As discussed in previous blog entries (PNAC, PNALD, and IFAC, More on PNAC, Four advances for intestinal failure), the right amount of lipid and the type of lipid both can contribute to parenteral nutrition associated cholestasis (PNAC). More information about SMOFlipid which is a complex mixed-type lipid emulsion derived from soybean, coconut, olive, and fish oils is available (JPGN 2012; 54: 797-802). SMOF contains 30% soybean oil, 30% MCT, 25% monounsaturated fatty acids, and 15% fish oil.
This study had a retrospective cohort comparison design & examined serum bilirubin over 6 months in children with PN-associated cholestasis (PNAC). In one cohort, 8 patients received the SMOFlipid and the other 9 patients continued on Intralipid (IL).
The SMOF cohort was receiving 81% of caloric needs as PN at entry whereas the IL cohort was receiving 92%. Six months later, SMOF cohort was receiving 68% of caloric needs as PN compared with 50% for IL cohort. Nevertheless, the SMOF group had improved cholestasis with a median bilirubin drop of 99 μmol/L compared with an increase of 79 μmol/L among IL patients. Overall, 5 of 8 children in the SMOF group had resolution of jaundice compared with 2 of 9 in the IL group.
While the authors state that SMOF may have important properties to prevent PNALD, the study has limited ability to draw any firm conclusions.
The authors state that no other treatment innovations were introduced; however, the authors overlook the large discrepancy in lipid volume administered. The IL group was receiving much more lipid both before and during study. Prior to entry of study, the IL group was receiving about 3.1 g/kg/day whereas the SMOF group about 2 g/kg/day; the SMOF group continued initially at the same lipid dosing with the new formulation. This is one of the problems with historical controls. While the authors might believe that the cholestasis improved because of the lipid content, the key factor may in fact be the amount of lipid given.
In the same issue (JPGN 2012; 54: 803-11), specific plant sterols (PS) were elevated among neonates with intestinal failure-associated liver disease (IFALD). This study looked at 28 neonates and 11 children from Finland who required PN for more than 28 days. Specific markedly-elevated PS included stigmasterol, sitosterol, avenasterol and campesterol (Table 4 in study). Some of these PS in the neonates were more than 20-fold higher than healthy controls.