Phototherapy: The challenge to accurately measure irradiance

Determination of intensity and spread of light to the surrounding in conventional phototherapy and comparison with novel converging photo unit — an observational study

Background

Blue light phototherapy used extensively in the management of hyperbilirubinemia has many side effects like dry eyes, blurring, headache, and altered circadian rhythm. Healthcare providers working around the phototherapy are unduly exposed to these side effects. Altered circadian rhythm results in disruption in the sleep-wake cycle affecting healthcare providers particularly working during the night shift. The constant glare of the blue light interrupts in clinical observation of the baby on phototherapy. With the intent of providing effective phototherapy with minimal exposure of blue light to healthcare providers, a light source called the photo unit was designed and developed.

The objective of this study was to estimate the intensity and spread of blue light to the surrounding in conventional phototherapy and to compare the same with newly developed converging photo unit.

Results

The therapeutic range of irradiance was noted up to 22 inch in diameter with conventional phototherapy compared to only 7 inch with our photo unit. The light spread with a conventional phototherapy unit was seen beyond 50 inch in all directions whereas was confined to 19-inch diameter with photo unit.

Conclusion

Photo unit developed by the authors has minimal divergence of light to the surrounding, thereby mitigating the side effects of blue light exposure to the people working in the vicinity. Multiple of these photo units can be used to make a phototherapy device.

Standardization of phototherapy for neonatal hyperbilirubinemia using multiple-wavelength irradiance integration

BACKGROUND

Phototherapy with radiation of 460-490 nm wavelengths provides the most potent therapeutic effect for neonatal jaundice. However, the efficacy of phototherapy has been estimated using single-wavelength detectors with sensitivity at approximately 460 nm. Cyclobilirubin formation capacity (CFC), which comprises the sum of the irradiance values from three wavelengths multiplied by their specific coefficients, has been proposed as an alternative marker to evaluate the efficacy of phototherapy. This study aimed to test whether two types of phototherapy devices with distinct spectral characteristics provide similar therapeutic effects on adjustment of device-to-patient distances to deliver similar CFCs.

METHODS

Using a three-wavelength spectroradiometer, CFCs and footprints of the light-emitting diode and fluorescent tube devices were assessed. Having determined the device-specific distances that ensured similar CFCs, 32 newborn infants, requiring phototherapy for hyperbilirubinemia, were randomized into the light-emitting diode and fluorescent tube groups. The total serum bilirubin levels before and after phototherapy were assessed.

RESULTS

The light-emitting diode and fluorescent tube devices had comparable CFCs at distances of 60 and 50 cm, respectively. Phototherapy reduced the total serum bilirubin levels from 18.1 to 14.6 mg/dL and from 19.1 to 15.1 mg/dL in the light-emitting diode and fluorescent tube groups, respectively. The two groups did not differ significantly with respect to the patients' clinical backgrounds, serum bilirubin levels, or changes before and after phototherapy.

CONCLUSION

At similar CFCs, the two phototherapy devices reduced the total serum bilirubin levels by comparable amounts. Hence, determining CFCs may help predict phototherapy efficacy. This may ensure better safety and greater efficacy of the treatment for newborn infants.

Factors influencing irradiance of locally fabricated phototherapy devices in Jos, north-central Nigeria

Locally fabricated phototherapy devices (LFPDs) are widely used in Nigeria for the treatment of neonatal jaundice. Ours was a cross-sectional observational study of all LFPDs in major hospitals in Jos between January and March 2015. We evaluated a total of 24 LFPDs. The irradiance at the level of the baby was in the range of 2-23.9 µW/cm²/nm. Fourteen devices had the recommended irradiance of ≥10 µW/cm²/nm and none had irradiance in the intensive range. Decreasing distance from the baby, presence of reflectors and increasing number of flourecent tubes significantly contributed to higher irradiance. A combination of six tubes, presence of reflectors and a distance of 10 cm from the baby produced a mean irradiance of 23.40 µW/cm²/nm. The irradiance of LFPDs varies widely and can be improved by simple modifications.

Irradiance levels of phototherapy devices: a national study in Dutch neonatal intensive care units

OBJECTIVE

The objective of this study is to determine whether irradiance levels of phototherapy (PT) devices in Dutch neonatal intensive care units (NICUs) increased between 2008 and 2013.

STUDY DESIGN

Irradiance of all types of PT devices, used in combination with incubators, was measured with a Dale 40 Radiometer (Fluke Biomedical, Everett, WA, USA) in all 10 Dutch NICUs.

RESULTS

Irradiance increased in seven NICUs. Median (range) irradiance increased from 9.7 (4.3-32.6) to 16.4 (6.8-41) μW cm^-2 nm^-1 for 24 overhead devices (P=0.004) and from 6.8 (0.8-15.6) to 22.3 (1.1-36.3) μW cm^-2 nm^-1 for 12 underneath devices (P=0.014). Five light-emitting diode (LED)-based devices were used in 2013 and one in 2008. The mean distance between overhead PT device and infant decreased by ~9 cm (P<0.001). Significantly more devices delivered minimal (10 μW cm^-2 nm^-1) recommended irradiance levels (80 vs ~45%; P=0.002).

