Protein-sparing effect of substrate infusion in surgical patients is governed by the clinical state, and not by the individual substrate infused

Nutrition support in the pediatric surgical patient

This article deals with the nutritional needs of pediatric patients. It begins by discussing the caloric requirements of different pediatric patients and moves on to a breakdown of the specific nutrients required. It then progresses to a detailed description of the enteral and parenteral modalities for delivery of nutrition to pediatric patients. The article concludes with a discussion of specific problems and disorders encountered in pediatric surgical patients.

Hypocaloric peripheral parenteral nutrition with lipid emulsion in postoperative gastrointestinal cancer patients

AIM: To investigate the use of lipid emulsion substituting for glucose in postoperative hypocaloric peripheral parenteral nutrition (HPPN).

METHODS: This prospective, randomized study was conducted on 20 postoperative gastrointestinal cancer patients. They were randomized and equally divided into interventional group and control group, and both were administered isocaloric and isonitrogenous diets with for lipid emulsion substituting for partial glucose loads in the interventional group.

RESULTS: Nutritional parameters and biochemical data were compared between the two groups before and after 6-d of HPPN. Most investigated variables showed no significant changes after administration of HPPN with lipid emulsion. However, the postoperative triglyceride level was significantly lower in the interventional group than in the control group (P < 0.05). In comparison with lipid emulsion, glucose administration resulted in less decrease in postoperative prealbumin level (P < 0.05).

CONCLUSION: In addition to supplementing with essential fatty acid, it seems that HPPN with lipid emulsion is well-tolerated and beneficial to postoperative gastrointestinal cancer patients.

ESPEN Guidelines on Parenteral Nutrition: non-surgical oncology

Parenteral nutrition offers the possibility of increasing or ensuring nutrient intake in patients in whom normal food intake is inadequate and enteral nutrition is not feasible, is contraindicated or is not accepted by the patient. These guidelines are intended to provide evidence-based recommendations for the use of parenteral nutrition in cancer patients. They were developed by an interdisciplinary expert group in accordance with accepted standards, are based on the most relevant publications of the last 30 years and share many of the conclusions of the ESPEN guidelines on enteral nutrition in oncology. Under-nutrition and cachexia occur frequently in cancer patients and are indicators of poor prognosis and, per se, responsible for excess morbidity and mortality. Many indications for parenteral nutrition parallel those for enteral nutrition (weight loss or reduction in food intake for more than 7-10 days), but only those who, for whatever reason cannot be fed orally or enterally, are candidates to receive parenteral nutrition. A standard nutritional regimen may be recommended for short-term parenteral nutrition, while in cachectic patients receiving intravenous feeding for several weeks a high fat-to-glucose ratio may be advised because these patients maintain a high capacity to metabolize fats. The limited nutritional response to the parenteral nutrition reflects more the presence of metabolic derangements which are characteristic of the cachexia syndrome (or merely the short duration of the nutritional support) rather than the inadequacy of the nutritional regimen. Perioperative parenteral nutrition is only recommended in malnourished patients if enteral nutrition is not feasible. In non-surgical well-nourished oncologic patients routine parenteral nutrition is not recommended because it has proved to offer no advantage and is associated with increased morbidity. A benefit, however, is reported in patients undergoing hematopoietic stem cell transplantation. Short-term parenteral nutrition is however commonly accepted in patients with acute gastrointestinal complications from chemotherapy and radiotherapy, and long-term (home) parenteral nutrition will sometimes be a life-saving maneuver in patients with sub acute/chronic radiation enteropathy. In incurable cancer patients home parenteral nutrition may be recommended in hypophagic/(sub)obstructed patients (if there is an acceptable performance status) if they are expected to die from starvation/under nutrition prior to tumor spread.

Risks and benefits of nutritional support during critical illness

Critically ill patients who depend on intensive care for more than a few days reveal profound erosion of lean body mass, which is thought to contribute to high morbidity and mortality. Despite a shortfall of evidence that supplemental feeding actually alters clinical outcome of these life-threatening disease states, this observation evoked an almost universal, albeit often inappropriate, use of nutritional support (NS) in the critically ill, administered via the parenteral or the enteral route. Lack of knowledge and overenthusiasm subsequently resulted in complications associated with both parenteral nutrition (PN) and enteral nutrition (EN), which led to the standing controversy over which should be preferred. With time, however, it became clear that EN and PN are not mutually exclusive and that critically ill patients requiring NS should be fed according to the functional status of the gastrointestinal tract. In addition, tight blood glucose control with insulin is advised in fed critically ill patients because overall metabolic control appears to surpass any outcome benefit attributed to the route of feeding. Recently, various special nutritional formulas have been suggested to prevent or treat multiorgan failure in the critically ill, among other pathways via modulation of immune function. Although special nutritional formulas may be promising in a variety of clinical settings, based on currently available data, these cannot be recommended for routine use in critically ill patients.

