Edgar J. Poth lecture. The surgeon and gut maintenance

Nutrition Support in Adult Trauma Patients

Nutrition supplementation is paramount to the care of severely injured patients. Despite its widespread use in trauma patients, many areas of clinical practice remain controversial. The purpose of this paper is to critically review the literature studying the use of enteral vs parenteral nutrition (PN) and to provide the rationale for early enteral nutrition. Additional controversies confronting clinicians are reviewed, including the use of immune-enhancing agents and the optimal site for enteral nutrition delivery (gastric vs small intestinal). Evidence-based recommendations for clinical practice are presented when available.

Effect of glutamine on intestinal mucosal integrity and bacterial translocation after abdominal radiation

This study evaluates the effect of oral glutamine on intestinal mucosal integrity and bacterial translocation in rats. 80 animals were randomised into four groups: group 1 (chow diet and water), group 2 (chow diet and glutamine 3%), group 3 (radiation, chow diet and water), group 4 (radiation, chow diet and glutamine 3%). Groups 1 and 2 were fed for 5 days, then sacrificed. Groups 3 and 4 were fed for 12 days, irradiated on the 5th day and sacrificed on 1st, 3rd and 7th post-radiation days. Cultures from the mesenteric lymph nodes (MLN), portal vein (PV) and aorta (A) were taken and two tissue samples were also taken from the terminal ileum for light and electron microscopic examination. In non-radiated rats glutamine did not alter the histologic parameters of villous height (VH), mitoses per crypt (M/C) and muscle thickness (MT). Group 3 rats had severe mucosal damage associated with a significant decrease of VH (p < 0.0001) and M/C (p < 0.01) on 1st and 3rd post-radiation days respectively. In contrast, group 4 rats maintained their mucosal structure and had a significant increase of VH and M/C (p < 0.0001) on post-radiation days 1 and 3. Bacterial translocation in MLN was 87.5% (p < 0.002) and 75% (p < 0.04) on 1st and 3rd post-radiation days respectively in group 3, and fell significantly to 12.5% (p < 0.002) in group 4. The data demonstrate that glutamine helps maintain the integrity of the intestinal mucosa and thereby reduces the incidence of bacterial translocation following abdominal irradiation.

Nutrition support of the trauma patient

Hypercatabolism after trauma may lead to acute protein malnutrition, ultimately resulting in multiple organ failure. Nutrition support may prevent this sequence. This review addresses the need for early nutrition support, the preferred route of substrate delivery, and the potential advantages of "immune-enhancing" diets.

Duodenal versus gastric feeding in ventilated blunt trauma patients: a randomized controlled trial

OBJECTIVE

To evaluate transpyloric feeds as they have been proposed as a means of providing enteric nutrition more rapidly and minimizing morbidity in ventilated trauma patients.

METHODS

Between July of 1994 and June of 1997, 80 adult ventilated trauma patients were enrolled in a randomized controlled trial of duodenal versus gastric feeds. Feeding was initiated within 72 hours of injury.

RESULTS

Forty-three patients received gastric feeds (G), and 37 patients received duodenal feeds (D). Mean age was 34.7+/-15.7 years (G) and 33.6+/-17.5 years (D); the difference in age was not significant (NS). Mean Injury Severity Score was 30.0+/-11 (G), 33.0+/-9.7 (D), NS. Mean Acute Physiology and Chronic Health Evaluation (APACHE II) score was 18.0+/-6.0 (G) and 18.0+/-7.4 (D), NS. Thirty-four of 43 patients were men (G) and 28 of 37 patients were men (D), NS. Use of narcotics and paralytics between the two groups was not significantly different. Energy requirements were 1.4 times basal energy expenditure at 2,127+/-304 Kcal (G) and 2,089+/-274 Kcal (D), NS. Intensive care unit length of stay was a median of 7 days (range, 3-32 days) (G) and 10 days (range, 3-24 days) (D), NS. Number of days on ventilator was a median of 5 days (range, 3-15 days) (G) and 9 days (range, 2-13 days) (D), NS. Hospital length of stay was a median of 25 days (range, 9-88 days) (G) and 30 days (range, 16-47 days) (D), NS. Recorded morbidity was not significantly different. Pneumonia rates were 42% (G) and 27% (D), NS. Time to tolerate full-strength feeds for 24 consecutive hours was 43.8 hours +/-22.6 (G) and 34.3 hours +/-7.1 (D), difference significant at p = 0.02.

