Effect of intravenous L-carnitine on growth parameters and fat metabolism during parenteral nutrition in neonates

Effects of L-Carnitine Supplementation on the Rate of Weight Gain and Biomarkers of Environmental Enteric Dysfunction in Children with Severe Acute Malnutrition: A Double-Blind Randomized Controlled Clinical Trial

BACKGROUND

Severe acute malnutrition (SAM) is a major public health concern among low- and middle-income countries, where the majority of the children encountering this acute form of malnutrition suffer from environmental enteric dysfunction (EED). However, evidence regarding the effects of L-carnitine supplementation on the rate of weight gain and EED biomarkers in malnourished children is limited.

OBJECTIVES

We aimed to investigate the role of L-carnitine supplementation on the rate of weight gain, duration of hospital stays, and EED biomarkers among children with SAM.

METHODS

A prospective, double-blind, placebo-controlled, randomized clinical trial was conducted at the Nutritional Rehabilitation Unit (NRU) of Dhaka Hospital, International Centre for Diarrheal Disease Research, Bangladesh. Children with SAM aged 9-24 mo were randomly assigned to receive commercial L-carnitine syrup (100 mg/kg/d) or placebo for 15 d in addition to standard of care. A total of 98 children with Weight-for-Length-z-score (WLZ) < -3 Standard deviation were enrolled between October 2021 and March 2023. Analyses were conducted on an intention-to-treat basis.

RESULTS

The primary outcome variable, "rate of weight gain," was comparable between L-carnitine and placebo groups (2.09 ± 2.23 compared with 2.07 ± 2.70; P = 0.973), which was consistent even after adjusting for potential covariates (age, sex, Weight-for-Age z-score, asset index, and WASH practices) through linear regression [ß: 0.37; 95% confidence interval (CI): -0.63,1.37; P = 0.465]. The average hospital stay was ∼4 d. The results of adjusted median regression showed that following intervention, there was no significant difference in the EED biomarkers among the treatment arms; Myeloperoxidase (ng/mL) [ß: -1342.29; 95% CI: -2817.35, 132.77; P = 0.074], Neopterin (nmol/L) [ß: -153.33; 95% CI: -556.58, 249.91; P = 0.452], alpha-1-antitrypsin (mg/mL) [ß: 0.05; 95% CI: -0.15, 0.25; P = 0.627]. Initial L-carnitine (μmol/L) levels (median, interquartile range) for L-carnitine compared with placebo were 54.84 (36.0, 112.9) and 59.74 (45.7, 96.0), whereas levels after intervention were 102.05 (60.9, 182.1) and 105.02 (73.1, 203.7).

CONCLUSIONS

Although our study findings suggest that L-carnitine bears no additional effect on SAM, we recommend clinical trials with a longer duration of supplementation, possibly with other combinations of interventions, to investigate further into this topic of interest. This trial was registered at clinicaltrials.gov as NCT05083637.

Carnitine supplementation increases serum concentrations of free carnitine and total acylcarnitine in preterm neonates: A retrospective cohort study

OBJECTIVE

Our goal was to determine the efficacy of the American Society for Parenteral and Enteral Nutrition's recommended carnitine dosage of 5 mg/kg/day in maintaining normal serum free carnitine and total acylcarnitine levels in preterm neonates receiving parenteral nutrition (PN).

STUDY DESIGN

A retrospective cohort study was conducted on neonates born <30 weeks gestation and weighing <1250 g, comparing those who received carnitine supplementation to those without supplementation. Free carnitine and total acylcarnitine data were collected from routine newborn screens in the first days of life and on full enetral feeds. Univariate analysis was performed, and those factors that were significantly different between the two groups were adjusted for using mixed effects analysis.

RESULTS

There were 108 supplemented and 45 unsupplemented neonates in the study. At baseline, free carnitine (19.8 ± 3.3 vs 18.9 ± 3.7 µmol/L, P = 0.53) and total acylcarnitine (26.6 ± 5.1 vs 22.5 ± 7.1 µmol/L, P = 0.11) were similar between the two groups. At full enteral feeds, compared with unsupplemented group, supplemented infants had significantly higher free carnitine (27.1 ± 16.4 vs 17.1 ± 8.5 µmol/L, P < 0.001) and total acylcarnitine (30.3 ± 11.5 vs 20.2 ± 10.1 µmol/L, P < 0.001). None of the supplemented neonates developed biochemical carnitine deficiency as compared with 18% in the unsupplemented group (P < 0.001). No difference was observed in time to reach full lipid provision, and there were no differences in the change in the triglyceride levels from baseline to the time on full PN lipid provision (P = 0.39).

CONCLUSION

Preterm neonates routinely supplemented with parenteral carnitine at 5 mg/kg/day demonstrated higher free carnitine and total acylcarnitine levels at full feeds, with none developing biochemical carnitine deficiency.

Carnitine deficiency in preterm infants: A national survey of knowledge and practices

OBJECTIVE

Lipid supplementation improves developmental outcomes in preterm infants. Carnitine is essential for lipid metabolism; however, despite high risk for carnitine deficiency, there are no standards for carnitine supplementation in preterm infants receiving total parenteral nutrition (TPN). Our objective was to assess knowledge, beliefs and practices regarding preterm carnitine deficiency and supplementation among neonatal practitioners.

