In Vitro Evaluation of The Efficacy and Safety of Light Emitting Diodes (LEDs) for Neonatal Phototherapy † 1175

Phototherapy (PT) is frequently used for the control of neonatal jaundice. Its efficacy is dependent on the irradiance, exposed body surface, and is optimal with blue light, which overlaps the bilirubin (BR) absorption spectrum. Current devices use broad wavelength light sources which can emit UV and/or IR radiation in addition to visible light outside the BR absorption spectrum. These wavelengths are mostly responsible for the reported side effects of PT through interaction with endogenous or administered photosensitizers (PS). We are developing PT devices using new gallium nitride-based blue, blue-green, green, and white LEDs. These low-weight, low-voltage, low-power devices emit narrow wavelength band (40nm) high intensity light. These characteristics allow for the design of portable PT devices with optimal efficacy and minimal potential side effects. We evaluated LED efficacy and safety with an in vitro model consisting of sets of 5mm diameter LEDs mounted on circuit boards over which we placed two-mL clear glass vials containing 25uL of 20mg BR/dL of 4% human serum albumin, 200uL 0.1M KPO4 buffer, pH 7.4, and 5uL volumes of natural, riboflavin (RF), or synthetic, tin mesoporphyrin (SnMP), photosensitizers to yield final concentrations of 5uM. The vials were exposed at 21°C to LED light and that of conventionally-used PT devices [Bili-Lite (Olympic Medical) and PhotoSpot (Healthdyne Technologies)] at the recommended distances given in (). After 30 min of light exposure, 800uL buffer was added and the BR concentration was measured by a UB Analyzer. We express efficacy as the mean±SD of% BR degraded compared to dark controls [n=5, (A)] and evaluate side effects as enhancement of% BR degraded in the presence of photosensitizers [(B), (C)]. The results show that:1) LED (contact) application was as effective at degrading BR as standard PT application at a distance; 2) LEDs enhance photosensitizing reactions with RF comparatively; and 3) the photosensitization with SnMP is minimal compared to control and much less than RF. We conclude that it is now possible to select an effective PT light source which can balance efficacy against potential side effects. Table

Table 1 No caption available.

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