Clinical outcome and immunology of postoperative arginine, omega-3 fatty acids, and nucleotide-enriched enteral feeding: a randomized prospective comparison with standard enteral and low calorie/low fat i.v. solutions

Dietary Whey Protein Supplementation Increases Immunoglobulin G Production by Affecting Helper T Cell Populations after Antigen Exposure

Whey protein is a by-product of cheese and casein manufacturing processes. It contains highly bioactive molecules, such as epidermal growth factor, colony-stimulating factor, transforming growth factor-α and -β, insulin-like growth factor, and fibroblast growth factor. Effects of whey protein on immune responses after antigen (hemagglutinin peptide) injection were evaluated in rats. Experimental diets were formulated based on NIH-31M and supplemented with 1% amino acids mixture (CON) or 1% whey protein concentrate (WPC) to generate isocaloric and isonitrogenous diets. Rats were fed the experimental diets for two weeks and then exposed to antigen two times (Days 0 and 14). Blood was collected on Days 0, 7, 14, and 21 for hematological analysis. The WPC group showed decreased IgA and cytotoxic T cells before the antigen injection (Day 0) but increased IgG, IL-2, and IL-4 after antigen injection due to increased B cells and T cells. Helper T cells were increased at Days 14 and 21, but cytotoxic T cells were not affected by WPC. WPC may activate adaptive immunity (IgG) against antigen by modulating helper T cells. Bioactive molecules might contribute to the immune-enhancing effects of whey protein concentrate.

Modulatory Effect of Dietary Polyunsaturated Fatty Acids on Immunity, Represented by Phagocytic Activity

Lately, dietary polyunsaturated fatty acids (PUFAs) have shown substantial importance in human and animal nutrition, especially those of the n-3 group. Development and optimal functioning of the immune system are directed affected by diet. These dietary fatty acids have an important impact on the health and immune competence of various species including human beings. They are essential for the modulation of immune responses in health and disease. Fatty acid composition of immune cells can be modulated by the action of dietary fats and the outcomes in the composition can produce functional effects on reactivity and functioning of immune cells in a short period. There are several mechanisms involved in impacting dietary fatty acids on immune function; however, lipid mediator synthesis from PUFAs is of great importance in terms of inflammation. The objectives of this article are reviewing studies on the impact of PUFA in the diet on phagocytosis of chickens, murine, rats, ruminants, and humans. It also sheds light on the possible mechanism by which this immunomodulation occurs.

Immunonutrition vs Standard Nutrition for Cancer Patients: A Systematic Review and Meta-Analysis (Part 1)

The aim of this study was to determine the efficacy of immunonutrition vs standard nutrition in cancer patients treated with surgery. Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, EBSCOhost, and Web of Science were searched. Sixty-one randomized controlled trials were included. Immunonutrition was associated with a significantly reduced risk of postoperative infectious complications (risk ratio [RR] 0.71 [95% CI, 0.64-0.79]), including a reduced risk of wound infection (RR 0.72 [95% CI, 0.60-0.87]), respiratory tract infection (RR 0.70 [95% CI, 0.59-0.84]), and urinary tract infection (RR 0.69 [95% CI, 0.51-0.94]) as well as a decreased risk of anastomotic leakage (RR 0.70 [95% CI, 0.53-0.91]) and a reduced hospital stay (MD -2.12 days [95% CI -2.72 to -1.52]). No differences were found between the 2 groups with regard to sepsis or all-cause mortality. Subgroup analyses revealed that receiving arginine + nucleotides + ω-3 fatty acids and receiving enteral immunonutrition reduced the rates of wound infection and respiratory tract infection. The application of immunonutrition at 25-30 kcal/kg/d for 5-7 days reduced the rate of respiratory tract infection. Perioperative immunonutrition reduced the rate of wound infection. For malnourished patients, immunonutrition shortened the hospitalization time. Therefore, immunonutrition reduces postoperative infection complications and shortens hospital stays but does not reduce all-cause mortality. Patients who are malnourished before surgery who receive arginine + nucleotides + ω-3 fatty acids (25-30 kcal/kg/d) via the gastrointestinal tract during the perioperative period (5-7 days) may show better clinical efficacy.

AHNS Series - Do you know your guidelines?: Assessment and management of malnutrition in patients with head and neck cancer: Review of the NCCN Clinical Practice Guidelines In Oncology (NCCN Guidelines)

This article is a part of the "Do you know your guidelines" series by the Education Committee of the American Head and Neck Society. The aim is to summarize the core principles outlined by the NCCN Clinical Practice Guidelines In Oncology (NCCN Guidelines^® ) on management of malnutrition in patients with head and neck cancer. We outline the current recommendations from the National Comprehensive Cancer Network^® (NCCN^® ) for the screening and management of malnutrition, including indications for nutritional supplementation and placement of a nasogastric or gastrostomy tube. We also include a brief review of the available literature on additional screening tools, alternative guidelines, as well as an update on the emerging data surrounding the use of immune-enhancing nutrition.

Pharmaconutrition administration on outcomes of elective oncological surgery for gastrointestinal malignancies: is timing everything?-a review of published meta-analyses until the end of 2016

The last 25 years have seen an increasing number of publications attesting the benefits of pharmaconutrition in the management of patients undergoing elective oncological gastrointestinal surgery. A number of randomized controlled trials and meta-analyses suggest the use of pharmaconutrition in this group of patients produces superior outcomes to standard nutritional formulations in terms of postoperative infective complications, anastomotic breakdown and length of hospital stay. The use of pharmaconutrition products, therefore, has gained increasing acceptance for use in elective gastrointestinal oncological surgical populations and been incorporated into practice guidelines. However, there remains doubts as to the robustness of such data supporting these recommendation. This is because studies reporting improved outcomes with pharmaconutrition (I) frequently compare this intervention with non-equivalent control groups; (II) do not report on the actual nutritional provision received by study participants; (III) overlook the potential impact of industry funding on research conducted and (IV) do not adopt a multi-disciplinary approach to the research undertaken. For these reasons, a critical re-appraisal of the use and recommendations of pharmaconutrition in this group of patients is urgently warranted to resolve some of the above mentioned issues. The aim of this review was to analyse meta-analyses published until the end of 2016 in this area to highlight the strengths and weakness of the present research and prioritize certain areas which will benefit from future research.

Meta-analysis of immunonutrition in major abdominal surgery

Background

The objective of this study was to evaluate the potential benefits of immunonutrition in major abdominal surgery with special regard to subgroups and influence of bias.

Methods

A systematic literature search from January 1985 to July 2015 was performed in MEDLINE, Embase and CENTRAL. Only RCTs investigating immunonutrition in major abdominal surgery were included. Outcomes evaluated were mortality, overall complications, infectious complications and length of hospital stay. The influence of different domains of bias was evaluated in sensitivity analyses. Evidence was rated according to the GRADE Working Group grading of evidence.

