Enteral versus parenteral feeding. Effects on septic morbidity after blunt and penetrating abdominal trauma

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.

Cholecystokinin modulates mucosal immunoglobulin A function

BACKGROUND

We have established that mucosal immunoglobulin A (IgA) production is highly dependent on cholecystokinin release and is markedly suppressed by glucocorticoids. The purpose of the present study was to examine the role of cholecystokinin on the functional responsiveness of the mucosal IgA system in glucocorticoid treated rats.

METHODS

A total of 24 Fischer rats were assigned to three groups of 8 animals each. Animals were injected with vehicle (CON), dexamethasone (DEX) (0.08 mg/150 g), or DEX (0.08 mg/150 gm) and ARL1294KF (500 ng twice daily), a novel and potent long-acting cholecystokinin agonist (DEX+CCK). Animals were treated for 48 hours and killed. Duodenum was harvested, and the total mucosal concentration of cholecystokinin was measured by radioimmunoassay. Mucosal IgA was assayed by quantitation of immunoreactive cells in the ileum. Bacterial adherence was evaluated by quantitative culture of vigorously washed stripped cecal mucosa. Transepithelial electrical resistance, a measure of tight junction permeability, was assessed by mounting strips of adjacent cecal mucosa in Ussing chambers.

RESULTS

Glucocorticoid administration resulted in a statistically significant (p < 0.001) decrease in duodenal cholecystokinin, decreased IgA, and impaired mucosal immunity (increased bacterial adherence and decreased tissue resistance). Cholecystokinin administration preserved mucosal immune function in DEX-treated rats.

CONCLUSIONS

Cholecystokinin may play an important role in maintaining the functional responsiveness of mucosal immunity during catabolic stress.

Postoperative care and complications of damage control surgery

Damage control procedures are being used with increasing frequency as the physiologic limits of the surgical patient are approached and recognized. These patients are returned to the SICU, where rapid restoration of circulating volume, normothermia, maintenance of oxygen delivery, and correction of transfusion-associated coagulopathy are essential to the success of the technique, which requires expeditious reoperation and completion of definitive surgical management. The potential need for early return to the operating room to control surgical bleeding must be recognized, as well as the difficulty in distinguishing between surgical bleeding and ongoing hemorrhage due to hypothermia and coagulopathy. Because the damage control technique is resource intensive and involves numerous personnel, organization and leadership are important to success.

Enteral nutrition in acute pancreatitis

A recent prospective and randomized study comparing enteral nutrition with total parenteral nutrition has shown that enteral nutrition may be a cost-effective alternative to total parenteral nutrition in patients with acute pancreatitis.

Early postoperative enteral nutrition improves peripheral protein kinetics in upper gastrointestinal cancer patients undergoing complete resection: a randomized trial

BACKGROUND

Patients with upper gastrointestinal (GI) tract malignancies are at risk for malnutrition and postoperative morbidity and mortality. We examined the protein kinetic effects of early enteral feeding in this population and compared it with results in patients receiving IV fluid.

METHODS

Twenty-nine patients undergoing resection of an upper GI tract malignancy were prospectively randomized to either enteral feeding starting on postoperative day (POD) 1 via a jejunostomy tube (FEED, n = 12) or IV fluid (IVF, n = 17). On POD5, all patients underwent a protein metabolic study using [3H]phenylalanine to determine forearm skeletal muscle (nmol phenylalanine/100 g/min) protein net balance. Free fatty acids (FFA, mEq/dL) and insulin levels (mU/mL) were measured.

RESULTS

Protein net balance was significantly less negative in the FEED group compared with the IVF group (-1.4 +/- 0.8 vs -5.0 +/- 1.4, p < .05). Respiratory quotient was significantly increased in patients receiving enteral feeding (0.85 +/- 0.02 vs 0.78 +/- 0.02 FEED vs IVF, p < .05). FFA levels were significantly decreased in the FEED group (0.36 +/- 0.04 vs 0.85 +/- 0.07, p < .05). Insulin levels were significantly elevated in the FEED group (19.8 +/- 4.5 vs 9.3 +/- 0.8, p < .05). Insulin levels correlated with amino acid fluxes.

CONCLUSIONS

Postoperative enteral nutrition in upper GI cancer patients results in an improvement in protein kinetic net balance and amino acid flux across peripheral tissue. In addition, insulin levels are elevated, and this elevation correlates with amino fluxes across the forearm. By improving peripheral protein kinetics, early postoperative enteral nutrition may potentially contribute to a decrease in postoperative morbidity and mortality in upper gastrointestinal cancer patients.

1997 Harry M. Vars Research Award. Does the route of feeding modify gut barrier function and clinical outcome in patients after major upper gastrointestinal surgery?

BACKGROUND

Direct experimental evidence suggests that total enteral nutrition (TEN) reduces septic morbidity compared with bowel rest and total parenteral nutrition (TPN) and that mucosal support and maintenance of gut barrier function is a key mechanism. This effect is supported indirectly by clinical studies, but this question has not previously been investigated directly in the postoperative patient. This study examined the hypothesis that early enteral feeding after major upper gastrointestinal surgery may modulate gut barrier function and decrease the risk of major infective complications compared with bowel rest and parenteral nutrition.

METHODS

A randomized clinical trial of 67 patients (TPN = 34; TEN = 33) fed postoperatively for 7 days was performed. Thirty-day major morbidity and mortality were monitored. Intestinal permeability was measured using the lactulose/mannitol test preoperatively and on postoperative days 1 and 7. Systemic anti-endotoxin core immunoglobulin G and M antibodies and serum albumin and C-reactive protein were quantified at these time points.

