Soybean oil emulsion administration during parenteral nutrition in the preterm infant: effect on essential fatty acid, lipid, and glucose metabolism

Fish oil- and soy oil-based lipid emulsions in neonatal parenteral nutrition: a systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The precise role of fish oil-based lipid emulsions (FBL=any lipid emulsion containing any amount of fish oil) and soy oil-based lipid emulsions (SBL=any lipid emulsion not containing fish oil or containing at least 50% soy oil) in neonatal parenteral nutrition (PN) needs to be explored.

SUBJECTS/METHODS

The PubMed, MedLine and Google Scholar databases were searched for randomised control trials in which PN with FBL and SBL was the only difference between intervention and control groups. Methodological quality was assessed based on the Cochrane handbook for systemic reviews and Jadad's score. Revman 5.2 software was used for meta-analysis.

RESULTS

Of 420 trials, 25 met the inclusion criteria. The aggregate results showed that both FBLs and SBLs are beneficial. FBLs were associated with significantly lower incidences of cholestasis (relative risk (RR)=0.50; 95% confidence interval (CI)=0.27-0.92, P=0.03) compared with SBLs. FBLs also had a tendency to improve the rates of weight gain, increase in head circumference and the time to regain birth weight (mean difference (MD)=0.24; 95% CI=-0.63-0.15). SBLs were associated with reduced duration of respiratory support (MD=2.22, 95% CI=0.35-4.09, P=0.02) and mortality rate in the first 28 days (RR=1.24, 95% CI=-0.72-2.13).

CONCLUSIONS

Both FBLs and SBLs are beneficial for neonatal PN. FBLs reduce cholestasis, and SBLs reduce the duration of respiratory support.

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.

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.

Levels of lipids in preterm infants fed breast milk

BACKGROUND

Actual recommendations in preterm infants limit parenteral fat intake to 3-4 g/kg/d. This is based on clinical studies where fat administration was adjusted to achieve levels close to those recommended in adults for atherosclerosis prevention. Data about lipid profiles of breast fed preterm infants who may have fat intakes of up to 7 g/kg/d and could serve as reference are not available.

OBJECTIVE

To establish full lipid profiles in healthy fully breast fed preterm infants and to test the hypothesis that breast milk fat intake leads to serum triglycerides higher than those achieved under full parenteral fat administration.

DESIGN

Serum triglycerides, cholesterol, VLDL, LDL, HDL (all pre- and postprandial), as well as triglycerides in breast milk were measured in 65 healthy, fully breast fed, stable growing preterm infants stratified in 500 g intervals (mean gestational age: 31+/-4 weeks, birth weight: 1500+/-600 g, age at study: 25+/-16 d).

RESULTS

Median fat intake was 7.0 g/kg/d (interquartile range: 5.8;8.1) and led to the following serum levels: triglycerides 0.9 (0.6;1.1), cholesterol 3.1 (2.6;3.5), VLDL 0.5 (0.3;0.6), LDL 1.3 (1.1;1.6), HDL 1.1 (0.8;1.4)mmol/L. Small for gestational age infants showed higher triglycerides (p=0.005). Triglycerides (r2=0.08, p=0.023), postprandial triglyceride increase (r2=0.21, p<0.001), cholesterol (r2=0.16, p<0.001) and HDL (r2=0.16, p<0.001) were correlated with weight at study.

CONCLUSION

Though higher by a factor of two, fat intake by breast milk leads to considerably lower lipid levels when compared to published values obtained under parenteral fat intake. Results suggest that either fat absorption is reduced in preterm infants, or the composition of breast milk supports a lower profile of fat levels when compared to commercially available parenteral fat emulsions.

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.