CONCLUSION

Length of stay and ventilator days were not significantly different. A larger trial would be required to determine differences in the rates of pneumonia <20%. Transpyloric-duodenal feeds significantly reduce the time required to achieve targeted enteric nutrition.

Nutritional modulation of gut inflammation

Nutritional therapy is an important component of the management of gastrointestinal inflammation, which disrupts the gut mucosal barrier leading to sepsis, SIRS and MODS. Future studies will be needed to define the role of specific nutrients in enhancing mucosal barrier function and supporting general immune function, and how this affects morbidity and mortality of critically-ill patients.

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.

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.

Bacterial translocation and enteral nutrition in humans: an outsider looks in

PURPOSE

To assess the literature documenting the existence of bacterial translocation in humans, the effects of enteral nutrition on bacterial translocation in humans, and the hypothesis that enteral nutrition prevents bacterial translocation in humans.

DATA IDENTIFICATION

Sources included Medline search, references from review articles, and references from animal and human studies.

STUDY SELECTION

The goal was to include all animal and human studies directly addressing questions of bacterial translocation and nutritional status or nutritional support.

DATA EXTRACTION

An attempt was made to briefly summarize methodology and findings of relevent studies. No general attempt was made to assess quality of individual studies.

RESULTS OF DATA SYNTHESIS

Bacterial translocation is a well documented phenomenon in animal models. Starvation and malnutrition of themselves do not induce bacterial translocation, but may facilitate translocation in the presence of other systemic insults. Parenteral nutrition and many forms of enteral nutrition may induce and/or facilitate bacterial translocation. Chow and certain fiber sources seem protective. Moderate direct and several lines of indirect evidence support the existence of bacterial translocation in humans. There is no direct evidence and questionable indirect evidence suggesting that enteral nutrition prevents or modifies bacterial translocation in humans.

CONCLUSIONS

The hypothesis relating enteral nutrition and bacterial translocation in critically ill patients remains attractive, but unproven.

Insulin-like growth factor-I prevents gut atrophy and maintains intestinal integrity in septic rats

BACKGROUND

The effects of insulin-like growth factor-I (IGF-I) on gut metabolism, structure, and barrier function as well as its general anabolic effects were investigated in septic rats.

METHODS

Thirty-three male Wistar rats that underwent cecal ligation were randomly divided into one of the following two groups: (1) received only total parenteral nutrition (control group) or (2) received total parenteral nutrition with IGF-I (IGF group) at a dose of 4 mg/kg/d for 3 days.

RESULTS

During the 3-day period, the body weight of rats in the IGF group increased significantly over that of rats in the control group (17.1 +/- 2.6 vs 5.8 +/- 4.6 g, p < .01). The total and free IGF-I plasma concentrations were significantly higher in the IGF group than in the control group. The cumulative nitrogen balance was significantly more positive for the IGF group (423.9 +/- 24.3 mg of nitrogen) than for the control group (290.8 +/- 26.0 mg of nitrogen). The weights of thymus, spleen, and kidneys were significantly increased in the IGF group compared with weights in the control group. Treatment with IGF-I improved the gut mucosal weight in all regions of the gut examined, including duodenum, jejunum, ileum, and colon. Histologic and biochemical analyses of the jejunum showed greater villus height and crypt depth and higher mucosal DNA and protein content in the IGF group. The arterial concentration of endotoxin was not significantly different between the two groups, whereas its level in portal blood was significantly lower in the IGF group (23.2 +/- 9.9 pg/mL) than in the control group (95.5 +/- 37.9 pg/mL), an indication that IGF-I treatment decreased the amount of endotoxin that traversed the gut barrier.