METHODS

Cross-sectional electronic survey administered via a nationally representative listserv of neonatal practitioners.

RESULTS

492 respondents participated in the survey. Only 21% of respondents were aware that carnitine is secreted by the placenta. 72% believed that carnitine deficiency was common, and 60% believed deficiency could have serious consequences. Five percent routinely screened for deficiency, and 40% routinely provided carnitine supplementation. Respondents with >5 years' experience were more likely to report using carnitine supplementation (50% vs. 38%).

CONCLUSIONS

Although most respondents believed that carnitine deficiency is common and could have serious consequences, few screened for deficiency and fewer than half routinely supplemented. Thus, many preterm infants remain at risk for carnitine deficiency. Further research is needed to elucidate the risks of carnitine deficiency in these vulnerable infants.

Laboratory Monitoring of Children on Home Parenteral Nutrition: A Prospective Study

BACKGROUND

The primary hypothesis of this article is that a team approach in creating a protocolized laboratory monitoring schedule for home parenteral nutrition (PN) patients improves patient safety by decreasing the occurrence of nutrition deficiencies and is cost-effective.

METHODS

In this prospective cohort study of home PN patients, each patient followed an established protocol of laboratory monitoring and weekly review by an interdisciplinary team of dietitians, nurses, and physicians. Data collected included anthropometric measurements, laboratory results, deviations from laboratory protocols, laboratory charges, PN shortage information, and means of ameliorating such shortages. Cost-effectiveness analysis was only performed for nonmicronutrient laboratory tests.

RESULTS

Fifteen children (male, n = 6) with a median age of 59 months (range, 19-216) were included in this study. Primary diagnoses included short bowel syndrome (47%) and intestinal pseudo-obstruction (40%). Patients received PN mixtures from 6 different infusion companies and experienced 60 different shortages in the PN formulation requiring adjustments or substitutions (mean, 4 shortages per patient). All patients had appropriate growth and complete micronutrient monitoring. No patient experienced any clinical symptoms due to shortages. The median number of laboratory draws/patient per month was 2.9 preprotocol compared with 1.14 postprotocol (P = .003). The median per patient per month charges were $2014 (interquartile range [IQR], 1471-2780) preprotocol compared with $792 (IQR, 435-1140) postprotocol (P = .002).

CONCLUSIONS

A structured team approach to laboratory monitoring of home PN patients can simplify PN management, significantly decrease monthly laboratory costs, and lead to fewer laboratory draws while improving micronutrient monitoring and preventing deficiencies.

Optimizing nutrition of the preterm infant

The goal of nutrition of the preterm infant is to meet the growth rate of the healthy fetus of the same gestational age and to produce the same body composition of the healthy fetus in terms of organ growth, tissue components, and cell number and structure. Nutritional quantity and quality are fundamental for normal growth and development of preterm infants, including neurodevelopmental outcomes. Failure to provide the necessary amounts of all of the essential nutrients has produced not only growth failure, but also increased morbidity and less than optimal neurodevelopment. Growth velocities during the NICU hospitalization period for preterm infants exert a significant effect on neurodevelopmental and anthropometric outcomes. Despite the obvious need for optimal nutrition, growth failure is almost universal among preterm infants. There is every reason, therefore, to optimize nutrition of the preterm infant, in terms of total energy and protein, but also in terms of individual components such as amino acids, specific carbohydrates and lipids, and even oxygen. This review presents scientific rationale for nutrient requirements and practical guidelines and approaches to intravenous and enteral feeding for preterm infants. Intravenous feeding, including amino acids, should be started right after birth at rates that are appropriate for the gestational age of the infant. Enteral feeding should be started as soon as possible after birth, using mother's colostrum and milk as first choices. Enteral feeding should begin with trophic amounts and advanced as rapidly as tolerated, decreasing IV nutrition accordingly, while maintaining nutrient intakes at recommended rates. Feeding protocols are valuable for improving nutrition and related outcomes. Further research is needed to determine the optimal nutrition and rate of growth in preterm infants that will achieve optimal neurocognitive benefits while minimizing the longer-term risk of chronic diseases.

The Use of Carnitine in Pediatric Nutrition

Carnitine is synthesized endogenously from methionine and lysine in the liver and kidney and is available exogenously from a meat and dairy diet and from human milk and most enteral formulas. Parenteral nutrition (PN) does not contain carnitine unless it is extemporaneously added. The primary role of carnitine is to transport long-chain fatty acids across the mitochondrial membrane, where they undergo beta-oxidation to produce energy. Although the majority of patients are capable of endogenous synthesis of carnitine, certain pediatric populations, specifically neonates and infants, have decreased biosynthetic capacity and are at risk of developing carnitine deficiency, particularly when receiving PN. Studies have evaluated for several decades the effects of carnitine supplementation in pediatric patients receiving nutrition support. Early studies focused primarily on the effects of supplementation on markers of fatty acid metabolism and nutrition markers, including weight gain and nitrogen balance, whereas more recent studies have evaluated neonatal morbidity. This review describes the role of carnitine in metabolic processes, its biosynthesis, and carnitine deficiency syndromes, as well as reviews the literature on carnitine supplementation in pediatric nutrition.

