Increased intestinal permeability associated with infection in burn patients

Enteral supplementation enriched with glutamine, fiber, and oligosaccharide prevents gut translocation in a bacterial overgrowth model

BACKGROUND

Normal gut flora plays an important role in the intestinal mucosal barrier function under various critical conditions. The flora may alter after severe insults, such as trauma and shock. Enteral nutrition should preserve the gut environment; however, full support is usually difficult for severely ill patients because of impaired gastrointestinal motility. Currently, we have commercial enteral supplementation product enriched with glutamine, dietary fiber, and oligosaccharide (GFO) in Japan. This study examines the hypothesis that the enteral supplementation ameliorates gut injury induced by a bacterial overgrowth model, even in small volumes and quantities.

MATERIALS

Balb/c mice received antibiotics (4 mg/mL of streptomycin) in their drinking water for 4 days to kill the normal gut flora after which they were orally inoculated with a streptomycin-resistant strain of Escherichia coli, known as E. coli C-25. The mice that were administered bacterial monoassociation received 0.5 mL of GFO twice daily (GFO group) or 10% of glucose solution (GLU group). Unsupplemented drinking water was used for control animals (control) whose gut flora was normal. The mice were killed and their mesenteric lymph nodes complex was harvested and processed to test gut bacterial translocation. The cecal population levels of bacteria and ileum histology were also examined.

RESULTS

The incidence and magnitude of gut translocation to the lymph nodes complex in the GLU group were significantly higher than those in the control (p < 0.01). Treatment with GFO prevented the gut translocation although animals in the GFO group had same level of the cecal bacterial population. Histologic findings in the ileum were not different between the GLU and GFO.

CONCLUSION

GFOs supplement prevented gut translocation for bacterial overgrowth even in small volumes and quantities. The intestinal histologic findings could not explain the protective mechanisms of GFO. Further studies may be needed to elucidate the benefit of the partial enteral nutrition.

Second hit post burn increased proximal gut mucosa epithelial cells damage

Secondary infections after burn are common and are a major contributor to morbidity and mortality. We previously showed that burn disrupted proximal gut mucosal homeostasis through increased epithelial cell apoptosis. In the present study, we sought to determine whether proximal gut mucosal disruption is additively affected by secondary endotoxemia after a severe burn. C57BL/6 mice received 30% total body surface area full-thickness scald burns and were randomized to receive saline or LPS 1 mg/kg body weight given intraperitoneally 72 h after burn. Proximal small bowel was harvested 12 h after LPS injection. Mucosal height and epithelial cell number were assessed on hematoxylin-eosin sections, intestinal epithelial cell apoptosis was identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, and cell proliferation by immunohistochemical staining for proliferating cell nuclear antigen. Results showed that proximal gut mucosa impairment occurred 12 h after injury, including significantly decreased proximal gut wet weight, gut mucosal height, and epithelial cell number associated with increased proximal gut epithelial apoptosis (P < 0.05). This impairment diminished 72 h after burn. Second-hit endotoxemia caused additional proximal gut mucosa damage with decreased proximal gut weight, cell number, and mucosal height (P < 0.05) and significantly increased small intestinal epithelial apoptosis and mucosal atrophy, even after the first event, indicating a second detrimental effect of endotoxemia after the initial injury.

Immunonutrition in critically ill patients: a systematic review and analysis of the literature

BACKGROUND

The role of immuno-modulating diets (IMDs) in critically ill patients is controversial.

OBJECTIVE

The goal of this meta-analysis was to determine the impact of IMD's on hospital mortality, nosocomial infections and length of stay (LOS) in critically ill patients. Outcome was stratified according to type of IMD and patient setting.

DATA SOURCES

MEDLINE, Embase, Cochrane Register of Controlled Trials.

STUDY SELECTION

RCT's that compared the outcome of critically ill patients randomized to an IMD or a control diet.

DATA SYNTHESIS

Twenty-four studies (with a total of 3013 patients) were included in the meta-analysis; 12 studies included ICU patients, 5 burn patients and 7 trauma patients. Four of the studies used formulas supplemented with arginine, two with arginine and glutamine, nine with arginine and fish oil (FO), two with arginine, glutamine and FO, six with glutamine alone and three studies used a formula supplemented with FO alone. Overall IMD's had no effect on mortality or LOS, but reduced the number of infections (OR 0.63; 95% CI 0.47-0.86, P = 0.004, I(2) = 49%). Mortality, infections and LOS were significantly lower only in the ICU patients receiving the FO IMD (OR 0.42, 95% CI 0.26-0.68; OR 0.45, 95% CI 0.25-0.79 and WMD -6.28 days, 95% CI -9.92 to -2.64, respectively).

CONCLUSIONS

An IMD supplemented with FO improved the outcome of medical ICU patients (with SIRS/sepsis/ARDS). IMDs supplemented with arginine with/without additional glutamine or FO do not appear to offer an advantage over standard enteral formulas in ICU, trauma and burn patients.

Immunonutrition in critically ill patients: a systematic review and analysis of the literature

BACKGROUND

The role of immuno-modulating diets (IMDs) in critically ill patients is controversial.

OBJECTIVE

The goal of this meta-analysis was to determine the impact of IMD's on hospital mortality, nosocomial infections and length of stay (LOS) in critically ill patients. Outcome was stratified according to type of IMD and patient setting.

DATA SOURCES

MEDLINE, Embase, Cochrane Register of Controlled Trials.

STUDY SELECTION

RCT's that compared the outcome of critically ill patients randomized to an IMD or a control diet.

DATA SYNTHESIS

Twenty-four studies (with a total of 3013 patients) were included in the meta-analysis; 12 studies included ICU patients, 5 burn patients and 7 trauma patients. Four of the studies used formulas supplemented with arginine, two with arginine and glutamine, nine with arginine and fish oil (FO), two with arginine, glutamine and FO, six with glutamine alone and three studies used a formula supplemented with FO alone. Overall IMD's had no effect on mortality or LOS, but reduced the number of infections (OR 0.63; 95% CI 0.47-0.86, P = 0.004, I(2) = 49%). Mortality, infections and LOS were significantly lower only in the ICU patients receiving the FO IMD (OR 0.42, 95% CI 0.26-0.68; OR 0.45, 95% CI 0.25-0.79 and WMD -6.28 days, 95% CI -9.92 to -2.64, respectively).

CONCLUSIONS

An IMD supplemented with FO improved the outcome of medical ICU patients (with SIRS/sepsis/ARDS). IMDs supplemented with arginine with/without additional glutamine or FO do not appear to offer an advantage over standard enteral formulas in ICU, trauma and burn patients.

