Richard A. Helms

Enhanced lipid utilization in infants receiving oral l-carnitine during long-term parenteral nutrition

Fourteen infants requiring long-term total parenteral nutrition but able to tolerate small quantities of enteral feedings were randomized into carnitine treatment and placebo control groups. All infants had received nutritional support devoid of carnitine. Plasma carnitine levels and observed plasma lipid indices were not different before supplementation. Under standardized, steady-state conditions, 0.5 g/kg fat emulsion (intralipid) was administered intravenously over 2 hours both before and after infants received 7 days of continuous nasogastric or gastric tube L-carnitine (50 mumol/kg/day) or placebo. Plasma triglyceride, free fatty acid, acetoacetate, beta-hydroxybutyrate, and carnitine concentrations were observed at 0 (start of lipid infusion), 2, and 4 hours for pre- and post-treatment periods, and in addition at 6 and 8 hours after carnitine supplementation. Infants receiving carnitine had significantly greater beta-hydroxybutyrate plasma concentrations (P less than 0.05) and carnitine (P less than 0.001) at 0, 2, 4, 6, and 8 hours, and greater plasma acetoacetate concentrations (P less than 0.05) at 2, 4, 6, and 8 hours, compared with controls. Twenty-four-hour urinary carnitine excretion was very low for both groups before supplementation; after supplementation, excretion was higher (P less than 0.05) in the carnitine group. No significant differences were found between groups for plasma triglyceride or free fatty acid concentrations at any observation period. This study demonstrated enhanced fatty acid oxidation, as evidenced by increased ketogenesis, with L-carnitine supplementation in infants receiving long-term total parenteral nutrition.

Risk factors affecting infiltration of peripheral venous lines in infants

The influence of 11 variables on the infiltration of peripheral venous lines (PVLs) was evaluated during 151 infusions in patients younger than 1 year of age. Infusions were followed from the time of cannula placement to discontinuation. Fifty-eight percent of PVLs were infiltrated by 36.30 +/- 33.53 hours (mean +/- SD; median 40 hours, range 10 to 187 hours). No difference between infiltrated and noninfiltrated PVLs was noted with regard to patient age, gender, weight, cannula type, cannula gauge, cannula site, infusion device, potassium or dextrose concentration, medications, or rate of solution administration (P greater than 0.05). Infiltration was observed more often in black than in white infants (P = 0.03) and in patients with lower controller solution head heights (P = 0.01). The time to infiltration was decreased significantly for steel verus Teflon cannulas (P = 0.02), for administration of intravenous medication versus no administration of medication (P = 0.03), for peripheral parenteral nutrition solutions compared with 5% or 10% dextrose solutions (P = 0.014), and with increasing cannula gauge (P = 0.05). The time to infiltration did not differ significantly for gravity-controlled versus positive-pressure infusion device delivery (P = 0.51) or for potassium concentrations less than or equal to 20 mEq/L versus greater than 20 mEq/L (P = 0.13). Infusion device occlusion alarms were associated with only 19% of infiltrations. No sloughing of skin or necrosis of tissue occurred related to infiltration.

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.

Effect of Intravenous L-Carnitine on Growth Parameters and Fat Metabolism during Parenteral Nutrition in Neonates

To determine whether intravenous carnitine can improve nutritional indices, neonates requiring parenteral nutrition were randomized into carnitine treatment (n = 23) and control (n = 20) groups. Observed plasma lipid indices, carnitine and nitrogen balances, and plasma carnitine concentrations were not different in the prestudy period. Under standardized, steady-state conditions, 0.5 g/kg Intralipid was administered intravenously over 2 hr prior to carnitine administration, after infants received 7 days of 50 mumol/kg/day, and after a second 7 days of 100 mumol/kg/day of continuous intravenous L-carnitine as part of parenteral nutrition. Triglyceride (TGY), free fatty acid (FFA), acetoacetate (AA), beta-hydroxybutyrate (BOB), and plasma carnitine concentrations were measured prior to and at 2, 4, and 6 hr after the initiation of the lipid bolus. Twenty-four-hour urine collections for nitrogen and carnitine balance were obtained on days 7 and 14. Neonates receiving carnitine had significantly greater concentrations of plasma carnitine on days 7 and 14 (p less than 0.001). Greater nitrogen (p less than 0.05) and carnitine (p less than 0.001) balances and weight gain (week 2, p less than 0.05) were found in the carnitine-supplemented group when compared with controls. On day 14, (BOB + AA)/FFA ratios were significantly higher (p less than 0.05), and peak TGY concentrations and 6-hr FFA concentrations were significantly lower (p less than 0.05) in the treatment group. Carnitine supplementation was associated with modest increases in growth and nitrogen accretion possibly by enhancing the neonates ability to utilize exogenous fat for energy.

Retinol-binding protein and prealbumin: useful measures of protein repletion in critically ill, malnourished infants.

