Chemical Variables and New Lamps in Phototherapy

Ente, Gerald; Lanning, Edward W.; Cukor, Peter; Klein, Richard M.

doi:10.1203/00006450-197204000-00006

Cited by 16 publications

(5 citation statements)

References 7 publications

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“…Time then became the analog of photon fluence. Exposures were conducted for 0, 4,8,12,16,20, and 24 min.…”

Section: Methodsmentioning

confidence: 99%

“…The clinical application of this phenomenon has been widely used as phototherapy in the treatment of neonatal hyperbilirubinemia. Investigations designed to delineate the effective wavelengths have employed broad spectrum light sources and have indicated that irradiance with light of wavelengths of 425-475 nm is maximally effective both in vitro (2,7,8,10, 13,25,31) and in vivo (1,11,17,24,29,33,36). But one study performed in vitro with a relatively narrow spectral source suggested wavelengths at 490 nm might also be efficacious (10).…”

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confidence: 99%

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The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

1983

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SummaryMonochromatic light was provided by a continuous wave Argon ion laser. We chose to study the in vitro effects of light at 457.9, 465.8, 476.5, 488.0, 501.7, and 514.5 nm as representative of a reasonably evenly spaced samplig across the blue-green spectrum. The in vivo experiments were conducted at 457.9, 476.5, 488.0, and 514.5 nm.In vitro light at 488.0 nm appeared to be more effective than the others studied.After 24 h of irradiance, the in vivo decline in serum bilirubin concentration produced by light at 488.0 nm was one-and-one-half, two, and four times as effective as light at 457.9, 476.5 and 514.5 nm, respectively. By 48 h of exposure, the declines produced by light at 457.9 nm and 488.0 nm are significantly superior to that at 476.5 nm and 514.5 nm, but they do not differ from one another.The photon-induced chemical alteration of bilirubin has been demonstrated by various light sources both in vitro and in vivo. The clinical application of this phenomenon has been widely used as phototherapy in the treatment of neonatal hyperbilirubinemia. Investigations designed to delineate the effective wavelengths have employed broad spectrum light sources and have indicated that irradiance with light of wavelengths of 425-475 nm is maximally effective both in vitro (2,7,8,10, 13,25,31) and in vivo (1,11,17,24,29,33,36). But one study performed in vitro with a relatively narrow spectral source suggested wavelengths at 490 nm might also be efficacious (10). More recently, Lilien et al. (27) have performed experiments that also suggest that wavelengths of light beyond the 425475 nm range are efficacious in vitro.Radiant energies within the 400-500 nm range exhibit potential for inducing damage to tissues. Light from standard fluorescent lamps causes breaks in DNA strands in vitro (3, 35) and increases sister chromatid exchanges and other chromosomal alterations in cultured cells (4,18,21,23,32,35,37). An increased frequency of sister chromatid exchange has been reported in some infants after phototherapy (12). Although we know of no reports regarding any increase in sister chromatid exchange in vivo in response to monochromatic light, the occurrence seems likely; thus, the widespread use of phototherapy has generated concern regarding the potential for long-term mutagenic and carcinogenic effects. Inasmuch as most published data suggest that the offending wavelengths are principally in the ultraviolet range, some recent work has implicated light of wavelengths exceeding 300 nm (9) and, indeed, some alterations appear to occur maximally in response to wavelengths of light between 420-500 nrn (35). Although the magnitude of these latter risks has not been quantitated as they may relate to the clinical setting, it seems desirable to more precisely define the most efficacious wavelengths for the photoalteration of bilirubin that results in its enhanced excretion. This is particularly needed in the design of future phototherapy instruments to be used in the management of neonatal hyperbilirubinemia. Preliminary po...