Results

A total of 83 RCTs with 7116 patients were included. Mortality was not altered by immunonutrition. Taking all trials into account, immunonutrition reduced overall complications (odds ratio (OR) 0·79, 95 per cent c.i. 0·66 to 0·94; P = 0·01), infectious complications (OR 0·58, 0·51 to 0·66; P < 0·001) and shortened hospital stay (mean difference –1·79 (95 per cent c.i. –2·39 to –1·19) days; P < 0·001) compared with control groups. However, these effects vanished after excluding trials at high and unclear risk of bias. Publication bias seemed to be present for infectious complications (P = 0·002). Non-industry-funded trials reported no positive effects for overall complications (OR 1·13, 0·88 to 1·46; P = 0·34), whereas those funded by industry reported large effects (OR 0·66, 0·48 to 0·91; P = 0·01).

Conclusion

Immunonutrition after major abdominal surgery did not seem to alter mortality (GRADE: high quality of evidence). Immunonutrition reduced overall complications, infectious complications and shortened hospital stay (GRADE: low to moderate). The existence of bias lowers confidence in the evidence (GRADE approach).

Preoperative Immunonutrition and Elective Colorectal Resection Outcomes

BACKGROUND

Randomized controlled trials demonstrate the efficacy of arginine-enriched nutritional supplements (immunonutrition) in reducing complications after surgery. The effectiveness of preoperative immunonutrition has not been evaluated in a community setting.

OBJECTIVE

This study aims to determine whether immunonutrition before elective colorectal surgery improves outcomes in the community at large.

DESIGN

This is a prospective cohort study with a propensity score-matched comparative effectiveness evaluation.

SETTINGS

This study was conducted in Washington State hospitals in the Surgical Care Outcomes Assessment Program from 2012 to 2015.

PATIENTS

Adults undergoing elective colorectal surgery were selected.

INTERVENTIONS

Surgeons used a preoperative checklist that recommended that patients take oral immunonutrition (237 mL, 3 times daily) for 5 days before elective colorectal resection.

MAIN OUTCOME MEASURES

Serious adverse events (infection, anastomotic leak, reoperation, and death) and prolonged length of stay were the primary outcomes measured.

RESULTS

Three thousand three hundred seventy-five patients (mean age 59.9 ± 15.2 years, 56% female) underwent elective colorectal surgery. Patients receiving immunonutrition more commonly were in a higher ASA class (III-V, 44% vs 38%; p = 0.01) or required an ostomy (18% vs 14%; p = 0.02). The rate of serious adverse events was 6.8% vs 8.3% (p = 0.25) and the rate of prolonged length of stay was 13.8% vs 17.3% (p = 0.04) in those who did and did not receive immunonutrition. After propensity score matching, covariates were similar among 960 patients. Although differences in serious adverse events were nonsignificant (relative risk, 0.76; 95% CI, 0.49-1.16), prolonged length of stay (relative risk, 0.77; 95% CI, 0.58-1.01 p = 0.05) was lower in those receiving immunonutrition.

LIMITATIONS

Patient compliance with the intervention was not measured. Residual confounding, including surgeon-level heterogeneity, may influence estimates of the effect of immunonutrition.

CONCLUSIONS

Reductions in prolonged length of stay, likely related to fewer complications, support the use of immunonutrition in quality improvement initiatives related to elective colorectal surgery. This population-based study supports previous trials of immunonutrition, but shows a lower magnitude of benefit, perhaps related to compliance or a lower rate of adverse events, highlighting the value of community-based assessments of comparative effectiveness.

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.

Clinical and immunological impact of early postoperative enteral immunonutrition after total gastrectomy in gastric cancer patients: a prospective randomized study

BACKGROUND

Enteral immunodiet has been gaining increasing attention, but experimental data of its clinical effects in patients with gastric cancer are inconsistent, contradictory, and poorly investigated. The aim of this study was to assess the impact of early postoperative enteral immunonutrition on clinical and immunological outcomes in a homogeneous group of gastric cancer patients submitted to total gastrectomy.

METHODS

A total of 109 patients with gastric cancer were randomized to receive early postoperative enteral immunonutrition (formula supplemented with arginine, omega-3 fatty acids and ribonucleic acid [RNA]), or an isocaloric-isonitrogenous control. The postoperative outcome was evaluated based on clinical variables, including postoperative infectious complications, anastomotic leak rate, and length of hospitalization. In addition, state of cellular immunity was evaluated and compared between the 2 groups.

RESULTS

The incidence of postoperative infectious complications in the immunodiet group (7.4%) was significantly (p < .05) lower than that of the control group (20%), as well as the anastomotic leak rate (3.7% in immunodiet group vs 7.3% in standard nutrition group, p < .05). Mortality rate did not show any significant differences; patients of the immunodiet group were found to have a significantly reduced length of hospitalization (12.7 ± 2.3 days) when compared with standard diet group (15.9 ± 3.4 days, p = .029). The data on cellular immunity showed that the postoperative CD4(+) T-cell counts decreased in both groups, but the reduction in the IED group was significantly higher (p = .032) compared with the SND group.

CONCLUSIONS

Early postoperative enteral immunonutrition significantly improves clinical and immunological outcomes in patients undergoing gastrectomy for gastric cancer.

A meta-analysis of the effect of combinations of immune modulating nutrients on outcome in patients undergoing major open gastrointestinal surgery

BACKGROUND

Immune modulating nutrition (IMN) has been shown to reduce complications after major surgery, but strong evidence to recommend its routine use is still lacking.

OBJECTIVE

The aim of this meta-analysis was to evaluate the impact of IMN combinations on postoperative infectious and noninfectious complications, length of hospital stay, and mortality in patients undergoing major open gastrointestinal surgery.

METHODS

Randomized controlled trials published between January 1980 and February 2011 comparing isocaloric and isonitrogenous enteral IMN combinations with standard diet in patients undergoing major open gastrointestinal surgery were included. The quality of evidence and strength of recommendation for each postoperative outcome were assessed using the GRADE approach and the outcome measures were analyzed with RevMan 5.1 software (Cochrane Collaboration, Copenhagen, Denmark).

RESULTS

Twenty-six randomized controlled trials enrolling 2496 patients (1252 IMN and 1244 control) were included. The meta-analysis suggests strong evidence in support of decrease in the incidence of postoperative infectious [risk ratio (RR) (95% confidence interval [CI]): 0.64 (0.55, 0.74)] and length of hospital stay [mean difference (95% CI): -1.88 (-2.91, -0.84 days)] in those receiving IMN. Even though significant benefit was observed for noninfectious complications [RR (95% CI): 0.82 (0.71, 0.95)], the quality of evidence was low. There was no statistically significant benefit on mortality [RR (95% CI): 0.83 (0.49, 1.41)].