CONCLUSIONS

These results indicate that IGF-I can improve gut metabolism and reduce mucosal atrophy and that it may play a role in maintaining the gut barrier function in sepsis.

Enteral glutamine increases growth and absorptive capacity of intestinal mucosa in the malnourished rat

BACKGROUND

Glutamine is an important nutrient for the small intestine. Beneficial effects of glutamine could be related to restoration of optimal intestinal barrier functions.

METHODS

Thirty-eight Sprague-Dawley rats were allocated to three main groups. Experimental groups (n = 22) were malnourished and laparotomized. Sham groups (n = 11) were laparotomized without prior malnutrition. These groups were refed with or without oral glutamine for 3 days. The control group (n = 5) was given chow. Permeability was assessed by the 6-h urinary recovery of orally given polyethylene glycols, PEG 400/1000. Mucosal proliferation was estimated by DNA content and 1-h incorporation of 3H-thymidine intravenously.

RESULTS

In the malnourished groups glutamine resulted in higher thymidine incorporation (p < 0.05) and better absorption of small PEG molecules (p < 0.05).

CONCLUSION

The effects of oral glutamine on permeability after malnourishment and laparotomy are proposed to be related to an increase in absorptive area.

Occurrence of intraperitoneal septic complications after hepatic resections between 1985 and 1990

In this study, the risk factors related to intraperitoneal septic complications occurring after hepatectomy (IPSCH) as well as the effect of various perioperative variables on the outcome of IPSCH between 1985 and 1990 were analyzed. Twenty-one of 211 patients (10.0%) developed IPSCH. The findings in the patients with IPSCH were compared with those in 190 patients without IPSCH. The significant variables associated with the development of IPSCH included a high incidence of accompanying chronic renal failure (14.3% vs 2.1%), a larger blood loss during surgery (2,130 vs 1,340 ml) as well as a greater amount of intraoperative blood replacement (1,130 vs 570 ml), and a greater weight of the resected liver (367 vs 233 g). IPSCH occurred in 10 of 12 patients who had postoperative bile leakage. Eighteen patients (85.7%) with IPSCH were discharged from the hospital after non-operative management; however, the hospital death rate (14.3% vs 1.1%) was significantly higher in patients with IPSCH. This review suggests that the incidence of IPSCH has not decreased recently. Thus, to prevent IPSCH, at least following bile leakage, it is necessary to perform a careful division of the liver parenchyma followed by a bile leakage test, and when this complication occurs unexpectedly in patients who have a good functional reserve of the remnant liver, IPSCH can be effectively drained percutaneously under ultrasound guidance.

Cytokines and metabolic dysfunction after severe head injury

Patients with head injury must overcome central as well as peripheral metabolic insults. In addition to specific tissue damage to the brain, a cellular biochemical cascade occurs that can negatively affect organ function, cause a systemic response to injury, and may cause secondary tissue injury. The metabolites involved in this cascade are numerous and complex. Cytokines are important cell-to-cell communication mediators during injury. It is speculated that cytokines, such as interleukin 1 (IL-1), interleukin 6 (IL-6), tumor necrosis factor (TNF), and interleukin 8 (IL-8), which are found in elevated amounts in both human and basic trials after head injury, play a role in the cellular cascade of injury. Some of the metabolic events produced by small doses of cytokine infusion in animals, as well as humans, include fever, neutrophilia, muscle breakdown, altered amino acid metabolism, depression of serum zinc levels, production of hepatic acute phase reactants, increased endothelial permeability, and expression of endothelial adhesion molecules. These are all known sequelae of severe head injury. Cytokines have also been implicated in organ failure. Infusion of cytokines in basic science trials revealed that organ functions of the gut, liver, and lung are negatively altered by high-dose cytokine infusion. Infusion of certain cytokines has been shown to cause death of brain cells, increase blood-brain barrier permeability, and cause cerebral edema. This suggests that cytokines may also play a role in the sequelae of organ demise. These effects of cytokines have been attenuated in basic trials by blocking the initial signaling system of cytokines or by decreasing serum cytokine activity. We hypothesize that cytokines that are elevated after head injury play a role in the pathology of injury, including altered metabolism and organ demise.

