Human and rat lungs were degassed and filled with air and physiological salt solution for determination of pressure-volume relationships. Extracts were prepared from the specimens and examined for their surface film-forming activity. Both the aeration of the alveolar structure of the lungs at functional residual pressure and the surface activity of the extracts showed wide variation. Numerical ratios were defined to express these two properties quantitatively, and a high degree of correlation was observed between them. The range of correlation was extended by treating the rat lungs with nonionic detergents. These findings support the hypothesis that the stability of the pulmonary alveolar structure is dependent on intrinsic surface-active material and have encouraged further attempts at formulating a theory of alveolar mechanics, taking surface forces into account. The theory is presented, and some of its weaknesses are pointed out. Submitted on October 21, 1960

ABSTRACT. Objective. The aim of this study was to evaluate the accuracy and clinical usefulness of a new computer-driven, hand-held device (Chromatics Colormate III) to estimate serum bilirubin from skin-reflectance (skin color) of neonates.Study Design. A total of 2441 infants (both term and premature) at two hospitals had repeated measurements of transcutaneous bilirubin. Of these infants, 900 had one or more laboratory determinations of serum bilirubin. Many of the infants had early measurements 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 laboratory 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 standardized color tiles and repeated measurements by multiple operators.Results. The range of serum bilirubin measurements that had concurrent skin color measurements was 3.22 to 338.1 mol/L (0.2 to 21 mg/dL). The linear regression indicated an r ‫؍‬ 0.956, and 95% of the skin color measurements were within 32.2 mol/L (2.0 mg/dL). There was no interference with the accuracy of the device because of infant race or weight, or because of the use of phototherapy. The device provided reproducible information when infants were tested repeatedly over 30 minutes; the coefficient of variation for the transcutaneous bilirubin measurement was 3.1% around a mean estimate of 135.32 mol/L (8.4 mg/dL).Conclusion. The Chromatics Colormate III allows for a clinically useful estimate of serum bilirubin in a wide variety of infants. By using a color discrimination algorithm and obtaining a skin measurement before 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. Pediatrics 1998; 102(3). URL: http://www.pediatrics.org/cgi/content/full/ 102/3/e28; jaundice, newborn, transcutaneous.

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