Correction: The effect of light wavelength on in vitro bilirubin photodegradation and photoisomer production.

Following publication of this article, the authors noticed that an incorrect affiliation was assigned to the author "Lucie Muchová". The original article has now been updated so that the author "Lucie Muchová" is associated with the "Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University, Katerinská 32, 120 00 Prague, Czech Republic". This has been corrected in both the PDF and HTML versions of the article.

The effect of light wavelength on in vitro bilirubin photodegradation and photoisomer production.

BACKGROUND: The action spectrum for bilirubin photodegradation has been intensively studied. However, questions still remain regarding which light wavelength most efficiently photodegrades bilirubin. In this study, we determined the in vitro effects of different irradiation wavelength ranges on bilirubin photodegradation. METHODS: In our in vitro method, normalized absolute irradiance levels of 4.2 × 1015 photons/cm2/s from light-emitting diodes (ranging from 390-530 nm) and 10-nm band-pass filters were used to irradiate bilirubin solutions (25 mg/dL in 4% human serum albumin). Bilirubin and its major photoisomer concentrations were determined; the half-life time of bilirubin (t1/2) was calculated for each wavelength range, and the spectral characteristics for bilirubin photodegradation products were obtained for key wavelengths. RESULTS: The in vitro photodegradation of bilirubin at 37 °C decreased linearly as the wavelength was increased from 390 to 500 nm with t1/2 decreasing from 63 to 17 min, respectively. At 460 ± 10 nm, a significantly lower rate of photodegradation and thus higher t1/2 (31 min) than that at 500 nm (17 min) was demonstrated. CONCLUSION: In our system, the optimum bilirubin photodegradation and lumirubin production rates occurred between 490 and 500 nm. Spectra shapes were remarkably similar, suggesting that lumirubin production was the major process of bilirubin photodegradation.

Phototherapy device effectiveness in Nigeria: irradiance assessment and potential for improvement.

This study investigated the effectiveness of simple-to-implement adjustments of phototherapy devices on irradiance levels in a cross-section of Nigerian hospitals. A total of 76 phototherapy devices were evaluated in 16 hospitals while adjustments were implemented for a subset of 25 devices for which consent was obtained. The mean irradiance level was 7.6 ± 5.9 µW/cm(2)/nm for all devices prior to adjustments. The average irradiance level improved from 9.0 µW/cm(2)/nm to 27.3 µW/cm(2)/nm for the adjusted group (n = 25) compared with 6.8 ± 5.4 µW/cm(2)/nm for the unadjusted group (n = 51). Simple, inexpensive adjustments to phototherapy devices with sub-optimal irradiance levels can significantly improve their effectiveness to acceptable international standards and should be widely promoted in resource-constrained settings.

The need to implement effective phototherapy in resource-constrained settings.

Phototherapy is the treatment of choice to reduce the severity of neonatal unconjugated hyperbilirubinemia regardless of its etiology. Its implementation requires a technical framework that conforms to existing evidence-based guidelines that promote its safer and effective use worldwide. Optimal use of phototherapy has been defined by specific ranges of total serum bilirubin thresholds configured to an infant's postnatal age (in hours) and potential risk for bilirubin neurotoxicity. Effective phototherapy implies its use at specific blue light wavelengths (peak emission, 450 ± 20 nm) and emission spectrum (range, 400-520 nm), preferably in a narrow bandwidth that is delivered at an irradiance of ≥30 µW/cm(2)/nm to up to 80% of an infant's body surface area. However, this is often not feasible in clinical settings with limited or constrained resources. To identify and bridge implementation barriers, we propose minimum criteria for device performance for safe and practical use of phototherapy as a prophylactic intervention to prevent severe hyperbilirubinemia.