Stimulation of gluconeogenesis by intravenous lipids in preterm infants: response depends on fatty acid profile

In preterm infants, both hypo- and hyperglycemia are a frequent problem. Intravenous lipids can affect glucose metabolism by stimulation of gluconeogenesis by providing glycerol, which is a gluconeogenic precursor, and/or free fatty acids (FFA), which are stimulants of the rate of gluconeogenesis. In 25 preterm infants, glucose production and gluconeogenesis were measured using stable isotope techniques during a 6-h infusion of glucose only, glucose plus glycerol, or glucose plus an intravenous lipid emulsion. Two lipid emulsions differing in FFA composition were used: Intralipid ( approximately 60% polyunsaturated FFA) and Clinoleic (approximately 60% monounsaturated FFA). The rate of glucose infusion was 22 micromol x kg(-1) x min(-1) in all groups. During the study infusion, the FFA concentrations were higher in both lipid groups vs. the glycerol group (P < 0.001). Compared with baseline, the glucose production rate increased in the Intralipid group, whereas it decreased in the other groups (P = 0.002) due to a significant increase in gluconeogenesis in the Intralipid group (P = 0.016). The plasma glucose concentration was significantly higher during Intralipid infusion vs. the other groups (P = 0.046). Our conclusion was that Intralipid enhanced glucose production by increasing gluconeogenesis in preterm infants. This can be ascribed to the stimulatory effect of FFA in addition to any effect of glycerol alone. The lack of stimulation of gluconeogenesis in the Clinoleic vs. the Intralipid group suggests that different classes of fatty acids exert different effects on glucose kinetics in preterm infants.

Metabolism and nutritional support in the surgical neonate

Various factors can influence the metabolism of surgical neonates. These include prematurity, operative stress, critical illness, and sepsis. The nutritional management of surgical infants with congenital or acquired intestinal abnormalities has improved after the introduction of parenteral nutrition. This article is focused on the energy and protein metabolism of surgical neonates with particular reference to the metabolic response to operative trauma and sepsis. The metabolic utilization of intravenous nutrients also is discussed. The metabolic response to operative trauma is different between neonates and adults. Infants have high rates of protein turnover and are avid retainers of nitrogen. Energy expenditure increases only transiently (4 to 6 hours) after major surgery in neonates. Protein turnover and catabolism seems not to be affected by major operative procedures in neonates. In neonates on parenteral nutrition, carbohydrate and fat have an equivalent effect on protein metabolism. The main determinants of fat utilization are carbohydrate intake and resting energy expenditure. Parenteral nutrition in surgical neonates is associated with increased production of oxygen-free radicals. This seems to be related to intravenous fat administration. Promoting fat utilization by reducing the carbohydrate to fat ratio in the intravenous diet reduces free radical activity to a similar extent as fat exclusion. Glutamine appears to be safe for use in neonates and infants and is "conditionally essential" in very-low birth weight infants and in septic neonates. Enteral glutamine supplementation in very-low birth weight infants reduces the risk of sepsis. The metabolism of surgical neonates is affected by operative trauma, critical illness, and sepsis. Nutritional support in surgical neonates has a profound impact on outcome. Exogenous glutamine can modulate immune, metabolic, and inflammatory responses. Further investigations are needed to clarify the clinical benefit of parenteral or enteral glutamine administration in surgical neonates.

Early feeding strategies in preterm and critically ill neonates

This two-part article presents feeding strategies for the NICU population over the first several weeks of life. It focuses primarily on the theory and approach to feeding extremely low birth weight (ELBW) infants, but also addresses some issues pertinent to larger, ill infants. The premise for these recommendations is that avoiding early malnutrition in ELBW and ill infants has both short- and long-term benefits. Many practitioners may consider our approach to be somewhat aggressive. In this strategy, total parenteral nutrition (TPN) is initiated in the first hours after birth and is given together with initially small, and then increasing, enteral feedings beginning on the first or second day of life. The role of the TPN is to provide rapid, maximal nutrition and that of the early enteral feedings is to "prime" the gut and stimulate normal gastrointestinal tract activity.

Intravenous nutrition and postnatal growth of the micropremie

There is a growing body of evidence that early nutritional practices may affect short-term growth and developmental outcome. In addition, they may play a role in determining adult health and disease. There is much that needs to be learned about safe and efficacious nutrient administration in the ELBW population; about techniques to assess the effect of different nutritional strategies; and about the long-term effects of these regimen or development outcome, growth, and disease.

