Favorable Fish Oil Outcomes in High Risk Preterm Infants

Briefly noted: M Sorrell et al. JPGN 2017; 64: 783-88. In this small study with 13 infants (mean gestational age of 28 weeks) who had short bowel syndrome or severe dysmotility and direct bilirubin ≥4 mg/dL (mean 9.8 at enrollment), patients received a fish oil-based lipid emulsion (1 g/kg/d). They were compared with 119 GA-matched controls.

Overall, the authors found the fish oil supplement to be safe.  All patients had resolution of cholestasis. They note the difficulty of proving effectiveness and performing studies in this population.  “Neonatologists…find themselves faced with …a growing body of uncontrolled data that suggests benefits of an unapproved treatment…An attempt to perform a randomized controlled comparison of a plant-based lipid emulsion to FishLE in preventing PNALD in infants at risk was terminated early after an interim analysis revealed much lower than expected incidence of PNALD…[making] trials ethically problematic.”

My take: The data remain incomplete and make it difficult to use a therapy like Omegaven that is quite expensive (not covered) and not FDA approved.  The availability of SMOFlipid is likely to result in less usage of plant-based soy products.

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Rodin Museum

Stick with the (intestinal) rehab program?

More data on the progress of treatment of short bowel syndrome (SBS) programs:

  • Avitzur J, et al. JPGN 2015; 61: 18-23

In this study, the researchers from Toronto and the Group for Improvement of Intestinal Function and Treatment (GIFT) retrospectively examine 84 patients over 3 time periods: 1999-2002, 2003-2005, and 2006-2009.

Key points:

  • Across those time periods, the authors find fewer SBS patients that needed to be listed for transplantation despite similar baseline characteristics.  In addition, many more patients in the late period were removed from the transplant waiting list due to clinical improvement.
  • Another important finding was a drop in mortality (15% vs >60%) and a shift from previous causes like liver failure and sepsis to death from other comorbid conditions.
  • “Since 2009, we have performed only 1 IT [intestinal transplant].”  They note this is a worldwide trend with ~50% reduction in pediatric IT since 2008.
  • Even with ultrashort bowel (small bowel length <30 cm), there are reports that “50% of these patients achieved PN independence within 2 years.”  As such, this is a declining indication for IT listing. In this study, ultrashort bowel was the reason for listing in 11% in the last period compared 21% in the first time period.

Why is this happening?

The authors credit the intestinal rehab program (IRP) for this impact along with specific management changes including new lipid emulsions/lipid minimization to reduce IFALD, use of ethanol locks to reduce bloodstream infections, and bowel reconstructive procedures (e.g. STEP).

Briefly noted: Merras-Salmio L, Pakarinen MP. JPGN 2015; 61: 24-9. This second retrospective study (n=48) from Finland reinforces the view of improvements in cholestasis  and prognosis from 1988-2014.  Similar strategies, as noted above, were implemented in SBS management protocols.

Bottomline: The outlook has improved for SBS.  While this is good news, at the same time, there will be less pediatric gastroenterologists with extensive intestinal transplantation experience.

In Wyoming often there are stretches of nearly deserted highways

In Wyoming often there are stretches of nearly deserted highways

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Omega-3 Fatty Acids, Lipid Emulsions, and Hepatic Pathology

Many have advocated for the use of parenteral fish oil lipids like Omegaven which are rich in omega-3 polyunsaturated fatty acids (O3FAs), though the data in support of them are limited (New lipid emulsions — lacking data to support usage ).

A recent study (J Pediatr 2014; 165: 59-64) identified seven liver-inclusive intestinal transplants who had received O3FAs.   This retrospective review study took place between 2003-2012.  These seven patients had received O3FAs for a mean of 62% of their total life span before transplant.  While these patients almost all had resolution of cholestasis (mean total bilirubin 0.7 mg/dL at time of transplant), advanced fibrosis (stage 3 or 4) was noted on explant pathology.  The histologic inflammatory scores were lower (P=.056) in comparison to O6FA group.