RESULTS

No clinical benefit was observed in patients fed enterally compared with the parenterally fed group. Intestinal permeability was increased on the 1st postoperative day in association with evidence of endotoxin exposure. By day 7, enteral feeding compared with parenteral feeding had failed to significantly influence any of the gut barrier or systemic parameters.

CONCLUSIONS

This randomized controlled trial of TEN vs TPN after major upper gastrointestinal surgery failed to show a clinical benefit for the enteral route. Moreover, enteral nutrition did not modulate gut barrier function postoperatively.

A prospective, randomized trial of intravenous fat emulsion administration in trauma victims requiring total parenteral nutrition

OBJECTIVE

Intravenous fat infusions are a standard component of total parenteral nutrition (TPN). We studied the effects of withholding fat infusions in trauma patients requiring TPN.

DESIGN

Polytrauma patients receiving TPN were randomized to receive a standard fat emulsion dose (L) or to have fat infusions withheld (NL) for the first 10 days of TPN. The two groups received the same amino acid and carbohydrate dose (isonitrogenous, nonisocaloric).

MATERIALS AND METHODS

Clinical outcome parameters were measured. T-cell function was assessed by measuring lymphokine activated killer and natural killer cell activity.

MEASUREMENTS AND MAIN RESULTS

Demographics including Injury Severity Score (27 +/- 8; 30 +/- 9) and APACHE II scores (23 +/- 6; 22 +/- 5) were similar for the L (n = 30) and NL (n = 27) groups, respectively. Differences (p < 0.05) were found in length of hospitalization (L = 39 +/- 24; NL = 27 +/- 16), intensive care unit length of stay (L = 29 +/- 22; NL = 18 +/- 12), and days on mechanical ventilation (L = 27 +/- 21; NL = 15 +/- 12). The L group had a higher number of infections (72 in 30) than the NL group (39 in 27) and T-cell function was depressed in this group.

CONCLUSIONS

Intravenous fat emulsion infusions during the early postinjury period increased susceptibility to infection, prolonged pulmonary failure, and delayed recovery in critically injured patients. It is not clear whether the improved outcome in the NL group was directly related to withholding the fat infusions or due to the hypocaloric nutritional regimen (underfeeding) these patients received.

Recovery of gut-associated lymphoid tissue and upper respiratory tract immunity after parenteral nutrition

OBJECTIVE

The authors characterize the recovery of parenteral nutrition-induced changes in gut-associated lymphoid tissue (GALT) and upper respiratory tract immunity with enteral nutrition and provide further information defining the effects of enteral feeding on mucosal immunity.

SUMMARY BACKGROUND DATA

The small intestine plays a prominent role in development and maintenance of mucosal immunity, both intestinal and extraintestinal, primarily through immunoglobulin A (IgA)-mediated mechanisms. Prior research has shown that mice fed total parenteral nutrition (TPN) have reduced GALT T and B cells, the cells responsible for IgA production, as well as impaired upper respiratory tract immunity to viral challenge of previously immunized animals. The recovery of TPN-induced changes in GALT and upper respiratory tract immunity after enteral refeeding is studied.

METHODS

Male institute of Cancer Research mice received 5 days of TPN followed by 0 to 4 days of chow. Small intestinal GALT was characterized by flow cytometry. In a second experiment, animals were immunized intranasally with moused-adapted influenza virus. Three weeks later, one group received a 5-day course of TPN followed by enteral refeeding for 5 days. A second group received TPN alone. Both groups were challenged with intranasal virus and killed 40 hours postchallenge to determine viral shedding from the upper respiratory tract.

RESULTS

Animals fed TPN only had significantly fewer GALT lymphocytes compared with those chow-fed control subjects. Peyer's patch counts increased after a single day of refeeding, returning to normal levels by 48 hours. Lamina propria counts remained significantly depressed after 24 hours of refeeding, but also returned to normal after 48 hours of refeeding. The T-cell and B-cell populations mimicked total cell patterns. Lamina propria CD4+/CD8+ ratio returned to normal only after 72 hours of refeeding. None of the 9 animals refed enterally for 5 days were positive for viral shedding, compared with 8 of 12 matched TPN-fed animals.

CONCLUSIONS

Enteral refeeding after TPN is associated with rapid repletion of GALT cellularity, initially within Peyer's patches and subsequently within the lamina propria. Refeeding corrects the impairment of IgA-mediated upper respiratory tract antiviral immunity occurring with TPN administration. This work further enhances the authors' knowledge of the underlying immunologic differences influenced by routes of nutrition.

Nutritional support of the hospitalized patient

Comprehensive care of patients in hospitals includes assessment of nutritional status and provision of appropriate support. This approach is facilitated by knowledge of the essential differences in metabolism between starved and stressed states. Nutritional assessment and care of patients in a hospital are based on answers to the following questions: Who gets it? When do they get it? How much do they get? What route is used to administer it? What kind do they get? What are common complications of enteral and parenteral support? What nutritional aspects are pertinent to common diseases?

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.

Randomized trial of immune-enhancing enteral nutrition in burn patients

BACKGROUND

"Immune-enhancing" diets (IEDs) are aimed at improving outcomes in patients suffering trauma and infection. This study was conducted to evaluate a popular IED in patients suffering burn injury.

METHODS

Fifty burned patients were randomized to receive either Impact (Sandoz Nutrition, Minneapolis, Minn), an IED enhanced with omega-3 fatty acids, arginine, and RNA, or Replete (Clintec, Deerfield, Ill), our standard high-protein diet. Feedings were begun within 48 hours of injury, and continued until patients supported themselves with oral intake.

