Transcutaneous Bilirubinometer

Neonatal jaundice occurs in nearly 70% of term and 80% of preterm babies. Management of jaundiced neonates often requires measurement of total serum bilirubin (TSB). Total serum bilirubin (TSB) is commonly determined by spectro-photometric methods by analyzing plasma or serum sample. Such techniques require drawing of blood causing pain and trauma to the neonate. In addition, there is a wide range of intraand inter-laboratory variability in the performance of the bilirubin analyzers. These problems have led to search for a non-invasive, reliable technique for estimation of TSB. A large number of studies have demonstrated the possibility of prediction of serum bilirubin in neonates by measuring the yellowness of the skin in the jaundiced neonate using transcutaneous bilirubino-meters. Principle High correlation between cutaneous bilirubin and TSB form the basis of Transcutaneous Bilirubinometry. These meters work by directing light into the skin of the neonate and measuring the intensity of specific wavelength that is returned. The number of wavelengths, used is variable in different transcutaneous bilirubinometers. The meter analyzes the spectrum of optical signal reflected from the neonate’s subcutaneous tissues. These optical signals are converted to electrical signal by a photocell. These are analyzed by a microprocessor to generate a serum bilirubin value. The major skin components, which impart the spectral reflectance in neonate, are (i) melanin, (ii) dermal maturity, (iii) hemoglobin, and (iv) bilirubin. Earlier, the transcutaneous bilirubinometers utilized only a few wavelengths. In these meters, there was no provision to overcome the impact of dermal maturity and melanin content. Therefore, separate analysis for each patient population (different ages and races) was required one had to refer to different conversion tables for each population. However, a new product, Bilicheck (Specter, Inc) performs a spectral analysis at more than 100 different wavelengths. By subtracting the spectral contribution of the known components, the bilirubin absorbance is quantified. The available meters can be divided into 2 categories: (i) Multi wavelength Spectral Reflectance meters (Bilicheck) (ii) Two-wavelength (460 nm, 540 nm) Spectral Reflectance meters (Minolta, Bili-test)