Gut luminal lactate measured by microdialysis mirrors permeability of the intestinal mucosa after ischemia

The aim of the present study was to investigate the influence of a prolonged initial intestinal ischemic insult on transmucosal permeability after a subsequent ischemic event and whether microdialysis of biomarkers released to the gut lumen is able to reflect changes in intestinal permeability. The superior mesenteric artery was cross-clamped for 60 min followed by 4 h of reperfusion in 16 pigs. Nine pigs had a second cross-clamp of 60 min and 3 h of reperfusion, whereas seven pigs were observed for a further 4 h of reperfusion. Intestinal mucosal integrity was assessed by permeability of C-polyethylene glycol (PEG-4000) over the gut mucosa, luminal microdialysis of lactate, glucose and glycerol, and tonometry. During reperfusion, the PEG-4000 amount in venous blood was two times higher after the first than after the second ischemia (area under the curve, 44,780 [13,441-82,723] vs. 22,298 (12,213-49,698] counts min mL(-1), P=0.026 [mean {range}]). There was less lactate detected in the gut lumen after the second ischemia compared with the first (area under the curve, 797 [412-1,700] vs. 1,151 [880-1,969] mmol min L(-1), P=0.02) and a lower maximum concentration (4.8 [2.7-9.4] vs. 8.5 [5.0-14.9] mM, P=0.01). The same pattern was also seen for luminal glycerol and glucose. During the second ischemia, the intestinal mucosal/arterial CO2 gap was identical to the level during the first ischemic episode. A prolonged ischemic insult of the intestine confers protection, for reduced hyperpermeability against further ischemia. Microdialysis of biomarkers mirrors permeability changes associated with this type of protection. Lactate reflects permeability across the intestinal mucosa more precisely than glycerol.

Bacterial metabolism and health-related effects of galacto-oligosaccharides and other prebiotics

Most studies involving prebiotic oligosaccharides have been carried out using inulin and its fructo-oligosaccharide (FOS) derivatives, together with various forms of galacto-oligosaccharides (GOS). Although many intestinal bacteria are able to grow on these carbohydrates, most investigations have demonstrated that the growth of bifidobacteria, and to a lesser degree lactobacilli, is particularly favoured. Because of their safety, stability, organoleptic properties, resistance to digestion in the upper bowel and fermentability in the colon, as well as their abilities to promote the growth of beneficial bacteria in the gut, these prebiotics are being increasingly incorporated into the Western diet. Inulin-derived oligosaccharides and GOS are mildly laxative, but can result in flatulence and osmotic diarrhoea if taken in large amounts. However, their effects on large bowel habit are relatively minor. Although the literature dealing with the health significance of prebiotics is not as extensive as that concerning probiotics, considerable evidence has accrued showing that consumption of GOS and FOS can have significant health benefits, particularly in relation to their putative anti-cancer properties, influence on mineral absorption, lipid metabolism, and anti-inflammatory and other immune effects such as atopic disease. In many instances, prebiotics seem to be more effective when used as part of a synbiotic combination.

Metabolic effects of enteral versus parenteral alanyl-glutamine dipeptide administration in critically ill patients receiving enteral feeding: a pilot study

BACKGROUND

Glutamine (Gln) may become conditionally indispensable during critical illness. The short-term metabolic effects of enteral versus parenteral Gln supplementation are unknown in this clinical setting.

OBJECTIVES

We studied metabolic effects of intravenous (i.v.) alanyl-Gln dipeptide (AG) supplementation and enteral (e.n.) AG supplementation on plasma Gln concentration, antioxidant status, plasma lymphocyte subset number, gut permeability and nitrogen balance in adult critically ill patients requiring tube feeding compared to a control group not receiving Gln supplementation.

METHODS

In a double-blind, pilot clinical trial, 44 medical and surgical ICU patients received identical Gln-free tube feedings 24 h/day and were randomized to either isonitrogenous control (n=15), e.n. AG (n=15) or i.v. AG (n=14) groups (AG). Twelve patients were discontinued from the study. The goal AG dose was 0.5 g/kg/day. Biochemical and metabolic endpoints were measured at baseline and on day 9 (plasma Gln, antioxidant indices, lymphocyte subsets; serum IGF-1 and IGF-binding protein-3; intestinal permeability). Nitrogen balance was determined between study days 6 and 8.

RESULTS

Illness severity indices, clinical demographics, enteral energy and nitrogen intake and major biochemical indices were similar between groups during study. Plasma Gln was higher in the i.v. AG (565+/-119 microM, mean+/-SEM) vs the e.n. AG (411+/-27 microM) group by day 9 (p=0.039); however, subjects in the i.v. AG group received a higher dose of AG (i.v. AG 0.50 versus e.n. AG 0.32+/-0.02 g/kg/day; p<0.001). E.n. AG subjects showed a significant increase in plasma alpha-tocopherol levels over time and maintained plasma gamma-tocopherol concentrations. There were no differences between groups for plasma concentrations of vitamin C, glutathione, malondialdehyde (MDA), T-lymphocyte subsets, intestinal permeability or nitrogen balance.

CONCLUSIONS

This study showed that alanyl-Gln administration by enteral or parenteral routes did not appear to affect antioxidant capacity or oxidative stress markers, T-lymphocyte subset (CD-3, CD-4, CD-8) number, gut barrier function or whole-body protein metabolism compared to unsupplemented ICU patients requiring enteral tube feeding. Enteral Gln appeared to maintain plasma tocopherol levels in this pilot metabolic study.

Pathological changes in the gastrointestinal tract of a heavily radiation-exposed worker at the Tokai-mura criticality accident

Gastrointestinal syndrome after high-dose acute radiation whole body exposure is difficult to treat, although it is a well-known complication. In this report, we describe the clinical and pathological features of a patient who died after the criticality accident which occurred in Japan on 30 September 1999. The patient was estimated to have been exposed to 16-25 Gy equivalent of gamma ray, and died of multiple organ failure after acute radiation syndrome, especially gastrointestinal syndrome, on day 82. The stomach and small intestine contained a large amount of blood clots and the gastrointestinal epithelial cells were almost totally depleted at autopsy. In addition, the degree of the mucosal damage was dependent on the segment of the gastrointestinal tract; the mucosa of stomach, ileum and ascending colon was entirely depleted, but the esophagus, descending and sigmoid colon and rectum retained a small portion of the epithelial cells. From the posture of the patient at the time of exposure, the absorbed dose was presumed to be highest in the right-anterior abdomen. This agreed with the pathological differences in the mucosal damage by the position in the abdomen, which depended presumably on the radiation dose. This is the first report documenting the relationship between the absorbed dose and the severity of gastrointestinal damages in vivo.