Open and closed suction drainage after hepatic resection

A retrospective study was conducted to compare open conduit drains with closed suction drains, with regard to the occurrence of intraperitoneal septic complications after hepatectomy (IPSCH). The subjects comprised 50 consecutive Japanese patients who underwent hepatic resection followed by the insertion of a closed suction drain and the control group comprised 50 patients in whom a simple conduit drain had been placed following liver surgery. There were no significant differences between the two groups in sex, age, underlying liver disease, or the type of hepatectomy performed; nor was there a significant difference in the incidence of IPSCH, the simple conduit drain group versus the closed suction drain group being (10% versus 8%, respectively). However, bile leakage was highly related to IPSCH, the incidence being 60% and 100% in the simple conduit drain and closed suction drain groups, respectively. Thus, to prevent IPSCH, the treatment of bile leakage is a much more important factor than the type of drain used.

Acute mesenteric ischemia: pathophysiology, diagnosis, and treatment

Ischemia has traditionally been viewed as arising only from abnormalities of oxygen dynamics, namely the cellular hypoxia resulting from the imbalances between oxygen supply, consumption, and demand. Recently, it has become clear that such a view is too restrictive. Hypoperfusion may be caused by both anatomic and functional impediments to either inflow or to outflow from an organ. Furthermore, the pathophysiologic consequences are likely to involve not only cellular hypoxia, but also a restricted supply of nutrients and other important molecules and an abnormal elimination of physiologic wastes such as carbon dioxide. Hence the recommendation that ischemia be defined as a dual defect of oxygen deficit and carbon dioxide excess. AMI is, therefore, a severe anatomic or functional impediment to the splanchnic circulation, resulting in a dual defect of intestinal hypoxia and cellular hypercarbia. Although the functional and structural consequences of cellular hypoxia are well known, the pathophysiology of cellular hypercarbia has only begun to be explored. AMI syndromes include three related processes: occlusive mesenteric ischemia, nonocclusive ischemia, and sepsis-induced SI. Leakage of bacteria or bacterial toxins into the circulation during mesenteric ischemia forms the basis of the systemic components of this syndrome. Striving for an earlier diagnosis, treating the systemic (septic) consequences, and taking measures to promptly restore mucosal oxygen balance through aggressive pharmacologic and appropriate surgical intervention have significantly improved the prognosis. About 80% of patients with acute arterial embolism, 60% of those with nonocclusive ischemia, and only 20% of patients with arterial thrombosis are expected to live without significant residual nutritional deficits. The cause of death is usually sepsis and multisystem organ failure, and therefore, further reductions in mortality are likely to occur with the improved prevention and treatment of sepsis.

Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis

This two-part meta-analysis combined data from eight prospective randomized trials designed to compare the nutritional efficacy of early enteral (TEN) and parenteral (TPN) nutrition in high-risk surgical patients. The combined data gave sufficient patient numbers (TEN, n = 118; TPN, n = 112) to adequately address whether route of substrate delivery affected septic complication incidence. Phase I (dropouts excluded) meta-analysis confirmed data homogeneity across study sites, that TEN and TPN groups were comparable, and that significantly fewer TEN patients experienced septic complications (TEN, 18%; TPN, 35%; p = 0.01). Phase II meta-analysis, an intent-to-treat analysis (dropouts included), confirmed that fewer TEN patients developed septic complications. Further breakdown by patient type showed that all trauma and blunt trauma subgroups had the most significant reduction in septic complications when fed enterally. In conclusion, this meta-analysis attests to the feasibility of early postoperative TEN in high-risk surgical patients and that these patients have reduced septic morbidity rates compared with those administered TPN.

