Early enteral feeding in postsurgical cancer patients. Fish oil structured lipid-based polymeric formula versus a standard polymeric formula

Nutrition and gastrointestinal cancer

The present review addresses data from randomized clinical trials on perioperative nutrition in patients with gastrointestinal cancer. It is important to appreciate that different approaches can be used with regard to timing of administration of nutritional support (preoperative versus postoperative), route of administration (parenteral versus enteral) and composition of the admixtures given (standard versus immune-enriched diets). The rationale underlying these approaches may also vary, and may include correction of nutritional status, attenuation of the acute-phase response through better preservation of gut function, and potentiation of the immune response.

Effect of nutritional state of brain-dead organ donor on transplantation

OBJECTIVE

We describe the effect of the metabolic and nutritional modifications caused by severe illness or injury in brain-dead organ donors on transplant organ function. Malnutrition is frequently found in brain-dead organ donors and nutrients may interfere with different organ functions.

METHODS

Literature was obtained from MEDLINE using the key words organ donation, brain death, transplantation, nutrition, fish oil, amino acids.

RESULTS

In the liver, infusion of large quantities of dextrose can restore glycogen reserves but may induce hyperglycemia and a hyperosmolar hepatic state. Feeding improves protein synthesis in hepatocytes, and fat (fish oil) administration in particular increases the hepatic energy and adenosine triphosphate content. Amino acids have a significant effect on regenerating hepatic tissue when given with fat and glucose. In the heart, free fatty acids administered during reperfusion improve cardiac functional recovery, and administration of propofol, a general anesthetic agent enriched with fatty acids, have protective effects on ischemia-and-reperfusion injury. Glutamine also can induce graft protection during ischemia-and-reperfusion injury. Renal function is improved by fish oil supplementation. In addition, effective renal plasma flow, glomerular filtration rate, and renal blood flow are increased, apparently by a reduction in thromboxane B2 production. Glycine or alanine can protect renal tubules from stress injury.

CONCLUSION

Nutrition plays an important role in the modulation of organ function after transplantation.

Continuous enteral feeding has an attenuating effect on the exocrine pancreas in rats

INTRODUCTION

Recent clinical observations suggest that continuous enteral feeding (CEF) may exert a beneficial effect in the management of inflammatory pancreatic diseases. Its effects on the exocrine pancreas, however, remain only partially investigated.

AIM

To examine the effects of CEF on the exocrine pancreas in rats.

METHODOLOGY

Eight male Wistar rats were intrajejunally cannulated, and CEF was started on postoperative day 6. In 10 control animals, laparotomy was followed by intragastric feeding (GF) with the same nutriment (Osmolite, Abbott) from postoperative day 6. The daily discharge was 24 kcal in both groups. After 5 days of feeding, the pancreas was removed; its weight and its protein, DNA, trypsin, and lipase contents were determined; and the exocrine pancreas was also examined for structural changes.

RESULTS

The results revealed no significant difference in body weight loss between the two groups of animals, whereas the pancreas weight/body weight ratio was lower (p < 0.01) in the CEF group. The pancreatic protein, DNA, and enzyme contents were decreased (p < 0.01) after CEF as compared with the values for the GF group. Histologic examinations demonstrated clear decreases in acinar size and in the zymogen content of the pancreas in the CEF animals.

CONCLUSION

This study clearly indicates that CEF reduces the enzyme production of the pancreas.

Randomized structured triglycerides increase lymphatic absorption of tocopherol and retinol compared with the equivalent physical mixture in a rat model of fat malabsorption

Previously we demonstrated that the digestion, absorption and lymphatic transport of lipid and key essential fatty acids (EFA) from randomly interesterified fish oil/medium-chain structured triglycerides (STG) were significantly higher than an equivalent physical mixture (PM) in a normal lymph fistula rat model and in a rat model of lipid malabsorption caused by ischemia/reperfusion (I/R) injury. The goals of this study were to further explore the potential absorptive benefits of STG by comparing the intestinal absorption and lymphatic transport of tocopherol and retinol when delivered gastrically with either STG or PM under normal conditions and after I/R injury to the small bowel. Food-deprived male Sprague-Dawley rats were randomly assigned to two treatments (sham controls or I/R). Under halothane anesthesia, the superior mesenteric artery (SMA) was occluded for 20 min and then reperfused in I/R rats. The SMA was isolated but not occluded in control rats. In both groups, the mesenteric lymph duct was cannulated and a gastric tube was inserted. Each treatment group received 1 mL of the fish oil/MCT STG or PM (7 rats/group) along with (14)C-alpha-tocopherol and (3)H-retinol through the gastric tube followed by an infusion of PBS at 3 mL/h for 8 h. Lymph was collected hourly for 8 h. Under steady-state conditions, the amount of (14)C-alpha-tocopherol and (3)H-retinol transported into lymph was significantly higher in the STG-fed rats compared with those fed PM in both control and I/R groups. In addition, control and I/R rats given STG had earlier steady-state outputs of (14)C-alpha-tocopherol and (3)H-retinol and maintained approximately 30% higher outputs in lymph throughout the 8-h lymph collection period compared with rats given the PM. We conclude that STG provides the opportunity to potentiate improved absorption of fat-soluble vitamins under normal and malabsorptive states.

Lymphatic transport of fat in rats with normal- and malabsorption following intake of fats made from fish oil and decanoic acid. Effects of triacylglycerol structure

Fish oils contain essential polyunsaturated fatty acids of the n-3 family. In fat malabsorption the n-3 fatty acids are poorly absorbed. Absorption may be improved by modifying the fatty acid profile of fish oil through interesterification with medium chain fatty acids. We examined the absorption of fish oil interesterified with decanoic acid in rats with normal- and malabsorption compared to a physical mixture and the fish oil itself. The interesterified fats were: 1) a regiospecific fat with decanoic acid located mainly in the sn1/3-positions and a long chain fatty acid from fish oil in the sn2-position, 2) a fat with a random distribution of fatty acids in all positions of the triacylglycerol. The main mesenteric lymph duct was cannulated for collection of lymph. In the malabsorbing rats the common bile duct was cannulated as well to divert both pancreatic juice and bile. The fatty acid composition in lymph samples collected for 24 hours was determined. Accumulated transport of n-3 fatty acids from fish oil was improved in malabsorbing rats and recoveries of fatty acids after 24 hours were improved in both rats with normal- and malabsorption administered the randomized fat compared to fish oil.