Glucose-lipid ratio is a determinant of nitrogen balance during total parenteral nutrition in critically ill patients: a prospective, randomized, multicenter blind trial with an intention-to-treat analysis

OBJECTIVE

Protein sparing, the major goal of nutritional support, may be affected by the glucose/lipid ratio. This study in critically ill patients compared the efficacy and tolerance of two isocaloric isonitrogenous total parenteral nutritions (TPN) having different glucose/lipid ratios.

DESIGN

Multicentric prospective randomized study.

PATIENTS

47 patients with SAPS I score higher than 8 and requiring exclusive TPN.

INTERVENTIONS

Patients received glucose/lipid ratios of 50/50 or 80/20. For 7 days all patients received 32 glucidolipidic kcal/kg and 0.27 g/kg nitrogen daily. All-in-one bags were prepared using industrial mixtures and a fat emulsion.

MEASUREMENTS AND RESULTS

We determined TPN efficacy by nitrogen balance, urinary 3-methylhistidine/creatinine ratio, transthyretin and tolerance by glycemia, and liver enzymes. After controlling for five variables with significant effects, patients receiving the 50/50 ratio during TPN had significantly higher nitrogen balance than those receiving the 80/20 ratio. The daily difference in mean nitrogen sparing effect in favor of the latter group was 1.367 g (95% CI 0.0686-2.048). Glycemia on day 4 and gamma-glutamyltranspeptidase on day 8 were higher in group receiving the the 80/20 ratio.

CONCLUSIONS

In critically ill patients TPN at a glucose/lipid ratio of 80/20 ratio induces a small nitrogen sparing effect compared to the ratio of 50/50, at the expense of poorer glycemic control. The clinical significance is unclear.

Propofol use precludes prescription of estimated nitrogen requirements

The objective was to determine whether reducing enteral nutrition to accommodate 1% Propofol-derived energy results in suboptimal nitrogen prescription. This was a prospective observational study of 85 consecutive patients requiring mechanical ventilation and receiving 1% Propofol. Enteral nutrition prescription often failed to meet nitrogen requirements (<90%, in 50.6%; <80%, in 21.1%), whereas fat provided 51% of total energy input, exceeding 2 g fat/kg/d in 20%. However, gastroparesis was common, resulting in suboptimal nutrition (median of requirements: energy 71%; nitrogen 57%). If energy balance had been strictly maintained, substituting 1% with 2% Propofol would reduce the number of patients failing to meet nitrogen requirements (1% vs 2%: <90%: in 58.8% vs 17.6%, P< .001; <80% in 35.3% vs 4.7%, P< .014). These effects are directly related to the amount of fat delivered with Propofol. Intensive care unit-associated gastroparesis commonly reduces enteral nutrition input. However, even where this is overcome, use of 1% Propofol frequently precludes prescription of estimated nitrogen requirements; either 2% Propofol or a non-Propofol alternative should be considered.

Nutrition support is not beneficial and can be harmful in critically ill patients

The introductory remark by Lucretius serves as a reminder that nutrient intake can have very different consequences in different subjects. In the patient with an acute or serious illness, metabolic derangements can transform a substance that is normally a source of energy into a source of metabolic toxins. The potential for organic nutrients to become organic toxins in the diseased host is a phenomenon that deserves more attention in the debate about the value of nutrition support in critically ill patients.

Nutrition care of patients with acute and chronic respiratory failure

Nutrition is intimately linked to pulmonary function and an understanding of these relationships have therapeutic utility. Malnutrition is known to be associated with impaired mechanical function of the lung in both chronic and acute respiratory insufficiency. Refeeding results in improvement in functional characteristics and may be critical in the weaning of patients from mechanical ventilation. In contrast, overfeeding may result in an increased ventilatory demand resulting in the inability to wean from respiratory support. This article considers the background as well as recommendations for the nutritional care of patients with acute and chronic respiratory failure.