RESULTS

Forty-nine patients completed the study. The two feeding groups did not differ with respect to age, burn size, incidence of inhalation injury, or the quantity of calories and protein received. There were no differences between groups in mortality, length of hospitalization, hospital charges, days of ventilator support, or incidence of complications. Patients with inhalation injuries required more ventilatory support, and had longer lengths of hospitalization and higher costs.

CONCLUSIONS

Administration of an IED has no clear advantages over the use of less expensive high-protein enteral nutrition in burn patients.

Effects of an immune-enhancing diet in critically injured patients

OBJECTIVE

To determine the effects of an immune-enhancing experimental diet (XD = supplemental arginine, trace elements, and increased omega-3 fatty acids) versus standard diet (SD), on immune cell function and clinical outcome of critically injured patients.

DESIGN

Prospective randomized clinical trial of patients admitted to the surgical intensive care unit after trauma (Injury Severity Score > 13).

MATERIALS AND METHODS

Patients received early enteral nutrition with either XD or SD for a minimum of 5 days.

MEASUREMENTS

Mortality, intensive care unit, ventilator, and hospital days, as well as incidence of adult respiratory distress syndrome (ARDS) and infectious complications were recorded. Nutritional parameters were also studied. Peripheral blood leukocytes were isolated from normal volunteers and from patients on days 1, 6, and 10 of feeding.

MAIN RESULTS

Demographics and injury severity were similar in both groups. Both SD (n = 21) and XD (n = 22) groups revealed depressed monocyte function (tumor necrosis factor, prostaglandin E2, and procoagulant activity) on day 1 compared with a reference group (p < 0.05). However, monocytes from XD patients began to "normalize" their response (tumor necrosis factor, prostaglandin E2, and procoagulant activity) by day 6. Although ARDS occurred more frequently in the XD group (45 vs. 19%), the majority of ARDS in both groups occurred very early, with only three patients in the XD (13.6%) and one patient in the SD (4.7%) groups developing ARDS after study entry. XD patients remained on the ventilator longer (16.4 vs. 9.7 days) and in the hospital longer (32.9 vs. 22 days) compared with the SD group, but overall mortality was nearly identical (4.5 vs. 5%).

CONCLUSION

The exact role and timing for diets with immune-enhancing effects has yet to be defined.

Is circulating endotoxin the trigger for the systemic inflammatory response syndrome seen after injury?

OBJECTIVE

Patients with severe traumatic or burn injury and a mouse model of burn injury were studied early after injury to determine the relation of plasma endotoxin (lipopolysaccharide [LPS]) to the production of proinflammatory cytokines and subsequent resistance to infection.

SUMMARY BACKGROUND DATA

Elevated levels of plasma LPS have been reported in patients after serious injury. It has been suggested that circulating LPS may be a trigger for increased proinflammatory cytokine production and may play a role in the septic syndromes seen in a substantial portion of such patients. Yet, despite multiple reports of leakage of LPS from the gut and bacterial translocation after injury in animal models, there is little direct evidence linking circulating LPS with production of inflammatory mediators.

METHODS

The authors studied serial samples of peripheral blood from 10 patients with 25% to 50% surface area burns and 8 trauma patients (injury Severity Score, 25-57). Patients were compared with 18 healthy volunteers. The study was focused on the first 10 days after injury before the onset of sepsis or the systemic inflammatory response syndrome. Plasma samples were assayed for LPS, and adherent cells from the blood were studied for basal and LPS-stimulated production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6). The correlation of increased plasma LPS with TNF-alpha production was studied as was the association of increased plasma LPS and increased TNF-alpha production with subsequent septic complications. We also studied a mouse model of 25% burn injury. Burn mice were compared with sham burn control subjects. Plasma samples were assayed at serial intervals for LPS, and adherent cells from the spleens were studied for basal- and LPS-stimulated production of TNF-alpha, IL-1 beta, and IL-6. Expression of the messenger RNAs for IL-1 beta and TNF-alpha also was measured. The relation of increased TNF-alpha production with mortality from a septic challenge, cecal ligation and puncture (CLP), was determined. Finally, the effect of administration of LPS to normal mice on subsequent mortality after CLP and on TNF-alpha production was studied.

RESULTS

Elevated plasma LPS (> 1 pg/mL) was seen in 11 of the 18 patients within 10 days of injury and in no normal control subjects. In this period, patients as compared with control subjects showed increased stimulated production of TNF-alpha, IL-1 beta, and IL-6. Increased TNF-alpha production was not correlated with elevated plasma LPS in the same patients. Neither increased plasma LPS nor increased TNF-alpha production early after injury was correlated with subsequent development of systemic inflammatory response syndrome or sepsis in the patients. Burn mice, as compared with sham burn control subjects, showed elevated plasma LPS levels chiefly in the first 3 days after injury. Increased stimulated production of proinflammatory cytokines by adherent splenocytes from the burn mice also was seen at multiple intervals after injury and did not correlate with mortality from CLP. Increased production of TNF-alpha and IL-1 beta was associated with increased expression of messenger RNAs for these cytokines. Finally, two doses of 1 ng LPS administered 24 hours apart to normal mice had no effect on mortality from CLP performed 7 days later nor on the production of TNF-alpha at the time of CLP.

CONCLUSIONS

These findings call into question the idea that circulating LPS is the trigger for increased proinflammatory cytokine production, systemic inflammatory response syndrome, and septic complications in injured patients.

