The Effect of Lipid Emulsions on Free Fatty Acids and Free Bilirubin in Premature Newborns
Phase: PHASE4
Conditions: Prematurity
Sponsor: The University of Texas Health Science Center, Houston

IRB APPROVAL DATE: 09/25/2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The effect of lipid emulsions on free fatty acids and free bilirubin in premature newborns 
 
NCT03857646 
 
Version Date: 09/25/2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

IRB APPROVAL DATE: 09/25/2019 
 
Meredith Collins, MD 
Cody Arnold, MD 
 
Title: The effect of lipid emulsions on free fatty acids and free bilirubin in premature newborns 
 
Background: 
Recently published reports have renewed concerns that that lipid infusions might decrease bilirubin binding 
capacity (BBC) via competition for albumin binding sites from free fatty acids (FFA) such that free bilirubin (Bf) 
might rise to dangerous levels, particularly in newborns delivered at <28 weeks gestational age.1 2 Most 
recently, Hegyi showed elevated levels of unbound free fatty acid (FFAu) and free (unbound) bilirubin (Bf) with 
lipid infusion rates >2.5 g/kg/day, while previously Amin showed that a similar dose response measuring total 
free fatty acids (FFAt), which is almost entirely bound to albumin.1,3 
 
To date, the associations of lipid emulsions, FFA, and Bf, have only been studied with one soy-based lipid 
emulsion product, Intralipid. Soy based lipid emulsions are associated with cholestatic liver injury, particularly 
in premature newborns.3 However, there is evidence that a newer lipid formulation based on a mixture of soy, 
medium chain triglycerides, olive oil and fish oil (SMOF), causes less liver injury.4 5 It is believed that SMOF is 
more tolerable to the liver because of the reduced phytosterol components. 1 To date, neither FFA or Bf levels 
have been measured with SMOF or concurrently compared to levels with Intralipid, However, there is evidence 
that plasma triglyceride and other fat levels are higher with SMOF than Intralipid. D’Ascenzo conducted a small 
randomized trial comparing IL and SMOF in newborns infusing at 3.5g/kg/day and found that triglyceride (TG) 
levels were 39% higher in patients receiving with SMOF versus IL (231 vs 166 mg/dl).6 Although FFA levels 
were not measured in the D’Ascenzo study, a previous study in premature newborns receiving Intralipid 
reported a strong positive correlation (r = 0.89, P < 0.001) between triglyceride and FFA levels.7 
 
The primary research question for the present study is whether the observed difference in TG levels with IL 
versus SMOF might also be associated with a difference in FFA and Bf levels. Based on previous reports of 
higher triglyceride levels with SMOF versus Intralipid and a positive correlation between triglyceride and FFA 
levels, FFAu levels would be expected to be higher with SMOF than Intralipid. However, it is possible that the 
triglyceride – FFA correlation observed with Intralipid may not be observed with SMOF. In any case, clinicians 
should know whether FFA and Bf levels are increased, decreased, or equivalent with SMOF versus IL. 
 
Hypothesis: 
At a dose of 3 g/kg/day, patients receiving Intralipid will have lower mean concentrations of free bilirubin 
(primary outcome) and free fatty acids (secondary outcome) than patients receiving SMOF. 
 
Study Population: 64 Premature newborns (<32 weeks gestation, stratified <28 weeks versus >28 weeks) <8 
days of age and receiving lipid infusions <1 g/kg/day at enrollment and anticipated to be treated with 3 
g/kg/day for a minimum of 48 hours. 
 
Patients with direct hyperbilirubinemia >1.8 mg/dl, with suspected sepsis meeting SIRS criteria, undergoing 
treatment with a continuous infusion of morphine or positive blood cultures at the time of enrollment will be 
ineligible to enroll in the study. Patients on continuous infusion of pressors (dopamine, dobutamine, 
epinephrine, etc.) will be ineligible to enroll in the study if they have single lumen central access; patients with 
multiple lumen access will not be excluded. 
 
