P.B. Soeters

Glutamine and the preservation of gut integrity

Parenteral glutamine dipeptide improves nitrogen balance in postoperative patients on total parenteral nutrition (TPM). Animal studies show that the structure and function of the gut is preserved by glutamine. It is not known if this is the case in human beings. 20 patients admitted to hospital for total parenteral nutrition were randomly allocated to receive parenteral nutrition enriched with glycyl-L-glutamine (Gln TPN), or standard parenteral nutrition (STPN). Mucosal biopsy specimens were taken from the second part of the duodenum before starting parenteral nutrition, and after two weeks. The ratio between the urine concentrations of lactulose and mannitol after enteral administration was used to measure intestinal permeability. After two weeks of parenteral nutrition in the GlnTPN group, intestinal permeability was unchanged, whereas permeability in the STPN group increased. Villus height was unaltered in the GlnTPN group but in the STPN group it decreased. The addition of glutamine to parenteral nutrition prevents deterioration of gut permeability and preserves mucosal structure.

ESPEN Guidelines on Parenteral Nutrition: Surgery

In modern surgical practice it is advisable to manage patients within an enhanced recovery protocol and thereby have them eating normal food within 1-3 days. Consequently, there is little room for routine perioperative artificial nutrition. Only a minority of patients may benefit from such therapy. These are predominantly patients who are at risk of developing complications after surgery. The main goals of perioperative nutritional support are to minimize negative protein balance by avoiding starvation, with the purpose of maintaining muscle, immune, and cognitive function and to enhance postoperative recovery. Several studies have demonstrated that 7-10 days of preoperative parenteral nutrition improves postoperative outcome in patients with severe undernutrition who cannot be adequately orally or enterally fed. Conversely, its use in well-nourished or mildly undernourished patients is associated with either no benefit or with increased morbidity. Postoperative parenteral nutrition is recommended in patients who cannot meet their caloric requirements within 7-10 days orally or enterally. In patients who require postoperative artificial nutrition, enteral feeding or a combination of enteral and supplementary parenteral feeding is the first choice. The main consideration when administering fat and carbohydrates in parenteral nutrition is not to overfeed the patient. The commonly used formula of 25 kcal/kg ideal body weight furnishes an approximate estimate of daily energy expenditure and requirements. Under conditions of severe stress requirements may approach 30 kcal/kg ideal body weights. In those patients who are unable to be fed via the enteral route after surgery, and in whom total or near total parenteral nutrition is required, a full range of vitamins and trace elements should be supplemented on a daily basis.

Perioperative nutritional support: a randomised clinical trial

Ever since methods of artificial nutritional support became available, attempts have been made using this form of treatment to reduce mortality and morbidity in surgical patients. Many trials have addressed this question, but very few have given a meaningful answer because of conceptual and methodological flaws. We therefore undertook a prospective randomised trial investigating the effects of at least 10 days pre-operative total parenteral nutrition (TPN) (n = 51) or total enteral nutrition (TEN) (n = 50) providing 150% basal energy expenditure (BEE) non-protein energy, to reduce major postoperative complications and mortality in a homogeneous patient group with signs of depletion. 50 patients served as a depleted control group (D) and 49 patients served as a non-depleted reference group (ND) and were operated upon without delay. Depleted control patients suffered significantly more septic complications than did patients in the non-depleted reference group (p < 0.05). There was no significant difference, however, in septic complications between either of the nutritional support groups and the non-depleted control group. In high risk patients, with weight loss >10% of body weight and over 500 ml blood loss during operation, a significant decrease in major complications was observed (p < 0.05) as a result of nutritional support. We conclude that pre-operative nutritional support, in patients with severe depletion, results in a reduction in major complications to a degree that justifies its routine use in this selected group of patients.