CONCLUSIONS

IMN is beneficial in reducing postoperative infectious and noninfectious complications and shortening hospital stay in patients undergoing major open gastrointestinal surgery.

Correlation between the pretherapeutic neutrophil to lymphocyte ratio and the pathologic response to neoadjuvant chemotherapy in patients with advanced esophageal cancer

BACKGROUND

An elevation in the neutrophil-to-lymphocyte ratio (NLR) has been shown to be associated with a poorer prognosis in patients with various tumors. The aim of this retrospective study was to clarify the correlation of the pretherapeutic NLR with the prognostic value of the pathologic response to neoadjuvant chemotherapy (NAC) in patients with advanced esophageal cancer.

METHODS

This study was a retrospective review of 83 patients undergoing NAC for advanced esophageal cancer following esophagectomy. The NLR was measured before NAC, and the pathologic responses to NAC were evaluated.

RESULTS

A comparison was performed for those whose pathology responded (responders) (G3/G2/G1b) and nonresponders (G1a/G0). In a univariate analysis, the cStage (P = 0.005), cN (P = 0.0001), and NLR (P = 0.005) were statistically significant parameters. A multivariate analysis revealed that the factors independently associated with pathologic responses were the pretreatment NLR (<2.2/≥2.2) (P = 0.043) and lymph nodes metastasis (P = 0.002). The pretreatment NLR (<2.2/≥2.2) was found to be a statistically significant useful predictive marker for a pathologic response (P = 0.001). The pathologic response rates were 56% in the patients with an NLR <2.2 and 21% in patients with an NLR of ≥2.2.

CONCLUSIONS

Our study is the first to demonstrate that the pretherapeutic NLR can be used as a predictor for chemosensitivity of thoracic esophageal cancer. Preoperative evaluation based on the clinical N stage and NLR may be easily used in routine clinical practice.

Prospective randomized trial of preoperative enteral immunonutrition followed by elective total gastrectomy for gastric cancer

BACKGROUND

Perioperative enteral immunonutrition is thought to reduce postoperative morbidity in patients undergoing major gastrointestinal surgery. This study assessed the clinical effects of preoperative enteral immunonutrition in well nourished patients with gastric cancer undergoing total gastrectomy.

METHODS

Well nourished patients with primary gastric cancer, fit for total gastrectomy, were randomized to either a control group with regular diet, or an immunonutrition group that received regular diet supplemented with 1000 ml/day of immunonutrients for 5 consecutive days before surgery. The primary endpoint was the incidence of surgical-site infection (SSI). Secondary endpoints were rates of infectious complications, overall postoperative morbidity and C-reactive protein (CRP) levels on 3-4 days after surgery.

RESULTS

Of 244 randomized patients, 117 were allocated to the control group and 127 received immunonutrition. SSIs occurred in 27 patients in the immunonutrition group and 23 patients in the control group (risk ratio (RR) 1.09, 95 per cent confidence interval 0.66 to 1.78). Infectious complications were observed in 30 patients in the immunonutrition group and 27 in the control group (RR 1.11, 0.59 to 2.08). The overall postoperative morbidity rate was 30.8 and 26.1 per cent respectively (RR 1.18, 0.78 to 1.78). The median CRP value was 11.8 mg/dl in the immunonutrition group and 9.2 mg/dl in the control group (P = 0.113).

CONCLUSION

Five-day preoperative enteral immunonutrition failed to demonstrate any clear advantage in terms of early clinical outcomes or modification of the systemic acute-phase response in well nourished patients with gastric cancer undergoing elective total gastrectomy.

REGISTRATION NUMBER

ID 000000648 (University Hospital Medical Information Network (UMIN) database).

Perioperative immunonutrition for gastrointestinal cancer: a systematic review of randomized controlled trials

BACKGROUND

To improve the clinical outcome, immunonutrition (IN) was usually used in the patients undergoing elective gastrointestinal caner surgery. However, its effectiveness remains uncertain.

METHODS

Randomized controlled trials (RCTs) published between 1995 and 2011 were identified and extracted by two reviewers independently from electronic databases, including PubMed, EMBASE, and Cochrane Library. The quality of included trials was assessed according to the handbook for Cochrane reviewer (V5.0.1). Statistical analysis was carried out with RevMan software.

RESULTS

Nineteen RCTs involving a total of 2331 patients were included in our meta-analysis. The results showed perioperative IN significantly reduced length of hospital stay (WMD, -2.62; 95% CI, -3.26 to -1.97; P < 0.01) and morbidity of postoperative infectious complication (RR, 0.44; 95% CI, 0.32 to 0.60; P < 0.01) compared with standard diet. Moreover, perioperative IN also significantly decreased morbidity of postoperative non-infectious complication in comparison with standard diet (RR, 0.72; 95% CI, 0.54 to 0.97; P = 0.03).

CONCLUSION

Perioperative IN is effective and safe to reduce postoperative infection, non-infection complication and length of hospital stay.

The relationships of nutrients, routes of delivery, and immunocompetence

Malnutrition has marked consequences on surgical outcomes. Adequate nutrition is important for the proper functioning of all organ systems, particularly the immune system. Determination of the type and amount of nutrient supplementation and the appropriate route of nutrient delivery is essential to bolster the immune system and enhance the host's response to stress. Correct administration of immunonutrients could lead to reductions in patient morbidity following major surgery, trauma, and critical illness.

Are we jumping the gun with pharmaconutrition (immunonutrition) in gastrointestinal onoclogical surgery?

Over the last 20 years there has been considerable research into the use of immunonutrition, also referred to as pharmaconutrition, in the management of patients undergoing and recovering from elective gastrointestinal surgery for malignancy. In this group of patients, the use of pharmaconutrition seems to confer superior outcomes to standard nutrition formulations with regards to postoperative infective complications and length of hospital stay. It is therefore frequently recommended for use in elective gastrointestinal oncological surgical populations. However, it remains unclear whether the data supporting these recommendation is robust. Studies reporting improved outcomes with pharmaconutrition frequently compare this intervention with non-equivalent control groups, do not report on the actual nutritional provision received by study participants, overlook the potential impact of industry funding on the conduct of research and do not adopt a multi-disciplinary approach to the research undertaken. For these reasons, an urgent critical re-appraisal of the use and recommendations of pharmaconutrition in this group of patients is warranted to resolve some of the above mentioned issues.

Management of enterocutaneous fistulas

Management of enterocutaneous fistulas (ECFs) involves (1) recognition and stabilization, (2) anatomic definition and decision, and (3) definitive operation. Phase 1 encompasses correction of fluid and electrolyte imbalance, skin protection, and nutritional support. Abdominal imaging defines the anatomy of the fistula in phase 2. ECFs that do not heal spontaneously require segmental resection of the bowel segment communicating with the fistula and restoration of intestinal continuity in phase 3. The enteroatmospheric fistula (EAF) is a malevolent condition requiring prolonged wound care and nutritional support. Complex abdominal wall reconstruction immediately following fistula resection is necessary for all EAFs.