Modulation of postoperative immune and inflammatory response by immune-enhancing enteral diet in gastrointestinal cancer patients

AIM: To evaluate if the administration of an enteral diet supplemented with glutamine, arginine and ω-3 fatty acids modulates inflammatory and immune responses after surgery.

METHODS: A prospective randomized double-blind, clinical trial was performed. Forty-eight patients with gastrointestinal cancer were randomized into two groups, one group was given an isocaloric and isonitrogenous standard diet and the other was fed with the supplemented diet with glutamine, arginine and ω-3 fatty acids. Feedings were started within 48 h after operation, and continued until day 8. All variables were measured before operation and on postoperative day 1 and 8. Immune responses were determined by phagocytosis ability, respiratory burst of polymorphonuclear cells, total lymphocytes lymphocyte subsets, nitric oxide, cytokines concentration, and inflammatory responses by plasma levels of C-reactive protein, prostaglandin E2 level.

RESULTS: Tolerance of both formula diets was excellent. There were significant differences in the immunological and inflammatory responses between the two groups. In supplemented group, phagocytosis and respiratory burst after surgery was higher and C-reactive protein level was lower (P < 0.01) than in the standard group. The supplemented group had higher levels of nitric oxide, total lymphocytes, T lymphocytes, T-helper cells, and NK cells. Postoperative levels of IL-6 and TNF-α were lower in the supplemented group (P < 0.05).

CONCLUSION: It was clearly established in this trial that early postoperative enteral feeding is safe in patients who have undergone major operations for gastrointestinal cancer. Supplementation of enteral nutrition with glutamine, arginine, and ω-3 fatty acids positively modulated postsurgical immunosuppressive and inflammatory responses.

Lipid modulation and systemic inflammation

N-6 and n-3 PUFAs from the diet are absorbed and reach the cell where they interact with fatty acid binding proteins within cell membranes and cytoplasm. They are processed in the endoplasmic reticulum (desaturation-elongation reactions, lipid synthesis, eicosanoid and epoxide production) and in peroxisomes (beta-oxidation, synthesis, oxidation products). They interact with receptors, ion channels, and nuclear elements; the result is modulation of gene expression. PUFA-induced alterations result in modulation of local and systemic inflammation and inflammatory disease activity.

Structured lipids improve fat absorption in normal and malabsorbing rats

The presence of medium-chain fatty acids in dietary fatty acid as well as the triacylglycerol structure may influence the absorption and lymphatic transport of fatty acids. We compared the lymphatic transport and recovery of fatty acids from four intragastrically administered fats based on rapeseed oil and decanoic acid in two rat models of normal absorption and malabsorption, respectively. The fats were: 1) a fat with a regiospecific structure, 2) a similar fat but with a random distribution of fatty acids in the triacylglycerol molecule, 3) a physical mixture of tridecanoin and rapeseed oil and 4) rapeseed oil as control. Lymph samples were collected for 24 h. Significantly higher recoveries were observed of total fatty acids, oleic acid, linoleic acid and linolenic acid from the specific oil in malabsorbing rats and of linoleic acid in normal rats fed specific oil compared with those fed rapeseed oil. Furthermore, the recoveries of oleic acid and linolenic acid from the specific oil in normal rats were higher than those from the other oils. In malabsorbing rats, the transport of all fats was approximately 90% less than that of normal rats. The present study demonstrates improved hydrolysis and absorption of the specific oil compared with the other oils examined both in rats with normal absorption and in rats with malabsorption.

Nutritional support of the cancer patient: issues and dilemmas

Malnutrition in cancer patients results from multifactorial events and is associated with an alteration of quality of life and a reduced survival. A simple nutritional assessment program and early counselling by a dietitian are essential to guide nutritional support and to alert the physician to the need for enteral (EN) or parenteral nutrition (PN). A daily intake of 20-35 kcal/kg, with a balanced contribution of glucose and lipids, and of 0.2-0.35 g nitrogen/kg is recommended both for EN and PN, with an adequate provision of electrolytes, trace elements and vitamins. EN, always preferable for patients with an intact digestive tract, and PN are both safe and effective methods of administering nutrients. The general results in clinical practice suggest no tumor growth during nutritional support. The indiscriminate use of conventional EN and PN is not indicated in well-nourished cancer patients or in patients with mild malnutrition. EN or PN is not clinically efficacious for patients treated with chemotherapy or radiotherapy, unless there are prolonged periods of GI toxicity, as in the case of bone marrow transplant patients. Severely malnourished cancer patients undergoing major visceral surgery may benefit from perioperative nutritional support, preferably via enteral access. Nutritional support in palliative care should be based on the potential risks and benefits of EN and PN, and on the patient's and family's wishes. Research is currently directed toward the impact of nutritional pharmacology on the clinical outcome of cancer patients. Glutamine-supplemented PN is probably beneficial in bone marrow transplant patients. Immune diets are likely to reduce the rate of infectious complications and the length of hospital stay after GI surgery. Further studies are needed to determine the efficacy of such novel approaches in specific populations of cancer patients, and should also address the question of the overall cost-benefit ratio of nutritional pharmacology, and the effect of nutritional support on length and quality of life.

Nutritional and metabolic aspects of pancreatic cancer

Most patients with pancreatic cancer suffer from a variety of severe metabolic and nutritional disturbances. Despite this fact, the role of perioperative nutritional support for these patients remains controversial. This review highlights the results of randomized prospective clinical trials, and meta-analyses that have addressed this issue. The 'current opinion' put forth in this discussion is based on these reviews, and on personal observations in treating more than 500 patients.

