Phototherapy (PT)

• TSB = Total Serum Bilirubin
• If used appropriately, phototherapy should lower the bilirubin level in all but the most vigorously hemolyzing infants

Indications

• when the patient has pathologic unconjugated hyperbilirubinemia
• On readmission, for treatment of TSB >= 20 (use therapeutic dose; many full-term infants are underdosed)
• In the NICU: as ppx to prevent TSB from reaching a dangerous level (use prophylactic dose)
• The AAP guidelines on PT in infants of 35 weeks or more gestation calls for the use of intensive phototherapy. Intensive PT implies the use of irradiance in the 430 to 490 nm band of at least 30 microwatts/cm2/nm delivered to as much of the infant's surface area as possible

How does it work?

• Light energy can change toxic native unconjugated 4Z-15Z bilirubin to:
  1. photorubin (4Z-15E bilirubin), an unconjugated configurational isomer (a reversible rxn that occurs in the bowel, away from light -> which is why 'rebound' can occur, unless ongoing hemolysis is occurring), which is excreted in bile.  Most bilirubin goes to photorubin.
  2. lumirubin, an unconjugated structural isomer (irreversible rxn), which is excreted in urine. Much less lumirubin is formed vs photorubin, but lumirubin is cleared from the serum much more rapidly.
  3. oxidized to monopyrroles, dipyrroles (only small amounts), excreted in urine, a slow process and only a minor contributor
• Photons are absorbed by bilirubin molecules in the skin and subcutaneous tissue, therefore the largest TSB drop occurs severe jaundice, when bilirubin has accumulated in the skin/subq.

What type of light is used?

• Bilirubin penetrates the skin and is absorbed maximally by bilirubin in the blue spectrum (420-490 nm)
• Light sources include: fluorescent tubes, light emitting diodes, tungsten, halogen and fiberoptic lights
• For intensive PT
  • Most effective "super blue" or "special blue" fluorescent tubes: F20T12/BB by GE, Westinghouse, Sylvania OR TL52/20W by Phillips, Eindhoven, the Netherlands
  • LED
  • another light source with blue-green output
• For standard (vs intensive) PT, virtually all light sources are effective.
  • broad-spectrum white, broad-spectrum blue
  • iregular' blue tubes (F20t12/B) provide much less radiance than special blue tubes
• Less effective: green light.
• UV light is NOT used for PT. Only a small amt of UV light is emitted by fluorescent tubes and halogen bulbs in wavelengths that do not cause erythema. Almost all the UV light is absorbed by the glass wall of the fluorescent tube and the acrylic glass (Plexiglass) of the PT unit

Procedure

• Continuous vs intermittent PT: If TSB >20, continuous PT until TSB down to a satisfactory level. Then can interrupt PT with feeding or brief visits with parents
• Monitor serum bili and Hct q4-8 hr in those infants with hemolytic dz or if near toxic levels
• Skin color: can't be relied upon for effectiveness of phototx, because you can appear jaundiced even if bili is increased.
• daily weights and urine output should be monitored every shift.

Factors that influence the efficacy of PT

1. Dosage
   • type of light source, see above
   • Spectral irradiance:
     • Measured in microwatts/cm2/nm. Can be measured with a radiometer recommended by the manufacturer of the PT system. AAP recommends measurements be taken below the center of the light. It is useful to perform periodic measurements.
     • a function of both distance and light source
     • Standard units deliver 8-10. Intensive PT delivers 30 or more.
     • if using special blue tubes, bring tubes as close as 10 cm (use an open bassinet, not incubator); do not do this with halogen, tungsten or any other spot PT because heat up considerable - burn danger. Putting special blue tubes 10-15 cm above infant will deliver at least 35 uW/cm2/nm and at this distance, naked term infants are comfortable and do not get cold or become overheated.
     • surface area exposed: for maximum exposure, line sides of bassinet, warmer bed or incubator with aluminum foil. Use fiberoptic pads (bili blanket). It is usually unnecessary to remove the diaper during phototherapy, unless TSB is rising and approaching exchange transfusion level. To keep control over the mess that loose phototherapy stools can cause, a surgeon's face mask may be used as an alternative to a diaper.  Protect retina with eye patches, because light can be toxic to the retina.
2. Cause of Jaundice: less likely to be effective if
   • jaundice is caused by hemolysis (start PT at a lower TSB level and use intensive PT. Failure of PT suggests hemolysis is the cause of jaundice
   • if cholestasis is present (high direct bilirubin -> watch for bronze baby syndrome or blistering)
3. TSB at start of PT: the higher the PT, the more rapid the decline in TSB with PT. Use intensive PT for higher TSB levels
4. Dark skin does not reduce efficacy of PT

How fast should TSB fall?

• Anticipate a more rapid decrease when TSB > 20 mg/dL. In some infants with TSB >30, TSB can drop as much as 10 within a few hours.
• For infants sent home and readmitted, intensive PT can cause a decline of TSB by 30-40% in the first 24 hours. The most significant decline occurs in the first 4 to 6 hours.

When to dc PT?

• depends on infant age at initiation of PT and cause of hyperbili
• If readmitted and  TSB > 20, dc when TSB <= 13
• If PT needed during birth-hospitalization, start PT at a lower threshold and stop at a lower level, since it is more likely that hemolytic disease is the cause, and significant rebound is more common.

What about rebound?

