Immune-enhancing enteral formulas: are they beneficial in critically ill patients?

Nutrition and cutaneous wound healing

Wound healing is a complex and energy-demanding process. The relationship between nutrition and wound healing has been recognized for many centuries. Several studies have indicated that nutritional deficiencies are more prevalent among patients with chronic wounds. Malnutrition may alter the inflammatory response, collagen synthesis, and wound tensile strength, all of which are crucial for wound healing. Although the specific role of nutrition and supplementation in wound care remains uncertain, it is necessary to identify and correct nutritional imbalances to avoid any potential deterioration of the healing process. It is also important to recognize the differences in pathophysiology between acute and chronic wounds. A burn, surgical, or a traumatic wound is different from a diabetic foot ulcer, which is different from a pressure ulcer. Chronic wounds are more prevalent in the aging population, and patients often have underlying comorbidities, such as diabetes mellitus, peripheral vascular disease, connective tissue disease, or other systemic illnesses that may alter energy metabolism and contribute to impaired healing. Management approaches to acute wound care may not apply universally to chronic wounds. In this review, we discuss the available data and possible roles for nutrition in wound healing.

Early enteral immunonutrition vs. parenteral nutrition in critically ill patients without severe sepsis: a randomized clinical trial

OBJECTIVES

We compared early parenteral nutrition (PN) and early enteral immunonutrition (iEN) in critically ill patients, distinguishing those with and without severe sepsis or septic shock (SS) on admission to intensive care units (ICUs).

DESIGN AND SETTING

Multicenter, randomized, unblinded clinical trial in 33 Italian general ICUs.

PATIENTS AND PARTICIPANTS

The study included 326 patients, 287 of whom did not have SS on ICU admission. Eligibility criteria excluded the two tails in the spectrum of critical conditions, i.e., patients either too well or too ill. Of the patients recruited 160 were randomized to iEN (142 without SS) and 166 to PN (145 without SS).

INTERVENTIONS

Patients were randomized to two arms: early iEN or early PN.

MEASUREMENTS AND RESULTS

Primary endpoint was 28-day mortality for all patients and the occurrence of SS during ICU stay for patients admitted without such condition. While 28-day mortality did not differ between iEN and PN (15.6% vs. 15.1%), patients without SS who received iEN had fewer episodes of severe sepsis or septic shock (4.9% vs. 13.1%). ICU length of stay was 4 days shorter in patients given iEN.

CONCLUSIONS

Compared to parenteral nutrition iEN appears to be beneficial in critical patients without severe sepsis or septic shock. Parenteral nutrition in these patients should be abandoned, at least when enteral nutrition can be administered, even at an initial low caloric content.

Reducing costs and patient morbidity in the enterally fed intensive care unit patient

BACKGROUND

Critically ill patients are at high risk for nosocomial infections and resultant organ dysfunction and death. These patients typically have protracted intensive care unit (ICU) courses and consume increasingly limited resources. Enteral nutrition with specific immune-modulating components has been previously shown to improve outcomes in select populations of patients, but results have been mixed in critically ill patients. Impact 1.5 (Novartis Nutrition, Minneapolis, MN) is a commercially available enteral formula containing ingredients known to improve several parameters of immune function. We hypothesized that administration of Impact 1.5 tube feedings would reduce the incidence of nosocomial infection and ICU resources in critically ill patients admitted to the ICU for severe trauma, burns, or sepsis insults.

METHODS

The Impact 1.5 group (n = 17) was compared with a historical cohort of ICU patients (n = 21) of similar illness severity that received a standard high-energy enteral formula. The incidence of nosocomial infections and mortality, and the consumption of multiple ICU resources were examined. A cost analysis based on these results was then performed to determine the cost effectiveness of this proprietary immunonutrition enteral formula.

RESULTS

A pronounced reduction in nosocomial pneumonia (12% vs 52%, p < .01) was identified, with consequent trends toward a reduction in duration of mechanical ventilation and ICU length of stay. Urinary tract infections that may have less influence on ICU resources were increased in the Impact 1.5 group. No difference in mortality was identified, despite the inclusion of patients with severe sepsis in the study group. According to the average number of ICU days required for each study cohort, the Impact 1.5 group led to a cost savings of at least $193,350.00.

CONCLUSIONS

ICU patients with significant illness severity experienced a decrease in the incidence of an important nosocomial infection that is commonly associated with increased use of ICU resources and length of stay. This decrease in patient morbidity led to substantial cost savings despite the small size of our study trial.

Effects of immunonutrition on intestinal mucosal apoptosis, mucosal atrophy, and bacterial translocation in head injured rats

BACKGROUND

Immunonutrition has been demonstrated to modulate gut function, reduce infectious complications, hospital stay, and ventilator days in the critical patients.

AIM OF THE STUDY

We assessed the effect of immunonutrition for the prevention of intestinal mucosal atrophy, apoptosis, and bacterial translocation in head injured rats.

METHODS

Thirty five rats were randomised into 5 groups. Following moderate closed head injury, in Group 1; Standard Enteral Nutrition, Group 2; Immunonutrition, Group 3; TPN, Group 4; pe. saline were applied. Group 5 was control group (chow-fed). The rats were sacrificed and segments of the ileum were removed for histologic examination, and samples of tissues taken for microbiologic evaluation.

RESULTS

Both intestinal apoptosis and mucosal atrophy were significantly lower in Group 2 and Group 5 (p<0.008). Bacterial translocation was significantly lower in Group 2 than Group 1 (p<0.008).

CONCLUSION

The enteral immunonutrition prevents intestinal barrier function in brain injured rats.

Early enteral immunonutrition in patients with severe sepsis: results of an interim analysis of a randomized multicentre clinical trial

OBJECTIVE

To compare the mortality of critically ill patients given either enteral feeding with an immune-enhancing formula or parenteral nutrition (PN). We report the results of a planned interim analysis on patients with severe sepsis which was undertaken earlier than planned once a meta-analysis suggested excess mortality in patients with severe sepsis given enteral immunonutrition.

DESIGN

Randomised multicentre unblinded controlled clinical trial.

SETTING

Thirty-three General Intensive Care Units in Italy.

PATIENTS AND PARTICIPANTS

Among the 237 recruited patients, 39 had severe sepsis or septic shock; 21 of them received PN.

INTERVENTIONS

Eligible patients received either total PN or enteral nutrition, the latter containing extra L-arginine, omega-3 fatty acids, vitamin E, beta carotene, zinc, and selenium.

MEASUREMENTS AND RESULTS

The primary endpoint for the subgroup analysis on patients with severe sepsis was mortality on Intensive Care Unit (ICU). The ICU mortality of patients with severe sepsis given enteral nutrition (EN) was higher than for those given PN (44.4% vs 14.3%; p=0.039). More patients given EN than patients given PN still had severe sepsis when they died (38.9% vs 9.5%, p=0.055). Recruitment of patients with severe sepsis was subsequently stopped.

CONCLUSIONS

Our results show that enteral immunonutrition, compared to PN, may be associated with excess mortality in patients with severe sepsis.

Nutrition for the critically ill child: enteral and parenteral support

The requirements of growth and organ development create a challenge in nutrition management for the pediatric patient. The stress of critical illness further complicates the delivery of adequate nutrients. