Phototherapy efficacy depends on lamp output, exposed skin area, positioning, hydration, and minimal interruptions.
Lamps and irradiance
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Blue LED lamps have a long life of up to 50,000 hours, use less electricity, and deliver high irradiance that produces a faster decline in total serum bilirubin (TSB).
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Measure irradiance periodically and ensure a minimum of 30 microwatt/cm²/nm in the 460–490 nm wavelength range.
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Change lamps if irradiance falls below the specified level or according to the manufacturer's recommendation.
Exposure and supportive measures
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Expose the maximal skin surface area. For a neonate in an incubator, direct the light perpendicularly onto the neonate.
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Avoid obstructing light with equipment, a large diaper or eye patch, a cap, tape, dressings, or electrodes.
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Maintain hydration through frequent breastfeeding and minimize interruptions during feeding or procedures.
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Maintain an ambient temperature of 25–28°C to prevent hypothermia or hyperthermia. Remove clothing except the diaper; the illustrated setup includes an eye cover.
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White bed covers and curtains reflect the phototherapy light.
Suggested thresholds for preterm neonates below 35 weeks
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The table provides broad TSB thresholds in mg/dL by gestation and postnatal age. In the following sequences, ages are 24 hours, 48 hours, and 72 hours or more.
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For gestation below 28 weeks, phototherapy thresholds are 4–5, 6–8, and 7–10 mg/dL; exchange transfusion thresholds are 7–8, 10–12, and 13–16 mg/dL.
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For gestation of 28–31 weeks, phototherapy thresholds are 5–6, 8–9, and 10–12 mg/dL; exchange transfusion thresholds are 8–9, 12–13, and 16–18 mg/dL.
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For gestation of 32 weeks or more within this preterm table, phototherapy thresholds are 5–6, 9–10, and 12–14 mg/dL; exchange transfusion thresholds are 9–10, 14–15, and 18–20 mg/dL.
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Lower gestational age and lower postnatal age generally correspond to lower treatment cutoffs. The source advises consulting the charts rather than memorizing these broad thresholds.