• usually 1-2 mg/dL rebound
• studies indicate it is unnecessary to keep an infant in the hospital to check for rebound
• however, if infant had sig hemolytic dz during birth hospitalization, do f/u TSB 24 hours after dc. (The AAP has repeatedly recommended f/u within 48 hours if a patient has been discharge at less than 48 hours of age, a recommendation that is widely ignored. BUT the recommendation has become stricter, and 2 day f/u is necessary if the infant has spent less than 72 hours in the hospital)
• if infant was re-admitted for PT, followup TSB is unnecessary due to low risk of hemolytic disease and rebound, however clinical assessement should be done a day after PT is dc'ed, and TSB can be obtained if clinically indicated

Complications

• remarkably safe
• reports of significant toxicity are exceptionally rare
• if cholestasis occurs "bronze baby syndrome" can occur: skin, serum and urine turn dark, greyish brown. Mechanism unknown, but may be related to porphyrins and other metabolites in plasma. The syndrome is not a contraindication to PT, but if TSB isn't falling, consider exchange tranfusion
• if patient has severe cholestatic jaundice, purpuric and bullous eruptions have been reported (rare)
• ABSOLUTE CONTRAINDICATION: congenital porphyria or family history of porphyria (severe blistering and photosensitivity), concomitant use of photosensitizing drugs

Notes

• Home phototherapy: recommended only at TSB levels 2 to 3 mg below those recommended for hospital PT.
• Sunlight is NOT recommended by the AAP, because a naked infant in the sun begs to be sunburned; even indoor exposure by a window is dangerous because of the variance of indoor temperatures.

Comments on fiberoptic blanket (BiliBlanket) phototherapy

• “There is no standardized method for delivering phototherapy…Some neonates with uncomplicated nonhemolytic jaundice may be treated with phototherapy at home… With proper instruction of the parents or guardians, phototherapy can be provided by using a freestanding device or a fiber optic blanket." Guidelines for Perinatal Care (ABP/ACOG)
• Pubmed Search string: ((hyperbilirubinemia) OR ("Hyperbilirubinemia, Neonatal"[Mesh])) AND ((blanket) OR (fiberoptic))
• Cochrane Study
• 1: Cochrane Database Syst Rev. 2001;(1):CD002060.
• Fibreoptic phototherapy for neonatal jaundice.  Mills JF, Tudehope D.
• Department of Neonatology, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia, 3052. millsj@cryptic.rch.unimelb.edu.au
• BACKGROUND: Phototherapy is used to treat newborn infants with hyperbilirubinaemia. Fibreoptic phototherapy is a new mode of phototherapy which is reported to lower serum bilirubin (SBR) while minimising disruption of normal infant care. OBJECTIVES: To evaluate the efficacy of fibreoptic phototherapy. SEARCH STRATEGY: The standard search strategy of the Cochrane Collaboration was used including searches of the Cochrane Controlled Trials Register, MEDLINE, EMBASE and discussion with experts in the field. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials evaluating the efficacy of fibreoptic phototherapy in the management of newborn infants with hyperbilirubinaemia. DATA COLLECTION AND ANALYSIS: Thirty-one studies were identified of which 24 met inclusion criteria. They evaluated the efficacy of fibreoptic phototherapy in a number of different clinical situations and patient populations. MAIN RESULTS: Fibreoptic phototherapy was more effective at lowering SBR than no treatment but less effective than conventional phototherapy (percentage change in SBR after 24 hours of treatment: WMD -10.7%, 95%CI -18.14, -3.26 and WMD 3.59%, 95%CI 1.27, 5.92 respectively). Fibreoptic phototherapy was equally as effective as conventional phototherapy in preterm infants and when two fibreoptic devices were used simultaneously (change in SBR after 24 hours of treatment: WMD 1.7%, 95%CI -2.65, 6.05 and change in SBR per day over whole treatment period: WMD 2.82%, 95%CI -1.84, 7.48 respectively). A combination of fibreoptic and conventional phototherapy was more effective than conventional phototherapy alone (duration of phototherapy: WMD -12.51 hr, 95%CI -16.00, -9.02, meta-analysis affected by heterogeneity). No conclusion can be made on the superiority of one fibreoptic device over another as the two studies comparing them (one favouring BiliBlanket, the other finding no difference) did not contain a common outcome measure. REVIEWER'S CONCLUSIONS: Fibreoptic phototherapy has a place in the management of neonatal hyperbilirubinaemia. It is probably a safe alternative to conventional phototherapy in term infants with physiological jaundice. No trials have been identified which support the widely-held view that fibreoptic devices interfere less with infant care or impact less on parent-child bonding.
• Lakartidningen. 2001 Nov 7;98(45):4964-5, 4968-9.
• [Fiberoptic phototherapy of neonatal jaundice. Comments to a Cochrane report]     [Article in Norwegian]    
• Hansen TW.  Nyfødtseksjonen, Barneklinikken, Rikshospitalet, Oslo, Norge. t.w.r.hansen@klinmed.uio.no.    Twenty-four studies filled the inclusion criteria for a Cochrane report on the use of fiberoptic phototherapy for neonatal jaundice. Fiberoptic phototherapy lowers serum bilirubin and may have a place in the treatment of neonatal jaundice. In term and near-term infants fiberoptic phototherapy is inferior to conventional phototherapy, whereas in premature infants the effects are comparable. A better effect is achieved when conventional and fiberoptic phototherapy are combined as compared to conventional phototherapy alone. Fiberoptic phototherapy has not been shown to interfere less with parent-infant bonding than conventional phototherapy. There continues to be a great need for research concerning phototherapy for neonatal jaundice.

References
Contemporary Pediatrics. A primer on phototherapy for the jaundiced newborn. Jun 1, 2005. By: M. Jeffrey Maisels, MB, BCH
and other sources
Maisels MJ, Conrad S. Transcutaneous bilirubin measurements in full-term infants. Pediatrics 1982;70:464-467.
Hyperbilirubinemia. In: Guidelines for Perinatal Care, Frigoletto FD and Little GA (eds). 1992, American Academy of Pediatrics, Elk Grove, IL, pp 208-210.