A prospective, randomized clinical trial on perioperative feeding with an arginine-, omega-3 fatty acid-, and RNA-enriched enteral diet: effect on host response and nutritional status

BACKGROUND

The use of immune-enhancing enteral diets in the postoperative period has given contrasting results. The purpose of this prospective, randomized, double-blinded clinical study was to evaluate the effect of immunonutrition given perioperatively on cytokine release and nutritional parameters.

METHODS

Patients with cancer of the stomach or colo-rectum were eligible. Subjects consumed 1 L/d of either a control enteral formula (n = 25; control group) or a formula supplemented with arginine, omega-3 fatty acids, and RNA (n = 25; verum group) for 1 week before surgery. Both formulas were given by mouth. Six hours after the operation, jejunal infusion with the same diets was started and maintained for 7 days. Blood was drawn at different time points to assess albumin, prealbumin (PA), transferrin, cholinesterase activity, retinol binding protein (RBP), interleukin-2 receptors alpha (IL-2Ralpha), IL-6, and IL-1 soluble receptors (IL-1RII). The composite score of delayed hypersensitivity response (DHR) to skin test also was determined (the higher the score, the lower the immune response).

RESULTS

During the 7 days of presurgical feeding, none of the above parameters changed in either group. Eight days after operation, in the control group, the concentration of PA and RBP was lower than in the verum group (0.18 vs 0.26 g/L for PA and 30.5 vs 38.7 mg/L for RBP; p < .05). IL-2Ralpha concentration was 507 pg/mL in the verum group vs 238 pg/mL in the control group (p < .001), whereas IL-6 and IL-1RII were higher in the control group than in the verum group (104 vs 49 and 328 vs 183 pg/mL, respectively; p < .01). The DHR score was 0.68 in the control group vs 0.42 in the verum group (p < .05).

CONCLUSIONS

Perioperative feeding with a supplemented enteral diet modulates cytokine production and enhances cell-mediated immunity and the synthesis of short half-life proteins.

Does neoadjuvant chemotherapy for carcinoma in the thoracic esophagus increase postoperative morbidity?

OBJECTIVES

The aims of this study were to examine whether neoadjuvant chemotherapy for a carcinoma in the thoracic esophagus increased the incidence of postoperative complications, and which clinicopathological factors may affect postoperative complications after esophagectomy.

SUBJECTS AND METHODS

One hundred and forty-four patients who underwent neoadjuvant chemotherapy followed by esophagectomy for a carcinoma in the thoracic esophagus were reviewed in a retrospective study. Ninety-six patients received neoadjuvant chemotherapy and 48 did not. The postoperative complications were grouped either general complications (Complications A) or surgery-related complications (Complications B). Complications A consisted of pulmonary, cardiac, hepatic, renal, and neurological complications, and catheter sepsis. Complications B consisted of a gastrointestinal tract leak, gastrointestinal tract necrosis, an intrathoracic or intraabdominal abscess, hemorrhage, ileus, and vocal cord palsy. In these two categories of complications, 17 factors obtained from subjects were compared between patients with complications and those without by univariate and multivariate analyses.

RESULTS

The patient characteristics did not differ between patients who received neoadjuvant chemotherapy and those without. The preoperative serum albumin level was higher in patients without complication than in those with complication in both two categories of complications (Complications A: p = 0.001, Complications B: p = 0.05). The proportion of patients who received neoadjuvant chemotherapy did not differ between patients with complication and those without complication in either category of complications. Multivariate analysis showed that preoperative Onodera's Prognostic Nutritional Index was the only factor reducing the incidence of complications A (p = 0.02, Odds ratio: 0.63).

CONCLUSION

Neoadjuvant chemotherapy was well tolerated and was not associated with any increased morbidity or mortality after esophagectomy for a carcinoma in the thoracic esophagus.

Lymphatic absorption of structured triglycerides vs. physical mix in a rat model of fat malabsorption

Comparison was made between the intestinal absorption and lymphatic transport of a randomly interesterified fish oil and medium-chain triglyceride (MCT) structured triglycerides (STG) vs. the physical mix in rat small intestine following ischemia and reperfusion (I/R) injury. Under halothane anesthesia, the superior mesenteric artery (SMA) was occluded for 20 min and then reperfused in I/R rats. The SMA was isolated but not occluded in control rats. In both treatment groups, the mesenteric lymph duct was cannulated and a gastric tube was inserted. Each treatment group received 1 ml of the fish oil-MCT STG or physical mix (7 rats/group) through the gastric tube followed by an infusion of PBS at 3 ml/h for 8 h. Lymph was collected hourly for 8 h. Lymph triglyceride, cholesterol, and decanoic and eicosapentaenoic acids increased rapidly and maintained a significantly higher output (P < 0.01) with STG compared with physical mix in control rats over 8 h. After I/R, lymphatic triglyceride output decreased 50% compared with control. Gastric infusion of STG significantly improved lipid transport by having a twofold higher triglyceride, cholesterol, and decanoic and eicosapentaenoic acids output to lymph compared with its physical mix (P < 0.01). We conclude that STG is absorbed into lymph significantly better than physical mix by both the normal intestine and the intestine injured by I/R.

Effect of enteral feeding with eicosapentaenoic acid, gamma-linolenic acid, and antioxidants in patients with acute respiratory distress syndrome. Enteral Nutrition in ARDS Study Group

OBJECTIVES

Recent studies in animal models of sepsis-induced acute respiratory distress syndrome (ARDS) have shown that a low-carbohydrate, high-fat diet combining the anti-inflammatory and vasodilatory properties of eicosapentaenoic acid (EPA; fish oil), gamma-linolenic acid (GLA; borage oil) (EPA+GLA), and antioxidants improves lung microvascular permeability, oxygenation, and cardiopulmonary function and reduces proinflammatory eicosanoid synthesis and lung inflammation. These findings suggest that enteral nutrition with EPA+GLA and antioxidants may reduce pulmonary inflammation and may improve oxygenation and clinical outcomes in patients with ARDS.