Detectable serum flagellin and lipopolysaccharide and upregulated anti-flagellin and lipopolysaccharide immunoglobulins in human short bowel syndrome

Gut barrier dysfunction may occur in short bowel syndrome (SBS). We hypothesized that systemic exposure to flagellin and lipopolysaccharide (LPS) in SBS might regulate specific immune responses. We analyzed serial serum samples obtained from parenteral nutrition (PN)-dependent patients with SBS versus non-SBS control serum. Serum from 23 adult SBS patients was obtained at baseline and 4, 8, 12, 16, 20, and 24 wk in a trial of modified diet with or without growth hormone. Control serum was obtained from 48 healthy adults and 37 adults requiring PN during critical illness. Serum flagellin was detected by an ELISA recognizing an array of gram-negative flagellins, and LPS was detected by limulus assay. Serum flagellin- and LPS-specific immunoglobulin levels (IgM, IgA, and IgG) were determined by ELISA. Serum flagellin and LPS were undetectable in control subjects. In contrast, serum flagellin, LPS, or both were detected in 14 SBS patients (61%) during one or more time points [flagellin alone, 5/23 (22%); LPS alone, 6/23 (26%); or flagellin + LPS, 3/23 (13%)]. Flagellin-specific serum IgM, IgA, and IgG levels were markedly increased in SBS patients compared with both control populations and remained elevated during the 6-mo study period. LPS-specific IgA was significantly higher in SBS patients compared with healthy controls; LPS-specific IgM, IgA, and IgG levels each decreased over time in association with PN weaning. We conclude that adults with PN-dependent SBS are systemically exposed to flagellin and LPS, presumably from the gut lumen. This likely regulates innate and adaptive immune responses to these specific bacterial products.

Standardized concept for the treatment of gastrointestinal dysmotility in critically ill patients--current status and future options

Inhibition of gastrointestinal motility is a major problem in critically ill patients. Motor stasis gives rise to subsequent complications including intolerance to enteral feeding, enhanced permeability of the atrophic intestinal mucosa and conditions as severe as systemic inflammatory response syndrome, sepsis and multiple organ failure. Although the diagnosis of motility disturbances in critically ill patients is difficult, the type and site of the disturbance are important to consider in the analysis of the condition and in the choice of therapeutic approach. The pharmacological treatment of impaired gastrointestinal motility is difficult to handle for the clinician, because the underlying mechanisms are complex and not fully understood and the availability of pharmacological treatment options is limited. In addition, there is a lack of controlled studies on which to build an evidence-based treatment concept for critically ill patients. Notwithstanding this situation, there has been remarkable progress in the understanding of the integrated regulation of gastrointestinal motility in health and disease. These advances, which largely relate to the organization of the enteric nervous system and its signaling mechanisms, enable the intensivist to develop a standardized concept for the use of prokinetic agents in the treatment of impaired gastrointestinal motility in critically ill patients.

Decisions to be made when initiating enteral nutrition

Enteral nutrition support is preferred to parenteral or no nutritional support, but many patients who could benefit receive inadequate enteral feeding. Many decisions must be made before initiating enteral nutrition support; including if and when enteral nutrition should be started, which formula should be used, and how enteral nutrition support should be monitored. The gastroenterologist should be able to understand and evaluate these decisions in all patients potentially requiring nutritional support.

Beneficial effect of enteral feeding

The last 4 decades have seen an explosion in nutritional research investigating both clinical and laboratory issues occurring in diverse groups of patients who cannot maintain a normal oral diet. Over the past 25 years, researchers have investigated how the administration of macro- and micronutrients via the gastrointestinal tract provides additional benefit over parenteral administration of similar nutrients. The administration of enteral feeding provides effects that are far beyond those of merely administering macro- and micronutrients. Rather, the processing of nutrients via the gastrointestinal tract stimulates a complex response that has implications for body composition and for immunologic integrity. Route and type of nutrition are important aspects of successful patient recovery.

Bacterial translocation: overview of mechanisms and clinical impact

Bacterial translocation (BT) is a phenomenon in which live bacteria or its products cross the intestinal barrier. Gut translocation of bacteria has been shown in both animal and human studies. BT and its complications have been shown clearly to occur in animal models, but its existence and importance in humans has been difficult to ascertain. We review the mechanisms of BT and its clinical impact based on the current literature.

The effect of glutamine-enriched enteral nutrition on intestinal permeability in very-low-birth-weight infants: a randomized controlled trial

BACKGROUND

Very-low-birth-weight (VLBW) infants are susceptible to glutamine depletion. Glutamine depletion has negative effects on intestinal integrity. The lower infection rate in VLBW infants receiving glutamine-enriched enteral nutrition may originate from improved intestinal integrity, as reflected by decreased intestinal permeability. The aim of our study was to investigate whether glutamine-enriched enteral nutrition in VLBW infants enhances the normal decrease in intestinal permeability, as measured by the sugar absorption test (SAT).

METHODS

In a double-blind, randomized, placebo-controlled trial, VLBW infants (gestational age <32 weeks or birth weight <1,500 g) received enteral glutamine supplementation (0.3 g/kg/d) or an isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Intestinal permeability, determined from the urinary lactulose/mannitol (L/M) ratio after an oral dose of lactulose and mannitol, was assessed at 4 time points: before the start of the study, and at days 7, 14, and 30 of life.

RESULTS

At least 2 SATs were performed in 45/52 (86%) and 45/50 (90%) infants in the glutamine-supplemented and control groups, respectively. Baseline patient and nutrition characteristics were not different between the groups. There was no effect of glutamine-enriched enteral nutrition on the decrease of the L/M ratio between the start and end of the study (p = .78). In both treatment groups, median urinary lactulose concentrations decreased (p < .001), whereas median urinary mannitol concentrations increased (p = .003).

CONCLUSIONS

Glutamine-enriched enteral nutrition does not enhance the postnatal decrease in intestinal permeability in VLBW infants. Any beneficial effect of glutamine may involve other aspects of intestinal integrity; for example, modulation of the intestinal inflammatory response.

Critical care nutrition: getting involved as a gastrointestinal endoscopist

The route, timing, and volume of enteral feeding delivered to a patient in the intensive care unit have a profound effect on clinical outcome. At the height of critical illness, problems with ileus, aspiration, and the systemic inflammatory response syndrome make the provision of enteral nutrients a difficult and somewhat risky endeavor. The gastrointestinal endoscopist has the technical skills to place feeding tubes deep within the jejunum and an underlying expertise in gut physiology to monitor patients effectively once feeds are initiated. Attention to detail in the techniques for attaining enteral access, early identification of potential problems, and quick institution of simple endoscopic strategies help improve delivery of nutrition support, minimize the likelihood for in-hospital complications, and optimize patient outcome.