Evaluation of serum carnitine levels for pediatric patients receiving carnitine-free and carnitine-supplemented parenteral nutrition

PURPOSE

Carnitine is a carrier molecule transporting long-chain fatty acids (LCFAs) into the mitochondria for fatty acid β-oxidation. The purpose of this study is to evaluate the role of carnitine supplementation in parenteral nutrition (PN) within the pediatric population. Our goal was to determine a weight range for which empiric carnitine supplementation is justified and to determine a weight range at which a carnitine level should first be drawn to confirm a deficiency prior to supplementation. Secondarily, we tried to determine a relationship among carnitine deficiency, hypoglycemia, and hypertriglyceridemia.

METHODS

This was a retrospective observational study to evaluate 2 groups of pediatric patients (weighing 0.68 kg to 60 kg) who were NPO and receiving PN. The first group of patients (n = 454) received carnitine supplementation (15 mg/kg/day) upon initiation of PN. The second group (n = 299) did not receive carnitine supplementation until they were determined to have a carnitine deficiency.

RESULTS

The data indicated that 82% of the patients weighing less than 5 kg were deficient. Patients weighing more than 5 kg had serum carnitine levels within the normal range. Therefore, patients receiving PN and weighing less than 5 kg should be supplemented with carnitine. Comparison of triglyceride, glucose, and carnitine showed no statistically significant difference (P = .1936).

CONCLUSION

Patients weighing more than 5 kg should have serum carnitine levels drawn within 7 days to determine whether supplementation is needed. There is no statistical correlation among carnitine deficiency, hypoglycemia, and hypertriglyceridemia.

Plasma citrulline concentration as a biomarker for bowel loss and adaptation in hospitalized pediatric patients requiring parenteral nutrition

BACKGROUND

Citrulline is a nonessential amino acid produced solely in the enterocyte. Plasma citrulline concentration has been proposed as a noninvasive biomarker for bowel length, function, and dependency on parenteral nutrition (PN). The purpose of this study was to determine if citrulline concentrations differed between pediatric patients with and without small bowel loss requiring specialized nutrition support.

METHODS

This was a retrospective categorical analysis of citrulline concentrations from previously published studies. Patients were included if they were receiving PN, more than 30 days of age, and if they had at least 2 plasma citrulline concentrations. Patients with renal insufficiency and who received outpatient PN treatment were excluded. Patients were categorized as either having or not having small bowel loss.

RESULTS

Thirty-six patients were included for analysis (18 per category). The median citrulline concentration was significantly lower in the group with bowel loss, 8.4 µmol/L vs 10.5 µmol/L (P < .0005), and undetectable citrulline concentrations occurred more often in the bowel loss group, 40% vs 8% (P < .0005). In 13 patients who received enteral nutrition during the study periods, plasma citrulline concentrations increased only in patients without bowel loss.

CONCLUSIONS

These data confirm previous studies and identify decreased citrulline concentrations in pediatric patients with bowel dysfunction in the absence of bowel loss. These data also represent the first serial citrulline concentrations over a 21-day period. The increase in citrulline concentrations only in fed patients without bowel loss suggests that citrulline concentrations could provide a biomarker for bowel function and adaptation.

Strategies for feeding the preterm infant

According to many experts in neonatal nutrition, the goal for nutrition of the preterm infant should be to achieve a postnatal growth rate approximating that of the normal fetus of the same gestational age. Unfortunately, most preterm infants, especially those born very preterm with extremely low birth weight, are not fed sufficient amounts of nutrients to produce normal fetal rates of growth and, as a result, end up growth-restricted during their hospital period after birth. Growth restriction is a significant problem, as numerous studies have shown definitively that undernutrition, especially of protein, at critical stages of development produces long-term short stature, organ growth failure, and both neuronal deficits of number and dendritic connections as well as later behavioral and cognitive outcomes. Furthermore, clinical follow-up studies have shown that among infants fed formulas, the nutrient content of the formula is directly and positively related to mental and motor outcomes later in life. Nutritional requirements do not stop at birth. Thus, delaying nutrition after birth 'until the infant is stable' ignores the fundamental point that without nutrition starting immediately after birth, the infant enters a catabolic condition, and catabolism does not contribute to normal development and growth. Oxygen is necessary for all metabolic processes. Recent trends to limit oxygen supply to prevent oxygen toxicity have the potential, particularly when the blood hemoglobin concentration falls to less than 8 g/dl, to develop growth failure. Glucose should be provided at 6-8 mg/min/kg as soon after birth as possible and adjusted according to frequent measurements of plasma glucose to achieve and maintain concentrations >45 mg/dl but <120 mg/dl to avoid the frequent problems of hyperglycemia and hypoglycemia. Similarly, lipid is required to provide at least 0.5 g/kg/day to prevent essential fatty acid deficiency. However, the high rate of carbohydrate and lipid supply that preterm infants often get, based on the incomplete assumption that this is necessary to promote protein growth, tends to produce increased fat in organs like the liver and heart as well as adipose tissue. More and better essential fatty acid nutrition is valuable, but more organ and adipose fat has no known benefit and many problems. Amino acids and protein are essential not only for body growth but for metabolic signaling, protein synthesis, and protein accretion. 3.5-4.0 g/kg/day are necessary to produce normal protein balance and growth in very preterm infants. Attempts to promote protein growth with insulin has many problems - it is ineffective while contributing to even further organ and adipose tissue fat deposition. Enteral feeding always is indicated and to date nearly all studies have shown that minimal enteral feeding approaches (e.g., 'trophic feeds') promote the capacity to feed enterally. Milk has distinct advantages over formulas in avoiding necrotizing enterocolitis (NEC), and while feeding is associated with NEC, minimal enteral feeding regimens produce less NEC than those geared towards more aggressive introduction of enteral feeding. Finally, overfeeding has the definite potential to produce adipose tissue, or obesity, which then leads to insulin resistance, glucose intolerance, and diabetes. This scenario occurs more commonly as infants are fed more and gain weight more rapidly after birth, regardless of their birth weight. Infants with IUGR and postnatal growth failure may be uniquely 'set up' for this outcome, while infants with in utero obesity, such as infants of diabetic mothers, already are well along this adverse outcome pathway.