DESIGN

Prospective, multicentered, double-blind, randomized controlled trial.

SETTING

Intensive care units of five academic and teaching hospitals in the United States.

PATIENTS

We enrolled 146 patients with ARDS (as defined by the American-European Consensus Conference) caused by sepsis/pneumonia, trauma, or aspiration injury in the study.

INTERVENTIONS

Patients meeting entry criteria were randomized and continuously tube-fed either EPA+GLA or an isonitrogenous, isocaloric standard diet at a minimum caloric delivery of 75% of basal energy expenditure x 1.3 for at least 4-7 days.

MEASUREMENTS AND MAIN RESULTS

Arterial blood gases were measured, and ventilator settings were recorded at baseline and study days 4 and 7 to enable calculation of PaO2/FIO2, a measure of gas exchange. Pulmonary neutrophil recruitment was assessed by measuring the number of neutrophils and the total cell count in bronchoalveolar lavage fluid at the same time points. Clinical outcomes were recorded. Baseline characteristics of 98 evaluable patients revealed that key demographic, physiologic, and ventilatory variables were similar at entry between both groups. Multiple bronchoalveolar lavages revealed significant decreases (approximately 2.5-fold) in the number of total cells and neutrophils per mL of recovered lavage fluid during the study with EPA+GLA compared with patients fed the control diet. Significant improvements in oxygenation (PaO2/FIO2) from baseline to study days 4 and 7 with lower ventilation variables (FIO2, positive end-expiratory pressure, and minute ventilation) occurred in patients fed EPA+GLA compared with controls. Patients fed EPA+GLA required significantly fewer days of ventilatory support (11 vs. 16.3 days; p = .011), and had a decreased length of stay in the intensive care unit (12.8 vs. 17.5 days; p = .016) compared with controls. Only four of 51 (8%) patients fed EPA+GLA vs. 13 of 47 (28%) control patients developed a new organ failure during the study (p = .015).

CONCLUSIONS

The beneficial effects of the EPA+GLA diet on pulmonary neutrophil recruitment, gas exchange, requirement for mechanical ventilation, length of intensive care unit stay, and the reduction of new organ failures suggest that this enteral nutrition formula would be a useful adjuvant therapy in the clinical management of patients with or at risk of developing ARDS.

The gut's role in metabolism, mucosal barrier function, and gut immunology

The gastrointestinal tract functions not only to absorb nutrients, it also plays an important immunologic role during health and critical illness. Under experimental and certain clinical conditions, stimulating the gut attentuates the stress response and avoids mucosal atrophy and increases permeability. Gut stimulation prevents atrophy of the gut-associated lymphoid tissue, the body's major defender of moist mucosal surfaces. A better understanding of gut function and improved nutrient delivery has clinical implications in the treatment of critically ill patients.

The anti-catabolic effects of n-3 fatty acids

The reversal of catabolic processes remains a significant challenge, partly related to the complexity of such processes and our incomplete understanding of the mechanisms involved. The n-3 fatty acids may be able to attenuate catabolism. This review examines the potential sites of action for these fatty acids and the evidence that supports their anti-catabolic properties.

Intestinal permeability after early postoperative enteral nutrition in patients with upper gastrointestinal malignancy

BACKGROUND

Increased intestinal permeability may lead to sepsis in resected upper gastrointestinal (GI) cancer patients. This study sought to determine whether these patients demonstrated increased intestinal permeability and if early postoperative enteral nutrition would alter this result.

METHODS

Nineteen patients undergoing complete resection of upper GI malignancy were randomized into two groups: the nonfed group received IV crystalloid, and the fed group started enteral nutrition by jejunostomy on postoperative day (POD) 1. Six nonoperative volunteers were controls. The lactulose/mannitol test was performed on PODs 1 and 5. Ten grams of lactulose and 5 g of mannitol were given, and urine was collected for 6 hours.

RESULTS

All patients (nonfed, 1.895+/-0.34; fed, 0.893+/-0.24) had elevated lactulose/mannitol ratios on POD 1 vs controls (0.262+/-0.1; p < .008 and p = .05). These elevated levels returned toward control levels in both groups by day 5 (nonfed, 0.533+/-0.1, p = .06; fed, 0.606+/-0.12, p = .08).

CONCLUSIONS

Major upper GI surgery for malignancy resulted in a significant increase in intestinal permeability on POD 1. With or without enteral nutrition, this measure of intestinal permeability returned to normal on POD 5 in well-nourished patients.

Lipids in enteral nutrition

Lipids in enteral nutrition facilitate the presentation of a high energy source with low osmotic impact. Focus has shifted from macronutrients towards the inclusion of special nutrients and growth factors. Recent advances in the design of triacylglycerol lipids with specific structures facilitate the absorption of essential fatty acids of the n-3 series, which provide specific benefits with respect to tissue repair and to the immune system. Enteric formulations containing n-3 lipids are proving to be of value in sustaining seriously ill patients. Information from well-controlled trials is generally consistent in establishing the benefits of formulations containing n-3 lipids.

Translocação bacteriana: efeito de dieta imunoestimuladora em ratos com oclusão intestinal

Este estudo tem por objetivo avaliar a ocorrência de translocação bacteriana em ratos submetidos a oclusão intestinal e verificar a capacidade de uma dieta imunoestimuladora em reduzir a incidência de translocação bacteriana nestes animais. Foram utilizados 24 ratos da linhagem Wistar, adultos, machos, pesando entre 180 e 240g, que foram divididos em três grupos, contendo oito animais cada. Ao grupo C (Controle) foi oferecida uma ração padrão para ratos, ao grupo I (Imunomodulação), uma dieta imunoestimuladora, e ao grupo D (Desnutrição) foi oferecida uma dieta padrão com a metade da oferta. Após sete dias, todos os animais foram submetidos a oc1usão intestinal por ligadura do íleo terminal. Após 18 horas da operação, com técnica asséptica, o abdome foi aberto e foram retirados 6ml de sangue da veia cava inferior, para determinação da glicemia, albumina e contagem de leucócitos. O baço, fígado e linfonodo mesentérico foram removidos separadamente, para estudo rnicrobiológico, e segmento do jejuno proximal, para estudo histológico. A ingesta calórica foi semelhante nos grupos C e I e a metade no grupo D. A média de glicemia foi inferior no grupo D. As culturas do linfonodo mesentérico, baço e fígado foram positivas em todos os animais do grupo D, em 58,3% dos ratos do grupo I e em 66,6% dos ratos do grupo C. As alterações histológicas foram mínimas quando comparados os três grupos. Conclui-se que a translocação bacteriana ocorre em ratos submetidos a oclusão intestinal e que o suporte nutricional com dieta imunoestimuladora é capaz de reduzir a incidência de translocação bacteriana em ratos com oclusão intestinal.