Perioperative nutrition in abdominal surgery: recommendations and reality

Introduction. Preoperative malnutrition is a major risk factor for increased postoperative morbidity and mortality. Definition and diagnosis of malnutrition and its treatment is still subject for controversy. Furthermore, practical implementation of nutrition-related guidelines is unknown. Methods. A review of the available literature and of current guidelines on perioperative nutrition was conducted. We focused on nutritional screening and perioperative nutrition in patients undergoing digestive surgery, and we assessed translation of recent guidelines in clinical practice. Results and Conclusions. Malnutrition is a well-recognized risk factor for poor postoperative outcome. The prevalence of malnutrition depends largely on its definition; about 40% of patients undergoing major surgery fulfil current diagnostic criteria of being at nutritional risk. The Nutritional Risk Score is a pragmatic and validated tool to identify patients who should benefit from nutritional support. Adequate nutritional intervention entails reduced (infectious) complications, hospital stay, and costs. Preoperative oral supplementation of a minimum of five days is preferable; depending on the patient and the type of surgery, immune-enhancing formulas are recommended. However, surgeons' compliance with evidence-based guidelines remains poor and efforts are necessary to implement routine nutritional screening and nutritional support.

Nutrition therapy for the critically ill surgical patient: we need to do better!

BACKGROUND

To identify opportunities for quality improvement, the nutrition adequacy of critically ill surgical patients, in contrast to medical patients, is described.

METHODS

International, prospective, and observational studies conducted in 2007 and 2008 in 269 intensive care units (ICUs) were combined for purposes of this analysis. Sites provided institutional and patient characteristics and nutrition data from ICU admission to ICU discharge for maximum of 12 days. Medical and surgical patients staying in ICU at least 3 days were compared.

RESULTS

A total of 5497 mechanically ventilated adult patients were enrolled; 37.7% had surgical ICU admission diagnosis. Surgical patients were less likely to receive enteral nutrition (EN) (54.6% vs 77.8%) and more likely to receive parenteral nutrition (PN) (13.9% vs 4.4%) (P < .0001). Among patients initiating EN in ICU, surgical patients started EN 21.0 hours later on average (57.8 vs 36.8 hours, P < .0001). Consequently, surgical patients received less of their prescribed calories from EN (33.4% vs 49.6%, P < .0001) or from all nutrition sources (45.8% vs 56.1%, P < .0001). These differences remained after adjustment for patient and site characteristics. Patients undergoing cardiovascular and gastrointestinal surgery were more likely to use PN, were less likely to use EN, started EN later, and had lower total nutrition and EN adequacy rates compared with other surgical patients. Use of feeding and/or glycemic control protocols was associated with increased nutrition adequacy.

CONCLUSIONS

Surgical patients receive less nutrition than medical patients. Cardiovascular and gastrointestinal surgery patients are at highest risk of iatrogenic malnutrition. Strategies to improve nutrition performance, including use of protocols, are needed.

Immunonutrition in high-risk surgical patients: a systematic review and analysis of the literature

BACKGROUND

Immunomodulating diets (IMDs) have been demonstrated to improve immune function and modulate inflammation. However, the clinical benefit of these diets in patients undergoing elective surgery is controversial. The goal of this meta-analysis was to determine the impact of IMDs on the clinical outcomes of high-risk patients undergoing elective surgery.

METHODS

The review included prospective, controlled, clinical trials that compared the clinical outcome of elective surgical patients who were randomized to receive an IMD or a control enteral diet. Studies were stratified according to the type of IMD and the timing of the initiation of the IMD. Data were abstracted on study design, study size, patient population, and IMD used. The outcomes of interest were the acquisition of new infections, wound complications, length of hospital stay (LOS), and mortality. Meta-analytic techniques were used to analyze the data.

RESULTS

Twenty-one relevant studies were identified, which included a total of 1918 patients. Immunonutrition significantly reduced the risk of acquired infections, wound complications, and LOS. The mortality rate was 1% in both groups. The treatment effect was similar regardless of the timing of the commencement of the IMD. The benefits of immunonutrition required both arginine and fish oil.

CONCLUSIONS

An immunomodulating enteral diet containing increased amounts of both arginine and fish oil should be considered in all high-risk patients undergoing major surgery. Although the optimal timing cannot be determined from this study, it is suggested that immunonutrition be initiated preoperatively when feasible.

Immunonutrition in gastrointestinal surgery

BACKGROUND

Patients undergoing major gastrointestinal surgery are at increased risk of developing complications. The use of immunonutrition (IN) in such patients is not widespread because the available data are heterogeneous, and some show contradictory results with regard to complications, mortality and length of hospital stay.

METHODS

Randomized controlled trials (RCTs) published between January 1985 and September 2009 that assessed the clinical impact of perioperative enteral IN in major gastrointestinal elective surgery were included in a meta-analysis.

RESULTS

Twenty-one RCTs enrolling a total of 2730 patients were included in the meta-analysis. Twelve were considered as high-quality studies. The included studies showed significant heterogeneity with respect to patients, control groups, timing and duration of IN, which limited group analysis. IN significantly reduced overall complications when used before surgery (odds ratio (OR) 0·48, 95 per cent confidence interval (c.i.) 0·34 to 0·69), both before and after operation (OR 0·39, 0·28 to 0·54) or after surgery (OR 0·46, 0·25 to 0·84). For these three timings of IN administration, ORs of postoperative infection were 0·36 (0·24 to 0·56), 0·41 (0·28 to 0·58) and 0·53 (0·40 to 0·71) respectively. Use of IN led to a shorter hospital stay: mean difference -2·12 (95 per cent c.i. -2·97 to -1·26) days. Beneficial effects of IN were confirmed when low-quality trials were excluded. Perioperative IN had no influence on mortality (OR 0·90, 0·46 to 1·76).

CONCLUSION

Perioperative enteral IN decreases morbidity and hospital stay but not mortality after major gastrointestinal surgery; its routine use can be recommended.

Metabolic support of the enterocutaneous fistula patient

Enterocutaneous fistula (ECF) is a challenging clinical problem with many etiologies; however, the most common cause is iatrogenic, complicating abdominal surgery. Advances in the overall care of the ECF patient have resulted in dramatic reductions in morbidity and mortality over the last five decades. A structured approach to the management of ECF has been shown to result in improved outcomes. Initial physiologic stabilization of the postoperative patient, focused on hemodynamic and fluid support as well as aggressive sepsis control are the critical initial maneuvers. Subsequent optimization of nutrition and wound care allows the patient to regain a positive nitrogen balance, and allow for healing. Judicious use of antimotility agents as well as advanced wound care techniques helps to maximize healing as well as quality of life, and prepare patients for subsequent definitive surgery.