Relative bioavailability of carnitine supplementation in premature neonates

BACKGROUND

Carnitine is an important nutrient in the infant diet. We compared total plasma carnitine concentrations in premature neonates supplemented with carnitine via parenteral and enteral nutrition.

METHODS

This is a post hoc analysis of plasma total carnitine concentrations and carnitine intake in neonates randomized in a previous study to receive 20 mg/kg/d carnitine supplementation over 8 weeks. Neonates received l-carnitine initially via parenteral nutrition (PN). When neonates were fed enterally, oral supplementation of l-carnitine was given in divided doses with each feeding.

RESULTS

Sixteen neonates (27 +/- 2 weeks gestation; 2.9 +/- 1.0 days postnatal age at enrollment; 965.6 +/- 279.1 g birth weight) are included. Concentrations were below reference range (31.1-60.5 nmol/mL) at baseline and exceeded reference range from week 1 through the last study period. Concentrations were not different from week 1 (108 +/- 49) through weeks 4 (87 +/- 34) and 8 (83 +/- 31). Carnitine intakes and concentrations were compared in neonates receiving 100% parenteral carnitine at week 1 (n = 6) and 100% enteral carnitine at week 8 (n = 8). Concentrations at week 1 (100.1 +/- 27.9) were not different (p = .19) from week 8 (78.6 +/- 29.3); an estimate of relative bioavailability was 78.6%. Bioavailability with paired analysis of neonates (n = 5) receiving 100% parenteral carnitine at week 1 and 100% enteral carnitine at week 8 was 83.7% +/- 41.2% (30.1%-140.6%).

CONCLUSIONS

Parenteral and enteral supplementation of 20 mg/kg/d carnitine results in plasma total carnitine concentrations that exceed the reference range. Concentrations are not different between parenteral to enteral supplementation, suggesting that enteral carnitine is well absorbed when given daily in divided doses with enteral feedings.

Carnitine supplementation in premature neonates: Effect on plasma and red blood cell total carnitine concentrations, nutrition parameters and morbidity

BACKGROUND & AIMS

Carnitine may be considered conditionally essential in the neonatal population. The purpose of this study was to evaluate the effects of long-term carnitine supplementation on total carnitine status and morbidity in premature neonates.

METHODS

In this prospective, randomized, placebo-controlled, double-blinded study, premature neonates received carnitine supplementation (20mg/kg/day) or placebo. Plasma (nmol/ml) and red blood cell (RBC) (nmol/mg hemoglobin) total carnitine concentrations, 24-h nitrogen excretion, intake and weight, and respiratory, gastroesophageal, and infectious morbidity were assessed.

RESULTS

Twenty-nine neonates (13 placebo, 16 carnitine; 27+/-2 weeks gestation; 976+/-259g birthweight) were studied for up to 8 weeks. Plasma total carnitine concentrations exceeded the reference range in the carnitine group (weeks 1-8); however, concentrations did not reach reference range until week 4 in the placebo group. RBC total carnitine concentrations increased, but remained below reference range in both the carnitine (weeks 1-6) and placebo (weeks 1-8) groups. Carnitine group neonates regained their birthweight more rapidly than placebo group neonates (day of life 11.8+/-6 vs. 16.9+/-6.3, P=0.034). In addition, percent periodic breathing calculated from cardiopulmonary trend monitor data (weeks 1-8) was lower in the carnitine group (0.4+/-0.9 vs. 1.4+/-1.9, P=0.014). There was no difference with respect to other markers of respiratory, gastroesophageal and infectious morbidity or nitrogen balance.

CONCLUSIONS

Carnitine supplementation at 20mg/kg/day results in increased plasma and RBC total carnitine concentrations, has a positive effect on catch-up growth, and may improve periodic breathing in premature neonates.

Lack of effect of L-carnitine supplementation on weight gain in very preterm infants

OBJECTIVE

Carnitine transfer across the placenta occurs predominantly during the third trimester. Unless L-carnitine is provided, very preterm infants develop carnitine deficiency. Although breast milk and infant formulas contain L-carnitine, parenteral nutrition solutions do not routinely provide L-carnitine. We hypothesized that prolonged L-carnitine supplementation in very preterm infants would improve weight gain and shorten length of stay in the hospital.