CONCLUSION

Irradiance of PT devices still varies, but has markedly improved since 2008 due to shorter distances between PT device and infant, and introduction of better performing LED-based devices.

LED versus daylight phototherapy at low irradiance in newborns ≥35 weeks of gestation: randomized controlled trial

OBJECTIVE

To compare the decline in TSB after 24 h of LED or fluorescent phototherapy from below in breastfed neonates ≥35 weeks of gestation.

METHODS

Seventy-four neonates treated with a 17-bulb blue LED were compared with 76 neonates treated with a 7-bulb daylight device in a rooming-in unit. Spectral irradiance was measured at 5 points on a 30 × 60 cm rectangle on the gel transparent mattress.

RESULTS

TSB of 14.0 ± 1.2 mg/dL at 64 ± 15 h after birth when starting phototherapy were similar in both groups. TSB declined by 0.16 ± 0.09 in the LED versus 0.16 ± 0.08 mg/dL/hour in the daylight group after 24 h of therapy (p = 0.87). Mean irradiance (μW/cm(2)/nm) was 10.5 ± 0.9 (32.5 at the central, 5.9 at the superior and 3.9 for the inferior points) in the LED versus 8.7 ± 0.6 (range, 8.3 to 9.8) in the daylight group (p < 0.001). Hypothermia (<36.0 °C) was more frequent in LED than in fluorescent (23% versus 9%; p = 0.02) group.

CONCLUSION

LED with heterogeneous irradiance was as effective as daylight phototherapy with homogeneous irradiance; however there is a greater need for rigorous control of the room temperature (NCT01340339).

Efficacy of light-emitting diode versus other light sources for treatment of neonatal hyperbilirubinemia: a systematic review and meta-analysis

Various light-emitting diode (LED) phototherapy devices have been trialled on the assumption of a more effective spectral distribution of the light emitted. We reviewed the current literature to determine whether LED is more effective than other types of phototherapy. Eligible studies were randomized controlled trials of LED versus other phototherapies. Studies were found to be of medium quality based on a components approach. Data were statistically aggregated within a very homogeneous population (term or late preterm neonates). Results appeared robust at sensitivity analysis. Five hundred and eleven neonates were included in the meta-analysis. LED and other phototherapy devices appeared to be equally effective in reducing total serum bilirubin (TSB) in term or late preterm neonates. The pooled mean TSB rate of decrease was 3.269 μmol/L/h (0.191 mg/dL/h) and 3.074 μmol/L/h (0.18 mg/dL/h) in the LED and conventional arms, respectively [average difference in TSB rate of decrease = 0.194 μmol/L/h (0.011 mg/dL/h) in favour of LED phototherapy; p = 0.378].

CONCLUSION

No significant difference in TSB rate of decrease was detected between LED and other types of phototherapy. Further randomized controlled trials are needed to ascertain whether LED phototherapy may be more effective when increasing the spectral power, or in certain selected subpopulations.

The side effects of phototherapy for neonatal jaundice: what do we know? What should we do?

Neonatal phototherapy (NNPT), a noninvasive, easily available therapy, has been widely used for the treatment of neonatal jaundice for more than half a century. Its efficiency in decreasing plasma bilirubin concentration is well documented, and NNPT leads to greatly reduced exchange transfusion rates for neonates with hyperbilirubinemia. It is generally accepted that the side effects of NNPT are not serious and seem to be well controlled. This review will focus on these possible side effects as well as the approaches to minimize them.

Irradiance readings of phototherapy equipment: Nigeria

Phototherapy devices (n = 63) at twelve nurseries in Nigeria were evaluated. Irradiance was measured using the BiliBlanket Meter II. Irradiance readings ranged from 0.5 to 18.4 μW/cm(2)/nm; phototherapy units varied widely, including locally made units, reconditioned machines, and modern equipment. Imported "intact" machines with all blue bulbs had higher irradiance readings than locally made devices using primarily daylight bulbs (2.5-18.4 μW/cm(2)/nm vs 0.5-4.2 μW/cm(2)/nm). The distance between infant and phototherapy units ranged from 45 to 60 cm, far exceeding the recommended distance of about 10 cm. Only 6% of the machines provided irradiance of >10 μW/cm(2)/nm. None delivered intensive phototherapy (irradiance ≥ 30 μW/cm(2)/nm). Phototherapy devices in developing countries should be assessed for irradiance, and the infant be placed at a distance of about 10 cm from the device. Phototherapy devices with adequate irradiance would reduce the need for exchange blood transfusion and the burden of acute bilirubin encephalopathy in developing countries.

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.