The impact of immunostimulating nutrition on infectious complications after upper gastrointestinal surgery: a prospective, randomized, clinical trial

BACKGROUND AND AIM

Immunomodulating nutrition is supposed to reduce the number of complications and lengthen of hospital stay during the postoperative period in patients after major gastrointestinal surgery. The aim of the study was to assess the clinical effect of immunostimulatory enteral and parenteral nutrition in patients undergoing resection for gastrointestinal cancer in the group of well-nourished patients.

MATERIAL AND METHODS

Between June 1, 2001, and December 31, 2005, a group of 214 well-nourished patients was initially assessed (150 men, 64 women, mean age 61.2 years) to participate in the study. Nine patients were subsequently excluded and the remaining 205 subjects were randomly assigned in a 2 x 2 factorial design into 4 study groups, ie, standard enteral nutrition (n = 53), immunomodulating enteral nutrition (n = 52), standard parenteral nutrition (n = 49), and immunomodulating enteral nutrition (n = 51). The study was designed to test the hypothesis that immunonutrition and enteral nutrition would reduce the incidence of infectious complications after upper gastrointestinal surgery; the secondary objective of the study was to evaluate the effect of nutritional intervention on overall morbidity and mortality rates, and hospital stay. The study was registered in the Clinical Trials Database-number NCT 00558155.

RESULTS

The overall morbidity rate was 33% and the incidence of individual complications was comparable between all groups. Infectious complications occurred in 26 of 102 patients given standard diets and in 22 of 103 patients receiving immunomodulatory formulas (odds ratio 0.81; 95% CI, 0.43-1.50). There were no significant differences between infectious complications in patients using parenteral nutrition (22 of 100 patients) and parenteral formulas (26 of 105, odds ratio 1.14; 95% CI, 0.61-2.14). Neither immunostimulating formulas nor enteral feeding significantly affected secondary outcome measures, including overall morbidity and mortality rates, and hospital stay.

CONCLUSIONS

Our study failed to demonstrate any clear advantage of routine postoperative immunonutrition in patients undergoing elective upper gastrointestinal surgery. Both enteral and parenteral treatment options showed similar efficacy, tolerance, and effects on protein synthesis. Parenteral nutrition composed according to contemporary rules showed similar efficiency to enteral nutrition. However, because of its cost-efficiency, enteral therapy should be considered as the treatment of choice in all patients requiring nutritional therapy.

Enteral versus parenteral nutrition after gastrointestinal surgery: a systematic review and meta-analysis of randomized controlled trials in the English literature

BACKGROUND

Although previous studies recommend the use of enteral nutrition (EN), the benefit of EN after elective gastrointestinal surgery has not been comprehensively demonstrated as through a meta-analysis. Our aim is to determine whether enteral nutrition is more beneficial than parenteral nutrition.

METHODS

A search was conducted on Medline, Web of Science, the Cochrane Library electronic databases, and bibliographic reviews. The trials were based on randomization, gastrointestinal surgery, and the reporting of at least one of the following end points: any complication, any infectious complication, mortality, wound infection and dehiscence, anastomotic leak, intraabdominal abscess, pneumonia, respiratory failure, urinary tract infection, renal failure, any adverse effect, and duration of hospital stay.

RESULTS

Twenty-nine trials, which included 2,552 patients, met the criteria. EN was beneficial in the reduction of any complication (relative risk (RR), 0.85; 95% confidence interval (CI), 0.74-0.99; P = 0.04), any infectious complication (RR, 0.69; 95% CI, 0.56-0.86; P = 0.001), anastomotic leak (RR, 0.67; 95% CI, 0.47-0.95; P = 0.03), intraabdominal abscess (RR, 0.63; 95% CI, 0.41-0.95; P = 0.03), and duration of hospital stay (weighted mean difference, -0.81; 95% CI, -1.25-0.38; P = 0.02). There were no clear benefits in any of the other complications.

CONCLUSION

The present findings would lead us to recommend the use of EN rather than PN when possible and indicated.

L-arginine reduces cell proliferation and ornithine decarboxylase activity in patients with colorectal adenoma and adenocarcinoma

PURPOSE

Evidence suggests that the majority of colorectal carcinomas arise from adenomas, and L-arginine suppresses colorectal tumorigenesis. We suppose that L-arginine may inhibit the process of carcinogenesis from colorectal adenoma to adenocarcinoma. The aim of this study was to investigate the effects of L-arginine on the formation and development of colorectal tumors.

EXPERIMENTAL DESIGN

We selected 60 patients with colorectal cancer and 60 patients with colorectal adenoma (CRA) and divided them into four groups of 30 patients each. We gave 30 g (120 mL) of L-arginine everyday for 3 days to the test groups, whereas L-arginine was substituted by 5% glucose in the control groups. The expression of the proliferating cell nuclear antigen, survivin, and nitric oxide synthase was examined immunohistochemically, and ornithine decarboxylase (ODC) activity was examined spectrophotometrically. Serum nitric oxide (NO) was detected by the Griess assay.

RESULTS

In patients with CRA, the proliferating cell nuclear antigen and survivin labeling indexes and ODC activity of the tumor and paratumor mucosa in the L-arginine-treated group after L-arginine treatment were significantly lower as compared with the corresponding pretreatment values (P < 0.01). Moreover, inducible nitric oxide synthase expression in the tumor markedly increased after L-arginine treatment (P < 0.05). Serum NO levels in the patients with colorectal cancer were markedly higher than those in the patients with CRA, and L-arginine treatment was responsible for this increase (P < 0.05).

CONCLUSIONS

Our results show that L-arginine can restrain crypt cell hyperproliferation and the expression of survivin, an inhibitor of apoptosis protein. This suggests that L-arginine can block the formation and development of colorectal tumors, and this effect might be related to the increased serum NO concentration and decreased ODC activity.

Who benefits from nutritional support: what is the evidence?

Nutritional support, including oral nutritional supplements, enteral tube feeding and parenteral nutrition, can be an important part of the management of any patient. Malnutrition is common and costly, clinically and financially, if left untreated. In patients with, or at risk of, malnutrition, the appropriate use of nutritional support can prevent complications arising, produce other clinical, functional and financial benefits, and can be life saving in some situations. This article discusses the evidence from systematic reviews and meta-analyses of the effectiveness of nutritional support.

Eicosapentaenoic acid (EPA, an omega-3 fatty acid from fish oils) for the treatment of cancer cachexia

BACKGROUND

Cancer cachexia is a distressing weight loss syndrome commonly seen in advanced cancer patients. It is associated with reduced quality of life and shorter survival time. Eicosapentaenoic acid (EPA) is a long chain polyunsaturated fatty acid found naturally in some fish which has been used to decrease weight loss, promote weight gain and increase survival times in patients affected with cancer cachexia.