Endotoxin temporarily impairs canine jejunal absorption of water, electrolytes, and glucose

Enteral feeding during and after episodes of sepsis may be beneficial. The aim of our study was to determine the effects of a single sublethal dose of endotoxin on canine jejunal absorption. Following a 240 kcal liquid meal, absorption studies were performed in eight dogs with 75 cm jejunal Thiry-Vella fistulas. These fistulas were perfused with an isotonic solution containing polyethylene glycol to calculate absorption. Each dog was then given a single dose of Escherichia coli lipopolysaccharide, 200 microg/kg intravenously, and the studies were repeated for the next 3 days. Following endotoxin bolus infusion, net absorption of water, electrolytes, and glucose was decreased for 2 days and returned to baseline values on postendotoxin day 3. A single sublethal dose of endotoxin temporarily impairs canine jejunal absorption. Although enteral feeding may be advantageous, jejunal absorption may be temporarily impaired following an episode of endotoxemia.

Nutrition support in clinical practice: review of published data and recommendations for future research directions. National Institutes of Health, American Society for Parenteral and Enteral Nutrition, and American Society for Clinical Nutrition

In the last 30 years, marked advances in enteral feeding techniques, venous access, and enteral and parenteral nutrient formulations have made it possible to provide nutrition support to almost all patients. Despite the abundant medical literature and widespread use of nutritional therapy, many areas of nutrition support remain controversial. Therefore, the leadership at the National Institutes of Health, The American Society for Parenteral and Enteral Nutrition, and The American Society for Clinical Nutrition convened an advisory committee to perform a critical review of the current medical literature evaluating the clinical use of nutrition support; the goal was to assess our current body of knowledge and to identify the issues that deserve further investigation. The panel was divided into five groups to evaluate the following areas: nutrition assessment, nutrition support in patients with gastrointestinal diseases, nutrition support in wasting diseases, nutrition support in critically ill patients, and perioperative nutrition support. The findings from each group are summarized in this report. This document is not meant to establish practice guidelines for nutrition support. The use of nutritional therapy requires a careful integration of data from pertinent clinical trials, clinical expertise in the illness or injury being treated, clinical expertise in nutritional therapy, and input from the patient and his/her family.

Effect of glutamine-enriched total parenteral nutrition on small intestinal gut-associated lymphoid tissue and upper respiratory tract immunity

BACKGROUND

Our prior work shows that total parenteral nutrition (TPN) causes small intestinal gut-associated lymphoid tissue (GALT) atrophy, lowers small intestinal immunoglobulin A (IgA) levels, and impairs secretory IgA-mediated mucosal immunity of the upper respiratory tract. These experiments examine whether an isonitrogenous 2% glutamine-enriched TPN solution prevents these changes.

METHODS

Institute of Cancer Research mice were randomized to chow (chow), intravenous feeding of a TPN solution (TPN), or glutamine-enriched TPN (glutamine) groups. After mice were fed for 5 days, lymphocytes were isolated from Peyer's patches, the intraepithelial layer, and lamina propria to determine cell yields and phenotypes. Total small intestinal IgA levels were analyzed by means of enzyme-linked immunosorbent assay. In a second series of experiments, mice underwent intranasal inoculation with H1N1 virus to establish immunity. After 3 weeks mice were randomized to chow, TPN, or glutamine groups. After feeding for 5 days, mice were rechallenged with intranasal virus and killed at 40 hours to determine viral shedding from the upper respiratory tract.

RESULTS

Total lymphocyte yield in the Peyer's patches, the intraepithelial layer, and lamina propria, small intestinal IgA levels, and the CD4+/CD8+ ratio in the lamina propria decreased with TPN but remained normal with glutamine. On rechallenge, 87% of the mice in the TPN group shed virus in nasal secretions, whereas only 38% of the glutamine-treated group (p < 0.05 versus TPN) and 7.1% of the chow group (p < 0.002 versus TPN) were virus positive.

CONCLUSIONS

Isonitrogenous supplementation of TPN with 2% glutamine improves IgA-mediated protection in the upper respiratory tract and normalizes GALT populations.

Early enteral nutrition in gastrointestinal surgery: a pilot study

There is still some concern about the safety of early enteral nutrition (EN) to patients with recent anastomoses. A pilot trial was carried out on a prospective basis to evaluate the tolerance and clinical outcome of 56 patients who received early EN following gastrointestinal (GI) surgery. A continuous infusion of an elemental, peptide-based diet was administered using a nasointestinal feeding tube placed beyond the pylorus by the operating surgeon. Tube feeds were started at 6.07 +/- 4.99 h after surgery and advanced as tolerated to a rate of 60 mL/h on the third postoperative day. Patients received the diet either proximal or distal (in the case of gastrectomies) to their recent anastomosis. Forty-six patients met the inclusion criteria and were included in the analysis. EN was well tolerated with a low incidence of side effects (19.5%), nausea and vomiting being the most frequent. Oral feeding was started 2.89 +/- 1.28 d after surgery. There was one case of small bowel suture leakage, but no relationship to the tube feeding was established. Early EN appears to be a useful and safe therapeutic alternative for the postoperative management of patients undergoing GI surgery. It may contribute to faster recovery of bowel function and lead to a shorter hospital stay. Careful selection of patients is necessary in order to obtain the greatest benefit of early enteral feeding in this patient population.

Bedside videoscopic placement of feeding tubes: development of fiberoptics through the tube

OBJECTIVE

Transpyloric small intestine feeding tube placement can be difficult and tedious. Currently accepted techniques are associated with disadvantages and risk. The purpose of this study is to describe the development of a new technique: bedside videoscopic placement using fiberoptics through the tube.

DESIGN

Prospective, descriptive case study.

SETTING

Intensive care unit in a teaching hospital.

PATIENTS

Subjects were divided into two groups: a) group 1: eight healthy volunteers (seven male, one female); b) group 2: nine critically ill patients (six male, three female; eight of these patients were intubated).