The authors make several important points:

  • The “results provide additional evidence that the improvement in hyperbilirubinemia following O3FA substitution therapy does not consistently produce histologic recovery of the liver.”
  • This study does not address whether comparable improvements could have been obtained from lipid restriction among the O6FA group.
  • Only 1 of 20 studies of O3FA lipid emulsion in PNALD includes hepatic histopathology as an outcome measure.

This is not the first study that indicates that liver fibrosis may persist and progress on O3FA therapy (J Pediatr 2010; 156: 327-31, J Pediatr Surg 2010; 45: 95-9, JPGN 2013; 56: 364-9).

Bottomline: Continued investigation of O3FA emulsions in PNALD is needed and assessing liver histology may be needed prior to intestinal transplantation.

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Parenteral Omega-3 Lipid Emulsions and Risk of Bleeding

A recent study indicates that patient’s placed on omega-3 lipid emulsions (eg. Omegaven) may be at risk for bleeding due to platelet dysfunction (J Pediatr 2014; 164: 652-4).

While omega-3 lipid emulsions have received a lot of attention due to improvements in intestinal failure associated liver disease (IFALD) (see previous links to prior posts below), the amount of data supporting their usage and potential advantages compared with standard lipids at similar dosing remains limited.

This case report describes a 9-month old who developed life-threatening hemorrhage following a standard central line placement.  Due to difficulty stopping the bleeding, the patient’s omegaven was discontinued.  Standard workup for bleeding disorders were negative.  Subsequently, the authors investigated clot formation and platelet function in a neonatal animal model.

Key Result: Piglets treated with omegaven had a doubling of time to clot formation and marked platelet agonist inhibition.

The discussion notes that “there is an acknowledged risk of high dose O3FA lipids [omegaven] increasing bleeding time because of competitive inhibition of AA [arachidonic acid] production, hence decreased TxA2 [thromboxane A2].  In addition, platelet-derived growth factor-like protein and endothelial platelet activation factor are decreased.”

Take home points (from the authors):

  • “the case report and piglet studies together demonstrate that there is potential for a significant antiplatelet effect and inhibition of the coagulation cascade with O3FA therapy…”
  • “We would suggest discontinuation of Omegaven therapy 72 hours preoperatively in high-risk cases where bleeding may be difficult to directly control.”
  • “Institutionally, we have abandoned the sole use of Omegaven therapy.”

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New lipid emulsions — lacking data to support usage

According to a systematic review of the literature regarding ω-3 (n-3FA) fatty acid lipid emulsions, there is a “lack of sufficient high-quality data to support the use of parenteral n-3FA lipid emulsions in children” (JPEN 2013; 37: 44-55). Thanks to Kipp Ellsworth for this reference.

The authors of this study researched 4 databases up to March 2011 and extracted relevant studies.  Five randomized controlled trials and 3 high-quality prospective cohort studies were included.  The strength of evidence was “consistently low or very low across all lipid emulsion comparisons and outcomes.”

Specific criticisms:

  • Few studies examined important outcomes like length of hospital stay or intensive care stay.
  • There was lack of data on growth, cognitive development or potential long-term effects/harms.
  • All of the studies in children varied considerably with regard to the dosing regimens, duration of administration, and duration of followup.
  • The studies were small with sample sizes ranging from 28-91 patients.
  • The 5 RCTs had unclear risk of bias due to inadequate blinding of participants and study personnel.
  • All of the RCTs were funded by the manufacturer.
  • While some biochemical outcomes improved, no difference in mortality has been identified.  A biochemical response is a poor measure of effectiveness.  In fact, several studies have shown deterioration in liver histology and fibrosis despite improved biochemical measures in infants on Omegaven.
  • For Omegaven (fish oil) treatment, all studies used a historical control group.  In these studies, typically the Omegaven dose was half the dose of Intralipid used in the control group.

This article (in its Table 1) identifies the constituents in the commercial available lipid products which include Intralipid, Clinoleic, Liposyn II, Omegaven, SMOFLipid, and Lipoplus.  Intralipid which is widely used is devoid of substantial arachidonic acid (ARA) and docosahexaenoic adic (DHA).  This is particularly important in premature infants as noted in recent blogs:

Omegaven, in particular, and SMOFLipid, to a lesser degree, have much more AA and DHA.  As such, both of these emulsions have the potential improve vision and cognitive outcome in premature infants.