OBJECTIVES

To evaluate the effectiveness and safety of EPA in relieving symptoms associated with the cachexia syndrome in patients with advanced cancer.

SEARCH STRATEGY

Studies were sought through an extensive search of a range of electronic databases. Hand searching was conducted on selected journals and reference lists as well as contact made with investigators, manufacturers and experts. The most recent electronic search was conducted in February 2005.

SELECTION CRITERIA

Studies were included in the review if they assessed oral EPA compared with placebo or control in randomised controlled trials of patients with advanced cancer and either a clinical diagnosis of cachexia or self-reported weight loss of 5% or more.

DATA COLLECTION AND ANALYSIS

Both methodological quality evaluation of potential trials and data extraction were conducted by two independent review authors.

MAIN RESULTS

Five trials (involving 587 patients) met the inclusion criteria. Three trials compared EPA at different doses with placebo with two outcomes, nutritional status and adverse events comparable across two of the three included trials. In addition, two trials compared different doses of EPA with an active matched control. It was possible to compare the outcomes of weight, quality of life and adverse events across these two trials. There were insufficient data to define the optimal dose of EPA.

AUTHORS' CONCLUSIONS

There were insufficient data to establish whether oral EPA was better than placebo. Comparisons of EPA combined with a protein energy supplementation versus a protein energy supplementation (without EPA) in the presence of an appetite stimulant (Megestrol Acetate) provided no evidence that EPA improves symptoms associated with the cachexia syndrome often seen in patients with advanced cancer.

Postsurgical infections are reduced with specialized nutrition support

OBJECTIVE

The objective was to examine the relationship between pre-, peri-, and postoperative specialized nutritional support with immune-modulating nutrients and postoperative morbidity in patients undergoing elective surgery.

METHODS

Studies were identified by searching MEDLINE, review article bibliographies, and abstracts and proceedings of scientific meetings. All randomized clinical trials in which patients were supplemented by the IMPACT formula before and/or after elective surgery and the clinical outcomes reported were included in the meta-analysis. Seventeen studies (n=2,305), 14 published (n=2,102), and 3 unpublished (n=203), fulfilled the inclusion criteria. Ten studies (n=1,392) examined the efficacy of pre- or perioperative IMPACT supplementation in patients undergoing elective surgery, whereas 7 (n=913) assessed postoperative efficacy. Fourteen of the studies (n=2,083) involved gastrointestinal (GI) surgical patients. Postoperative complications, mortality, and length of stay in hospital (LOS) were major outcomes of interest.

RESULTS

IMPACT supplementation, in general, was associated with significant (39%-61%) reductions in postoperative infectious complications and a significant decrease in LOS in hospital by an average of 2 days. The greatest improvement in postoperative outcomes was observed in patients receiving specialized nutrition support as part of their preoperative treatment. In GI surgical patients, anastomotic leaks were 46% less prevalent when IMPACT supplementation was part of the preoperative treatment.

CONCLUSION

This study identifies a dosage (0.5-1 l/day) and duration (supplementation for 5-7 days before surgery) of IMPACT that contributes to improved outcomes of morbidity in elective surgery patients, particularly those undergoing GI surgical procedures. The cost effectiveness of such practice is supported by recent health economic analysis. Findings suggest preoperative IMPACT use for the prophylaxis of postoperative complications in elective surgical patients.

n-3 long-chain polyunsaturated fatty acids in type 2 diabetes: a review

Historically, epidemiologic studies have reported a lower prevalence of impaired glucose tolerance and type 2 diabetes in populations consuming large amounts of the n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) found mainly in fish. Controlled clinical studies have shown that consumption of n-3 LC-PUFAs has cardioprotective effects in persons with type 2 diabetes without adverse effects on glucose control and insulin activity. Benefits include lower risk of primary cardiac arrest; reduced cardiovascular mortality, particularly sudden cardiac death; reduced triglyceride levels; increased high-density lipoprotein levels; improved endothelial function; reduced platelet aggregability; and lower blood pressure. These favorable effects outweigh the modest increase in low-density lipoprotein levels that may result from increased n-3 LC-PUFA intake. Preliminary evidence suggests increased consumption of n-3 LC-PUFAs with reduced intake of saturated fat may reduce the risk of conversion from impaired glucose tolerance to type 2 diabetes in overweight persons. Reported improvements in hemostasis, slower progression of artery narrowing, albuminuria, subclinical inflammation, oxidative stress, and obesity require additional confirmation. Expected health benefits and public health implications of consuming 1 to 2 g/day n-3 LC-PUFA as part of lifestyle modification in insulin resistance and type 2 diabetes are discussed.

n-3 fatty acids, inflammation, and immunity--relevance to postsurgical and critically ill patients

Excessive or inappropriate inflammation and immunosuppression are components of the response to surgery, trauma, injury, and infection in some individuals and these can lead, progressively, to sepsis and septic shock. The hyperinflammation is characterized by the production of inflammatory cytokines, arachidonic acid-derived eicosanoids, and other inflammatory mediators, while the immunosuppression is characterized by impairment of antigen presentation and of T helper cell type-1 responses. Long-chain n-3 FA from fish oil decrease the production of inflammatory cytokines and eicosanoids. They act both directly (by replacing arachidonic acid as an eicosanoid substrate and by inhibiting arachidonic acid metabolism) and indirectly (by altering the expression of inflammatory genes through effects on transcription factor activation). Thus, long-chain n-3 FA are potentially useful anti-inflammatory agents and may be of benefit in patients at risk of developing sepsis. As such, an emerging application of n-3 FA is in surgical or critically ill patients where they may be added to parenteral or enteral formulas. Parenteral or enteral nutrition including n-3 FA appears to preserve immune function better than standard formulas and appears to partly prevent some aspects of the inflammatory response. Studies to date are suggestive of clinical benefits from these approaches, especially in postsurgical patients.

Lipids in the nutritional support of the critically ill patients

PURPOSE OF REVIEW

This review reports recent findings on lipid use in artificial nutrition in patients with acute respiratory failure or severe sepsis or undergoing major surgery. It examines current knowledge of fatty acid safety, biologic effects, and the impact on patients' morbidity and mortality. The newly emerging area of genotypic influence and timing of immunonutrition is also discussed.

