Phototherapy for neonatal hyperbilirubinaemia: the importance of dose.

The management of neonatal jaundice can be made much easier using simple methods that increase the radiant energy in the range 420 to 480 nm. Two groups of infants being treated for physiological jaundice during a period of 6 months were compared. The first group received treatment from two unmodified phototherapy units and the second from two units in which the horizontal frames housing the tube lights were lowered, thus providing a higher 'dose' of phototherapy. Measurements of irradiance from the four units were compared. An improvement in treatment was noted in the group receiving the higher dose with a decrease in duration of treatment and a greater rate of fall in the level of serum bilirubin. A dose response relationship was thus confirmed. Comparisons between previous studies are hindered by failure to recognise the varying contribution of background irradiance, the use of radiometers with differing spectral responses, and the use of different units for expressing results. Failure to appreciate the importance of dose must largely be responsible for the present wide variability in the effectiveness of phototherapy.