Green light phototherapy in newborn infants with ABO hemolytic disease

The effectiveness of phototherapy using blue-green light for neonatal hyperbilirubinemia - Danish clinical trials

The effectiveness of phototherapy for neonatal hyperbilirubinemia based on Danish clinical trials is presented. Randomized controlled trials on the quality of light showed that blue-green fluorescent light (peak emission at 490 nm) was more efficient than blue fluorescent light (peak emission at 452 nm); blue-green light-emitting diode (LED) light (peak emission at 478 nm) was more efficient than blue LED light (peak emission at 459 nm); and blue-green LED light (peak emission at 497 nm) was equivalent to blue LED light (peak emission at 459 nm). Bilirubin-reducing effects correlated with irradiance, dependent on hemoglobin concentration, and independent of rotating infants. Phototherapy from both above and below was more efficient than therapy applied only from above at high levels of irradiance. In conclusion, we estimate and recommend the use of blue-green LED light (peak emission at 480 nm) rather than blue light (peak emission at 460 nm) for treating of neonatal hyperbilirubinemia.

The role of phototherapy in the crash-cart approach to extreme neonatal jaundice

Extreme neonatal jaundice occurs infrequently but carries a high risk of permanent sequelae (kernicterus) when it does. Rapid therapeutic intervention has the potential to reduce this risk in some infants. Several case reports of infants with acute intermediate to advanced bilirubin encephalopathy shows that reversal may be possible. Phototherapy can be instituted at the flip of a switch, whereas other therapeutic measures necessarily involve delays. Therefore, high-intensity phototherapy must be regarded as an emergency measure in infants presenting with extreme jaundice and even more so in the presence of neurological symptoms. The principal and well-described effect of phototherapy involves conversion of bilirubin IXα (z, z) to more polar isomers, which are excreted in bile and urine. When care is taken to maximize the spectral power of phototherapy lights, and whenever possible with measures added to reduce the enterohepatic circulation of bilirubin, very rapid reductions in total serum bilirubin levels are possible. A hypothesis has been advanced that conversion of bilirubin to more polar photoisomers, which can reach relative concentrations of 20%-25% of total serum bilirubin within 1-2 hours, might have a direct neuroprotective effect. This theory posits that because polar molecules generally require a transporter to cross the blood-brain barrier, bilirubin photoisomers should be less prone to enter the brain. Although this theory has some support in in vitro toxicity studies, the evidence is controversial. Until further experimental support can be gained, photoconversion of bilirubin does not constitute a viable argument against instituting further measures against bilirubin neurotoxicity, such as intravenous immune globulin (when indicated) and exchange transfusion. Conversely, neither is the state of evidence an argument against immediate and effective phototherapy in the medical emergency of extreme neonatal jaundice.

A prospective randomized controlled study of phototherapy using blue and blue-green light-emitting devices, and conventional halogen-quartz phototherapy

OBJECTIVE

To determine the efficacy of blue versus blue-green phototherapy using new light sources with narrow luminous spectra. The devices made of high-intensity gallium nitride light-emitting diodes (LEDs) were also compared to conventional halogen-quartz bulbs phototherapy.

DESIGN

Prospective open randomized study.

PARTICIPANTS

A total of 114 jaundiced, but otherwise healthy term infants who met the entry criteria for phototherapy set by the American Academy of Pediatrics' Practice Parameter.

MAIN OUTCOME MEASURES

The duration of phototherapy and the rate of decrease in total serum bilirubin (TSB).

RESULTS

The mean TSB concentrations at initiation and termination of treatment, as well as the duration of phototherapy and the rate of decrease in TSB, were not statistically different in newborns receiving blue LED, blue-green LED or conventional phototherapy. The average rate of decrease in TSB (slope), after adjustment by a linear regression analysis for confounding factors, was -3.61 micromol/hour (95% confidence limits -5.47, -1.75) in the 25 newborns receiving blue LED phototherapy compared with -2.57 micromol/hour (-4.32, -0.82) in the 22 newborns treated with blue-green LED phototherapy and -3.42 micromol/hour (-5.02, -1.81) in the 57 newborns who received conventional phototherapy.

CONCLUSIONS

When using low light irradiance, there was no statistically significant difference in the effectiveness of phototherapy using blue-green LEDs, blue LEDs or conventional halogen-quartz bulbs.

Environmental light and the preterm infant

The lighting environment of the preterm baby is quite unlike that experienced at any other time of life. Physical and physiological factors control how much light reaches the retina of the preterm baby. With respect to the former, although many neonatal intensive care units are brightly and continuously lit, there is a trend to employ lower levels of illumination and to introduce cycling regimens. Physiological determinants of the retinal light dose include: eyelid opening and transmission, pupil diameter and the transmission characteristics of the ocular media. Early exposure to light does not significantly hasten or retard normal visual development, and it is not a factor in the development of retinopathy of prematurity. However, ambient neonatal intensive care unit illumination may be implicated in some of the more subtle visual pathway sequelae that cannot be attributed to other major complications of preterm birth including altered visual functions and arrested eye growth.

