The metabolic response to intravenous medium-chain triglycerides in infants after surgery

Parenteral nutrition-associated cholestasis and triglyceridemia in surgical term and near-term neonates: A pilot randomized controlled trial of two mixed intravenous lipid emulsions

BACKGROUND

Cholestasis is a common complication in infants receiving prolonged parenteral nutrition (PN). We studied the effects of two intravenous lipid emulsions composed with either 30% soybean oil, 30% medium-chain triglycerides (MCT), 25% olive oil, and 15% fish oil (SMOF) or with 50% MCT and 50% soybean oil n-6 (MCT/SOY) on the incidence of cholestasis in surgical term and near-term neonates.

METHODS

A single-center, double-blinded, randomized controlled trial compared the incidence of cholestasis using either SMOF or MCT/SOY in neonates born at gestational age ≥34 weeks undergoing major surgery. The primary outcome was the incidence of conjugated serum bilirubin >1 mg/dL. Other liver enzymes were assessed as secondary outcomes. A post-hoc analysis assessed serum triglycerides levels. Odds ratios were estimated by mixed-effects regression models.

RESULTS

Enrollment was prematurely interrupted because the MCT/SOY became unavailable, thus 49 infants (SMOF 22, MCT/SOY 27) completed the study. The exposure (time on PN, cumulative dose of lipids) was similar in both groups. Similar cumulative incidence rates were found for elevated conjugated bilirubinemia and other liver enzymes. Hypertriglyceridemia >250 mg/dL (12/49) was more frequent in MCT/SOY (37.0%, 95% CI 21.53-55.77) than in SMOF (9.1%, 95% CI 2.53-27.81, p = 0.024). Triglyceridemia at the first assessment (median 8 postnatal days) was significantly higher with MCT/SOY than with SMOF (181 vs. 134 mg/dL, p = 0.006). Over the whole study period, mean triglyceride concentration was 36.5 mg/dL higher with MCT/SOY compared with SMOF (p = 0.013).

CONCLUSION

Both emulsions had similar effects on the incidence of cholestasis and markers of liver integrity, but MCT/SOY induced higher serum triglyceride concentrations.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02633384.

Intravenous Lipid Emulsions in Parenteral Nutrition

Fat is an important macronutrient in the human diet. For patients with intestinal failure who are unable to absorb nutrients via the enteral route, intravenous lipid emulsions play a critical role in providing an energy-dense source of calories and supplying the essential fatty acids that cannot be endogenously synthesized. Over the last 50 y, lipid emulsions have been an important component of parenteral nutrition (PN), and over the last 10-15 y many new lipid emulsions have been manufactured with the goal of improving safety and efficacy profiles and achieving physiologically optimal formulations. The purpose of this review is to provide a background on the components of lipid emulsions, their role in PN, and to discuss the lipid emulsions available for intravenous use. Finally, the role of parenteral fat emulsions in the pathogenesis and management of PN-associated liver disease in PN-dependent pediatric patients is reviewed.

Use of parenteral lipid emulsions in French neonatal ICUs

OBJECTIVE

To determine the types of parenteral lipid emulsions currently used for preterm infants, their mode of delivery, and the main disease conditions that are considered by neonatologists as contraindications.

DESIGN

National survey using a questionnaire.

SETTING

155 neonatal departments in France.

RESULTS

100 (65%) neonatal departments participated in the survey. The most widely used lipid emulsion was the 20% soybean oil/coconut oil-based emulsion (68% of the units), followed by the soybean oil-based emulsion (28.5%) and the soybean oil/olive oil-based emulsion (3.5%). Peripheral venous access was considered to be a possible route for the infusion of lipid emulsions in only 58 (63.7%) of the units. In 80%-90% of the units, sepsis, hemodynamic failure, thrombocytopenia, disseminated intravascular coagulation, and hyperbilirubinemia were considered to be relative or absolute contraindications, whereas only hemodynamic failure, disseminated intravascular coagulation, and to a lesser extent sepsis were most often perceived as absolute contraindications.

CONCLUSIONS

Neonatologists are somewhat reluctant to use parenteral lipids when only peripheral venous access is available, despite the low osmolarity of the emulsions. This may impair, at least temporarily, the adequate supply of energy and/or essential fatty acids in infants who do not have central venous access. This study also shows a large heterogeneity of responses with regard to the contraindications for parenteral lipids.