RECENT FINDINGS

In acute respiratory distress syndrome, the debate concerning the use of long-chain fatty acids as opposed to physical mixtures of medium- and long-chain fatty acids, specifically regarding their effects on gas exchange and pulmonary hemodynamics, still remains unresolved. By contrast, providing fish oil fatty acids (mainly eicosapentaenoic and docosahexaenoic acids) and/or gamma-linolenic acid, seems to decrease harmful excessive inflammatory/immune activation and to improve clinical outcome. Similar effects, although not conclusively demonstrated, have been reported for n-3 fatty acid-enriched lipid emulsions in patients with sepsis. Few recent studies examined the impact of n-3 fatty acid-enriched enteral formulas on patients undergoing major surgery. Most studies focused on intravenous fish oil and suggest beneficial effects both on inflammatory/immune parameters and patient outcome. Studies suggest that lipid use in critically ill patients may be improved by increased knowledge of genetic determinants of severity of injury and response to therapeutic agents as well as by the development of tools that allow better timing of immunonutritional intervention.

SUMMARY

Overall, lipids, in particular n-3 fatty acids, emerge as powerful nutrients with pharmacologic properties potentially improving prognosis in critically ill patients. However, heterogeneity in study design makes the interpretation of available studies difficult. Consequently, larger prospective, randomized, double-blind trials with comparable methodologies are necessary for detailed evaluation of the pharmacologic impact of lipids. In addition, a better knowledge of the influence of genotypic variation and postinjury inflammatory/immune temporal patterns may improve our current therapeutic use of various fatty acids.

Effects of l-arginine-enriched total enteral nutrition on body weight gain, tumor growth, and in vivo concentrations of blood and tissue metabolites in rats inoculated with Walker tumor in the kidney

OBJECTIVE

We evaluated the effects of l-arginine-enriched total enteral nutrition (LATEN) on tumor-free and right kidney tumor-bearing rats through the determination of in vivo concentrations of metabolites to better understand intermediary metabolism in this model.

METHODS

Rats were individually housed in wire cages within a controlled environment (25 degrees C and 50% relative humidity) and exposed to a 12-h light-and-dark cycle. Rats comprised the following groups: tumor-free on enteral nutrition plus l-amino acid (n = 8); tumor-free on enteral nutrition plus l-arginine (n = 8); tumor bearing on enteral nutrition plus l-amino acids (n = 8); and tumor bearing on enteral nutrition plus l-arginine (n = 8). Rats had their right kidneys inoculated with saline or tumor cells and were subjected to laparotomy or gastrostomy on day 1 and received chow diet for the next 2 days. Gastrostomy with enteral nutrition was performed on days 3 to 9. On day 9, body weight gain, tumor growth as volume, in vivo blood (microM/mL), and tissue (microM/g) metabolite concentrations were determined. The Mann-Whitney U test was used to test significance.

RESULTS

LATEN in tumor-free rats decreased liver (0.25 +/- 0.03 versus 0.13 +/- 0.03 micromol/g, P < 0.05) and right kidney (0.13 +/- 0.1 versus 0.04 +/- 0.00 micromol/g, P < 0.05) ketone body concentrations. LATEN in tumor-bearing rats decreased blood pyruvate (0.17 +/- 0.01 versus 0.10 +/- 0.008 microM/mL, P < 0.005), lactate (5.2 +/- 0.3 versus 2.9 +/- 0.28 microM/mL, P < 0.01), and glucose (6.4 +/- 0.8 versus 3.7 +/- 0.5 microM/mL, P < 0.05). Glucose concentrations decreased in liver (13.9 +/- 2.0 versus 4.89 +/- 0.6 microM/g, P < 0.005) and tumor (3.5 +/- 0.8 versus 1.41 +/- 0.3 microM/g, P < 0.05). There were no changes in body weight gain (21 +/- 2.0 versus 30.3 +/- 3.6 g) or tumor growth (1.53 +/- 0.1 versus 1.26 +/- 0.01 cm(3)).

CONCLUSIONS

LATEN decreased ketone body concentrations in liver and kidney in tumor-free rats, possibly due to lower ketogenesis and decreased kidney uptake. In tumor-bearing rats, LATEN decreased lacticemia and glycemia and pyruvate blood concentrations. LATEN also reduced liver and tumor glucose concentrations in tumor-bearing animals. The possibility of LATEN-induced insulin and insulin-like growth factor-1 liberation signaling these changes is discussed.

Nutrition in the perioperative patient

The association of malnutrition with surgical morbidity and mortality is well recognized. The question of whether this relationship is causal or simply an association in sick patients has been hotly debated. The field of nutrition support has grown out of the belief that correcting malnutrition will modify associated risks for poor outcome. It has been easier to substantiate this belief in some clinical situations than in others. The evidence for nutrition support during the perioperative period is reviewed and recommendations are made about where nutrition support is most useful and where it may be counterproductive. Some of the important unanswered questions about perioperative nutrition support are raised.

Long-chain n-3 fatty acids and inflammation: potential application in surgical and trauma patients

Lipids used in nutritional support of surgical or critically ill patients have been based on soybean oil, which is rich in the n-6 fatty acid linoleic acid (18:2n-6). Linoleic acid is the precursor of arachidonic acid (20:4n-6). In turn, arachidonic acid in cell membrane phospholipids is the substrate for the synthesis of a range of biologically active compounds (eicosanoids) including prostaglandins, thromboxanes, and leukotrienes. These compounds can act as mediators in their own right and can also act as regulators of other processes, such as platelet aggregation, blood clotting, smooth muscle contraction, leukocyte chemotaxis, inflammatory cytokine production, and immune function. There is a view that an excess of n-6 fatty acids should be avoided since this could contribute to a state where physiological processes become dysregulated. One alternative is the use of fish oil. The rationale of this latter approach is that fish oil contains long chain n-3 fatty acids, such as eicosapentaenoic acid. When fish oil is provided, eicosapentaenoic acid is incorporated into cell membrane phospholipids, partly at the expense of arachidonic acid. Thus, there is less arachidonic acid available for eicosanoid synthesis. Hence, fish oil decreases production of prostaglandins like PGE2 and of leukotrienes like LTB4. Thus, n-3 fatty acids can potentially reduce platelet aggregation, blood clotting, smooth muscle contraction, and leukocyte chemotaxis, and can modulate inflammatory cytokine production and immune function. These effects have been demonstrated in cell culture, animal feeding and healthy volunteer studies. Fish oil decreases the host metabolic response and improves survival to endotoxin in laboratory animals. Recently clinical studies performed in various patient groups have indicated benefit from this approach.

Immunonutrition: problematic or problem solving?