INTERVENTIONS

Standard 12-Fr (4.0-mm) feeding tubes (n = 19) were placed. Two patients from group 2 had feeding tubes placed on two separate occasions. The feeding tubes were inserted by the oral (n = 8) or nasal (n = 11) route under direct vision, using a 6.7-Fr (2.2-mm) fiberoptic scope through the feeding tube.

MEASUREMENTS AND MAIN RESULTS

We visualized enteric structures clearly through the feeding tube in all subjects and patients. Based on visual landmarks, we advanced the feeding tube through the pylorus and into the duodenum in all individuals. Transpyloric tube placement was confirmed videoscopically (n = 19) and radiographically (n = 18). In three subjects from group 1, the feeding tube entered the first part of the duodenum, while, in the remainder of the subjects, the tube passed into or beyond the second portion of the duodenum. In eight (73%) of 11 attempts on the nine critically ill patients from group 2, the feeding tubes were advanced to the distal duodenum or jejunum. The time required for placement in group 2 ranged from 2 to 43 mins (mean 18 +/- 12 [SD]). The feeding tubes remained in place 10 +/- 4 days and patients met their estimated caloric needs within 24 hrs. Residual volumes of nutrition in the small bowel were < 5 mL. There were no documented episodes of aspiration.

CONCLUSION

This new technique has the potential for rapid, accurate, and safe feeding tube placement in patients requiring nutritional support.

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.

Role of glutamine in bacterial transcytosis and epithelial cell injury

BACKGROUND

L-Glutamine is the principal energy source for small intestinal enterocytes. Diminution of intestinal function, mucosal atrophy, and increased bacterial translocation have been noted during total parenteral nutrition (TPN). In a rat model of glutamine starvation, we previously showed that luminal glutamine is essential for optimal intestinal function. In this study, we examined the effect of apical vs basolateral glutamine on bacterial translocation in a Caco-2 cell culture system and bacteria-induced tissue injury in a weanling rabbit ileal loop model.

METHODS

Caco-2 cells were grown in a transwell system. After confluence, apical and basolateral chambers received defined media, and glutamine deprivation was carried out over a 4- to 48-hour period. Escherichia coli transcytosis and structure/function studies were then performed. In a second series of experiments, the effect of intraluminal glutamine supplementation was evaluated in an E. coli-induced tissue injury model in weanling rabbit ileal loops.

RESULTS

Expression of disaccharidases, glucoamylase, and Na+/K(+)-adenosine 5'-triphosphatase (ATPase) were significantly reduced when cells were deprived of glutamine from the apical side, and there was increased bacterial translocation across the monolayer. Transepithelial epithelial resistance (TEER) across the monolayer was also reduced in the glutamine-free cultures. Glutamine replenishment over 24 to 48 hours restored the original functions. Basolateral deprivation had a smaller effect on the Caco-2 cells. Typical necrotic mucosal injury caused by E. coli in the ileal loops was blocked by co-infiltration of the loops with glutamine.

CONCLUSIONS

This study demonstrates for the first time that the supply of glutamine from the apical side is of critical importance for maintaining optimal structure and function of the enterocytes. The effects are not acute or energy related. These observations have important clinical implications in the management of patients under critical care, including premature infants and patients receiving TPN, for whom lack of glutamine from the luminal side could produce mucosal dysfunction, resulting ultimately in severe atrophic/necrotic complications.

Nutritional management of the critically ill neurologic patient

To summarize, the event of severe neurologic injury results in significant metabolic changes. These changes cause increased requirements for protein and nonprotein calories, micronutrients, and small bowel feedings or TPN. Early feeding has been shown to improve survival. Therefore, every effort should be made to provide aggressive nutritional support within the first 72 hours after injury. Specific guidelines are as follows: Provide full-strength, full-rate feedings within 72 hours. Provide enteral nutrients via nasojejunal or percutaneous endoscopic jejunostomy feeding tube if access is available; attempt gastric feedings if not. Provide TPN within 48 hours if enteral access is not available and begin enteral feeding as soon as possible. Provide 2 to 2.3 g protein/kg/d if renal function is normal. Provide 40% to 70% above basal needs as total calories, with 30% to 40% of calories as lipid to minimize hyperglycemia. Provide protein as small peptides to improve tolerance, absorption, utilization, and gut integrity. Provide a lipid source with 50% to 70% medium-chain triglycerides and an omega-6 to omega-3 ratio of 2:1 to 8:1 to minimize negative effects of omega-6 fatty acids and provide an easily absorbed and utilized source of lipid.

Clinical practice guidelines in nutrition support: can they be based on randomized clinical trials?

As rationing of health care services becomes an increasing reality, the pressure to justify interventions such as nutrition support will intensify. The establishment of clinical practice guidelines is one means of providing practitioners with such justification, but clinical practice guidelines for nutrition support cannot be based primarily on prospective randomized trials. This situation arises as the result of limitations specific to nutrition support whereby the most malnourished patients-those who appear most likely to show a benefit from the treatment-cannot be randomized to a no feeding group and are therefore excluded from participation in the study. As the result of this limitation, marginal candidates for nutrition support have been included in some trials, potentially masking the benefits of this treatment. An additional problem limiting present interpretation of published reports of randomized trials in nutrition support is the fact that ongoing research continues to yield improvements in the clinical practice of nutrition support. Thus the nutrition support group in such trials may not have received this treatment according to current practice. The A.S.P.E.N. Guidelines, based on both randomized prospective trials and other types of evidence, represent an important contribution to the practice of nutrition support. Testing of the performance of these and other guidelines in clinical practice and further outcomes research will be important steps toward revision and improvement of nutrition support, but may be difficult to achieve in the near future.