Nutrient interactions with reference to amino acid and protein metabolism in non-ruminants; particular emphasis on protein-energy relations in man

Because the regulation of protein and energy balance is of major research interest in the nutrition and physiology of humans and animals, a selected account of interactions between protein and energy is given here, with particular emphasis on studies in human subjects. The discussion begins with reference to the relations between protein and energy intakes and nitrogen balance; selected aspects of the relations between protein dynamics and energy metabolism among the various mammalian species are then considered. This leads to a brief account of oxidative amino acid catabolism and its relevance to the assessment of amino acid requirements, particularly in adult man. It is concluded that obligatory oxidative losses of amino acids can be used to predict or approximate amino acid requirements in children and adults. The nitrogen-sparing properties of carbohydrate and lipid-derived fuels are then considered. Despite the well-known and profound, yet differential, impacts of dietary protein and energy sources, and their interactions on body protein balance, there remain wide gaps in our understanding of the mechanisms responsible for their effects, such as the quantitative and mechanistic involvement of hormones, including insulin and the counter-regulatory hormones, and the roles played by the major amino acids responsible for the interorgan transport of nitrogen and the regulation of urea production. Additional studies focusing on metabolic nitrogen trafficking would significantly enhance an understanding of how protein and energy interact to achieve the efficient utilization of dietary protein for maintenance and promotion of lean body gain.

Osmotic load from glucose polymers

Glucose polymer is a carbohydrate source with variable chain lengths of glucose units which may result in variable osmolality. The osmolality of two commercial glucose polymers was measured in reconstituted powder infant formulas, and the change in osmolality of infant milk formulas at the same increases in energy density (67 kcal/dL to 81 and 97 kcal/dL) from the use of additional milk powder or glucose polymers was compared. All samples were prepared from powders (to nearest 0.1 mg), and osmolality was measured by freezing point depression. For both glucose polymers the within-batch variability of the measured osmolality was less than 3.5%, and between-batch variability of the measured osmolality was less than 9.6%. The measured osmolality varies linearly with energy density (p less than 0.001) and was highest in infant formula reconstituted from milk powder alone. However, there exist significant differences in the measured osmolality between different glucose polymer preparations. At high energy densities (greater than or equal to 97 kcal/dL), infant milk formulas prepared with milk powder alone or with the addition of certain glucose polymer preparation may have high osmolality (greater than or equal to 450 mosm/kg) and theoretically predispose the infant to complications of hyperosmotic feeds.

Metabolic effects of cancer

The potential causes of deranged metabolism in cancer are discussed with emphasis on changes in energy metabolism of glucose, fat and protein. The implications of these changes for the treatment of cachexia are then considered.

Relative importance of amino acid infusion as a means of sparing protein in surgical patients

We performed isotopic infusions in 51 surgical patients to investigate the effectiveness of different substrates to conserve protein. All patients were initially studied in the basal state and then the effects of glucose infusion (GL, N = 13), lipid infusion (LIP, N = 11), or amino acid infusion (AA, N = 17) were determined. Ten patients receiving total parenteral nutrition (TPN) were also studied. The basal value for net protein catabolism (NPC) in GL patients was 1.53 +/- 0.4 (SEM) g/kg/day decreasing to 1.39 +/- 0.4 g/kg/day during glucose infusion (p less than 0.01). The basal NPC in the LIP group was 2.04 +/- 0.4 g/kg/day decreasing to 1.72 +/- 0.3 g/kg/day during lipid infusion (p less than 0.01). In the TPN patients the NPC was 0.79 +/- 0.46 g/kg/day whereas in the AA patients the basal value for NPC was 1.37 +/- 0.14 g/kg/day decreasing to -0.77 +/- 0.11 g/kg/day during amino acid infusion (p less than 0.0005). From our study we conclude that: (1) All substrates commonly used in intravenous feeding have the capacity to spare protein. (2) Protein sparing was more pronounced when a balanced amino acid infusion was used than with either glucose or lipid infusion alone. (3) This effect is not solely due to insulin secretion as larger insulin responses were seen with both GL and TPN patients. (4) These results may have implications for peripheral vein feeding with amino acid solutions where there is a contraindication for full TPN or the lack of resources for administering it.