STUDY DESIGN

The study was a double-blind parallel placebo-controlled randomized clinical trial. Eligible patients were <29 weeks of gestation, <72 hours of age, and did not have a potentially life-threatening congenital malformation or hereditary metabolic disorder. Patients were stratified by gestational age (23 to 25(6/7) and 26 to 28(6/7) weeks), and randomized to receive, either L-carnitine at a dose of 50 mumol/kg/day, or placebo. Carnitine was provided intravenously until the infants tolerated 16 ml/day of feeds. The sample size was calculated to have 80% power to detect a 10% increase in weight gain from birth until 36 weeks of postmenstrual age or discharge from the hospital. Secondary outcome variables included food efficiency (defined as weight gain divided by caloric intake), weight gain at 4 weeks of age, time to regain birth weight and length of stay.

RESULTS

Among the 63 infants enrolled in the trial, 32 were randomized to L-carnitine and 31 to placebo. L-Carnitine supplementation did not significantly affect average daily weight gain from birth until 36 weeks or hospital discharge, or any of the secondary outcome variables.

CONCLUSION

Prolonged supplementation of L-carnitine did not improve long-term weight gain in very preterm infants.

Carnitine supplementation for preterm infants with recurrent apnea

BACKGROUND

Apnea of prematurity is a common problem in preterm infants in the neonatal intensive care setting (NICU), often delaying their discharge home or transfer to a step down unit. Premature infants are at increased risk of carnitine deficiency. Carnitine supplementation has been used for both prevention and treatment of apnea.

OBJECTIVES

To determine whether treatment with carnitine will reduce the frequency of apnea, the duration of ventilation and the duration of hospital stay in preterm infants with recurrent apnea.

SEARCH STRATEGY

Computerised searches were carried out by two reviewers independently. Searches were made of MEDLINE (1966 to May 2004), EMBASE (1980 to May 2004), CINAHL (1982-2004 June 2004,1st week), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2004), abstracts of annual meetings of the Society for Pediatric Research (1995-2004), and contacts were made with the subject experts.

SELECTION CRITERIA

Only randomized or quasi-randomized treatment trials of preterm infants with a diagnosis of recurrent apnea of prematurity were considered. Trials were included if they involved treatment with carnitine compared to placebo or no treatment, and measured at least one of the following outcomes: failure of resolution of apneas, the duration of ventilation and the duration of hospital stay.

DATA COLLECTION AND ANALYSIS

Two reviewers evaluated the papers for inclusion criteria and quality. Corresponding authors were contacted for further information where needed.

MAIN RESULTS

No eligible trials were identified.

REVIEWERS' CONCLUSIONS

Despite the plausible rationale for the treatment of apnea of prematurity with carnitine, there are insufficient data to support its use for this indication. Further studies are needed to determine the role of this treatment in clinical practice.

L-carnitine reduces brain injury after hypoxia-ischemia in newborn rats

Perinatal hypoxia-ischemia remains a significant cause of neonatal mortality and neurodevelopmental disability. Numerous lines of evidence indicate that cerebral ischemic insults disrupt normal respiratory activity in mitochondria. Carnitine (3-hydroxy-4-N-trimethylammonium-butyrate) has an essential role in fatty acid transport in the mitochondrion and in modulating potentially toxic acyl-CoA levels in the mitochondrial matrix. There are no naturally occurring esterases available to reduce the accumulation of acyl-CoA but this process can be overcome by exogenous carnitine. We used a newborn rat model of perinatal hypoxia-ischemia to test the hypothesis that treatment with l-carnitine would reduce the neuropathologic injury resulting from hypoxia-ischemia in the developing brain. We found that treatment with l-carnitine during hypoxia-ischemia reduces neurologic injury in the immature rat after both a 7- and 28-d recovery period. We saw no neuroprotective effect when l-carnitine was administered after hypoxia-ischemia. Treatment with d-carnitine resulted in an increase in mortality during hypoxia-ischemia. Carnitine is easy to administer, has low toxicity, and is routinely used in neonates as well as children with epilepsy, cardiomyopathy, and inborn errors of metabolism. l-Carnitine merits further investigation as a treatment modality for the asphyxiated newborn or as prophylaxis for the at-risk fetus or newborn.

Clinical effects of L-carnitine supplementation on apnea and growth in very low birth weight infants

OBJECTIVE

Systemic carnitine deficiency may present with apnea, hypotonia, and poor growth. Premature infants often manifest these symptoms and are at risk of developing carnitine deficiency because of immaturity of the biosynthetic pathway, lack of sufficient predelivery transplacental transport, and lack of sufficient exogenous supplementation. This study was undertaken to examine the effect of carnitine supplementation in premature infants.

METHODS

Eighty preterm infants <1500 g were enrolled in a prospective, double-blind, placebo-controlled study of carnitine supplementation within 96 hours of delivery. Growth, length of hospital stay, and frequency and severity of apnea were the primary outcome measures.

RESULTS

Weight gain and change in length, fronto-occipital head circumference, mid arm circumference, and triceps skinfold thickness were similar between the carnitine-supplemented and placebo groups. The amount and severity of apnea and the overall length of hospitalization were also similar between the 2 groups. The carnitine levels in the supplemented group were significantly higher than in the placebo group at 4 and 8 weeks after study entry.