The effect of surgical trauma on the bacterial translocation from the gut

Bacterial translocation is the passage of viable bacteria from the lumen of the gastrointestinal tract through the intestinal mucosa to other sites. It is believed that bacterial translocation may lead to infection and septicemia. The purpose of this study was to determine what factors in experimental surgical trauma lead to bacterial translocation. Two-month-old Wistar albino rats were divided into five groups: (A) control; (B) anesthesia (ether inhalation); (C) anesthesia and surgery (median laparotomy and transient compression of the intestines); (D) fasting only; and (E) anesthesia, surgery, and fasting. After 48 hours, ileum, mesenteric lymph nodes, and blood were cultured for aerobic and anaerobic organisms. In each group the number of animals with bacteria overgrowth was calculated. The incidence of bacterial translocation to mesenteric lymph nodes and blood in groups B and D were similar to the controls (P greater than .01). There was a significant increase in the number of animals with bacterial translocation in groups C and E (P less than .001). The majority of translocating bacteria were E coli.

Intestinal permeability in pediatric gastroenterology

The role of the physiologic barrier function of the small bowel and its possible role in health and disease has attracted much attention over the past decade. The intestinal mucosal barrier for luminal macromolecules and microorganism is the result of non-immunologic and immunologic defense mechanisms. The non-immunologic mechanisms consist of intraluminal factors such as gastric acid, proteolytic activity, and motility and of mucosal surface factors like mucin and the microvillous membrane. The immunologic mechanisms include secretary IgA and cell-mediated immunity. Both types of mechanism are not completely mature at birth. Maturation of this barrier is not finished before the 2nd year of life. One of the aspects of the mucosal barrier function can be estimated by the intestinal permeability (IP) for macromolecules. We use the differential sugar absorption test (SAT), in which the ratio of urinary excretion of a relatively large molecule, lactulose, is compared with that of a relatively small molecule, mannitol, after oral ingestion. Although the small intestine is permeable to certain macromolecules in normal developmental conditions, an increased IP could be involved in the pathophysiology of several diseases, including infectious diarrhea, food allergy, celiac disease, and Crohn's disease. It can be concluded that IP, as measured with the SAT, reflects the state of the mucosal barrier and is altered in several gastrointestinal diseases. The SAT is a non-invasive IP test that can be of diagnostic help to demonstrate alterations in the small-mucosal barrier function and may be useful to evaluate therapeutic interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of an arginine-free enteral diet on wound healing and immune function in the postsurgical rat

Critically ill patients have increased rates of sepsis partly due to a down-regulated immune system. Nutrients may modulate the immune system. The following studies were performed to determine whether arginine is one of these "essential" nutrients for the immune system. Thirty-two male Sprague-Dawley rats (weighing 175 g) were divided into two groups that were pair-fed with either an elemental, arginine-supplemented enteral diet, or the same diet with arginine removed and replaced with glycine. Both diets were isocaloric, isoosmolar, and isonitrogenous. After 6 days on the diet, animals underwent testing. There were no significant differences between the arginine-supplemented and the arginine-free diet groups in blood glucose or hematocrit. The arginine-supplemented animals had higher serum albumin (4.1 +/- 0.1 mg/dL v 3.6 +/- 0.1 mg/dL; P = .035) and serum protein levels (5.2 +/- 0.1 mg/dL v 4.3 +/- 0.1 mg/dL; P = .041); and had higher thymus gland (0.53 +/- 0.03 g v 0.44 +/- 0.02 g; P less than .0001) and spleen weights (0.66 +/- 0.01 g v 0.57 +/- 0.01 g; P less than .01). Daily total urinary nitrogen excretion, nitrogen balance, and weight gain showed a tendency for the arginine-supplemented animals to retain more of their nitrogen calories. There was no difference in the amount of hydroxyproline (OHP) found in the wound cylinders of either group (both 25.6 micrograms OHP/cm polytetrafluoroethylene) but the arginine-supplemented group's wounds had greater wound bursting strengths (429 +/- 3 g/cm v 350 +/- 7 g/cm; P = .044).(ABSTRACT TRUNCATED AT 250 WORDS)