Nutrition and the immune system

Preoperative immunonutrition in patients undergoing liver resection: A prospective randomized trial

BACKGROUND

Preoperative supplementation with immunonutrients, including arginine and n-3 fatty acids, has been shown in a number of systematic reviews to reduce infectious complications in patients who have undergone gastrointestinal surgery. Limited information, however, is available on the benefits of nutritional supplementation enriched with arginine and n-3 fatty acids in patients undergoing liver resection.

AIM

To evaluate the effects of preoperative nutritional supplementation enriched with arginine and n-3 fatty acids on inflammatory and immunologic markers and clinical outcome in patients undergoing liver resection.

METHODS

Thirty-four patients undergoing liver resection were randomized to either five days of preoperative Impact^® [1020 kcal/d, immunonutrition (IMN) group], or standard care [no supplementation, standard care (STD) group]. Nutritional status was measured at study entry by subjective global assessment (SGA). Functional assessments (grip strength, fatigue and performance status) were carried out at study entry, on the day prior to surgery, and on postoperative day (POD) 7 and 30. Inflammatory and immune markers were measured at study entry, on the day prior to surgery, and POD 1, 3, 5, 7, 10 and 30. Postoperative complications were recorded prospectively until POD30.

RESULTS

A total of 32 patients (17 IMN and 15 STD) were analysed. All except four patients were SGA class A. The plasma ratio of (eicosapentaenoic acid plus docosahexaenoic acid) to arachidonic acid was higher in IMN patients on the day prior to surgery and POD 1, 3, 5 and 7 (P < 0.05). Plasma interleukin (IL)-6 concentrations were elevated in the IMN group (P = 0.017 for POD7). No treatment effect was detected for functional measures, immune response (white cell count and total lymphocytes) or markers of inflammation (C-reactive protein, tumour necrosis factor-α, IL-8, IL-10). There were 10 patients with infectious complications in the IMN group and 4 in the STD group (P = 0.087). Median hospital stay was 9 (range 4–49) d in the IMN group and 8 (3-34) d in the STD group (P = 0.476).

CONCLUSION

In well-nourished patients undergoing elective liver resection, this study failed to show any benefit of preoperative immunonutrition.

Inhibitory Effects of Pentobarbital and Phenobarbital on Human Neutrophil Functions

Neutrophils are important components of the immune system which protects the host from bacterial invasion. Phenobarbital and pentobarbital are used to treat seizures/convulsions in critically ill patients who are sometimes immunocompromised hosts. In the current study we examined the effect of pentobarbital and phenobarbital at clinically relevant concentrations and at 10 and 100 times these concentrations on several aspects of human neutrophil functions using ex vivo system. The two barbiturates impaired neutrophil chemotaxis but failed to suppress phagocytosis. Pentobarbital and phenobarbital also inhibited production of superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH·) by neutrophils in a dose-dependent manner. These drugs did not scavenge the reactive oxygen species (ROS) generated by the xanthine-xanthine oxidase system. Elevation of intracellular calcium concentrations ([Ca2+]i) in neutrophils by a stimulant was dose-dependently attenuated with pentobarbital and phenobarbital. The two anesthetics also decreased protein kinase C (PKC) activity. These effects on [Ca2+]i and PKC activity may represent a part of mechanisms responsible for inhibition of neutrophil functions. Further studies using in vivo systems are required to elucidate inhibitory effects of pentobarbital or phenobarbital on ROS production and chemotaxis in clinical settings.

Preoperative immunonutrition and its effect on postoperative outcomes in well-nourished and malnourished gastrointestinal surgery patients: a randomised controlled trial

BACKGROUND/OBJECTIVES

Invasive procedures such as surgery cause immunosuppression, leading to increased risk of complications, infections and extended hospital stay. Emerging research around immune-enhancing nutrition supplements and their ability to reduce postoperative complications and reduce treatment costs is promising. This randomised controlled trial aims to examine the effect of preoperative immunonutrition supplementation on length of hospital stay (LOS), complications and treatment costs in both well-nourished and malnourished gastrointestinal surgery patients.

SUBJECTS/METHODS

Ninety-five patients undergoing elective upper and lower gastrointestinal surgery were recruited. The treatment group (n=46) received a commercial immuno-enhancing supplement 5 days preoperatively. The control group (n=49) received no supplements. The primary outcome measure was LOS, and secondary outcome measures included complications and cost.