Effects of garlic oil and two of its major organosulfur compounds, diallyl disulfide and diallyl trisulfide, on intestinal damage in rats injected with endotoxin

Garlic and its active components are known to possess antioxidant and antiinflammatory effects. The present study investigated the effects of garlic oil and its organosulfur compounds on endotoxin-induced intestinal mucosal damage. Wistar rats received by gavage 50 or 200 mg/kg body weight garlic oil (GO), 0.5 mmol/kg body weight diallyl disulfide or diallyl trisulfide, or the vehicle (corn oil; 2 ml/kg body weight) every other day for 2 weeks before being injected with endotoxin (i.p., 5 mg/kg body weight). Control rats were administered with corn oil and were injected with sterile saline. Samples for the measurement of proinflammatory cytokines were collected 3 h after injection, and all other samples were collected 18 h after injection. The low dose of GO suppressed endotoxin-induced inducible nitric oxide synthase (iNOS) activity, ulceration, and apoptosis in the intestinal mucosa (P < 0.05). The high dose of GO significantly lowered the peripheral level of nitrate/nitrite and endotoxin-induced iNOS activity in the intestinal mucosa (P < 0.05) but worsened intestinal mucosal damage accompanied by elevated peripheral proinflammatory cytokines. Diallyl trisulfide but not diallyl disulfide showed similar toxic effect as that of high-dose GO. These results suggest the preventive effect and possible toxicity of garlic oil and its organosulfur compounds in endotoxin-induced systemic inflammation and intestinal damage.

Burns, bacterial translocation, gut barrier function, and failure

The development of systemic inflammation, acute lung injury, and multiple organ failure after a major thermal injury, as well as nonthermal forms of trauma, remain relatively common causes of morbidity and mortality. During the past two decades, increasing recognition that the ischemic gut may contribute to the development of sepsis and organ failure in burn patients, as well as other critically ill patient populations, has led to new hypotheses to explain burn-induced multiple organ failure as well as highlighted the importance of early enteral nutrition. Thus, the goal of this review will be to provide a perspective on the evolution of the gut hypothesis of systemic inflammation and distant organ dysfunction.

Burn Injury Exacerbates Hemodynamic and Metabolic Responses in Rats with Polymicrobial Sepsis

The most common and life-threatening complication of severe burn injury is infection, which often results in multiple organ failure (MOF). However, the mechanism of development of MOF after burn injury associated with infection is not fully understood. Our previous studies showed that when polymorphonuclear neutrophils (PMNs) are depleted, burn injury-induced increase in microvascular permeability to albumin is markedly attenuated. Thus, we hypothesized that the combination of burn injury and polymicrobial infection exacerbates PMN activation, increases intestinal microvascular permeability to albumin, and alters hemodynamics and metabolism more than burn injury or infection alone. Sprague-Dawley rats (250-275 g) were divided into four groups. In the burn group, rats were subjected to a 30% TBSA burn injury. In the cecal-ligation puncture (CLP) group, CLP was performed using a 22-gauge needle with one puncture. In burn+CLP group, rats were subjected to CLP immediately after burn procedure. In sham group, rats were subjected to sham procedures. Transient polymicrobial bacteremia and persistent polymicrobial bacteremia were induced in the CLP group and burn+CLP group, respectively. Microvascular permeability, myeloperoxidase, and PMN production of elastase and reactive oxygen species increased in the burn group and CLP group and further increased in the burn+CLP group. Hemodunamic and metabolic alterations on day 1 and 3 after injury correlated with those alterations. Although there was only a low mortality in the burn group and CLP group, there was a high mortality in burn+CLP group (79%). The mechanism of MOF that leads to high mortality in burn injury complicated by infection may involve uncontrolled microvascular damage mediated by PMN activation.

Intestinal permeability is increased in burn patients shortly after injury

There is increasing direct experimental and indirect clinical evidence to indicate that under certain conditions intestinal barrier function may be lost in trauma victims. No direct measurements, however, have been performed in patients to determine whether intestinal permeability is increased shortly after a major thermal injury in the absence of infection. Fifteen hemodynamically stable burn patients with burns on more than 20% of their body surface (39% ± 12%) had their intestinal permeability measured within 24 hours of injury with use of the two nonmetabolizable sugars lactulose and manmtol as permeability markers. Lactulose absorption was fourfold higher in the patients (223 ± 54 μmol) than in the controls (58 ± 77 μmole;p &lt; 0.02), whereas the lactulose/manmtol ratio was threefold higher (5.2 vs 1.7; p &lt; 0.05). Thus intestinal permeability was increased in patients with moderate to major burn injuries shortly after injury. (Surgery 1990;107:411-6).

Prebiotic ingestion does not improve gastrointestinal barrier function in burn patients

Prebiotics increase intestinal levels of health-promoting bacteria implicated in decreasing pathogen colonization, stimulating immune functions and stabilizing gut barrier functions, parameters which are altered in burn patients. We propose that regular intake of a prebiotic, oligofructose (OF), might help to improve the altered gastrointestinal (GI) permeability observed in burn patients. A randomized, double-blind, controlled clinical trial was carried out in 41 burn patients (mean burn surface area=17.1+/-8.2%) who ingested daily 6 g of oligofructose (OF group) or sucrose as placebo (Control group) during 15 days. Gastrointestinal permeability to sucrose and lactulose/mannitol (L/M) was evaluated on days 1 (before treatment) 3, 7, 14 and 21. A permeability test was also performed in 18 healthy subjects as controls. Thirty-one patients completed the protocol (dropout rate=24.4%). Healthy subjects had a basal sucrose excretion of 21.3 mg (14.0-32.5 mg) and a basal L/M ratio of 0.017% (0.009-0.022%). Sucrose excretion increased 5-fold and L/M ratio 4.4-fold in burn patients on day 1 and these high levels of marker excretion decreased significantly throughout the study (p=0.016 and 0.000001, respectively). No differences between the OF and Control groups were observed for sucrose excretion or L/M ratio. In conclusion, the normalization of gastrointestinal permeability is not accelerated by prebiotic intake.

Intestinal permeability and systemic infections in critically ill patients: effect of glutamine

OBJECTIVE

This article provides a critical review of the evidence indicating that an increase in intestinal permeability is associated with the installation of bacteremia, sepsis, and the multiple organ failure syndrome and that glutamine in pharmacologic doses reduces the acute increase of intestinal permeability and the infection frequency in critically ill patients.