The addition of immune-modulating nutrients to enteral formulas has been examined in clinical trials and meta-analyses. Enhancing immunity through diet is generally done by adding n-3 fatty acids, arginine, and nucleotides to an otherwise nutritionally complete formula. Despite flaws in many studies, a consistent trend to reduced infectious complications has been seen with immunonutrition, especially in patients undergoing surgery for upper gastrointestinal cancer or trauma. In critical care populations, however, the results have been mixed. In this review, we analyze these studies and focus on select clinical points that may explain the variation. One common flaw has been a failure to deliver an adequate nutrition volume. Few patients, especially in the earliest studies, received even close to goal feeding. A minimum quantity of immunonutrition may be required for effective reduction in infections. When feeding volumes are low, immunonutrition is usually not better than an isonitrogenous control. In more recent studies, practitioners have been increasingly aggressive with enteral feeding, and this has been reflected in improved outcomes from immunonutrition. Early delivery of immunonutrition (preoperatively in surgical patients with cancer) might be particularly beneficial. Another consideration is illness severity: we discuss evidence that the use of immunonutrition in moderate illness is more likely to be helpful, whereas severe sepsis is probably beyond the reach of any nutritional intervention, and mild illness is more likely to improve irrespective of feeding. If future trials can consider these vital points, level 1 recommendations in favor of immunonutrition might be justified, although presently such evidence is lacking for most clinical indications.

Effect of dietary whey protein concentrate on primary and secondary antibody responses in immunized BALB/c mice

Proteins derived from the whey fraction of bovine milk are known to modulate immune responses. We have previously described a rennet whey protein concentrate (WPC) that can boost intestinal tract antibody responses to orally administered T-dependent antigens. In the present study, we investigated the effects of feeding WPC to mice on specific antibody responses to several orally or parenterally administered antigens, including influenza vaccine, diphtheria and tetanus toxoids, poliomyelitis vaccine, ovalbumin and cholera toxin sub-unit. WPC-fed mice produced elevated levels of antigen-specific intestinal tract and serum antibodies against all tested antigens, compared to mice that were fed a standard chow diet. Both primary and secondary intestinal tract antibody responses were elevated by WPC feeding, while only secondary serum responses were increased in WPC-fed mice. Significant up-regulation of intestinal tract antibody was observed within 2 weeks of primary oral immunizations. A period of pre-feeding with WPC, prior to commencement of immunization, did not alter the kinetics or magnitude of immune enhancement. These results identify bovine WPC as a potentially important dietary protein supplement, capable of enhancing humoral immune responses to a range of heterologous antigens.

Effect of c-reactive protein and interleukins blood levels in postsurgery arginine-enhanced enteral nutrition in head and neck cancer patients

OBJECTIVE

It is known that the immune system is frequently affected in patients with head and neck cancer. Although immune dysfunction could be multifactorial, this immune system may be modulated by specific nutritional substrates, such as arginine. The aim of our study was to evaluate the effect of enteral nutrition supplemented with arginine on c-reactive protein (CRP), interleukin 6 (IL-6) and tumour necrosis factor (TNFalpha) in surgical head and neck cancer patients.

DESIGN

Randomized trial.

SETTING

Tertiary care.

SUBJECTS

A population of 36 patients with oral and laryngeal cancer were enrolled.

INTERVENTIONS

At surgery patients were randomly allocated to two groups: (a) patients receiving an enteral diet supplements with arginine and dietary fibre (group I, n=18); (b) patients receiving an isocaloric, isonitrogenous enteral formula (group II, n=18). Perioperatively and on postoperative day 5 the following parameters were evaluated: serum values of prealbumin, transferrin, albumin, total number of lymphocytes, interleukin 6, tumour necrosis factor alpha and c-reactive protein.

RESULTS

The mean age was 59.6+/-10.9 y (two females/34 males). No significant intergroup differences in the trend of the three plasma proteins and weight were detected. CRP decreased in both groups (group I: 152.9+/-76.9 vs 68.9+/-82.5 mg/dl; P<0.05; and group II: 105.9+/-92 vs 43.6+/-59.1 mg/dl; P<0.05). Interleukin 6 did not change (group I: 16.3+/-12.3 vs 35.6+/-83.4 pg/ml; NS; and group II: 22.8+/-40 vs 9.9+/-17.7 pg/ml; NS). TNFalpha did not show any differences (group I: 4.6+/-1.6 vs 5.1+/-1.5 pg/ml; NS; and group II: 8.8+/-6.1 vs 5.8+/-1.7 pg/ml; NS). Lymphocytes increased in both groups (group I: 1405.6+/-517 vs 1634+/-529 x 10(6)/ml; P<0.05; and group II: 1355+/-696 vs 1561+/-541 x 10(6)/ml; P<0.05).

CONCLUSIONS

Enhanced formula did not change IL6 and TNFalpha levels. Further studies are needed to determine whether route of nutrition or type of formula is the key in these patients.

Protective nutrients and functional foods for the gastrointestinal tract

Epithelial and other cells of the gastrointestinal mucosa rely on both luminal and bloodstream sources for their nutrition. The term functional food is used to describe nutrients that have an effect on physiologic processes that is separate from their established nutritional function, and some of these nutrients are proposed to promote gastrointestinal mucosal integrity. We review the recent in vitro, animal, and clinical experiments that evaluated the role of several types of gastrointestinal functional foods, including the amino acids glutamine and arginine, the essential micronutrients vitamin A and zinc, and 2 classes of food additives, prebiotics and probiotics. Many of the data from preclinical studies support a strong role for enteral nutrients in gastrointestinal health; in comparison, the data from human studies are limited. In some cases, impressive data from in vitro and animal studies have not been replicated in human trials. Other clinical trials have shown positive health benefits, but some of those studies were plagued by flaws in study design or analysis. The methods available to detect important changes in human gastrointestinal function and structure are still limited, but with the development of more sensitive measures of gastrointestinal function, the effects of specific nutrients may be more easily detected. This may facilitate the development of phase 3 clinical trials designed to more rigorously evaluate the effects of a particular nutrient by focusing on valid and reliable outcome measures. Regulatory changes in the way in which health claims can be made for dietary supplements should also be encouraged.

New management strategies in ARDS. Immunomodulation

Acute respiratory distress syndrome is a common condition among the critically ill and is associated with high morbidity and mortality [table: see text] rates. Improved understanding of the underlying inflammatory pathogenetics has encouraged the search for strategies that, by modifying this immune response, can improve outcome for this group of patients. Some agents are obviously anti-inflammatory. Others have been used primarily for other purposes; their immune effects are incidental, but no less important. Although immunomodulatory strategies have been discussed for many years, they now are beginning to show positive results, as in the study using activated protein C. Most patients with ARDS die with ARDS, rather than from ARDS. The approach to treatment must not be lung-limited but must take into account the systemic effects of the inflammatory response. The complex nature of the syndrome makes it likely that no single agent will provide the long-desired cure. Rather, it is probable that an individual patient will require a combination of several agents or different agents at different times during the disease process (Table 1). Mortality rates from ARDS already are beginning to fall with improved nutritional and ventilatory support. Positive results from trials using immunomodulatory agents are being reported, and soon such agents will form part of the routine management of patients with ARDS, further improving the outlook for these patients.