[6]

No evidenced-based guidelines to indicate when phototherapy should be discontinued in premature infants. In general, phototherapy is stopped when the total serum bilirubin level is several points lower than when it was started. Most practitioners routinely check a rebound bilirubin in all premature infants within 24-48 hours after discontinuation of phototherapy, or sooner if a hemolytic process is present.

A study by Chang et al developed a prediction rule to estimate the probability of rebound hyperbilirubinemia after inpatient phototherapy. The prediction rule consists of 3 variables, gestational age < 38 weeks, younger age at phototherapy initiation, and total serum bilirubin relative to the treatment threshold at phototherapy termination.[18]

 

Technique

Approach Considerations

See the list below:

  • Determine if the infant requires phototherapy based on the infant total serum bilirubin level, the gestation age, hours of life, and individual risk factors using established guidelines form the American Academy of Pediatrics.[6]

  • Place infant on warmer or in bassinet with diaper on and eye protection in place.

  • Position phototherapy device at bedside with lights set at recommended distance from the infant. For fluorescent and LED lights, this is as close as possible to the infant’s skin, typically less than 10 cm.[6] If using a halogen spot light, the light should be kept at the manufacturer recommended distance to avoid overheating.

  • Turn on the phototherapy lights.

  • Direct light towards the infant with exposure of maximal surface area. If halogen spotlights are used, more than one light may be required to cover the entire infant with light. This is typically done with one light directed at the chest and head, with the second directed at the abdomen and legs.

  • Measure the spectral irradiance of the phototherapy setup with a commercially available radiometer in several areas over the surface of the infant and average the results.[6] See the image below.

    neoBLUE light-emitting diode (LED) phototherapy ra neoBLUE light-emitting diode (LED) phototherapy radiometer.
  • Follow serial bilirubin levels to ensure the phototherapy is effectively decreasing the bilirubin level.

  • Intermittently repeat measurements of the spectral irradiance and maintain the lights in the proper position to provide maximum benefit.