Prevention of neonatal hypoglycaemia by oral lipid supplementation in low birth weight infants

Lipid Intake Enhances Muscle Growth But Does Not Influence Glucose Kinetics in 3-Week-Old Low-Birth-Weight Neonatal Pigs

BACKGROUND

Low-birth-weight (LBWT) neonates grow at a slower rate than their normal-birth-weight (NBWT) counterparts and may develop hypoglycemia postnatally.

OBJECTIVE

We investigated whether dietary lipid supplementation would enhance growth and improve glucose production in LBWT neonatal pigs.

METHODS

Twelve 3-d-old NBWT (1.606 kg) crossbred pigs were matched to 12 LBWT (1.260 kg) same-sex littermates. At 6 d of age, 6 pigs in each group were fed a low-energy (LE) or a high-energy (HE) isonitrogenous formula containing 5.2% and 7.3% fat, respectively. Body composition was assessed using dual-energy X-ray absorptiometry; plasma glucose and glycerol kinetics were assessed using stable isotope tracers. After killing, weights of skeletal muscles and visceral organs were measured. Data were analyzed by ANOVA for a 2 × 2 factorial design; temporal effects were investigated using repeated-measures analysis.

RESULTS

Lipid supplementation did not affect body weight of LBWT or NBWT pigs. However, liver and longissimus dorsi weights as a percentage of body weight were greater for pigs fed an HE diet than for those fed an LE diet (4.3% compared with 3.4% and 1.5% compared with 1.2%, respectively) but remained less for LBWT than for NBWT pigs (3.8% compared with 3.9% and 1.3% compared with 1.5%, respectively) (P < 0.05). In addition, hepatic fat content increased (7.9 compared with 2.6 g) in pigs fed the HE compared with those fed the LE formula (P < 0.05). Lipid supplementation did not influence plasma glucose concentration which remained lower in the LBWT than in the NBWT group (4.1 compared with 4.5 mmol/L) (P < 0.05).

CONCLUSIONS

Our data suggest that lipid supplementation modestly improved growth of skeletal muscle and the liver but did not affect glucose homeostasis in all groups, and glucose concentration remained lower in LBWT than in NBWT pigs. These data suggest that the previously reported hyperglycemic effect of lipid supplementation may depend on the route of administration or age of the neonatal pig.

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.

Community-based interventions for improving perinatal and neonatal health outcomes in developing countries: a review of the evidence

BACKGROUND

Infant and under-5 childhood mortality rates in developing countries have declined significantly in the past 2 to 3 decades. However, 2 critical indicators, maternal and newborn mortality, have hardly changed. World leaders at the United Nations Millennium Summit in September 2000 agreed on a critical goal to reduce deaths of children <5 years by two thirds, but this may be unattainable without halving newborn deaths, which now comprise 40% of all under-5 deaths. Greater emphasis on wide-scale implementation of proven, cost-effective measures is required to save women's and newborns' lives. Approximately 99% of neonatal deaths take place in developing countries, mostly in homes and communities. A comprehensive review of the evidence base for impact of interventions on neonatal health and survival in developing-country communities has not been reported.

OBJECTIVE

This review of community-based antenatal, intrapartum, and postnatal intervention trials in developing countries aimed to identify (1) key behaviors and interventions for which the weight of evidence is sufficient to recommend their inclusion in community-based neonatal care programs and (2) key gaps in knowledge and priority areas for future research and program learning.

METHODS

Available published and unpublished data on the impact of community-based strategies and interventions on perinatal and neonatal health status outcomes were reviewed. Evidence was summarized systematically and categorized into 4 levels of evidence based on study size, location, design, and reported impact, particularly on perinatal or neonatal mortality. The evidence was placed in the context of biological plausibility of the intervention; evidence from relevant developed-country studies; health care program experience in implementation; and recommendations from the World Health Organization and other leading agencies.

RESULTS

A paucity of community-based data was found from developing-country studies on health status impact for many interventions currently being considered for inclusion in neonatal health programs. However, review of the evidence and consideration of the broader context of knowledge, experience, and recommendations regarding these interventions enabled us to categorize them according to the strength of the evidence base and confidence regarding their inclusion now in programs. This article identifies a package of priority interventions to include in programs and formulates research priorities for advancing the state of the art in neonatal health care.

CONCLUSIONS

This review emphasizes some new findings while recommending an integrated approach to safe motherhood and newborn health. The results of this study provide a foundation for policies and programs related to maternal and newborn health and emphasizes the importance of health systems research and evaluation of interventions. The review offers compelling support for using research to identify the most effective measures to save newborn lives. It also may facilitate dialogue with policy makers about the importance of investing in neonatal health.

Plasma fatty acids and [13C]linoleic acid metabolism in preterm infants fed a formula with medium-chain triglycerides

Most preterm infant formulas contain medium-chain triacylglycerols (MCT), but the effects of MCT on polyunsaturated fatty acid status and metabolism are controversial. Thus, we studied the effects of MCT on linoleic acid metabolism using stable isotopes. Enterally fed preterm infants were randomized to receive for 7 days 40% of fat as MCT (n = 10) or a formula without MCT (n = 9). At study day 5, infants received orally 2 mg/kg body weight of (13)C-labeled linoleic acid. Fatty acids in plasma lipid classes and (13)C enrichment of phospholipid fatty acids were measured and tracer oxidation was monitored. Compared with the control group, the MCT group showed lower breath (13)CO(2) and higher plasma triacylglycerol contents of octanoic acid, of decanoic acid, and of total long-chain polyunsaturated fatty acids (57.1 +/- 4.4 micro mol/l vs. 37.9 +/- 4.8 micro mol/l, P < 0.01). Concentrations of several polyunsaturated fatty acids in plasma phospholipids and non esterified fatty acids were higher in the MCT group. (13)C concentrations in phospholipid n-6 fatty acids indicated no difference in the relative conversion of linoleic to arachidonic acid. We conclude that oral MCT effectively reduce polyunsaturated fatty acid and long chain polyunsaturated fatty acid oxidation in preterm infants without compromising endogenous n-6 long chain polyunsaturated fatty acid synthesis.

Neonatal glucose metabolism: differential diagnoses, evaluation, and treatment of hypoglycemia

Hypoglycemia is one of the most common clinical care issues facing the neonatal practitioner. Increasing evidence indicates that neonatal hypoglycemia may have long-term neurologic effects. Care is complicated by the lack of a clearly defined threshold for hypoglycemia in term and preterm infants, however, and by highly variable clinical signs and symptoms. Furthermore, many infants with low blood glucose measurements do not exhibit obvious signs of impairment. The complexity of neonatal glucose metabolism is illustrated by the variety of conditions producing or associated with both neonatal hypo- and hyperglycemia. Maintenance of euglycemia is especially challenging in the sick or low birth weight neonate. This article defines euglycemia by its range and reviews the differential diagnoses and etiology of hypoglycemia--as well as the principles of its management--in the neonatal period.