Cycled enteral antibiotics reduce sepsis rates in paediatric patients on long-term parenteral nutrition for intestinal failure

BACKGROUND

Long-term parenteral nutrition has transformed the prognosis for children suffering from intestinal failure. However, parenteral nutrition itself is associated with considerable morbidity and mortality including that caused by sepsis.

AIM

To examine a strategy of cycled enteral antibiotics in reducing the incidence of sepsis in paediatric intestinal failure patients.

METHODS

Retrospective analysis of the incidence of sepsis rates of patients on long-term parenteral nutrition, at a tertiary paediatric hospital. Patients were separated into those who received cycled enteral antibiotics and a control group. Sepsis rates before and during cycled enteral antibiotics were compared with comparable timeframes between the cycled enteral antibiotics and control groups. Central venous catheter removal rates were also compared.

RESULTS

Fifteen patients (eight cycled enteral antibiotics, & seven controls) received 9512 parenteral nutrition days, with a total of 132 sepsis episodes. All eight patients of the treatment group demonstrated a decrease in the frequency of episodes of sepsis following the introduction of cycled enteral antibiotics. The cycled enteral antibiotics group had a significant reduction in infection rate during the treatment period (from 2.14 to 1.06 per 100 parenteral nutrition days, P = 0.014: median effect size -1.04 CI 95%-1.93, -0.22), whereas the controls had no significant change (1.91 - 2.36 per 100 parenteral nutrition days P = 0.402: median effect size 0.92 CI 95%-1.96, 4.17). The central venous catheter survival rates increased in the cycled enteral antibiotics group from 0.44 central venous catheter removals per 100 parenteral nutrition days to 0.27 central venous catheter removals per 100 parenteral nutrition days, although this was not statistically significant.

CONCLUSIONS

Cycled enteral antibiotics significantly reduced the rate of sepsis in a small group of paediatric intestinal failure patients. Larger well-designed prospective studies are warranted to further explore this finding.

Systematic review: medical and nutritional interventions for the management of intestinal failure and its resultant complications in children

BACKGROUND

Intestinal failure (IF) affects a growing number of children due to increasing numbers of preterm infants surviving intestinal resection for necrotising enterocolitis and improving surgical techniques for congenital gut anomalies. Parenteral nutrition (PN) is the mainstay of therapy; enteral nutrition may have trophic effects on the gut.

AIM

To review systematically evidence for the effectiveness of medical and nutritional interventions in the treatment of IF in children.

METHODS

Retrieval of data from studies of patients aged <18 years and receiving >28 days of PN. Outcome measures were improvement in intestinal function, intestinal adaptation, growth, prevention and treatment of IF-associated liver disease, and mortality. Cochrane Database (November 2009), MEDLINE (1950-November 2009) and CINAHL (1982-November 2009) electronic database searches were made using keyword and subject headings (MeSH): IF, Short Bowel Syndrome (SBS), PN and Child. The level of the evidence (EL) was assessed using SIGN (Scottish Intercollegiate Guidelines Network) methodology (http://www.sign.ac.uk).

RESULTS

From 1 607 620 hits, 720 abstracts were reviewed. Thirty-three original articles were included. No studies were of high methodological quality.

CONCLUSIONS

The evidence base for medical and nutritional interventions in paediatric IF is limited and of poor quality. In the absence of randomised-controlled trials, this evidence base can improve through case control and cohort research; and with better multiagency communication, the study of inter-centre differences is possible. Achievable short-term goals would include the study of: optimal ursodeoxycholic usage, novel intralipid formulations, cycled enteral antibiotics, enteral probiotics and new enteral feeding strategies.

Neonatology/Paediatrics - Guidelines on Parenteral Nutrition, Chapter 13

There are special challenges in implementing parenteral nutrition (PN) in paediatric patients, which arises from the wide range of patients, ranging from extremely premature infants up to teenagers weighing up to and over 100 kg, and their varying substrate requirements. Age and maturity-related changes of the metabolism and fluid and nutrient requirements must be taken into consideration along with the clinical situation during which PN is applied. The indication, the procedure as well as the intake of fluid and substrates are very different to that known in PN-practice in adult patients, e.g. the fluid, nutrient and energy needs of premature infants and newborns per kg body weight are markedly higher than of older paediatric and adult patients. Premature infants <35 weeks of pregnancy and most sick term infants usually require full or partial PN. In neonates the actual amount of PN administered must be calculated (not estimated). Enteral nutrition should be gradually introduced and should replace PN as quickly as possible in order to minimise any side-effects from exposure to PN. Inadequate substrate intake in early infancy can cause long-term detrimental effects in terms of metabolic programming of the risk of illness in later life. If energy and nutrient demands in children and adolescents cannot be met through enteral nutrition, partial or total PN should be considered within 7 days or less depending on the nutritional state and clinical conditions.

