NONINVASIVE ESTIMATION OF SERUM BILIRUBIN

Objective. The aim of this study was to evaluate the accuracy and clin ical usefulness of a new computer-driven, hand-held device (Chromatics Colormate III) to estimate serum bilirubin from skin-reflectance (ski n color) of neonates. Study Design. A total of 2441 infants (both term and premature) at two hospitals had repeated measurements of transcut aneous bilirubin. Of these infants, 900 had one or more laboratory det erminations of serum bilirubin. Many of the infants had early measurem ents of skin color before the onset of jaundice. A visual estimate of the degree of jaundice was made by a health care worker when the labor atory study was drawn. A subgroup of 61 infants was also studied while undergoing phototherapy with a total of 284 comparisons obtained. The reproducibility of the instrument was assessed separately using stand ardized color tiles and reported measurements by multiple operators. R esults. The range of serum bilirubin measurements that had concurrent skin color measurements was 3.22 to 338.1 mu mol/L (0.2 to 21 mg/dL). The linear regression indicated an r = 0.956, and 95% of the skin colo r measurements were within 32.2 mu mol/L (2.0 mg/dL). There was no int erference with the accuracy of the device because of infant race or we ight, or because of the use of phototherapy. The device provided repro ducible information when infants were tested repeatedly over 30 minute s; the coefficient of variation for the transcutaneous bilirubin measu rement was 3.1% around a mean estimate of 135.32 mu mol/L (8.4 mg/dL). Conclusion. The Chromatics Colormate III allows for a clinically usef ul estimate of serum bilirubin in a wide variety of infants. By using a color discrimination algorithm and obtaining a skin measurement befo re the onset of icterus, this instrument can provide valuable clinical information that obviates the need for serum bilirubin determinations . Its use in newborn nurseries may allow physicians to shorten length of stay more safely and decrease the use of invasive blood tests.