DATA SOURCE

All studies published until December 2004 about intestinal permeability, bacterial translocation, and glutamine were located by search of PubMed and Web of Science. The reference lists of review articles and primary publications were also examined to identify references not detected in the computer search.

STUDY SELECTION

Clinical and experimental studies investigating the correlation between intestinal permeability, bacterial translocation, and frequency of infections, associated or not with the effect of glutamine administration.

DATA EXTRACTION

Information regarding patient population, experimental design, glutamine doses and routes of administration, nutritional therapy prescribed, methods used to assess intestinal permeability, metabolic variables, and the frequency of infections were obtained from the primary literature.

DATA SYNTHESIS

Intestinal permeability is increased in critically ill patients. The results have not always been consistent, but the studies whose results support the association between intestinal permeability and systemic infections have had better design and more appropriate controls. The administration of glutamine by the intravenous or oral route and at the doses recommended before or immediately after surgery, burns, or the administration of parenteral nutrition has a protective effect that prevents or reduces the intensity of the increase in intestinal permeability. Glutamine reduces the frequency of systemic infections and may also reduce the translocation of intestinal bacteria and toxins, but this has not been demonstrated.

CONCLUSIONS

Glutamine administration improves the prognosis of critically ill patients presumably by maintaining the physiologic intestinal barrier and by reducing the frequency of infections.

Sepsis in pediatric burn patients

OBJECTIVE

To review the specific infections common in pediatric burns, including their categorization, diagnosis, and treatment.

DESIGN

Review of the literature and expert opinion.

RESULTS

Children with serious burns are prone to a host of septic complications. This proclivity to infection is secondary to the immunosuppressive effect of burn injury, the loss of the skin and mucosal physical barriers, and the requirement for invasive support devices.

CONCLUSION

Sepsis is common in the pediatric burn patient and can markedly increase morbidity and mortality. Anticipation, prompt diagnosis of infection, and effective therapy can result in successful outcomes for many of these children.

Exacerbation of intestinal permeability in rats after a two-hit injury: burn and Enterococcus faecalis infection

OBJECTIVE

To determine alterations in intestinal epithelial permeability to solutes in burn injured rats with and without Enterococcus faecalis infection and the role of neutrophils in the intestinal permeability changes.

DESIGN

Prospective sham-controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Rats were subjected to 30% total body surface burn (B group), E. faecalis infection (EF group) induced via intra-abdominal implantation of bacterial pellet, or combination of burn injury and E. faecalis infection (B+EF group).

MEASUREMENTS AND MAIN RESULTS

In vivo measurements of intestinal permeability were carried out after intraluminal injection of H lactulose and C mannitol in the ileum of sham, B, EF, and B+EF groups of rats, 1 and 2 days after injury. Lactulose permeability was increased in the injured rat groups (B, EF, B+EF) on day 1 postinjury compared with sham. The combined injury group (B+EF) had the highest level of lactulose permeability. Although a significant change in lactulose permeability from day 1 to day 2 postinjury could not be demonstrated in the B and EF groups, lactulose permeability in the B+EF group on day 2 postinjury markedly decreased from day 1 but was still significantly higher than that in the sham group. Mannitol permeability was increased in all injured rat groups on day 1 postinjury; on day 2 it remained elevated post-B, decreased post-EF, and further increased after B+EF. Ex vivo measurements of lactulose movements across intestinal epithelial monolayers (IEC-18) were carried out in the presence of blood neutrophils from sham, B, EF, or B+EF rats. We also measured ex vivo transepithelial migration of neutrophils from sham, B, EF, or B+EF rat groups. Neither the transepithelial lactulose movement in the presence of neutrophils from, nor neutrophil migration in, the B or EF rats was significantly different from sham. However, a significant increase in transepithelial lactulose movement and neutrophil migration occurred in the B+EF group. Immunoblot analyses and in situ histochemical localizations of intestinal tight junction proteins, occludin and claudin-3, showed decreases in the distribution of occludin but not claudin-3 in the B, EF, and B+EF groups.

CONCLUSIONS

Alterations in intestinal solute permeability and disruption of tight junction integrity after a two-hit injury with burn and E. faecalis infection, but not after individual injuries of burn or E. faecalis infection, are likely associated with heightened neutrophil flux across the intestinal epithelium.

Selective decontamination of the digestive tract attenuated the myocardial inflammation and dysfunction that occur with burn injury

This study examined the effects of oral antibiotics to selectively decontaminate the digestive tract (SDD) on postburn myocardial signaling, inflammation, and function. We hypothesized that antibiotic therapy to eliminate pathogens from the gastrointestinal (GI) tract would reduce myocardial inflammatory responses and improve postburn myocardial performance. Sprague-Dawley rats received polymyxin E (15 mg), tobramycin (6 mg), and 5-flucytosin (100 mg) by oral gavage twice daily for 3 days preburn and 24 h postburn. Experimental groups included 1) sham burn given vehicle (3 ml water), 2) sham plus SDD, 3) burn over 40% total body surface area (TBSA) plus SDD, and 4) burn over 40% TBSA given vehicle. All burns received lactated Ringer solution (4 mg·kg−1·%burn−1); myocardial signaling (PKCε/p38 MAPK/NF-κB) was studied 2, 4, and 24 h postburn; and cytokine secretion (systemic and myocyte secreted cytokines, ELISA) and cardiac function were examined 24 h postburn. Vehicle-treated burn injury increased myocardial PKCε/p38 MAPK expression, promoted NF-κB nuclear translocation, promoted TNF-α, IL-1β, IL-6, and IL-10 secretion, and impaired myocardial function. SDD attenuated burn-related proinflammatory myocardial signaling, cytokine secretion, and myocardial contractile defects. Our data suggest that burn-related loss of GI barrier function and translocation of microbial products serve as upstream mediators of postburn myocardial inflammatory signaling and dysfunction.

The effects of thermal injury on transcellular permeability and intestinal P-glycoprotein in rats

This study was designed to assess intestinal drug transport via transcellular absorption and intestinal P-glycoprotein content following thermal injury in rats using propranolol as a marker substrate. Male, Sprague Dawley rats (n=30) underwent either a 30% total body surface area full thickness burn or sham treatment. Twenty-four hours later, animals were anesthetized, underwent laparotomy and the proximal jejunum was cannulated. The jejunal segment was perfused with buffer containing [3H] propranolol. Following euthanasia, jejunal tissue was harvested for Western immunoblotting of P-glycoprotein and villin, and immunohistochemical analysis of P-glycoprotein. Dramatic structural changes in jejunal integrity were observed following thermal injury; however, no significant differences in the absorption characteristics of propranolol following thermal injury were observed. Mean effective permeability of propranolol was 5.67+/-1.79 and 5.85+/-1.67cm/sx10(-5) for burn and sham groups, respectively (P>0.05). P-glycoprotein and villin content in the jejunum were significantly decreased in burn animals. The transcellular transport of propranolol is unaffected 24h following thermal injury in rats, despite alterations in intestinal P-glycoprotein content. The decrease in P-glycoprotein and villin content in thermally injured animals may reflect loss of mature enterocytes at the villus tips.