Metabolism and nutrition in the surgical neonate

Considerable improvements have been achieved in pediatric surgery during the last two decades: the mortality rate of neonates undergoing major operations has declined to less than 10%, and the morbidity of major operations has become negligible. This considerable improvement can be partly ascribed to a better understanding of the physiological changes that occur after an operation and to more appropriate management and nutrition of the critically ill and "stressed" neonates and children. The metabolic response to an operation is different in neonates from adults: there is a small increase in oxygen consumption and resting energy expenditure immediately after surgery with return to normal by 12-24 hours. The increase in resting energy expenditure is significantly greater in infants having a major operation than in those having a minor procedure. The limited increase in energy expenditure may be due to diversion of energy from growth to tissue repair. During parenteral nutrition, it is not advisable to administer more than 18 g/kg/day of carbohydrate because this intake will be associated with lipogenesis, increased CO(2) production, and increased free radical-mediated lipid peroxide formation. Glutamine intake is potentially beneficial during total parenteral nutrition, although a large, randomized, controlled trial in surgical neonates requiring parenteral nutrition is needed to provide evidence for its benefit.

Impaired energy metabolism during neonatal sepsis: the effects of glutamine

Neonatal sepsis is an important cause of morbidity and mortality as a result of multiple organ system failure, particularly in neonates requiring total parenteral nutrition. Suitable therapies and support are needed both to prevent sepsis and to prevent multiple organ failure. After bacterial infection, pro-inflammatory cytokines trigger the antimicrobial activity of macrophages and neutrophils, resulting in production of reactive species such as H2O2, NO, superoxide and peroxynitrite. However, excess production can lead to host tissue damage. Incubation of either hepatocytes or heart mitochondria from neonatal rats with these reactive species, or with cytokines, leads to impairment of mitochondrial oxidative function, and in an animal model of neonatal sepsis similar results to thein vitrofindings have been demonstrated. Recentin vivostudies, using indirect calorimetry of suckling rat pups, show that during endotoxaemia there is a profound hypometabolism, associated with hypothermia. Having determined that cellular oxidative function may be impaired during sepsis, it is of great importance to try to identify therapeutic measures. Much interest has been shown in glutamine, which may become essential during sepsis. It has been shown that hepatic glutamine is rapidly depleted during endotoxaemia. When hepatocytes from endotoxaemic rats were incubated with glutamine, there was a restoration of mitochondrial structure and metabolism.In vivo, intraperitoneal injection of glutamine into endotoxic suckling rats partially reversed hypometabolism, markedly reduced the incidence of hypothermia and improved clinical status. These results suggest that glutamine has a beneficial effect during sepsis in neonates.

Metabolic effects of intravenous LCT or MCT/LCT lipid emulsions in preterm infants

Most lipid emulsions for parenteral feeding of premature infants are based on long-chain triacylglycerols (LCTs), but inclusion of medium-chain triacylglycerols (MCTs) might provide a more readily oxidizable energy source. The influence of these emulsions on fatty acid composition and metabolism was studied in 12 premature neonates, who were randomly assigned to an LCT emulsion (control) or an emulsion with a mixture of MCT and LCT (1:1). On study day 7, all infants received [13C]linoleic (LA) and [13C]alpha-linolenic acid (ALA) tracers orally. Plasma phospholipid (PL) and triacylglycerol (TG) fatty acid composition and 13C enrichments of plasma PL fatty acids were determined on day 8. After 8 days of lipid infusion, plasma TGs in the MCT/LCT group had higher contents of C8:0 (0.50 +/- 0.60% vs. 0.10 +/- 0.12%; means +/- SD) and C10:0 (0.66 +/- 0.51% vs. 0.15 +/- 0.17%) than controls. LA content of plasma PLs was slightly lower in the MCT/LCT group (16.47 +/- 1.16% vs. 18.57 +/- 2.09%), whereas long-chain polyunsaturated derivatives (LC-PUFAs) of LA and ALA tended to be higher. The tracer distributions between precursors and products (LC-PUFAs) were not significantly different between groups. Both lipid emulsions achieve similar plasma essential fatty acid (EFA) contents and similar proportional conversion of EFAs to LC-PUFAs. The MCT/LCT emulsion seems to protect EFAs and LC-PUFAs from beta-oxidation.