Study Design: Randomized controlled trial, Intralipid versus SMOF lipid emulsion 
Primary outcome measures: 
• 
Bf serum levels during lipid infusion at 3 g/kg/day 
(first and second day of infusions at 3 g/kg/day) 
 
Secondary outcomes: 
• 
FFAu serum levels during lipid infusion at 3 g/kg/day 
(first and second day of infusions at 3 g/kg/day) 
IRB NUMBER: HSC-MS-18-1000 

IRB APPROVAL DATE: 09/25/2019 
 
• 
FFAt serum levels during lipid infusion at 3 g/kg/day 
(second day of infusion at 3 g/kg/day) 
• 
Direct bilirubin, proportion with peak >1.8 mg/dl 
• 
Serum triglyceride level, mean and proportion with peak value >350 mg/dl 
• 
Evaluation of growth at 28 days of life 
Methods 
Patients for whom informed consent has been obtained will be randomized to IL or SMOF using REDCap 
software. Treatment allocation per randomization (IL versus SMOF) will remain in effect through the 
intervention period: until the 2nd  blood sample at 3 g/kg/day or 2 weeks of age, whichever comes first. 
Clinicians cannot be masked to the lipid emulsion – see safety precautions, below 
 
Blood samples for the study will be obtained with blood draws for clinical measurement of bilirubin and/or 
triglyceride levels such that the study will not require additional interventions for blood sampling – see blood 
sampling schema below. When treated with 3 g/kg/day, blood will not be sampled if patients have received a 
mixture of SMOF and IL in the preceding 24 hours, or if SMOF or IL infusions were interrupted for >2 hours in 
the preceding 24 hours. Daily weights and serum bilirubin and triglyceride levels will be abstracted from the 
medical record. 
 
This study will also include measurements that were not included in previous studies in order to validate 
measures and obtain a fuller picture cause and effect mechanisms. These measures include serum albumin, 
bilirubin binding capacity, reserve bilirubin binding capacity, and 2 methods for measuring free fatty acid – both 
bound and unbound free fatty acids. Serum for FFAu and Bf and albumin, will be stored at -80 C and shipped 
to Fluoresprobe Sciences.8 9 Bilirubin binding capacity (BBC) and related measures will be measured with 
hematoflourometry within 12 hours of sampling.10  11  Total FFA will be measured at UT Houston SOM. 
 
Per usual care, lipids start at 1 g/kg/day and advance by 1 g/kg/day to a max of 3 g/kg/day as tolerated by the 
neonate. Blood samples will be collected when lipids are at the following amounts as listed below: 
 
Blood Sampling Schema: 
 
 
 
 
 
 
 
Two samples will be obtained with the lipid emulsion at 3 g/kg/day in order to follow these values in a steady 
state at the maximum dosage. 
 
Safety Precautions: 
During the intervention period (until the 2nd blood sample at 3 g/kg/day or 2 weeks of age, whichever comes 
first), the lipid emulsion may be changed without violating the study protocol so long as the change follows 
usual standard of care practice. Subject to change in NICU guidelines, IL will be discontinued or changed to 
SMOF if direct bilirubin level is >2.0 mg/dl, and SMOF will be changed to IL while potentially incompatible 
medications are infusing via the same intravenous line This means that that both lipid emulsion infusions will 
be managed following usual standard of care practice (i.e., in the same way as in patients not enrolled in the 
study). After the intervention period, lipid emulsion may be changed at the discretion of the attending physician. 
 
Data Analysis: Mean values will be compared using Student’s t test, over all patients and within gestational age 
strata. Proportions will be compared using the chi square test. Dose responses will be analyzed and compared 
using multilevel regression to account for repeated measures within patients. Point estimates and 95% 
confidence levels will be reported for all outcomes. 
IRB NUMBER: HSC-MS-18-1000 
Lipid 
Dose (g/kg) 
Total 
sample in 
(mL) 
1 
0.5 
2 
0.5 
3 
0.5 
3 
0.5 
Total 
2.0 

ubin from al
Data Management: Data will be entered and stored in a secure University of Texas Health Sciences REDCap 
database. 
 
Power and Sample Size: 
Based on the sample size calculation below, a feasible sample size of 64 patients (32 in 2 groups) would result 
in power of 0.81 with alpha at 0.05 to detect an 39% difference in mean Bf levels, SMOF versus IL infusing at 3 
g/kg/day. 
 