Revisional Surgery After Failed Vertical Banded Gastroplasty: Restoration of Vertical Banded Gastroplasty or Conversion to Gastric Bypass

Background: An increasing number of patients with a failed primary bariatric procedure present themselves for secondary treatment. Only a few studies have investigated critically the success of revisional surgery. In the present study, the effectiveness of revisional surgery for failed vertical banded gastroplasty (VBG) is analyzed: restoration of the VBG (reVBG) is compared to conversion to a Roux-en-Y gastric bypass (RYGB). Patients and Methods: From 1980 to 1996, 136 consecutive morbidly obese patients underwent primary RYGB (n = 20) or VBG (n = 16). Weight loss, indications and complications after revisional surgery were registered. The rate of revisional surgery after primary and secondary bariatric procedures was estimated by means of a Kaplan-Meier analysis. Results: Kaplan-Meier analysis revealed that 56% of the patients will eventually require revisional surgery after initial VBG over a 12-year period compared to 12% after initial RYGB (P < 0.01). After reVBG 68% will need revisional surgery over a 5-year period, while no further revisional surgery was required after conversion to a RYGB (P < 0.05). Body mass index dropped significantly after reVBG or conversion to RYGB for insufficient weight loss (P < 0.05), however, more revisional surgery was necessary after reVBG to achieve this result. The complication rate was comparable between reVBG and conversion to RYGB (33%). Conclusion: Conversion of a failed VBG to a RYGB is more effective than a reVBG, because conversion to RYGB provides satisfactory weight loss without requiring further revisional surgery.

Interorgan ammonia metabolism in liver failure

In the post-absorptive state, ammonia is produced in equal amounts in the small and large bowel. Small intestinal synthesis of ammonia is related to amino acid breakdown, whereas large bowel ammonia production is caused by bacterial breakdown of amino acids and urea. The contribution of the gut to the hyperammonemic state observed during liver failure is mainly due to portacaval shunting and not the result of changes in the metabolism of ammonia in the gut. Patients with liver disease have reduced urea synthesis capacity and reduced peri-venous glutamine synthesis capacity, resulting in reduced capacity to detoxify ammonia in the liver. The kidneys produce ammonia but adapt to liver failure in experimental portacaval shunting by reducing ammonia release into the systemic circulation. The kidneys have the ability to switch from net ammonia production to net ammonia excretion, which is beneficial for the hyperammonemic patient. Data in experimental animals suggest that the kidneys could have a major role in post-feeding and post-haemorrhagic hyperammonemia.During hyperammonemia, muscle takes up ammonia and plays a major role in (temporarily) detoxifying ammonia to glutamine. Net uptake of ammonia by the brain occurs in patients and experimental animals with acute and chronic liver failure. Concomitant release of glutamine has been demonstrated in experimental animals, together with large increases of the cerebral cortex ammonia and glutamine concentrations. In this review we will discuss interorgan trafficking of ammonia during acute and chronic liver failure. Interorgan glutamine metabolism is also briefly discussed, since glutamine synthesis from glutamate and ammonia is an important alternative pathway of ammonia detoxification. The main ammonia producing organs are the intestines and the kidneys, whereas the major ammonia consuming organs are the liver and the muscle.

Gut permeability, intestinal morphology, and nutritional depletion.

Nutritional depletion increases the risk for postoperative complications. The intestinal barrier may be important in the underlying pathophysiologic mechanism. In this study, 26 patients were evaluated to determine whether nutritional depletion was related to gut integrity and intestinal morphology. Nutritional depletion was estimated by calculating percentage ideal body weight (PIB) or percentage ideal fat free mass (PIFFM). To assess gut integrity, a lactulose/mannitol (L/M) test was performed. Duodenal biopsies were taken, and villous height, crypt depth, number of IgA-producing plasma cells, intraepithelial lymphocytes (IELs), and proliferating index were determined. The L/M ratio was increased, and villous height was decreased in depleted patients. Depletion was not associated with differences in the number of immune cells or proliferating index. The number of IgA-producing plasma cells was positively correlated with the L/M ratio. This study shows that nutritional depletion is associated with increased intestinal permeability and a decrease in villous height.