Comparison of the safety of early enteral vs parenteral nutrition in mild acute pancreatitis

BACKGROUND

This prospective study was designed to compare the safety, efficacy, cost, and impact on patient outcome of early total enteral nutrition (TEN) vs total parenteral nutrition (TPN) in acute pancreatitis.

METHODS

Patients admitted with acute pancreatitis or an acute flare of chronic pancreatitis, characterized by abdominal pain and elevated serum amylase and lipase, were randomized to receive either isocaloric and isonitrogenous TEN (via a nasojejunal feeding tube placed endoscopically) or TPN (via a central or peripheral line) started within 48 hours of admission.

RESULTS

Thirty patients were studied over 32 admissions (TEN given on 16 and TPN on 16) for acute pancreatitis. There were no differences on admission in mean age, Ranson criteria, multiple organ failure score (MOF), or APACHE III score between TEN and TPN groups. Although slower to approach goal feeding over the first 72 hours of admission, TEN patients received 71.3% goal calories by day 4 vs 85.2% for TPN patients (not significant). There were no deaths and no differences between groups in serial pain scores, days to normalization of amylase, days to diet by mouth, serum albumin levels, or percent nosocomial infection. However, the mean cost of TPN per patient was over four times greater than that for TEN ($3294 vs $761, respectively, p < .001). Mean serial Ranson criteria, APACHE III, and MOF scores recorded every 2 to 3 days decreased in the TEN group, whereas those in the TPN group increased. Only the difference in the third Ranson criteria (mean 6.3 days after admission) for the TEN and TPN groups (0.5 vs 2.8, respectively) reached statistical significance (p = .002). Stress-induced hyperglycemia was worse in the TPN group, as serum glucose levels increased significantly over the first 5 days of hospitalization (p < .02), whereas those in the TEN group showed no significant change. An exacerbation of pancreatitis, occurring in one TEN patient when the nasojejunal tube was dislodged into the stomach, resolved after placement back in the jejunum. Three patients who became asymptomatic and normalized amylase on TEN flared upon advancing to diet by mouth.

CONCLUSIONS

TEN for acute pancreatitis is as safe and effective, but is significantly less costly than TPN. Compared with TPN, TEN may promote more rapid resolution of the toxicity and stress response to pancreatitis. TEN via jejunal feeding should be used preferentially in this disease setting.

Enteral or parenteral nutrition? Pro-enteral

There is a convincing evidence for the superiority of enteral nutrition as compared with parenteral In critically ill and injured patients. The general objectives of providing nutritional support in the critically ill is to persevere body functions that are functioning normally and to facilitate recovery of those that are failing. The specific objective for enteral nutrition is, however, preservation and restoration of the gastrointestinal structure and function. Today, early enteral nutrition is an integral part of the acute management of critically ill patients. It is no longer a therapy which can be started "if" necessary just to prevent malnutrition. Early enteral nutrition can be successfully carried out in virtually all critically ill patients also after major abdominal surgery and in acute pancreatitis. There are very few contraindications for using enteral nutrition and severe complications are rare. Parenteral nutrition, on the other hand, is associated with increased incidence of infectious complications and is rarely indicated in critically ill patients.

The relation between nutrition and nosocomial pneumonia: randomized trials in critically ill patients

OBJECTIVE: To review the effect of enteral nutrition on nosocomial pneumonia in critically ill patients as summarized in randomized clinical trials. STUDY IDENTIFICATION AND SELECTION: Studies were identified through MEDLINE, SCISEARCH, EMBASE, the Cochrane Library, bibliographies of primary and review articles, and personal files. Through duplicate independent review, we selected randomized trials evaluating approaches to nutrition and their relation to nosocomial pneumonia. DATA ABSTRACTION: In duplicate, independently, we abstracted key data on the design features, population, intervention and outcomes of the studies. RESULTS: We identified four trials of enteral vs total parenteral nutrition, one trial of early enteral nutrition vs delayed enteral nutrition, one trial of gastric vs jejunal tube feeding, one trial of intermittent vs continuous enteral feeding, and three trials evaluating different enteral feeding formulae. Sample sizes were small, pneumonia definitions were variable and blinded outcome assessment was infrequent. Randomized trial evidence is insufficient to draw conclusions about the relation between enteral nutrition and nosocomial pneumonia. CONCLUSIONS: Nutritional interventions in critically ill patients appear to have a modest and inconsistent effect on nosocomial pneumonia. This body of evidence neither supports nor refutes the gastropulmonary route of infection.

Gastrointestinal, hepatic, and metabolic effects of enteral and parenteral nutrition in rats infused with tumor necrosis factor

BACKGROUND

We previously showed that continuous infusion of tumor necrosis factor-alpha (TNF-alpha) in orally fed rats caused weight and muscle wasting mainly because of anorexia. However, when we tried to prevent weight loss by giving total parenteral nutrition (TPN), TNF-infused rats developed hyperglycemia, azotemia, and hepatic abnormalities. The present study was designed to determine whether the enteral (ENT) feeding resulted in fewer complications than parenteral (TPN) feeding in TNF-infused rats (100 micrograms/kg/d).

METHODS

Forty-two rats were randomly allocated to four groups as follows: controls: TPN and ENT, and TNF-infused: TPN + TNF and ENT + TNF. All groups received the same liquid defined formula diet either enterally or parenterally (isocaloric and isonitrogenous). Twenty-six rats were used for studies of body composition and metabolism and 16 for vascular permeability.