CONCLUSION

Although preterm infants <1500 g have low carnitine levels, routine supplementation with carnitine has no demonstrable effect on growth, apnea, or length of hospitalization and thus seems to be unnecessary.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

Role of L-carnitine in apnea of prematurity: a randomized, controlled trial

OBJECTIVE

Carnitine is thought to be a conditionally essential biological cofactor for premature infants. A preliminary study suggested that carnitine could significantly reduce apnea of prematurity. The objective of this study was to evaluate critically the role of carnitine in idiopathic apnea of prematurity and to determine whether the use of carnitine would facilitate discontinuation of mechanical ventilatory support, shorten the duration of ventilatory support, and reduce the amount of time that such infants are exposed to both mechanical ventilation and oxygen. We also wanted to determine the effects of supplemental carnitine on weight gain, time to regain birth weight, time to achieve full enteral feedings, and length of hospital stay.

METHODS

A prospective, randomized, blinded trial was conducted on 44 preterm infants who were from the same neonatal intensive care unit and who were < or =32 weeks' gestational age with a postnatal age <48 hours and a birth weight <1500 g and required total parenteral nutrition (TPN). Infants were randomized to receive carnitine supplementation or placebo without crossover. Carnitine-supplemented infants received 30 mg/kg/d carnitine in their TPN until the they were tolerating 120 mL/kg/d enteral feedings, and then they received 30 mg/kg/d oral carnitine. The placebo group received TPN without supplemental carnitine; when they tolerated 120 mL/kg/d enteral feedings, they received an oral placebo. The 2 groups continued on their respective supplemental carnitine or placebo until 34 weeks' adjusted age, at which time the study period was completed. Twelve-hour cardiorespiratorygrams to record heart rate, respiratory impedance, and oxygen saturation, and a nasal thermistor to detect expiratory airflow were performed every 4 days on 3 occasions and at 30 and 34 weeks' adjusted age. Plasma carnitine levels were measured at day 14.

RESULTS

There were no significant differences between the 2 groups in the occurrence of apnea as detected by cardiorespiratorygram or nursing observation. There were no significant differences between the groups in regard to total days on ventilator, days of nasal continuous positive airway pressure, time to regain birth weight, time to reach enteral feedings of 120 mL/kg/d, discharge weight, adjusted age at discharge, need for oxygen at 28 days' and 36 weeks' adjusted age, or length of stay. The plasma carnitine level was a median of 15.5 micromol/L (range: 7.6-30.5) for the placebo infants compared with a median of 195.3 micromol/L (range: 71.7-343.6) for the carnitine infants.

CONCLUSIONS

In this blinded, randomized, placebo-controlled study, we found that infants who received supplemental carnitine did not demonstrate any reduction in apnea of prematurity, ventilator or nasal continuous positive airway pressure days, or the need for supplemental oxygen therapy. Although carnitine may be of significant nutritional benefit for very low birth weight infants, our study does not support its use to reduce apnea of prematurity or decrease dependence on mechanical ventilation.

Parenteral nutrition-associated liver complications in children

Parenteral nutrition is a life-saving therapy for patients with intestinal failure. It may be associated with transient elevations of liver enzyme concentrations, which return to normal after parenteral nutrition is discontinued. Prolonged parenteral nutrition is associated with complications affecting the hepatobiliary system, such as cholelithiasis, cholestasis, and steatosis. The most common of these is parenteral nutrition-associated cholestasis (PNAC), which may occur in children and may progress to liver failure. The pathophysiology of PNAC is poorly understood, and the etiology is multifactorial. Risk factors include prematurity, long duration of parenteral nutrition, sepsis, lack of bowel motility, and short bowel syndrome. Possible etiologies include excessive caloric administration, parenteral nutrition components, and nutritional deficiencies. Several measures can be undertaken to prevent PNAC, such as avoiding overfeeding, providing a balanced source of energy, weaning parenteral nutrition, starting enteral feeding, and avoiding sepsis.

Lipid metabolism of the micropremie

Intravenous lipid emulsions often provide substance for the very low-birth weight or extremely low-birth weight infant that need total parenteral nutrition. The process used in this type of treatment as well as the effects of such treatment are discussed at length in this article. Some of the main compounds of representative lipid emulsions are listed and evaluated and the benefits and consequences of their use are presented.

Carnitine supplementation of parenterally fed neonates

BACKGROUND

Carnitine, a quaternary amino acid, plays an important role in the oxidation of long chain fatty acids. Both breast milk and infant formulas contain carnitine. However, it is not routinely provided in parenteral nutrition solutions. Non supplemented parenterally fed infants have very low tissue carnitine levels. The clinical significance of this is uncertain. Carnitine deficiency may be an etiological factor in the limited ability of premature babies to utilize parenteral lipid. In vitro studies have suggested that fatty acid oxidation is impaired when the tissue carnitine levels fall below 10% of normal. Therefore relative carnitine deficiency may impair fatty acid oxidation, thus reducing the available energy and impairing growth.

OBJECTIVES

The primary aim of this review is to determine whether carnitine supplementation of parenterally fed neonates will improve weight gain. The secondary aims are to determine the effect on lipid tolerance and ketogenesis.

SEARCH STRATEGY

Computerised searches were carried out by both reviewers. Searches were made of Medline, Embase, The National Research Register (UK), the Cochrane Controlled Trials Register and expert informants. The MeSH headings used were carnitine and parenteral nutrition.