Role of intestine in postsurgical complications: involvement of free radicals

Surgery at any location in the body leads to surgical stress response and alterations in normal body homeostasis. The intestine is extremely sensitive to surgical stress even at remote locations and the gastrointestinal tract plays an important role in the development of postsurgical complications such as sepsis, the systemic immune response syndrome (SIRS), and multiple organ failure syndrome (MOFS). The generation of free radicals and subsequent biochemical alterations at the cellular and subcellular level in the intestine has been suggested to play an important role in this process. These oxidative stress-induced events in the mucosa might act as an initiator of distant organ damage and also facilitate bacterial adherence onto the epithelium and translocation into the systemic circulation. This review attempts to highlight the important role of intestine and oxygen free radicals in initiating post-surgical complications.

Selective jejunal manipulation causes postoperative pan-enteric inflammation and dysmotility

BACKGROUND AND AIMS

Small bowel manipulation initiates an intense molecular and cellular inflammatory response within the jejunal muscularis, which causes ileus. The current objective was to investigate pan-enteric inflammatory molecular and functional motility alterations of the muscularis from the unmanipulated stomach and colon initiated by selective jejunal manipulation.

METHODS

Rat jejunum was manipulated, and animals sacrificed between 0-24 hours. In vivo gastric emptying, gastrointestinal transit, and in vitro colonic circular muscle recordings were measured. Reverse-transcriptase polymerase chain reaction (RT-PCR) and electromobility shift assay (EMSA) of gastric, jejunal, and colonic muscularis extracts were performed. Whole mounts were histochemically stained for myeloperoxidase leukocytes.

RESULTS

Surgical manipulation suppressed jejunal contractions that were significantly prevented by dexamethasone pretreatment. Selective jejunal manipulation also suppressed in vivo gastric emptying, gastrointestinal transit, and in vitro colonic circular muscle contractility. Nuclear factor interleukin-6 (NF-IL-6) was activated within the gastric and colonic muscularis. RT-PCR showed a 14.9-, 8.1-, and 11.4-fold up-regulation of IL-6 messenger RNA within the jejunal, gastric, and colonic muscularis, respectively. EMSA showed a 30.6-, 14.2-, and 20.8-fold increased activation of signal transducer and activator of transcription (STAT) proteins in jejunal, gastric, and colonic muscularis extracts, respectively. Tumor necrosis factor-alpha, cyclooxygenase-2, and inducible nitric oxide synthase showed a significant up-regulation in the manipulated jejunum, as well as the unmanipulated gastric and colonic muscularis. Neutrophils were significantly recruited into all gastrointestinal regions.

CONCLUSION

Selective small bowel manipulation leads to a molecular, cellular, and functional pan-enteric "field effect" phenomenon in the unmanipulated gastric and colonic muscularis.

Increased plasma D-lactate is associated with the severity of hemorrhagic/traumatic shock in rats

D-lactate is produced by indigenous bacteria in the gastrointestinal tract. Mammals do not have the enzyme systems to metabolize D-lactate rapidly. The present study was designed to determine the kinetics of circulating D-lactate levels and to examine whether the severity of shock affects circulating D-lactate levels in rats subjected to hemorrhagic/traumatic shock. Anesthetized rats underwent midline laparotomy (duration 30 min) and were bled to 30-35 mmHg mean arterial pressure (MAP). After the onset of decompensation, MAP was either increased to 40-45 mmHg immediately by administration of Ringer's solution (moderate shock) or after 40% of shed blood volume had been re-infused as Ringer's solution (severe shock). MAP was then maintained at 40-45 mmHg for 40 min by further administration of Ringer's solution (inadequate resuscitation). Subsequently, adequate resuscitation was performed for 60 min with shed blood and additional Ringer's solution. Metabolic acidosis was significantly more pronounced in severe than in moderate hemorrhagic/traumatic shock. Plasma D-lactate levels were already significantly increased at the end of severe hemorrhagic/traumatic shock and remained high during inadequate resuscitation. D-lactate levels were significantly higher after severe than after moderate shock. Endotoxin levels did not correlate with shock severity. Damage to the intestinal mucosa was more profound in severe shock than in moderate shock. Our data suggest that hemorrhagic/traumatic shock is associated with mucosal damage and increased plasma D-lactate levels. The severity of shock affects D-lactate concentrations in plasma. Plasma D-lactate may be a useful marker of intestinal injury after hemorrhagic/traumatic shock.

Effects of acid stress in adult Rana pipiens

The decline in frog populations is a well-recognized worldwide phenomenon and infectious disease has been implicated as a major cause in the global decline of amphibian populations. Rana pipiens are disappearing from many habitats where they used to flourish, and environmental acidification has been considered as a possible contributor to this disappearance. We present a model that integrates the results of several experiments on the effects of acid exposure on natural resistance and mortality of adult Rana pipiens. These studies suggest that different components of the natural defense mechanisms of these frogs have different acid sensitivities. We have shown previously that exposure to pH 5.5 leads to a reduction in splenic white blood cell number, viability, and to colonization of the spleen with both Gram positive and Gram negative bacteria. In this paper we show that exposure to pH 6.0 did not affect the number or viability of splenic white blood cells but did result in colonization of the spleen by bacteria. We also show that cold exposure by itself does not cause a systemic bacterial infection in adult Rana pipiens, but acid stress following cold exposure does. The data presented in this paper provide empirical evidence to support the hypothesis that acid stress may be a contributor to the decline of Rana pipiens in the northeastern region of the United States.

Intestinal epithelial hyperpermeability: update on the pathogenesis of gut mucosal barrier dysfunction in critical illness

PURPOSE OF REVIEW

Tight junctions between adjacent epithelial cells are essential for the maintenance of compositionally distinct fluid compartments in various organs, such as the liver, lungs, kidneys, and intestine. These epithelial organs are commonly affected in the condition known as multiple organ dysfunction syndrome, which can complicate the clinical course of patients with sepsis or other conditions associated with poorly controlled systemic inflammation. The gut serves as a useful model for this problem, and studies using reductionist in vitro models and experiments carried out using laboratory animals are starting to clarify the cellular and biochemical mechanisms that are responsible for intestinal epithelial hyperpermeability secondary to critical illness.