RESULTS

TPN + TNF and ENT + TNF rats showed significantly increased liver weights and significantly reduced carcass weights compared with controls. A significant reduction in the muscle weights and total protein, as well as hyperglycemia, azotemia, and abnormal liver enzymes was also seen in ENT + TNF rats compared with ENT rats. The gastric and small intestinal mucosa was inflamed in the ENT + TNF but not in the ENT, TPN + TNF, and TPN rats. The plasma TNF levels determined by bioassay were significantly increased in the TPN + TNF and ENT + TNF rats compared with controls. There was increased vascular permeability in the stomach and small and large intestine in the ENT + TNF rats compared with ENT rats. No significant changes in vascular permeability were seen in TPN and TPN + TNF rats.

CONCLUSIONS

ENT, but not TPN, resulted in prominent changes in the body composition and marked metabolic effects in the TNF-infused rats.

Dietary fatty acids modulate host bacteriocidal response,microbial translocation and survival following blood transfusion and thermal injury

The effect of dietary lipids on bacterial translocation, killing of translocated organisms and host survival was studied in a burned animal model. Balb/c mice were fed with one of the three experimental AIN-76A diets (containing 15% of energy from fish oil, safflower oil or a 50:50 mixture), AIN-76A without added lipids or a nonpurified stock diet. All animals were transfused on day 10. On day 15, the animals were gavaged with 10(10) 14C radiolabelled Escherichia coli and given a 20% burn injury. Survival was 84% in the fish oil group versus 36% in the safflower oil and 50:50 diet groups, and 25% and 20% in the two control groups (P < 0.0001). The numbers of viable translocating bacteria were reduced in all tested organs in the fish oil groups compared to the other groups. It is concluded that a diet enriched in fish oil has beneficial effects during gut-derived sepsis.

Erythromycin facilitates postpyloric placement of nasoduodenal feeding tubes in intensive care unit patients: randomized, double-blinded, placebo-controlled trial

BACKGROUND

To determine whether administration of erythromycin (E) could facilitate passage of a nasoenteric feeding tube into the duodenum for postpyloric feedings, this randomized, double-blind, placebo-controlled trial was performed.

METHODS

Fifty-seven patients were accrued from the surgical intensive care units (ICUs) of a tertiary-care university hospital. Patients enrolled were categorized as to the presence or absence of diabetes mellitus (DM). Those patients without DM were then subdivided into those with normal or depressed mental status. The three groups, normal (NMS), depressed mental status (DMS), or diabetes mellitus (DM), were then randomized independently to receive either E or placebo (P), followed by blind placement of a feeding tube. Tube placement was verified by an abdominal radiograph.

RESULTS

Overall, the rate of postpyloric placement was 61% (19/31) in the E group, significantly better than 35% (9/26) in the P group (p < .05). In patients with NMS, the success rate with E was improved (64%, 9/14) compared with that with P (9%, 1/11) (p < .0005). In the DMS group, there was a 50% success rate (6/12) with E versus 63% (5/8) with P (not significant [NS]). In the DM group, 80% (4/5) of the patients had placement of the tube in the duodenum with E and 43% (3/7) with P (NS).

CONCLUSIONS

These data suggest that, overall, E is effective in facilitating placement of a nasoenteric feeding tube into the duodenum in ICU patients. It is clearly beneficial in those patients with normal mental status and may be useful in patients with diabetes mellitus.

Bedside sonographic-guided versus blind nasoenteric feeding tube placement in critically ill patients

OBJECTIVE

To compare a blind manual bedside method for placing feeding tubes into the small bowel vs. a sonographic bedside technique in critically ill patients.

DESIGN

Prospective study with a random sample.

SETTING

Multidisciplinary intensive care unit in a tertiary care university hospital.

PATIENTS

Thirty-five adult patients. All patients were hemodynamically stable, mechanically ventilated, and required a nasoenteric tube placement for short-term enteral feeding due to impaired gastric emptying.

INTERVENTIONS

A well-known, blind, manual, bedside method for postpyloric tube placement was always attempted first in all cases. The technique was considered successful when a postpyloric location of the tip of the tube was achieved as shown by abdominal roentgenogram. However, if after 30 mins we failed to enter the small bowel, a radiologist attempted a sonographic bedside technique for postpyloric tube insertion. Finally, when the feeding tube was in place, before starting enteral nutrition, a nasogastric tube was inserted into the stomach.

MEASUREMENTS AND MAIN RESULTS

The blind manual method was successful in nine (25.7%) of the 35 patients and the final location of these feeding tubes was the proximal jejunum. The average time for placement of the feeding tubes with this manual technique was 13.9 +/- 7.4 mins (range 5 to 30). The sonographic technique was successful in 22 (84.6%) of the remaining patients and the final location of the feeding tubes was three (11%) tubes in the second portion of the duodenum, eight (31%) tubes in the third portion of the duodenum, and 11 (42%) tubes in the proximal jejunum. The average time for placement with the sonographic technique was 18.3 +/- 8.2 mins (range 5 to 35). The pyloric outlet was sonographically akinetic or severely hypokinetic in 13 patients, and in four of them, we were unable to achieve postpyloric tube placement. In these four patients, the tubes were subsequently placed by endoscopy.

CONCLUSIONS

The sonographic bedside technique for placing feeding tubes into the small bowel in critically III patients has a success rate of 84.6% (confidence interval 71% to 98%) after the failure of the blind bedside manual method, proving that the former is significantly more successful. This sonographic technique facilitates the insertion of the tubes in patients who cannot be moved and in those patients with severe impairment of the peristaltic activity of the stomach.

Enteral versus parenteral nutrition after oesophagogastric surgery: a prospective randomized comparison

BACKGROUND

There appears to be an emerging consensus that early postoperative nutritional support benefits the high-risk patient by decreasing septic morbidity, maintaining immunocompetence and improving wound healing. Enteral nutrition via a feeding jejunostomy has been associated with serious complications, with a reported mortality rate as high as 10%, while total parenteral nutrition has also been associated with a wide variety of complications.