Plasma prealbumin (PA) and retinol-binding protein (RBP) concentrations were serially measured in 25 critically ill, malnourished infants requiring parenteral nutrition to determine if these visceral protein markers are useful in assessing acute protein repletion. Significant increases in both proteins (p > 0.05) were noted as early as 5 to 7 days after institution of parenteral nutrition and continued significantly above baseline values through 2 weeks of observation. Gestational development (in infants less than 4 weeks old) and mean protein intake influenced visceral protein responses. Appropriate for ges-tational age neonates had more rapid and quantitatively greater PA responses (p > 0.05) than small for gestational age neonates. Small for gestational age neonates never exceeded baseline RBP responses. Average protein intake of ≥ 2 g/kg/day resulted in PA and RBP concentrations below baseline and significantly lower than infants on higher protein intakes (p > 0.05), at the end of 2 weeks. Average calorie intake of < 100 cal/kg/day had no differential influence on PA or RBP when compared with infants on less calories. Prealbumin values correlated with RBP values observed simultaneously (r = 0.588, p > 0.0001). We conclude that PA and RBP are useful measures of protein repletion in critically ill infants requiring parenteral nutrition.

E-Rosette Formation, Total T-Cells, and Lymphocyte Transformation in Infants Receiving Intravenous Safflower Oil Emulsion

There has been much concern about impaired immune function in children receiving infused lipid emulsions. Immunologic studies were carried out on 15 infants maintained on parenteral nutrition with intravenous safflower oil emulsion as part of the infusate. Significant increases in percentage rosette formation, total circulating T-cells, and mitogenesis to phytohemagglutinin and pokeweed mitogen were demonstrated after only 1 wk of lipid infusion. Additional parenteral nutrition did not further increase any immunologic parameter. These results suggest that infused safflower oil emulsion does not adversely alter cellular immune function.

Cysteine supplementation results in normalization of plasma taurine concentrations in children receiving home parenteral nutrition

We evaluated plasma sulfur amino acid concentrations in children with short gut syndrome receiving home parenteral nutrition (n = 6). Cysteine HCl addition to solutions formulated with a pediatric amino acid product will increase plasma taurine concentrations to within the normal reference range.

Enteral Fish Oil for Treatment of Parenteral Nutrition‐Associated Liver Disease in Six Infants with Short‐Bowel Syndrome

Study Objective. To evaluate the use of enteral fish oil for the treatment of parenteral nutrition‐associated liver disease (PNALD).

Assessing the Validity of Adjusted Urinary Urea Nitrogen as an Estimate of Total Urinary Nitrogen in Three Pediatric Populations

Nitrogen excretion is a useful measurement for determining efficiency of protein utilization. Knowledge of nitrogen losses is especially important in the treatment of stressed, postsurgical, or catabolic patients, in whom optimizing the amount of nitrogen intake in the diet may spare visceral and somatic proteins and encourage anabolism. Many methods have been used to estimate total urinary nitrogen (TUN) in different patient populations. Urinary urea nitrogen (UUN) values are routinely adjusted and used by investigators who are not able to measure TUN directly by either Kjeldahl or pyrochemoluminescent methods. The rationale for the use of adjusted UUN concentrations to predict TUN is based on adult experiences. No similar experience in pediatrics has been published. We have compared TUN with adjusted UUN in a study of 250 urine samples from pediatric patients (n = 34) and normal pediatric volunteers (n = 109). Our findings suggest that adjusted UUN (determined by previously established formulas) may be of limited use in estimating TUN in neonates, infants, and critically ill pediatric patients; however, adjusted UUN may be useful in approximating TUN in healthy school-aged children. Good correlations were found between UUN and TUN for critically ill children and postsurgical neonates and infants, suggesting that these newly described regression equations (once validated) may be useful in predicting TUN from a measured UUN.

Adequacy of sulfur amino acid intake in infants receiving parenteral nutrition

Taurine and cysteine are considered essential nutrients for the infant receiving parenteral nutrition (PN). To define the adequacy of sulfur amino acid content in a pediatric amino acid formulation, evaluation of urinary excretion, fractional excretion, and balance studies for taurine, total (free + bound) cyst(e)ine (cysteine + cystine), and methionine were completed under steady-state conditions of energy and protein intake in 18 preterm infants receiving PN. These infants had a mean gestational age of 34.5 ± 2.4 weeks, postnatal age of 19 ± 18 days, weighed 2.1 ± 0.5 kg, and received 100 ± 22 kcal/kg/day and 2.8 ± 0.1 g/kg/day of amino acids. Plasma concentrations for the sulfur-containing amino acids were within the reference range; however, the excretion and fractional excretion of taurine (3.7 ± 7.8 mg/kg/day, 17 ± 15%) and cyst(e)ine (12.0 ± 7.1 mg/kg/day, 33 ±19%) were at the upper limits of normal reported experience. Methionine excretion (0.9 ± 1.0 mg/kg/day) and fractional excretion (16 ± 22%) were within normal reported experience. For taurine, fractional excretion inversely correlated with weight at the time of study ( r = −0.59, P