D’Ascenzo conducted a small randomized trial comparing IL and SMOF in newborns and infusion at 
3.5g/kg/day and found that triglyceride (TG) levels were 39% higher with SMOF versus IL in patients receiving 
3.5 g/kg/day (table below).7 
 
Table 
Intralipid 
SMOF 
delta 
delta % 
Triglyceride) 
mean +SD 
166 +47 
mg/dl 
231 +59 
mg/dl 
65 
mg/dl 
39 % 
Triglyceride levels Intralipid vs SMOF at 3.5 g/kg/day (D’Ascenzo et al) 
 
Absent other relevant data, we hypothesize that mean FFAu and mean Bf levels will also be 39% higher with 
SMOF versus IL (day 2 at 3 g/kg/day). Hegyi reported FFAu of 67 + 173 and Bf levels of 15.9 + 8.5 (mean,SD) 
with IL infusions of 3 g/kg/day (figure 1). For reasons of feasibility but also because Bf levels are clinically more 
important, we based sample size and power calculations on Bf rather than FFAu. 
 
Figure  Effects of increasing intralipid dose from 0 to 3 g/kg/d (Hegyi et al) 
Given Bf levels (nM) of 15.9 + 8.5 with IL versus 22.1 + 8.5 with SMOF (delta = 39%), a sample size of 62 
patients (31 in 2 groups) will result in power of 0.81 with alpha at 0.05. Likewise, power will be 0.81 to detect 
an 39% decrease (SMOF 9.7 + 8.5). 
 
 
 
 
 
 
 
Observational Outcomes : 
 
IRB NUMBER: HSC-MS-18-1000 
Evaluation hematofluorometry’s capacity to detect displacement of bilir 
bumin by free fatty acids 
and of the correlation of Bf and the saturation index. 
IRB APPROVAL DATE: 09/25/2019 

IRB NUMBER: HSC-MS-18-1000 
IRB APPROVAL DATE: 09/25/2019 
 
Unrelated to comparisons between Intralipid and SMOF, a number of analyses will address important 
questions. Hematofluorometry is the methodology employed to measure bilirubin binding capacity (BBC). With 
total serum bilirubin (TSB) and Bf, BBC is one of three measured components in the bilirubin binding panel 
proposed by Ahlfors.10 11  12  Calculated components of the bilirubin binding panel include reserve bilirubin 
binding capacity (RBBC), calculated as the difference between BBC and bound bilirubin, and the bilirubin- 
albumin equilibrium dissociation constant (Kd). The clinical problem of unrecognized high Bf levels secondary 
to FFAs displacing bilirubin from albumin is a prime example of the potential utility of the bilirubin binding panel, 
and the limitations of relying on TSB alone. The question arises: should clinicians also measure BBC and Bf, 
and perhaps FFA, as they prescribe lipid emulsion during the first weeks after birth? The value of including 
BBC and RBBC in the bilirubin binding panel in addition to Bf is that the former measures should be give an 
earlier and more reliable danger signal. This is because Bf levels remain relatively stable until binding capacity 
is reached, then rises quadratically – such that the danger signal may only be appreciated too late. However, 
the capacity of hematofluorometry to detect FFAs effect on BBC in the clinical setting is uncertain. Specifically, 
there is a step in the measurement method that could, in theory, displace FFA from albumin such that the in- 
vivo effect on RBBC might be underestimated. In the current study, we can test the capacity of 
hematofluorometry to detect the effect of FFA on BBC in the following manor. To the extent that elevated Bf 
levels are caused by FFAs displacing bilirubin from albumin binding sites, measured BBC should decrease as 
Bf levels rise. It is believed that this phenomenon becomes when the molar ratios of FFA to albumin exceed 
~4:1(Amin, Maisels, Watchko, 2017).2 However, it is necessary to measure and adjust for concurrent changes 
in albumin concentrations because this also affects both Bf and BBC. 
 
The hematofluorometry saturation index, calculated as bound bilirubin divided by RBBC, provides a second 
means by which the capacity of hematofluorometry to detect displacement of bilirubin from albumin by FFAs 
can be evaluated. The saturation index (SI) has been reported to have a tight correlation with Bf (figure 2) .13 
However, the correlation is dependent on accurate measurement of BBC and RBBC. Finding that the 
correlation of SI and Bf persists at high Bf levels despite high FFA levels would provide evidence that BBC and 
RBBC are measured accurately under these conditions. Conversely, finding that SI-Bf correlation deteriorates 
as FFA and Bf levels rise would provide evidence that hematofluorometry may not be suitable for guiding 
decisions regarding phototherapy and lipid infusions for premature newborns. It is acknowledged that these 
analyses are dependent on observing adequate variation in FFA and Bf levels, and that FFA reach levels that 
are high enough to displace bilirubin from albumin – all of which have been observed in previous similar 
studies.1 
 