RESULTS

A nonsignificant trend towards a shorter LOS within the treatment group was observed (7.1 ± 4.1 compared with 8.8 ± 6.5 days; P=0.11). For malnourished patients, this trend was greater with hospital stay reduced by 4 days (8.3 ± 3.5 vs 12.3 ± 9.5 days; P=0.21). Complications and unplanned intensive care admission rates were very low in both the groups. The average admission cost was reduced by AUD1576 in the treatment group compared with the control group (P=0.37).

CONCLUSIONS

Preoperative immunonutrition therapy in gastrointestinal surgery has the potential to reduce the LOS and cost, with greater treatment benefit seen in malnourished patients; however, there is a need for additional research with greater patient numbers.

Re-examination of risk factors for non-Clostridium difficile-associated diarrhoea in hospitalized patients

AIM

This paper is a report of a study to determine the incidence of non-Clostridium difficile-associated diarrhoea in hospitalized patients and to re-evaluate clinical characteristics and other risk factors related to non-C. difficile-associated diarrhoea.

BACKGROUND

Numerous factors are thought to be responsible for diarrhoea in hospitalized patients. Reports about the diarrhoeal effects of some medications administered concomitantly with tube feeding have stimulated reappraisal of the influence of tube feeding as a potential cause.

METHOD

This study was a secondary analysis of data of 154 hospitalized patients collected during a prospective epidemiological study from 1992 to 1993. The secondary analysis was completed in 2006 in order to investigate unanswered questions of current importance.

FINDINGS

The sample was predominantly male and middle aged; approximately 50% were tube fed, and 25% were in an intensive care unit. The incidence of diarrhoea was 35%. Increased severity of illness as well as the combination of sorbitol-containing medication administration and tube feeding were found to be statistically significant factors in the development of diarrhoea.

CONCLUSION

As diarrhoea in hospitalized patients appears to be multifactorial, use of an algorithm to systematically evaluate and manage related factors is recommended.

Decreased peritoneal macrophage NF-κB translocation to the nucleus in protein energy malnutrition—a role for the glucocorticoid response?

BACKGROUND & AIMS

Protein energy malnutrition (PEM) induces immune suppression leading to increased morbidity and mortality. The mechanism(s) underlying PEM-mediated immune suppression remain unclear. Plasma glucocorticoid levels are elevated in PEM and it has been postulated that these increased levels may mediate macrophage (MØ) dysfunction in PEM. We have previously shown that nuclear factor kappa B (NF-kappaB) activation in response to LPS stimulation is diminished in peritoneal macrophages (PMØs) from PEM mice. We hypothesized that decreased NF-kappaB activation in lipopolysaccharide (LPS)-stimulated PMØs in PEM is mediated through increased circulating glucocorticoid levels.

METHODS

Mice were randomized to six groups of n = 15 each as follows: (1) control diet (24% casein) (C); (2) protein-free diet (PF); (3) mice with subcutaneously implanted corticosterone pellet on the control diet; (4) mice with subcutaneously implanted placebo pellet on the control diet; (5) adrenalectomized mice on the control diet; (6) adrenalectomized mice on the PF diet. Within each group, the mice were pair-fed for 7 days. At the end of the experimental time period, PMØs were harvested and NF-kappaB activation determined by electrophoretic mobility shift assay (EMSA).

RESULTS

Elevated circulating glucocorticoids diminished NF-kappaB activation but adrenalectomy failed to restore this diminution in a murine model of PEM.

CONCLUSION

NF-kappaB translocation to the nucleus in PEM is independent of elevated circulating glucocorticoid levels.

Use of indirect calorimetry to optimize nutrition support and assess physiologic dead space in the mechanically ventilated ICU patient: a case study approach

Indirect calorimetry (IC) is an accurate method of estimating a patient's energy expenditure, particularly the complex critically ill patient who benefits most from an individualized regimen of nutritional support. This bedside technique measures variables related to gas exchange and replaces assumptions about physiologic stress. When indirect calorimetry data are augmented by an arterial blood gas analysis of carbon dioxide (PaCO2), the dead space to tidal volume ratio (VD/VT) can be determined for an individual patient. These data can be valuable to the healthcare team when checking reasons for weaning failure. A case study approach to a 69-year-old man with acute respiratory distress syndrome and biliary sepsis will demonstrate the utility of this measurement. Attention to precise nutritional support and optimal gas exchange can influence the outcome of critically ill mechanically ventilated patients. This discussion highlights the potential benefits of indirect calorimetry for critical care nurses.