Therapeutic approaches to malnutrition in chronic dialysis patients: the different modalities of nutritional support

Protein-energy malnutrition (PEM) is a common complication in maintenance hemodialysis and chronic peritoneal dialysis patients and is a powerful predictor of morbidity and mortality. Although this association does not prove that malnutrition is a cause of this increased morbidity and mortality, it is consistent with this possibility. There are a number of modalities of nutritional support for the prevention or treatment of PEM in maintenance dialysis patients. Routine methods include preventing PEM before the onset of maintenance dialysis therapy, dietary counseling, maintenance of an adequate dose of dialysis, avoidance of acidemia, and aggressive treatment of superimposed catabolic illness. Specific treatments of chronic dialysis patients who have persistently inadequate nutritional intake include food supplements, enteral tube feeding, intradialytic parenteral nutrition, and total parenteral nutrition. More experimental forms of nutritional therapy include dialytic nutrition (eg, using peritoneal dialysate or hemodialysate that contains amino acids), appetite stimulants (eg, megestrol acetate), or growth factors (eg, anabolic steroids, recombinant human growth hormone, or insulin-like growth factor-I).

Immunonutrition in gastric cancer surgical patients

The aim of this study was to evaluate the potential advantages of perioperative versus postoperative administration of an enteral immune-enhancing diet on host defense and protein metabolism. Thirty subjects, candidates for gastrectomy for cancer, were randomly allocated into two groups. The first group (n = 15) received an enteral formula enriched with arginine, omega-3 fatty acids, and RNA 7 d before and 7 d after surgery; the second group (n = 15) received the same diet but only 7 d after surgery. Postoperative immune and inflammatory responses were investigated by phagocytosis ability of polymorphonuclear cells, interleukin-2 receptors (IL-2R), lymphocyte subsets, interleukin-6 (IL-6), and delayed hypersensitivity response (DHR). Prealbumin (PA), retinol binding protein, albumin, and transferrin were determined as protein synthesis indicators. Perioperative immunonutrition prevented the early postoperative impairment of phagocytosis, DHR, total number of lymphocytes, and CD4/CD8 ratio (P < 0.05 versus postoperative group). The IL-2R levels were significantly higher in the perioperative group (P < 0.05 versus postoperative on postoperative day [POD] 4 and 8). Perioperative group also showed lower levels of IL-6 (P < 0.05 versus postoperative on POD 1, 4, and 8) and higher levels of PA (P = 0.04 versus postoperative on POD 8). The perioperative administration of immunonutrition ameliorated the host defense mechanisms, controlled the inflammatory response, and improved the synthesis of short half-life constitutive proteins.

Nutrient pharmacotherapy for gut mucosal diseases

The use of nutrients for pharmacotherapy is a recent advance in the treatment of gastrointestinal disorders or alterations of gut function and structure. Nutrients may have a direct effect on the gut, or may enhance the response to medications. Alternatively, pharmacologic agents may improve the absorption of nutrients. Potentially, pharmacotherapy may be an adjunct to the traditional approach used in the treatment of compromised patients.

Early enteral nutrition in surgical patients

There is increasing evidence that delivery of nutrients via the gastrointestinal tract reduces the septic morbidity in severely injured patients. This article reviews the most current data and also reviews the importance of the gut-associated lymphoid tissue as an important factor in maintaining the host defenses.

Medium-chain triglyceride and n-3 polyunsaturated fatty acid-containing emulsions in intravenous nutrition

Medium-chain triglycerides and n-3 polyunsaturated fatty acid emulsions as a physical mixture have attracted increasing interest for use in parenteral nutrition and may play an important role in the development of structured triglycerides in a future generation of new lipids. Over the past two decades, the clinical use of intravenous emulsion for the nutritional support of hospitalized patients has relied exclusively on long-chain triglycerides providing both a safe, calorically dense alternative to dextrose and a source of essential fatty acids needed for biological membranes and maintenance of the immune function. During the past decade, the development of new triglycerides (medium- and long-chain triglyceride emulsions and structured triglyceride emulsions) for parenteral use have provided useful advances and opportunities to enhance nutritional and metabolic support. Medium-chain triglycerides and n-3 polyunsaturated fatty acid emulsions possess unique physical, chemical, and metabolic properties that make them theoretically advantageous over the conventional long-chain triglycerides. The physical mixture of medium- and long-chain triglycerides have been used clinically in patients with critical illness, liver disease, immunosuppression, pulmonary disease, and in premature infants, with good tolerance and the avoidance of some of the problems encountered with long-chain triglycerides alone.