SELECTION CRITERIA

Only randomised trials were considered. Trials were included if they involved carnitine supplementation alone, parenterally fed newborn infants, and measured at least one outcome of interest (weight gain, plasma fatty acids, plasma triglycerides, quantity of lipid tolerated, respiratory quotient or beta hydroxybutyrate levels).

DATA COLLECTION AND ANALYSIS

The two reviewers searched the literature separately and reached a consensus for inclusion of trials. Data were extracted and evaluated by the two reviewers independently of each other. Authors were contacted if possible to clarify or provide missing data.

MAIN RESULTS

Fourteen studies were identified, six met the selection criteria. The results of the review are limited by the fact that the studies were generally short term and studied different outcomes. One study examined short term and long term weight gain, three reported only short term weight gain, three reported biochemical results in response to a short lipid challenge, and two reported results obtained during normal parenteral nutrition. Among infants supplemented with carnitine, there was no evidence of effect on weight gain, lipid utilization or ketogenesis.

REVIEWER'S CONCLUSIONS

We found no evidence to support the routine supplementation of parenterally fed neonates with carnitine.

Lipid-laden macrophages in the tracheal aspirate of ventilated neonates receiving Intralipid: A pilot study

Lipid-laden macrophages (LLM) in tracheal aspirates are reported to be pathognomonic findings in exo- and endogenous lipoid pneumonia in adults. A pilot study was carried out to evaluate the effect of lipid infusion on the LLM index of the tracheal aspirates from ventilated neonates. All intubated infants were eligible for the study. Infants receiving parenteral nutrition had intravenous (IV) lipid introduced by 4-7 days of age; most samples after 7 days were from infants receiving IV lipid. Four infants received minimal gastric feeding; none had evidence of aspiration pneumonia. Tracheal aspirates from 28 infants were analyzed for the LLM index. Alveolar macrophages were graded 0-4 in direct relation to the amount of lipid per cell. One hundred macrophages were graded; the maximum possible LLM index was 400. Two hundred forty-five of 387 tracheal aspirate samples were acceptable for analysis. LLM indices increased during the first week after birth; the mean LLM index then continued in the same range, but with a wide distribution of individual values. The mean LLM index from infants receiving an IV lipid infusion during days 4-7 was 87.9 (SD = 44.8), and was significantly higher compared to 58.7 (SD = 40.8) in infants receiving no IV lipid (P < 0. 003). Tracheal aspirates from infants with and without IV lipid infusion yielded many LLM index values >100. These observations invalidate the use of the LLM index >100 as proof of aspiration pneumonia in this group of infants.

Primary and secondary alterations of neonatal carnitine metabolism

Carnitine plays an essential role in the transfer of long-chain fatty acids across the inner mitochondrial membrane, in the detoxification of acyl moieties, and in maintaining normal levels of free coenzyme A. Although carnitine can be synthesized in liver and kidney, normal adults obtain the majority of carnitine from the diet. Preterm newborns have a reduced capacity to synthesize carnitine. Total parenteral nutrition lacks carnitine and exposes very low birth weight infants to carnitine deficiency, with decreased production of ketones from long-chain fatty acids. Supplementation with low doses of carnitine improves nitrogen balance and growth in these infants. Carnitine deficiency can be part of a number of inherited and acquired diseases. Primary carnitine deficiency is an autosomal recessive disorder characterized by increased losses of carnitine in the urine and decreased accumulation in the heart and skeletal muscle caused by defective carnitine transport. This condition is corrected by high-dose carnitine supplementation. Secondary carnitine deficiency can be caused by increased losses, pharmacological therapy, or a number of inherited metabolic disorders that must be correctly diagnosed before initiating carnitine supplementation.

Neonatal nutritional carnitine deficiency: a piglet model

The clinical significance of nutritional carnitine deficiency remains controversial. To investigate this condition under controlled conditions, an animal model was developed using the parenterally alimented, carnitine-deprived newborn piglet. Forty-five piglets received total parenteral nutrition for 2-3 wk that was either carnitine-free or supplemented with 100-400 mg/L L-carnitine. Blood and a muscle biopsy were taken at the initial surgery. Carnitine balance studies were performed at 11-14 d of age. Blood, liver, heart, and skeletal muscle were taken at sacrifice for analysis of carnitine, electron microscopy, and oxidation studies. Carnitine-deprived piglets were in negative carnitine balance and had lower blood, urine, and tissue levels of carnitine than carnitine-supplemented animals. There was a positive correlation between excretion and plasma concentrations of free carnitine with an apparent renal threshold between 15 and 35 micromol/L. Plasma levels were correlated with liver and heart, but not muscle, concentrations of total acid-soluble carnitine. Carnitine-deprived piglets had evidence of lipid deposition in liver and skeletal muscle and tended to have a higher incidence of muscle weakness and cardiac failure. Basal rates of oxidation of [14C]palmitate to 14CO2 and 14C-acid-soluble products were lower in liver homogenates from carnitine-deprived piglets than in those from carnitine-supplemented animals and increased in a dose-dependent fashion with the addition of L-carnitine (0, 50, and 500 micromol/L) in vitro. In summary, carnitine deprivation in the neonatal piglet resulted in low carnitine status and morphologic/functional disturbances compatible with carnitine deficiency. The described animal model appears to be suitable for the investigation of neonatal nutritional carnitine deficiency.