Figure 2 
 
References 

IRB NUMBER: HSC-MS-18-1000 
IRB APPROVAL DATE: 09/25/2019 
 
1. Hegyi T, Kleinfeld A, Huber A, et al. Effects of Soybean Lipid Infusion on Unbound Free Fatty Acids and 
Unbound Bilirubin in Preterm Infants. J Pediatr. 2017;184:45-50.e1. doi:10.1016/j.jpeds.2016.12.026 
 
2. Amin SB, Maisels MJ, Watchko JF. Early Lipid Infusions and Unbound Bilirubin in Preterm Neonates: A 
Cause for Concern? J Pediatr. 2017;184:6-7. doi:10.1016/j.jpeds.2017.01.065 
 
3. Salama GS, Kaabneh MA, Almasaeed MN, Alquran MI. Intravenous lipids for preterm infants: a review. 
Clin Med Insights Pediatr. 2015;9:25-36. doi:10.4137/CMPed.S21161 
 
4. Diamond IR, Grant RC, Pencharz PB, et al. Preventing the Progression of Intestinal Failure–Associated 
Liver Disease in Infants Using a Composite Lipid Emulsion: A Pilot Randomized Controlled Trial of 
SMOFlipid. J Parenter Enter Nutr. 2017;41(5):866-877. doi:10.1177/0148607115626921 
 
5. Repa A, Binder C, Thanhaeuser M, et al. A Mixed Lipid Emulsion for Prevention of Parenteral Nutrition 
Associated Cholestasis in Extremely Low Birth Weight Infants: A Randomized Clinical Trial. J Pediatr. 
2018;194:87-93.e1. doi:10.1016/j.jpeds.2017.11.012 
 
6. D’Ascenzo R, Savini S, Biagetti C, et al. Higher Docosahexaenoic acid, lower Arachidonic acid and 
reduced lipid tolerance with high doses of a lipid emulsion containing 15% fish oil: A randomized clinical 
trial. Clin Nutr. 2014;33(6):1002-1009. doi:10.1016/j.clnu.2014.01.009 
 
7. Kao LC, Cheng MH, Warburton D. Triglycerides, free fatty acids, free fatty acids/albumin molar ratio, and 
cholesterol levels in serum of neonates receiving long-term lipid infusions: controlled trial of continuous and 
intermittent regimens. J Pediatr. 1984;104(3):429-435. 
 
8. Huber AH, Kampf JP, Kwan T, Zhu B, Kleinfeld AM. Fatty acid-specific fluorescent probes and their use in 
resolving mixtures of unbound free fatty acids in equilibrium with albumin. Biochemistry. 
2006;45(48):14263-14274. doi:10.1021/bi060703e 
 
9. Huber AH, Zhu B, Kwan T, Kampf JP, Hegyi T, Kleinfeld AM. Fluorescence sensor for the quantification of 
unbound bilirubin concentrations. Clin Chem. 2012;58(5):869-876. doi:10.1373/clinchem.2011.176412 
 
10. Lamola AA, Eisinger J, Blumberg WE, Patel SC, Flores J. Fluorometric study of the partition of bilirubin 
among blood components: Basis for rapid microassays of bilirubin and bilirubin binding capacity in whole 
blood. Anal Biochem. 1979;100(1):25-42. doi:10.1016/0003-2697(79)90105-2 
 
11. Lamola AA, Bhutani VK, Du L, et al. Neonatal bilirubin binding capacity discerns risk of neurological 
dysfunction. Pediatr Res. 2015;77(2):334-339. doi:10.1038/pr.2014.191 
 
12. Ahlfors CE. The Bilirubin Binding Panel: A Henderson-Hasselbalch Approach to Neonatal 
Hyperbilirubinemia. PEDIATRICS. 2016;138(4):e20154378-e20154378. doi:10.1542/peds.2015-4378 
 
13. Wells R, Hammond K, Lamola AA, Blumberg WE. Relationships of bilirubin binding parameters. Clin 
Chem. 1982;28(3):432-439.