Influence of arginine, omega-3 fatty acids and nucleotide-supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma

This study investigated the influence of an enteral diet supplemented with arginine, omega-3 fatty acids, and nucleotides (Impact, Sandoz Nutrition, Berne, Switzerland) on the incidence of systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) in patients after severe trauma. Thirty-two patients with an injury-severity score > 20 were included in this prospective, randomized, double-blind, controlled study. Primary endpoints were the incidence of SIRS and MOF. Secondary endpoints were parameters of acute phase and immune response as well as infection rate, mortality, and hospital stay. For statistical analysis 29 patients (test group n = 16, control n = 13) were eligible. In the test group, significantly fewer SIRS days per patient were found during 28 d. The difference was highly significant between d 8-14 (P < 0.001). MOF score was significantly lower in the test group on d 3 and d 8-11 (P < 0.05). Acute phase parameters showed lower C-reactive protein serum levels (significant on D day 4) and fibrinogen plasma levels (significant on d 12 and 14; P < 0.05). HLA-DR expression on monocytes showed significantly higher fluorescence activity on d 7. No significant difference was found for T-lymphocyte CD4/CD8 ratio, interleukin-2 receptor expression, infection rate, mortality (2/16 vs. 4/13), and hospital stay. The results of the study provide further support for beneficial effects of arginine, omega-3-fatty acids and nucleotide-supplemented enteral diet in critically ill patients.

Artificial nutrition after major abdominal surgery: impact of route of administration and composition of the diet

OBJECTIVE

To evaluate the impact of the route of administration of artificial nutrition and the composition of the diet on outcome.

DESIGN

Prospective, randomized, clinical trial.

SETTING

Department of surgery, university hospital.

PATIENTS

One hundred sixty-six consecutive patients undergoing curative surgery for gastric or pancreatic cancer.

INTERVENTIONS

At operation, the patients were randomized into three groups to receive: a) a standard enteral formula (control group; n = 55); b) the same enteral formula enriched with arginine, RNA, and omega-3 fatty acids (enriched group; n = 55); and c) total parenteral nutrition (TPN group; n = 56). The three regimens were isocaloric and isonitrogenous. Enteral nutrition was started within 12 hrs following surgery. The infusion rate was progressively increased to reach the nutritional goal (25 kcal/kg/day) on postoperative day 4.

MEASUREMENTS AND MAIN RESULTS

Tolerance of enteral feeding, rate and severity of postoperative complications, and length of hospital stay were recorded. Early enteral infusion was well tolerated. Side effects were recorded in 22.7% of the patients, but only 6.3% did not reach the nutritional goal. The enriched group had a lower severity of infection than the parenteral group (4.0 vs. 8.6; p < .05). In subgroups of malnourished (n = 78) and homologous transfused patients (n = 42), the administration of the enriched formula significantly reduced both severity of infection and length of stay compared with the parenteral group (p < .05). Moreover, in transfused patients, the rate of septic complications was 20.0% in the enriched group, 38.4% in the control group, and 42.8% in the TPN group.

CONCLUSIONS

Early enteral feeding is a suitable alternative to TPN after major abdominal surgery. The use of the enriched diet appears to be more beneficial in malnourished and transfused patients.

Efficacy of nutritional pharmacology in surgical patients

The present article reviews the current concepts of immune enhancement through nutritional support for the surgical patient as they are derived experimentally and clinically. Although the potential for altering outcome in surgical patients through nutritional enhancement exists, the authors caution against overzealous application of laboratory data in the clinical arena. Available clinical studies have, at best, only demonstrated modest benefits. It is appropriate that the current literature be critically reviewed to assess the efficacy of the agent(s) purported to be of clinical benefit. Although present reports of immune-enhancing nutrition regimens demonstrate no overwhelming benefits in the critically ill or immunocompromised patient, the pursuit of this science remains undaunted. Lessons learned from the past are leading to reinvestigations in the laboratory, as well as better designs of clinical trials that are free of distracting post-hoc analysis and performed clearly in an intention-to-treat manner.

A prospective, randomized trial of early enteral feeding after resection of upper gastrointestinal malignancy

OBJECTIVE

The purpose of the study was to determine whether early postoperative enteral feeding with an immune-enhancing formula (IEF) decreases morbidity, mortality, and length of hospital stay in patients with upper gastrointestinal (GI) cancer.

SUMMARY BACKGROUND DATA

Early enteral feeding with an IEF has been associated with improved outcome in trauma and critical care patients. Evaluable data documenting reduced complications after major upper GI surgery for malignancy with early enteral feeding are limited.

METHODS

Between March 1994 and August 1996, 195 patients with a preoperative diagnosis of esophageal (n = 23), gastric (n = 75), peripancreatic (n = 86), or bile duct (n = 11) cancer underwent resection and were randomized to IEF via jejunostomy tube or control (CNTL). Tube feedings were supplemented with arginine, RNA, and omega-3 fatty acids, begun on postoperative 1, and advanced to a goal of 25 kcal/kg per day. The CNTL involved intravenous crystalloid solutions. Statistical analysis was by t test, chi square, or logistic regression.

RESULTS

Patient demographics, nutritional status, and operative factors were similar between the groups. Caloric intake was 61% and 22% of goal for the IEF and CNTL groups, respectively. The IEF group received significantly more protein, carbohydrate, lipids and immune-enhancing nutrients than did the CNTL group. There were no significant differences in the number of minor, major, or infectious wound complications between the groups. There was one bowel necrosis associated with IEF requiring reoperation. Hospital mortality was 2.5% and median length of hospital stay was 11 days, which was not different between the groups.

CONCLUSION

Early enteral feeding with an IEF was not beneficial and should not be used in a routine fashion after surgery for upper GI malignancies.

Immediate postoperative enteral feeding results in impaired respiratory mechanics and decreased mobility

OBJECTIVE

The authors set out to determine whether immediate enteral feeding minimizes early postoperative decreases in handgrip and respiratory muscle strength.

SUMMARY BACKGROUND DATA

Muscle strength decreases considerably after major surgical procedures. Enteral feeding has been shown to restore strength rapidly in other clinical settings.

METHODS

A randomized, controlled, nonblinded clinical trial was conducted in patients undergoing esophagectomy or pancreatoduodenectomy who received immediate postoperative enteral feeding via jejunostomy (fed, n = 13), or no enteral feeding during the first 6 postoperative days (unfed, n = 15). Handgrip strength, vital capacity, forced expiratory volume in one second (FEV1), and maximal inspiratory pressure (MIP) were measured before surgery and on postoperative days 2, 4, and 6. Fatigue and vigor were evaluated before surgery and on postoperative day 6. Mobility was assessed daily after surgery using a standardized descriptive scale. Postoperative urine biochemistry was evaluated in daily 24-hour collections.

