No abstract

SummaryA noninvasive optical technique by which serum bilirubin can be estimated from skin spectral reflectance measurements has been further investigated. The original work on 30 healthy, full-term white infants and an independent study on 14 white and 30 black infants demonstrate that the method has potential not only for clinical use, but also for the study of the transport of bilirubin to, from and within the skin. The objectives of the present study are to evaluate the method on a larger sample population with special attention to natural skin pigmentation effects and the development of a physical model of the tissue to explain the relationship between serum bilirubin concentration and skin reflectance.Reflectance spectra (380-800 nm) and concurrent serum bilirubin measurements were taken on a sample population of 58 white and 45 full-term black infants (1-3 days of age). Multiple linear regression analysis, comprised of six wavelengths gave a correlation coefficient, r = 0.831 for the white infant group. For the black infant group, a five wavelength analysis provided r = 0.877 with the standard error of estimate being 21.46 mg/100 ml for both groups.The model for establishing a physical basis for the relationship shows that a transformed, normalized Kubeka-Monk function (460,510,420) is linearly related to serum bilirubin concentration. This function is determined from the spectral reflectance values at three wavelengths, 420, 460, and 510 nm. The wavelength combination is such that effects due to bemmlobin and melanin exchange transfusion or phototherapy (19). Early detection and continual monitoring of elevated bilirubin levels is essential if kernicterus is to be prevented. Although serum tests are relatively accurate and easily done, they are often delayed because of failure of visual detection of jaundice and the reluctance to perform invasive procedures particularly on the very small premature.To obviate these difficulties, a noninvasive optical technique was developed by which the reflectance at specific wavelengths could be used to determine the total serum bilirubin concentration. The original investigative work, previously reported by the authors (8), was performed on a sample of 30 caucasian, healthy, full-term infants. The results demonstrated that there was a strong relationship between skin reflectance and serum bilirubin concentration and that the method had potential not only as a research device for study of the blood-serum bilirubin transport system, but also as a tool for use in clinical screening for jaundice. This original work was followed by a recent, independent study (16) on 14 white and 30 black infants producing similar results although details of the method have not been published. However, because of the small sample population and the lack of data on natural skin pigmentation effects, in both of these studies, the generality of the method could not be fully tested. Hence, the present study was performed with the objectives to evaluate the method on a large sample of both blac...

No abstract