METHODS

Ninety-seven patients undergoing oesophagectomy or gastrectomy underwent pre-operative nutritional assessment and were randomized to receive either total parenteral nutrition (47 patients) or enteral nutrition (50 patients).

RESULTS

There was no significant difference in the number of catheter-related complications between the two groups, but 9 (45%) patients in the total parenteral nutrition group had major morbidity (potentially fatal in two patients) requiring active intervention.

CONCLUSIONS

This study demonstrates enteral nutrition to be safe and associated with mainly reversible minor complications. It is probable that immediate postoperative enteral feeding conserves the gut's integrity. Whether this leads to a reduction in postoperative septic complications has not been demonstrated by this study although there appears to be a trend in this direction, supporting the concept of enteral feeding as 'primary therapy'. This can be safely, simply and economically achieved using a feeding jejunostomy placed at the time of surgery.

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.

Sepsis and fat metabolism

Sepsis is a common surgical problem which can induce profound changes in the plasma concentrations of cytokines and hormones, leading to a catabolic state. Hypertriglyceridaemia and increased fat oxidation are the main features of altered fat metabolism encountered in this state. The endogenous catabolism of sepsis can be reduced by administering exogenous lipid emulsions as a source of metabolic fuel, although the changes in lipid metabolism associated with sepsis may affect the handling of these exogenous lipids. An exciting area for future research is an examination of the ability of lipid emulsions to reduce the morbidity and mortality associated with sepsis by altering immune responses, in addition to limiting catabolism.

Reversible impairment in monocyte major histocompatibility complex class II expression in malnourished surgical patients

BACKGROUND

Upregulation of major histocompatibility complex (MHC) class II antigen in response to the T-cell lymphokine interferon-gamma (IFN-gamma) is central to T cell-macrophage cooperation and immune homeostasis. We evaluated this property in malnourished surgical patients and assessed the impact of nutrition repletion with total parenteral nutrition (TPN).

METHODS

Sixty-two patients were studied: 37 malnourished and 25 controls. Whole blood was cultured with or without IFN-gamma (100 U mL-1), dual-labeled with anti-CD14 (monocyte) and anti-human leukocyte antigen-DR antibodies and analyzed by flow cytometry. Phagocytosis was measured by flow cytometry. In a second study, 10 severely malnourished patients received 5 days of TPN and MHC class II expression was measured at the end of this period.

RESULTS

The magnitude of the increase in monocyte MHC class II expression in response to IFN-gamma was significantly increased in the control group compared with the malnourished group (107% vs 53%; p < .05). This impairment directly correlated with severity of malnutrition, but did not correlate with age or disease type. The number of bacteria phagocytozed per cell was significantly decreased (p < .05) in the malnourished group. In study 2, there was a significant increase in MHC class II induction with IFN-gamma after short-term TPN (58% before vs 173% after, p < .001).

CONCLUSIONS

MHC class II induction in response to IFN-gamma is significantly impaired in malnourished patients, correlating with the severity of malnutrition. This defect is reversed by short-term TPN. These data identify the reversible loss of a key mechanism, fundamental to host defense, that may enhance the risk of infection in malnourished patients.

Complex pancreatic injuries

The majority of pancreatic injuries are minor in nature and can be managed easily and definitively with external drainage. The complexity of management increases significantly when a pancreatic ductal injury is present. It is requisite that thorough preoperative and intraoperative work-up be complete and systematic if injuries are to be properly recognized and managed. Once an injury has been detected, management guidelines based on injury classification can help to provide uniform results with minimal complications. In general, a conservative management scheme is indicated, the goals of such being preservation of pancreatic tissue and minimization of pancreaticoenteric anastomoses. Specific technical maneuvers may vary, but strict adherence to the basic concepts of hemorrhage control, contamination control, accurate pancreatic assessment, judicious resection, and adequate drainage can help to reduce the frequency of complications from these complex injuries.

Nutrition and the immune system

Malnutrition frequently contributes to the immunocompromise seen in hospitalized patients. Nutritional support corrects malnutrition and can reverse the associated immunocompromise. Developing an understanding of nutritional needs and the role of nutrition in immune function is essential to prevention and treatment of nutrition-related immunocompromise. Current research is defining the role of specific nutrients in immune function. Recent evidence also suggests that the route (enteral versus parenteral) of providing nutritional support can affect immune competence. Intervention trials may show a role of key nutrients in not only maintaining normal immune competence, but also in modulating immunologic outcomes in critically ill patients.

Enteral nutrition and the critically ill

Critically ill patients invariably require nutritional intervention. Traditionally, enteral nutrition has not been widely employed in this patient population. This is due in part to the success of present-day parenteral nutrition, and to difficulties encountered with enteral feeding. Recent evidence has demonstrated that enteral is preferable to parenteral nutrition in terms of cost, complications, gut mucosal maintenance, and metabolic and immune function. Enterally administered nutritional support can and should be utilised as the preferred route of nourishment for the critically ill. The appropriate choice of access and formula, as well as a rational strategy for implementation, should improve the likelihood of success. This article describes the unique features of critical illness as they pertain to nutritional support, the benefits of enteral nutrition, and the obstacles to success, and offers suggestions which may improve the ability to provide nutrients adequately via the intestinal tract.

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.

Early nutritional support in critical illness is important

The hypermetabolic state in critically ill patients is characterized by wasting of lean body mass and immunosuppression. The gut is among the most metabolically active organs. Failure to maintain gut function by way of early enteral nutrition can lead to increased infectious complications. Early enteral nutrition improves outcomes and may maintain muscle mass by blunting the cytokine-mediated hypermetabolic response.