Phospholipid-rich particles in commercial parenteral fat emulsions. An overview

In parenteral nutrition, the infusion of a fat EMU supplies both concentrated energy and covers the essential fatty acid requirements, the basic objective being to mimic as well as possible the input of chylomicrons into the blood. This objective is well met by the TAGRP of the EMU, which behave as true chylomicrons. However, commercial EMU also contain an excess of emulsifier in the form of PLRP. The number of these PLRP depends directly on the PL/TAG ratio of the EMU. They differ from the TAGRP by their composition (PL vs TAG and PL), their structure (PL in bilayer versus monolayer), and their granulometry (mean diameter 70-100 nm for PL vs 200-500 nm). The metabolic fate of the PLRP is similar in several ways to that of the TAGRP: exchanges of PL with the PL of the different cellular membranes and of the lipoproteins; captation of free CH from these same structures; and enrichment in apolipoproteins. However, because the TAGRP are the preferred substrates of the lipolytic enzymes, their clearance is much more rapid (half-life < 1 h) than that of the PLRP. As the infusion is continued, the PLRP end up accumulating and being transformed into LP-X (free CH/PL = 1; half-life of several days). As soon as the EMU is infused, the PLRP enter into competition with the TAGRP, in the lipolysis process as well as for sites of binding and for catabolism. The sites for catabolism of the two types of PAR are not the same: adipose tissues and muscles utilize the fatty acids and monoacylglycerols released by the lipolysis of the TAGRP; hepatocytes take up their remnants; the RES and the hepatocytes participate in the catabolism of the PLRP and the LP-X. Thus, prolonged infusion of EMU rich in PLRP leads to a hypercholesterolemia, or at least a dyslipoproteinemia, due to elevated LP-X, associated with a depletion of cells in CH, stimulating thus tissue cholesterogenesis. However, parenteral nutrition has evolved towards the utilization of EMU with a low PL/TAG ratio (availability of 30% formula) and less rapid delivery. For these reasons, the hypercholesterolemias that used to be observed with the 10% EMU have become much less spectacular or have even disappeared. It is interesting to note that patients on prolonged TPN, in particular those with a short small intestine, have weak cholesterolemia, reflecting a lowering of HDL and LDL not masked by elevated LP-X. At present, it seems difficult to produce sufficiently stable parenteral EMU devoid of PLRP. Notwithstanding, all the observations made since the introduction of the EMU in TPN are in favour of the use of PLRP-poor EMU. It is clear that the 10% formulas, and generally those with a PL/TAG ratio of 12/100, are ill-advised, especially in patients with a retarded clearance of circulating lipids.

The effects of dietary fish oil on alveolar type II cell fatty acids and lung surfactant phospholipids

The purpose of this study was to determine the responsiveness of alveolar type II cells to dietary fish oil and the consequent effects on alveolar and lung surfactant. Rats were fed a corn oil or a fish oil diet for four weeks. Dietary n-3 fatty acids were readily incorporated into the type II cell phospholipids as indicated by higher levels of eicosapentaenoic acid (2.77 +/- 0.10%) and docosahexaenoic acid (1.63 +/- 0.10%) in the group receiving the fish oil diet. The elevated levels of n-3 fatty acids were accompanied by concomitant reduction in arachidonic acid and linoleic acid. Neither eicosapentaenoic acid nor docosahexaenoic acid was incorporated into type II cell triacylglycerols. Feeding a fish oil containing diet increased surfactant phospholipids, particularly 1,2-disaturated acyl phosphatidylcholines in whole lung compared to a corn oil diet. However, the amount of surfactant found in the alveolus was not different between the two diet treatment groups. The results suggest that dietary n-3 fatty acids stimulate synthesis and/or inhibit degradation of lung surfactant without altering surfactant secretion in alveoli.