Monitoring intravenous fat emulsions in neonates with the fatty acid/serum albumin molar ratio.

Weekly determinations of the fatty acid/albumin molar ratio (FA/SA) were obtained 136 times on 50 neonates (birthweight range, 675-4300 grams; median, 1360 grams) to determine if our use of intravenous fat (IVF) was putting these newborns at risk for kernicterus. The FA/SA was measured using a convenient spectrophotometric technique which we have previously described (Berde CB, Kerner JA, Johnson JD: Clin Chem 26:1173-1177, 1980). Twenty-nine infants received IVF with doses from 0.5 to 3.3 gram/kilogram/day (mean 1.5 gram/kilogram/day), given over 24 hours whenever possible, most commonly begun in the second week of life when the bilirubin level was less than one half of the potential exchange level. Twenty-one infants received no IVF. Previous studies show that fatty acids do not begin to displace bilirubin from albumin until the FA/SA is greater than 6 in vivo, and greater than 4 in vitro. All our infants had safe values with mean FA/SA values of approximately 1.0. Continuous IVF as we administer it does not place neonates at risk for kernicterus. Centers administering IVF in the first week of life or by bolus should consider close monitoring of their infants with the FA/SA.