Influence of photoisomers in bilirubin determinations on Kodak Ektachem and Hitachi analysers in neonatal specimens study of the contribution of structural and configurational isomers

We compared data obtained with the Kodak Ektachem and Hitachi 717 Analysers and HPLC from 83 neonates under phototherapy. Total bilirubin values determined with the Kodak and Hitachi are in good agreement, but we observed a large discrepancy in the results for conjugated (Kodak) and direct (Hitachi) bilirubin. HPLC revealed that all the samples contained configurational isomers, while only 7.7% and 30.8% contained conjugated bilirubin and structural isomers, respectively. We developed a device for the specific and quantitative production of configurational or structural isomers, by irradiation with blue or green light. In vitro, total bilirubin values are coherent for the routine analysers in the presence of configurational or structural isomers. With configurational isomers, unconjugated bilirubin (Kodak) is lower than total bilirubin (Kodak), and conjugated bilirubin (Kodak) is always equal to zero, so the apparatus gives a false positive response for delta bilirubin. In contrast, the direct bilirubin (Hitachi) is constant. Furthermore, in the presence of structural isomers, unconjugated bilirubin (Kodak) is unexpectedly higher than total bilirubin (Kodak), conjugated bilirubin (Kodak) is proportional to the quantity of these isomers, and direct bilirubin (Hitachi) is constant. The contribution of photoisomers in bilirubin measurements is discussed.

Cells, bilirubin and light: formation of bilirubin photoproducts and cellular damage at defined wavelengths

Cultured cells from one human and one murine cell line were treated with bilirubin and irradiated with visible light of different wavelengths, either from phototherapy lamps or from a Xenon/Mercury lamp equipped with a monochromator. Bilirubin bound to human serum albumin was also irradiated with light. After irradiation, the bilirubin and its photoisomers were extracted and analysed with High Pressure Liquid Chromatography. The formation of single strand breaks in the DNA of treated cells was studied using a fluorescence marker. Cytotoxicity in the mouse skin cell line was measured by loss of the ability to form visible colonies in vitro. Green light exposure favours the production of lumirubin, while blue light causes more DNA damage and cytotoxicity. Green light may be more efficient and safer than shorter wavelength exposure when treating jaundiced newborns with phototherapy.

Clinical usefulness of high intensity green light phototherapy in the treatment of neonatal jaundice

Two matched groups of term newborn infants with idiopathic jaundice were subjected to intensive double direction green or blue light phototherapy (PT). The efficacy of treatment was expressed as rate of decline of serum bilirubin concentration after 6, 12 and 24 h of light exposure. More rapid response was obtained using conventional blue lamps (Philips TL/20W/52) than green lamps (Sylvania F20T12/G). Whole duration of PT was significantly shorter using blue lamps (P less than 0.05). However, less postphototherapy rebound was observed in babies treated with green light PT. It can be concluded that green light PT is useful but not preferable to blue light PT for clinical use in the treatment of neonatal jaundice.

Quantum yields for laser photocyclization of bilirubin in the presence of human serum albumin. Dependence of quantum yield on excitation wavelength

The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (phi LR) was measured at five monochromatic excitation wavelengths in the range 450-530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XIII alpha impurities. The values obtained (7.2-18 x 10(-4] were lower than those previously reported and showed the following wavelength dependence: 457.9 less than 488.0 less than 501.7 less than 514.5 approximately equal to 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15E and 4E,15Z isomers also was studied. This reaction became less regioselective for the 4Z,15E isomer with increasing wavelength. The observed wavelength dependence of phi LR and of the [4E,15Z]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formation in vivo at different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength-dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorption maximum.

Efficacy of fluorescent daylight, blue, and green lamps in the management of nonhemolytic hyperbilirubinemia

The efficacy of fluorescent daylight, green, and blue lamps in reducing bilirubin levels was compared in two groups of infants with nonhemolytic hyperbilirubinemia: healthy infants in a term nursery and infants in an intensive care unit. The decline of serum bilirubin concentration was most rapid with the blue lamps, with the duration of exposure required being significantly shorter than that with the other two types of light in both groups. The rate of decline over the first 24 hours, as well as the overall rate of decline for the whole duration of phototherapy, was also significantly greater with the blue lamps, the rate being about twice that for the green lamps in the infants in the intensive care unit; the daylight lamps were intermediate in efficacy. The daylight lamps permitted easy clinical monitoring with minimal side effects, whereas the green and blue lamps were equally disturbing to the attending personnel. The green lamps caused severe erythema and tanning in the initial 200 hours of phototherapy. It appears preferable to use either daylight lamps, which permit enhanced clinical monitoring with adequate efficacy, or special blue lamps, which provide maximal therapeutic effect, rather than green lamps, which offer neither.