RESULTS

Postoperative vital capacity (p < 0.05) and FEV1 (p = 0.07) were consistently lower (18%-29%) in the fed group than in the unfed group, whereas grip strength and maximal inspiratory pressure were not significantly different. Postoperative mobility also was lower in the fed patients (p < 0.05) and tended to recover less rapidly (p = 0.07). Fatigue increased and vigor decreased after surgery (both p < or = 0.001), but changes were similar in the fed and unfed groups. Intensive care unit and postoperative hospital stay did not differ between groups.

CONCLUSIONS

Immediate postoperative jejunal feeding was associated with impaired respiratory mechanics and postoperative mobility and did not influence the loss of muscle strength or the increase in fatigue, which occurred after major surgery. Immediate postoperative enteral feeding should not be routine in well-nourished patients at low risk of nutrition-related complications.

Effect of a fish oil structured lipid-based diet on prostaglandin release from mononuclear cells in cancer patients after surgery

BACKGROUND

The authors compared the effect on eicosanoid production (prostaglandin E2 [PGE2], 6-keto PGF 1 alpha, and thromboxane B2) from peripheral blood mononuclear cells (PBMC) of feeding an enteral diet containing a fish oil/medium-chain triglyceride structured lipid (FOSL-HN) vs an isonitrogenous, isocaloric formula (O-HN) in patients undergoing major abdominal surgery for upper gastrointestinal malignancies. A previous study, which used the same formulas and experimental design, suggested improved renal and liver function as well as a reduced number of gastrointestinal and infectious complications with the use of fish oil structured lipids. This study sought to investigate the potential mechanism for these effects by assessing eicosanoid production from PBMC with the two diets.

METHODS

This prospective, blinded, randomized trial was conducted in 20 patients who were jejunally fed either FOSL-HN or O-HN for 7 days. Serum chemistries, hematology, urinalysis, gastrointestinal complications, liver and renal function, and eicosanoid production from isolated PBMC, either unstimulated or stimulated with endotoxin, were measured at endotoxin baseline and on day 7. Comparisons were made in 10 and 8 evaluable patients based a priori on the ability to reach a tube feeding rate of > 40 mL/h.

RESULTS

Patients receiving FOSL-HN experienced no untoward side effects compared with patients given O-HN and demonstrated the same general trend toward improved hepatic, renal and immune function found in the previous study. There was a significant reduction in PGE2 (p < .03) and 6-keto PGF 1 alpha (p < .01) production from PBMC with endotoxin stimulation in patients receiving FOSL-HN.

CONCLUSIONS

The results of early enteral feeding with FOSL-HN after surgery in this follow-up study provide further support to claims of safety, tolerance, and improved physiologic function. There was an associated reduction in eicosanoid production from PBMCs, which is presumed to be the principal mechanism for these effects.

Dietary fish oil and fish and borage oil suppress intrapulmonary proinflammatory eicosanoid biosynthesis and attenuate pulmonary neutrophil accumulation in endotoxic rats

OBJECTIVE

Proinflammatory eicosanoids and cytokines are important mediators of local inflammation in acute lung injury. We determined if enteral nutrition with anti-inflammatory fatty acids, eicosapentaenoic acid, and gamma-linolenic acid would reduce the intrapulmonary synthesis of proinflammatory eicosanoids and cytokines and pulmonary neutrophil accumulation in a rat model of acute lung injury.

DESIGN

Prospective, randomized, controlled, double-blind study.

SETTING

Research laboratory at a university medical center.

SUBJECTS

Male Long-Evans rats (250 g).

INTERVENTIONS

Rats were randomly assigned to three dietary treatment groups and fed nutritionally complete diets (300 kcal/kg/day) containing 55.2% of the total calories from fat with either 97% corn oil, 20% fish oil, or 20% fish and 20% borage oil for 21 days. On day 22, bronchoalveolar lavage was performed 2 hrs after an intravenous injection of Salmonella enteritidis endotoxin (10 mg/kg) or saline. Bronchoalveolar lavage fluid was analyzed for leukotriene B4, leukotriene C4/D4, thromboxane B2, prostaglandin E2, 6 keto-prostaglandin F1alpha, tumor necrosis factor (TNF)-alpha, and macrophage inflammatory protein-2 (MIP-2). Lung myeloperoxidase activity (a marker for neutrophil accumulation) and phospholipid fatty acid composition were also determined.

MEASUREMENTS AND MAIN RESULTS

Lung phospholipid concentrations of arachidonic acid were lower and the concentrations of eicosapentaenoic acid and docosahexaenoic acid were higher with fish oil and fish and borage oil as compared with corn oil. Dihomo-gamma-linolenic acid, the desaturated and elongated intermediate of gamma-linolenic acid, increased with fish and borage oil as compared with fish oil and corn oil. The levels of leukotriene B4, leukotriene C4/D4, 6-keto-prostaglandin F1alpha, and thromboxane B2 with corn oil were significantly increased with endotoxin as compared with saline. In contrast to the corn oil group, endotoxin did not significantly increase bronchoalveolar lavage levels of leukotriene B4, leukotriene C4/D4, and thromboxane B2 above those of saline-treated rats with fish oil and fish and borage oil. Lung myeloperoxidase activity was significantly increased in endotoxin-treated rats compared with those rats given saline in all dietary treatment groups. However, lung myeloperoxidase activity was significantly lower with either fish oil or fish and borage oil as compared with corn oil after endotoxin. Although endotoxin increased the levels of TNF-alpha and MIP-2 with all dietary treatment groups as compared with saline-treated rats, there were no significant differences in the levels of either cytokine between the dietary treatment groups.