RECENT FINDINGS

One key factor that has been identified is excessive production of nitric oxide and related species, although other factors, such as increased expression of the cytokine interleukin 6, appear to be important as well. A newly described, cytokine-like molecule, high-mobility group B1, increases permeability of cultured epithelial monolayers in vitro and murine ileal mucosa in vivo.

SUMMARY

Epithelial dysfunction may be a common final pathway contributing to organ dysfunction in sepsis and other forms of critical illness.

Effects of interleukin-1alpha administration on intestinal ischemia and reperfusion injury, mucosal permeability, and bacterial translocation in burn and sepsis

OBJECTIVE

To evaluate the effect of interleukin-1alpha (IL-1alpha) on the mesenteric circulation, intestinal mucosal integrity, and bacterial translocation in a burn/endotoxemia chronic porcine model.

SUMMARY BACKGROUND DATA

Major burn and sepsis are associated with a high mortality, ischemia/reperfusion injury to the intestine, and an increased rate of bacterial translocation. Pathologic alterations of IL-1 synthesis, degradation, and binding to receptors have been reported. Manipulation of IL-1-mediated effects might be of therapeutic utility.

METHODS

Twenty-one female pigs were instrumented with an ultrasonic flow probe on the superior mesenteric artery and a catheter into the superior mesenteric vein. After 5 days, all animals were anesthetized, and 14 received 40% total body surface area third-degree burn. IL-1alpha was administered intravenously at 1,000 ng/kg to seven pigs immediately after burn. Eighteen hours after burn, 100 microg/kg lipopolysaccharide (LPS) was administered intravenously. Systemic and splanchnic hemodynamics were measured and blood samples were drawn for blood gas analysis. Intestinal permeability was assessed every 6 hours by measuring the lactulose/mannitol (L/M) excretion ratio. At the end of the study (42 hours), tissue samples were harvested for bacteriologic cultures.

RESULTS

Mesenteric blood flow was significantly decreased after burn and endotoxin. Administration of IL-1alpha significantly improved mesenteric blood flow postburn and post-LPS. Mesenteric oxygen supply and consumption showed a significant reduction after burn. In contrast, animals treated with IL-1alpha showed an increase in postburn mesenteric oxygen supply and consumption. LPS-induced mesenteric hypoxia was also ameliorated by IL-1alpha treatment. Intestinal permeability, as assessed by the L/M ratio, showed a 7- and 10-fold elevation after thermal injury and LPS, respectively. In contrast, IL-1alpha-treated animals showed an increase of only three- and fourfold in the L/M ratio, respectively. Bacterial translocation was significantly increased in the burn/endotoxin group. IL-1alpha significantly reduced the rates of bacterial translocation.

CONCLUSIONS

IL-1alpha treatment attenuates mesenteric ischemia and reperfusion injury induced by thermal injury and endotoxemia by improving mesenteric blood flow and oxygenation. Subsequently, IL-1alpha reduces intestinal permeability and bacterial translocation after burn and sepsis.

Comparative Study of Flux of FITC-labeled Dextran 4000 on Normal (iso)- and Hyper-osmolarity in Basal Side in Caco-2 Cell Monolayers

We have shown previously that the flux of fluorescein isothiocyanate dextran 4000 (FD-4) is transported across the Caco-2 cell monolayers in a polarized fashion favoring the basal to apical direction under normal conditions (i.e., isotonic solution in basal side). Furthermore, FD-4 transport may occur via a process that included a certain degree of substrate specificity for polysaccharide and transcytosis. In the present study, we compared the flux of FD-4 in the basal to apical direction (efflux) and the apical to basal direction (influx) in stress conditions (i.e., hyperosmolarity in basal side) to those in normal conditions (i.e., iso-osmolarity in basal side). The efflux of FD-4 was increased by hyperosmolarity in basal side, but the influx was decreased when compared with normal conditions. Neither dextran 10, 000 nor colchicine inhibited the efflux of FD-4 in hyperosmolarity conditions. The inhibition of efflux of FD-4 was observed not by S-nitroso-N-acetylpenicillamine but by sodium nitroprusside and sodium ferrocyanide. These results collectively suggest that hyperosmolarity in basal side accelerates the efflux of FD-4 across the transcellular route but not across the paracellular route in Caco-2 cell monolayers. And it is indicated that cyanide rather than nitric oxide is involved in dysfunction of the FD-4 efflux system irrespective of conditions such as normal osmolarity or hyperosmolarity.

Enteral access for nutritional support: rationale for utilization

Acquisition of enteral access and provision of a sufficient volume of enteral nutrients early in the hospital course of a critically ill patient afford an opportunity to improve the outcome of that patient through the progression of his or her disease process. Failure to use the enteral route of feeding not only squanders this opportunity, but may, in addition, promote a pro-inflammatory state, which exacerbates disease severity and worsens morbidity. Enteral feeding provides a conduit for the delivery of immune stimulants and serves as effective prophylaxis against stress-induced gastropathy and gastrointestinal hemorrhage. Tube placement beyond the stomach into the small bowel in hypermetabolic, severely ill patients prone to ileus and disordered gut motility aids delivery of enteral nutrients while reducing risk of aspiration. Endoscopic skills and expertise in gastrointestinal physiology are vital to the success of a nutrition support service and the provision of enteral tube feeding.

HMGB1 B box increases the permeability of Caco-2 enterocytic monolayers and impairs intestinal barrier function in mice

BACKGROUND & AIMS

High mobility group (HMG) B1 is a nonhistone nuclear protein that was recently identified as a late-acting mediator of lipopolysaccharide-induced lethality in mice. The proinflammatory actions of HMGB1 have been localized to a region of the molecule called the B box.

METHODS

To determine whether HMGB1 or B box are capable of causing derangements in intestinal barrier function, we incubated cultured Caco-2 human enterocytic monolayers with recombinant human HMGB1 or a 74-residue truncated form of the protein consisting of the B box domain.

RESULTS

Both HMGB1 and B box increased the permeability of Caco-2 monolayers to fluorescein isothiocyanate-labeled dextran (FD4) in a time- and dose-dependent fashion. The increase in permeability was reversible following removal of the recombinant protein. Exposure of Caco-2 cells to B box resulted in increased expression of inducible nitric oxide synthase messenger RNA and increased production of NO. When we used various pharmacologic strategies to inhibit NO production or scavenge NO or peroxynitrite (ONOO(-)), we abrogated B box-induced hyperpermeability. Administration of B box to wild-type mice increased both ileal mucosal permeability to FD4 and bacterial translocation to mesenteric lymph nodes. These effects were not observed in inducible nitric oxide synthase knockout mice.