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“…Time then became the analog of photon fluence. Exposures were conducted for 0, 4,8,12,16,20, and 24 min.…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

1983

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“…Light intensity is very important for success in therapy, but continuous illumination is just as important if not more so; in fact, it would seem best to use the lowest practical level of continuous illumination. 10 The method of illumination used in the present study may not be ideal for maximal effectiveness in phototherapy; but under certain conditions, especially where radiant heat is also required, it would seem to be a useful method for the continuous providing of both phototherapy and thermotherapy.…”

Section: Discussionmentioning

confidence: 94%

A Simple Method of Phototherapy: Inexpensive, Blue Incandescent Bulbs

Tan¹,

Boon²

1974

Clin Pediatr (Phila)

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A simple method of phototherapy using blue incandescent lamps is described. Altogether, 128 Chinese premature infants were studied, 68 with and 60 without phototherapy. In spite of the low intensity of illumination (25 to 30 footcandles), the phototherapy group had a significantly lower mean bilirubin level. Seven of 67 control infants needed exchange trans fusion, but none in the phototherapy group. The lamps were effective for "thermotherapy" as well.

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“…Data on the effectiveness of different bands within this range or in its neighborhood -i.e. in the near UV, violet or green -are still contradictory (6,7,9,12,21,23,27,28,31,32,34,36). But a realistic curve of the spectral efficiency is necessary for accurate measure ments of the photons applied.…”

Section: Introductionmentioning

confidence: 99%

Phototherapy in Gunn Rats

Ballowitz¹,

Geutler²,

Krochmann³

et al. 1977

Neonatology

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In order to get a more realistic spectral efficiency curve and to evaluate dose/response relationships in phototherapy, homozygous weanling Gunn rats – nondepilated, with fur – were illuminated under standardized conditions with 8 different fluorescent tubes. Some of the tubes were operated with different electric power. Clear spectral differences in the extent and the rapidity of the bilirubin decay could be ascertained. Furthermore, the sharpness of the bilirubin decrease depended on the baseline concentration. For the calculations the animals were therefore divided into 3 groups with starting levels of ≥ 8 mg%, 6.5–7.9 mg% and < 6.5 mg%. Correlating the spectral power distribution of the lamps with the bilirubin decomposition found in the experiment, the spectral response function s (λ)_{bili, rel} was calculated by an integral method. A comparison of our results with data from the literature shows that so far near UV radiation was evaluated too high. A new radiometer for digital measuring the effective irradiance E_bili was developed. On a logarithmic scale a comparatively sharp dose/response relationship could be demonstrated in dependence on the measured effective radiant exposure. Serum bilirubin decrease is directly proportional to log E_bili. A dose of about 2.5 mW · h/cm² is necessary to achieve a constant serum bilirubin decrease at all. Good results were obtained at doses of about 35 mW · h/cm² with the most efficient being at 160 mW · h/cm². Highly effective doses can be applied with different types of lamps. However, there are great differences in the time of illumination required. 24 h are necessary with daylight tubes (Osram L 20 W/19) to apply 20 mW · h/cm², whereas the same dose is already attained after 4 h with BAM blue tubes (Philips). The accuracy of the radiometer was finally controlled by screening Westinghouse special blue and Osram standard blue tubes with black tapes, so that the effective irradiance (E_bili) corresponded to that of Osram daylight tubes. The bilirubin decrease observed after this manipulation was nearly identical (not exceeding 1 SD of the daylight values). Since bilirubin decrease was sharper in the first few hours of illumination, continuous phototherapy was compared in some tests with 3 intermittent schedules: (a) 4 h light, 4 h dark, 4 h light; (b) 5 h light, 2 h dark, 5 h light, (c) alternately 2 h light and 2 h dark. There was no indication that more bilirubin could be removed per hour with intermittent phototherapy than with continuous illumination.

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Chemical Variables and New Lamps in Phototherapy

Cited by 16 publications

References 7 publications

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

The in Vitro and in Vivo Photoreactivity of Bilirubin: I. Laser-Defined Wavelength Dependence

A Simple Method of Phototherapy: Inexpensive, Blue Incandescent Bulbs

Phototherapy in Gunn Rats

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