|Factor||Mechanism/Clinical Relevance||Implementation and Rationale||Clinical Application|
|Spectrum of light emitted||Blue-green spectrum is most effective. At these wavelengths, light penetrates skin well and is absorbed maximally by bilirubin.||Special blue fluorescent tubes or other light sources that have most output in the blue-green spectrum and are most effective in lowering TSB.||Use special blue tubes or LED light source with output in blue-green spectrum for intensive PT.|
|Spectral irradiance (irradiance in certain wavelength band) delivered to surface of infant||↑ irradiance →||Irradiance is measured with a radiometer as μW/cm2 per nm. Standard PT units deliver 8–10 μW/cm2 per nm (Fig 6). Intensive PT requires >30 μW/cm2 per nm.||If special blue fluorescent tubes are used, bring tubes as close to infant as possible to increase irradiance (Fig 6). Note: This cannot be done with halogen lamps because of the danger of burn. Special blue tubes 10–15 cm above the infant will produce an irradiance of at least 35 μW/cm2 per nm.|
|↑ rate of decline in TSB|
|Spectral power (average spectral irradiance across surface area)||↑ surface area exposed||For intensive PT, expose maximum surface area of infant to PT.||Place lights above and fiber-optic pad or special blue fluorescent tubes* below the infant. For maximum exposure, line sides of bassinet, warmer bed, or incubator with aluminum foil.|
|→ ↑ rate of decline in TSB|
|Cause of jaundice||PT is likely to be less effective if jaundice is due to hemolysis or if cholestasis is present.||When hemolysis is present, start PT at lower TSB levels. Use intensive PT. Failure of PT suggests that hemolysis is the cause of jaundice. If ↑ direct bilirubin, watch for bronze baby syndrome or blistering.|
|(↑ direct bilirubin)|
|TSB level at start of PT||The higher the TSB, the more rapid the decline in TSB with PT.||Use intensive PT for higher TSB levels. Anticipate a more rapid decrease in TSB when TSB >20 mg/dL (342 μmol/L).|
PT indicates phototherapy; LED, light-emitting diode.
↵* Available in the Olympic BiliBassinet (Olympic Medical, Seattle, WA).