Plasma and tissue levels of lipids, fatty acids and plasma carnitine in neonates receiving a new fat emulsion

This study was undertaken to compare Intralipid with a new fat emulsion containing gamma-linolenic acid and carnitine, named Pediatric Fat Emulsion 4501, in neonates with regard to lipid and carnitine metabolism over a short period of total parenteral nutrition. There were 10 neonates in each group and they tolerated the total parenteral nutrition well. In spite of the gamma-linolenic acid supplementation in the new emulsion, arachidonic acid decreased significantly in plasma lipid esters and adipose tissue in both groups after 5 d of treatment. Also, there was a decrease in plasma docosahexaenoic acid which was more pronounced in the treatment group. The relative percentage values of linoleic and linolenic acids in adipose tissue were increased, indicating that newborns have a rapid accretion of fatty acids. Plasma-triglycerides were effectively cleared during the periods without fat infusion. In the group that received Pediatric Fat Emulsion 4501 the means of both free and total plasma carnitine concentrations increased significantly, whereas they tended to decrease in the Intralipid group.

Carnitine depletion during total parenteral nutrition despite oral L-carnitine supplementation

Carnitine CAR) plays an important role in the beta-oxidation of fatty acids. Less attention. however, has been paid to CAR compared to other nutrients even in total parenteral nutrition (TPN). To examine CAR metabolism during TPN and the effect of simultaneous oral L-CAR supplementation on CAR levels, the blood CAR level was measured in a 3-year-old boy receiving long-term TPN because of short bowel syndrome. Both the total and acyl CAR in the serum were evaluated under various nutritional conditions including oral supplementation of L-CAR. Low CAR concentrations were observed especially when lipid containing TPN regimens were in place. Oral L-CAR supplementation was not sufficient to restore the low CAR levels in the present index patient even when the dose was increased to 120 mg/kg in accordance with the result of the L-CAR absorption test that revealed poor intestinal absorption of this nutrient. Moreover, a markedly low CAR level was measured during the onset of sepsis in the patient, and the blood CAR was depleted when lipid metabolism was activated by lipid loading or sepsis. To date, the late effects of CAR depletion on child growth have not been well examined. It is recommended that the blood CAR level be maintained at normal levels before any prominent manifestations of the deficiency have developed. The intravenous administration of CAR appears to be necessary to supply a sufficient amount of CAR for patients with severe malabsorption.

Effects of parenteral L-carnitine supplementation on fat metabolism and nutrition in premature neonates

The effects of parenteral L-carnitine supplementation on fat metabolism, nutrient intake, and plasma and erythrocyte carnitine concentrations were studied in 43 very low birth weight infants. Infants were randomly assigned to control or carnitine-supplemented (50 mumol/kg per day) groups within two weight categories: group 1, 750 to 1000 gm, and group 2, 1001 to 1500 gm. Plasma total, free, and acyl carnitine levels, erythrocyte carnitine levels, serum beta-hydroxybutyrate and triglyceride levels, and total fat intake were monitored weekly until 50% of total caloric intake was met enterally. Neonates receiving carnitine had higher plasma carnitine levels than control groups (total carnitine: group 1, 75.2 +/- 22.9 vs 9.6 +/- 2.7 mmol/ml; group 2, 61.6 +/- 31.2 vs 13.0 +/- 9.2 nmol/ml). Levels of beta-OH-butyrate decreased from baseline in control neonates (group 1, 0.12 +/- 0.06 to 0.03 +/- 0.02 mmol/L; group 2, 0.11 +/- 0.03 to 0.05 +/- 0.02 mmol/L); they remained unchanged in supplemented groups. Thus ketogenesis appeared less impaired in infants receiving supplements. Supplemented group 2 tolerated more fat than control group 2; triglyceride levels remained acceptable in all groups. Carnitine group 2 had greater weight gain than control group 2 during the first 2 weeks of life. We conclude that very low birth weight infants requiring prolonged parenteral nutrition have carnitine deficiency with impaired ketogenesis. Parenteral administration of carnitine appears to alleviate this metabolic disturbance.

Nutritional requirements of extremely low birthweight infants

Extremely low birthweight (ELBW) infants are unique in many developmental characteristics that determine nutritional requirements, including: low energy reserves (both carbohydrate and fat); higher metabolic rate (intrinsically, due to a higher body content of more metabolically active organs, e.g. brain, heart, liver); higher protein turnover rate (especially when growing); higher glucose needs for energy and brain metabolism; higher lipid needs to match the in utero rate of fat deposition, and for essential fatty acids for brain, neural and vascular development; excessive evaporative rates, and occasionally very high urinary water and solute losses; low rates of gastrointestinal peristalsis; limited production of gut digestive enzymes and growth factors; high incidence of stressful events (e.g. hypoxemia, respiratory distress, sepsis); and abnormal neurological outcome if not fed adequately. Postnatally, ELBW infants do not grow well, or at all, often for weeks. This leads to a virtual "growth deficit", which has unknown consequences (which for the most part are not good) and requires excessive feeding later on to catch up to normal growth rates and body composition. The major future challenge for the nutrition of these infants is to define more accurately their nutritional requirements, particularly in the early postnatal period, in order to feed them more appropriately, to reduce to a minimum the nutritional and growth deficits that they so commonly develop and to prevent neurodevelopmental handicaps that are the result of nutritional deficiencies.