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PNAC, PNALD, and IFAC

Intravenous lipids may cause parenteral nutrition associated cholestasis (PNAC), parenteral nutrition associated liver disease (PNALD), or intestinal failure associated cholestasis (IFAC) (J Pediatr 2012; 160: 421-7 & editorial 361-2).  PNAC refers to cholestasis due to parenteral nutrition and PNALD refers to PNAC that has progressed to liver dysfunction or permanent liver injury.

In a previous blog (Four advances for intestinal failure), one of the advances for intestinal failure that was noted was the reduction of lipid infusions with parenteral nutrition which reduces IFAC.  This study adds additional information to this area.  In this prospective study, 31 patients were enrolled in a reduced IV fat emulsion group and compared with a matched historical control group.  The reduced fat group received 1gm/kg of a standard soybean-based lipid emulsion (liposyn 20%) twice weekly.  Patients were eligible if they received PN for >2 weeks and had a direct bilirubin >2.5 mg/dL.

Outcomes:

  • Total bilirubins dropped 0.73 mg/dL each week in the reduced fat group; in the control group, the bilirubin increased 0.29 mg/dL each week
  • Growth was similar in both groups
  • Essential fatty acid deficiency (biochemical not clinical features) was identified in 13 of 31 infants among the restricted IV fat emulsion group.

Essential fatty acid deficiency was defined as having a triene: tetraene ratio >0.05 (mild), >0.2 (moderate) or >0.4 (severe).

Limitations:

  • Historical control group & small study population
  • Fat-restricted group received enteral antibiotics which may have helped reduce cholestasis
  • Majority of patients with relatively short duration of TPN: 18 of 31 for less than one month

The reasons why lipids may contribute to PNAC/PNALD/IFAC include the presence of phytosterols.  This in turn may damage hepatocytes via the farnesoid X receptor.  One other aspect of the study was that the fat-restricted cohort had a higher mortality.  This was thought to be related to the cohort being sicker rather than to any nutritional effect.  Specific causes of death included respiratory failure in a patient with an abdominal wall defect, chylothorax/sepsis in a patient with a congenital diaphragmatic hernia, and cardiopulmonary failure in a patient with pulmonary hypoplasia.

The article does throw into question whether the use of a fish oil lipid preparation is needed to improve cholestasis.  In studies supporting fish oil preparations, a confounder was that the total lipid administered was reduced to 1 gm/kg/day in comparison to soybean lipids which were administered at 2-3 gm/kg/day.  This study suggests that reducing the total amount of lipid infusion is the more important factor.

The accompanying editorial makes a couple of useful points:

  • Increasing enteral feeds (>50%) is as effective as using less intravenous lipids
  • Use of standard lipids at 1gm/kg/day decreased IFAC from 15% to 4% in their intestinal failure patient population
  • Drastic reductions in lipids lead to essential fatty acid deficiency and should be avoided.
  • Use of Omegaven has not been shown to prevent liver fibrosis even with resolution of cholestasis; similarly, these studies do not inform fully on the long-term liver effects of reducing standard lipids
  • Neurologic followup will be important
  • Explains “Morton’s fork.”  John Morton was a 16th century Archbishop who wanted to increase taxes on people who were living lavishly.  In addition, he wanted to increase taxes on those living modestly (must be hiding wealth).

Additional references:

  • -NEJM 2010; 362: 181.  Letter to editor describes use of fish oil in (n=125) Boston pediatric patients.
  • -JPGN 2009; 48: 209. n=12. SBS.  9/12 improved with Omegaven. 3 had transplant (L-ITx). No controls.
  • -Pediatrics 2008; 121: e678-86. n=18.  Use of fish oil improved cholestasis compared to historical controls.
  • -Pediatrics 2006; 118: e197-e201.  Reversal of TPN-AC c IV omega-3 fatty acids (fish oil-derived) instead of intralipids