CONCLUSIONS

These data support the view that HMGB1 and B box are capable of causing alterations in gut barrier function via a mechanism that depends on the formation of NO and ONOO(-).

Current aspects of mucosal immunology and its influence by nutrition

BACKGROUND

A significant body of clinical literature demonstrates that enteral feeding significantly reduces the incidence of pneumonia compared to patients fed parenterally. An immunologic link between the gastrointestinal tract and respiratory tract is postulated via the common mucosal immune hypothesis. This hypothesis states that cells are sensitized within the Peyer's patches of the small intestine and are subsequently distributed to submucosal locations in both intestinal and extra intestinal sites. This system is exquisitely sensitive to route and type of nutrition.

DATA SOURCE

This review examines the laboratory data regarding cell numbers, cell phenotypes, cytokine profile, and immunologic function in both intestinal and extra intestinal sites in animals that have been administered either parenteral feeding or various types of enteral feeding. It also establishes links between a specific nutrient, glutamine, the enteric nervous system, by way of neuropeptides, and mucosal immunity.

CONCLUSION

Progress in understanding relationships between nutrient availability, enteric nervous system stimulation, and nutrient delivery on mucosal immunity offers opportunities to explore immune systems previously not appreciated by clinicians and basic scientists. These opportunities offer new challenges to the physician scientist, basic scientist, and clinician to understand, manipulate, and apply these concepts to the critically ill patient population by favorably influencing immunologic barriers and the inflammatory response.

Bacterial translocation: effects of artificial feeding

The most striking observation when reviewing recent literature in the field of bacterial translocation in the intestine is the small number of publications involving human subjects. Although there are some excellent reviews in this field published during the last 2 years, all experimental contributions come from animal experiments. It is therefore crucial to evaluate how valid the animal models are for human pathophysiology. Studies focusing on translocation as a major pathogenic mechanism are urgently needed to help clinicians to make correct decisions concerning protection of the gut and decide upon nutrition in the intensive care unit.

Role of nitric oxide in acidosis-induced intestinal injury in anesthetized rats

We investigated the pathogenic mechanism(s) of small intestinal injury during acidosis in relation to circulating nitric oxide (NO) in an experimental rat model. Rats were anesthetized, paralyzed, and mechanically ventilated with room air. Hydrochloric acid (0.16 mmol bolus followed by 0.132 mmol/kg/h) was infused through the jugular vein for 5 hours. Control rats received a saline infusion. Arterial blood gases, blood pressure, and blood pH were measured every 30 minutes. The involvement of NO in this acidosis model was assessed by measuring plasma concentration of nitrite/nitrate (NOx) and by evaluating inducible NO synthase (iNOS) expression in small intestinal mucosa. Intestinal injury was assessed by measuring myeloperoxidase (MPO) activity, thiobarbituric acid reactants (TBARS), and histologic scores. HCl infusion was associated with hypotension, decreased blood pH, increased plasma concentration of NOx, augmented intestinal mucosal iNOS expression, MPO activity, TBARS, and histopathologic injury scores. Pretreatment with an iNOS inhibitor, aminoguanidine (AG, 50 mg/kg), reversed HCl-induced hypotension without a change in blood pH. HCl-induced lesions, MPO activity, TBARS, and plasma NOx production were decreased by AG. Our data show that the pathogenic mechanisms of acidosis-induced small intestinal lesions involve up-regulation of NO production by increased expression of iNOS and augmentation of superoxide radicals and MPO activity.

Role of the gut lymphatic system in multiple organ failure

The central concept of this review is that gut-derived factors contained primarily in the mesenteric lymph rather than the portal blood contribute to distant organ injury. This hypothesis is supported by recent studies indicating that division of the mesenteric lymphatic ducts prevents lung injury after hemorrhagic shock and significantly ameliorates lung injury after thermal injury. The mechanism of hemorrhagic shock-induced lung injury appears to be through mesenteric lymph-induced activation of neutrophils and activation/injury of endothelial cells. This notion is supported by in vitro studies indicating that mesenteric lymph, but not portal vein plasma, collected after a nonlethal episode of hemorrhagic shock activates neutrophils, increases endothelial cell monolayer permeability, and can even cause endothelial cell death. This concept that gut-derived factors contained primarily in the mesenteric lymph rather than the portal system potentiate the development of distant organ (lung) injury, if correct, would help clarify several important issues. First, because the lung is the first organ exposed to mesenteric lymph (i.e., mesenteric lymph enters the subclavian via the thoracic duct), it would help explain the clinical observation of why the lung is generally the first organ to fail in severely injured patients. Second, this gut lymphatic hypothesis would provide new information on the pathophysiology of gut-induced lung injury. Finally, it would help explain the discordant results between experimental and some clinical studies on the role of gut injury and loss of gut barrier function in the development of a systemic inflammatory state and distant organ injury.

Effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients

The aim of the study was to analyse the effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients. A total of 22 patients with severe burns were randomly divided into an early enteral feeding group (EF) and a delayed enteral feeding group (DF). The levels of serum endotoxin and TNF-alpha were dynamically detected in the members of both groups, and two unmetabolized sugars (lactulose and mannitol) were orally administered to these patients 1, 3 and 5 days postburn. Intestinal permeability was evaluated by detecting the concentrations of lactulose and mannitol in the urine and the lactulose-mannitol ratio (L/M) ratio. The levels of serum endotoxin and TNF-alpha in severely burned patients were significantly higher than in normal subjects (P<0.01). The endotoxin level was positively related to the TNF-alpha level (rEF=0.93, P<0.01; rDF=0.80, P<0.05). The urinary lactulose levels in both groups were significantly higher than in normal (P<0.01), the urinary mannitol levels showed no obvious changes (P>0.05). The urinary L/M ratios in both groups were significantly higher than in normal subjects (P<0.01). The urinary L/M ratio was positively related to the serum endotoxin level (r=0.95, P<0.01). The urinary lactulose levels and the urinary L/M ratios in the EF group were significantly lower than in the DF group (P<0.01). The levels of serum endotoxin and TNF-alpha in the EF group were significantly lower than in the DF group (P<0.01). It is suggested that intestinal permeability was markedly higher after burns than normal, and was positively related to the gut-derived endotoxemia. Early enteral feeding may decrease intestinal permeability, preserve the intestinal mucosal barrier and have a beneficial effect on the reduction of enterogenic infection.