CONCLUSIONS

These results indicate that dietary fish oil and fish and borage oil as compared with corn oil may ameliorate endotoxin-induced acute lung injury by suppressing the levels of proinflammatory eicosanoids (but not TNF-alpha or MIP-2) in bronchoalveolar lavage fluid and reducing pulmonary neutrophil accumulation.

Clinical economics review: nutritional support

Nutritional support currently accounts for about 1% of the total health care costs in the USA. Interestingly, most of the prospective randomized controlled trials to date have not been able to demonstrate that this therapeutic intervention alters morbidity or mortality. In fact, parenteral nutritional support may predispose the recipients to developing systemic infections. There have been a few areas in which nutritional support may be of benefit. Enteral supplements given to underweight women who suffer hip fractures reduce the hospital stay and, presumably, overall cost. Preoperative parenteral nutritional support may produce a small absolute reduction in post-operative morbidity, but its cost becomes prohibitive. Preoperative enteral nutritional support, especially if carried out in the home, may be of benefit (using the most optimistic interpretation of a small number of trials); if so, it is an economically defensible intervention. Particular nutrients or diets may have specific effects on certain disease processes. Indirect comparisons have suggested that elemental diets can be used to treat flares of Crohn's disease (perhaps because putative food antigens are removed). However, corticosteroid therapy is more efficacious. Furthermore, it is less expensive to employ 6-mercaptopurine as the next modality in steroid failures. Branched-chain amino acid infusions may have some effect on hepatic encephalopathy, but again, lactulose is less expensive. Nutritional support is one area of medicine in which there has been far more enthusiasm than the data justify. Disease-associated malnutrition probably is a secondary phenomenon, not an important cause of morbidity. The widespread use of this modality cannot be justified in a cost-constrained health care system.

Immune-enhancing enteral formulas: are they beneficial in critically ill patients?

Over the last decade there has been considerable interest in the use of specific nutrients to alter the metabolic response to injury and infection, to improve immune function, and to prevent or reverse the severe catabolism and wasting of the lean body mass that accompanies critical illness. In this review, representative animal studies and, when available, human studies examining the potential benefits of these individual nutrients are summarized. The overview of basic investigations is by no means all-inclusive, and the emphasis of this manuscript is a review of the currently available clinical trials examining the potential benefits of combinations of these individual immunity-enhancing nutrients in human patients.

The new dietary fats in health and disease

Lipids are an integral part of the routine diet of patients and the general public. In this article, the physiologic properties of various dietary lipids are reviewed, beginning with those most commonly consumed-the long-chain triglycerides (LCTs) and extending to those with special purposes: the short- and medium-chain triglycerides. The nutritional dietary management of patients typically includes physical mixtures of lipids. Recently, structured triglycerides (STs), which combine advantages from conventional fats with those of special purposes, have become available. STs are currently developed by interesterifying a mixture of conventional fats and oils, usually with medium-chain triglycerides, to achieve a specific fatty acid profile. This results in a triglyceride containing combinations of short-, medium-, and long-chain fatty acids on a single glycerol backbone. They have unique chemical, physical, or physiologic properties that are not observed by simply blending mixtures of the starting fats and oils. A number of STs are under intense laboratory and clinical investigation in models of cancer, burns, and immune dysfunction. Much interest in the fatty acids resides in the sn-2 position on the glycerol molecule. This is because the fatty acid in the sn-2 position of triglycerides is preferentially absorbed as the 2-monoglyceride and serves as the template for reesterification by intestinal cells to re-form triglycerides. The sn-2 fatty acids are also preferentially preserved as components of chylomicrons and very-low-density lipoprotein particles for ultimate incorporation in tissue membranes. Technology is evolving to create STs with a selected fatty acid in this sn-2 position. For instance, incorporating linoleic, arachidonic, or eicosapentaenoic acid at the sn-2 position is being evaluated for the specific objective of modulating serum cholesterol concentrations and essential fatty acid absorption (a review of this work is included).

A randomized trial of isonitrogenous enteral diets after severe trauma. An immune-enhancing diet reduces septic complications

OBJECTIVE

The authors randomized patients to an enteral diet containing glutamine, arginine, omega-3 fatty acids, and nucleotides or to an isonitrogenous, isocaloric diet to investigate the effect of septic outcome. A third group of patients, without enteral access but eligible by severity of injury, served as unfed controls and were studied prospectively to determine the risk of infection.

SUMMARY BACKGROUND DATA

Laboratory and clinical studies suggest that diets containing specialty nutrients, such as arginine, glutamine, nucleotides, and omega-3 fatty acids, reduce septic complications. Unfortunately, most clinical trials have not compared these diets versus isonitrogenous, isocaloric controls. This prospective, blinded study randomized 35 severely injured patients with an Abdominal Trauma Index > or = 25 or a Injury Severity Score > or = 21 who had early enteral access to an immune-enhancing diet ([IED] Immun-Aid, McGaw, Inc., Irvine, CA; n = 17) or an isonitrogenous, isocaloric diet (Promote [Ross Laboratories, Columbus, OH] and Casec [Mead-Johnson Nutritionals, Evansville, IN]; n = 18) diet. Patients without early enteral access but eligible by severity of injury served as contemporaneous controls (n = 19). Patients were evaluated for septic complications, antibiotic usage, hospital and intensive care unit (ICU) stay, and hospital costs.

RESULTS

Two patients died in the treatment group and were dropped from the study. Significantly fewer major infectious complications (6%) developed in patients randomized to the IED than patients in the isonitrogenous group (41%, p = 0.02) or the control group (58%, p = 0.002). Hospital stay, therapeutic antibiotics, and the development of intra-abdominal abscess was significantly lower in patients receiving the IED than the other two groups. This improved clinical outcome was reflected in reduced hospital costs.

CONCLUSIONS

An IED significantly reduces major infectious complications in severely injured patients compared with those receiving isonitrogenous diet or no early enteral nutrition. An IED is the preferred diet for early enteral feeding after severe blunt and penetrating trauma in patients at risk of subsequent septic complications. Unfed patients have the highest complication rate.