Suppression of Cellular Immunity in Obstructive Jaundice Is Caused by Endotoxins: A Study With Germ-Free Rats

The increased susceptibility to infections after surgery in jaundiced patients is considered to be caused by an impairment of cellular immunity and/or nutritional status. Endotoxins are suggested to play a role in the pathogenesis. However, the mechanism of action is unknown. Germ-free rats were used to study the effect of biliary obstruction in a model with negligible amounts of endotoxin. Cellular immunity, production of tumor necrosis factor (as a mediator of endotoxin toxicity) by peritoneal macrophages, and the nutritional status were assessed. Significant suppression of cellular immunity was found in conventional rats with obstructive jaundice. In contrast, cellular immunity was not suppressed in jaundiced germ-free rats. Large amounts of tumor necrosis factor were spontaneously secreted by peritoneal macrophages of jaundiced conventional rats, whereas macrophages from jaundiced germ-free rats did not. Moreover macrophage activation (expressed in tumor necrosis factor production) was significantly related to suppression of cellular immunity. Weight changes and depression of albumin levels were not different in germ-free and conventional rats after bile duct ligation. The data presented indicate that suppression of cellular immunity in obstructive jaundice is caused by endotoxins, whereas the impaired nutritional status seems to not be affected by the presence of endotoxins.

Defining malnutrition: Mission or mission impossible?

OBJECTIVE Although screening for malnutrition in health care has expanded enormously, a gold standard for the optimal definition and operationalism of malnutrition is still lacking. This report reflects expert opinions on the elements of the definition and operationalism of malnutrition and is meant to trigger further debate within the nutritional societies. METHODS A Delphi study was performed consisting of three phases. After a literature review (phase 1), questions for a semistructured interviews (phase 2) were formulated. Subsequently, the results of these semistructured interviews were used to develop the final list of elements (for defining and operationalism of malnutrition). In phase 3 (final phase), experts were asked to provide written feedback regarding the ranking of elements concerning the importance of these elements. RESULTS Twenty-two experts (response 73.3%) were included in the final phase of this Delphi study. No overall agreement could be reached. The elements deficiencies of energy or protein and decrease in fat-free mass were most often mentioned to be particularly important in defining malnutrition. Elements mentioned to be important in operationalism of malnutrition were involuntary weight loss, body mass index, and no nutritional intake. Opinions on cutoff points regarding these elements differed strongly among experts. CONCLUSION This study shows that there is no full agreement among experts on the elements defining and operationalism of malnutrition. The results of this study may fuel the discussion within the nutritional societies, which will most ideally lead to an international consensus on a definition and operationalism of malnutrition.

Plasma-amino acid profiles in sepsis and stress

Sepsis has been associated with specific plasma amino acid patterns. Sixty-five patients were prospectively investigated as to whether these patterns are indeed sepsis specific, or specific for metabolic stress without concomitant sepsis, or associated with the presence of organ failure. Virtually all aminoacid levels were decreased by 10–30% (p < 0.05), whereas cystine and phenyl-alanine were significantly elevated. These changes were more pronounced in severe sepsis. Organ failure was not associated with significantly altered amino acid profiles. No differences were found between sepsis and stress without signs of sepsis. In addition, imminent death was not associated with aberrant amino acid profiles. We conclude that sepsis and metabolic stress are associated with changes in plasma amino acid profiles, but that such changes are aspeciflc and therefore poor indicators of disease severity.

Psychological functioning of morbidly obese patients after surgical treatment

OBJECTIVE: To investigate the long-term effects of surgically induced weight loss on the psychological functioning of morbidly obese patients.DESIGN: Comparison between preoperative and postoperative psychometric test results in a cross-sectional study.PATIENTS AND METHODS: Three psychometric tests were administered to 62 morbidly obese patients before and after surgery.RESULTS: The mean follow-up was 85.9±48.1 months. Surgical treatment resulted in a mean weight loss of 45.0±21.3 kg (P<0.0001). The psychometric test results before surgery demonstrated somatisation, depression, denial of emotional stress, social incompetence and an indifferent attitude towards certain aspects of interpersonal behaviour. All psychopathology, except for somatisation, disappeared after surgical treatment. Improvement of psychological functioning was determined by weight loss and not influenced by the surgical procedure. The level of self-esteem before surgery predicted 15.4% of the outcome variance (P<0.05).CONCLUSION: The psychopathology before surgery is almost totally reversed after sustained, surgically induced weight loss. This suggests that the preoperative psychological disturbances are the result, rather than the cause, of morbid obesity.