Background and Objective Phototherapy is widely applied for unconjugated hyperbilirubinemia. Recently, novel consensus-based treatment thresholds for jaundiced preterm infants were developed in The Netherlands. Factors affecting the efficacy of phototherapy may differ between hospitals. Irradiance of the light source is one of these factors. The dose of phototherapy should be 8–10 μW/cm²/nm to be effective. We analyzed practice patterns of phototherapy measuring irradiance of light sources in hospitals that have implemented the novel treatment thresholds.

Methods Irradiance of phototherapy lights in all Dutch neonatology intensive care units (n = 10) was measured using a Dale40 phototherapy radiometer (Fluke Biomedical). Irradiance was measured at 5 spots of a 35 cm-craniocaudal area illuminated by a phototherapy light using the local practice patterns of phototherapy. Mean and maximum of 5 measurements of irradiance levels were subsequently calculated per device and per NICU.

Results Phototherapy devices differ between NICUs; 5 conventional units and 3 fibre optic devices are used. Irradiance levels of these devices vary (mean of conventional units 12.63±10.9 μW/cm²/nm, mean of fibre optic devices 8.58±8.1 μW/cm²/nm). Maximum irradiance levels of participating hospitals are shown in the table.

Conclusions Considerable variability in phototherapy lights and irradiance levels exists for jaundiced preterm infants in and between the Dutch NICUs, supporting different practice patterns of phototherapy. Measuring irradiance is recommended to control the dose of phototherapy.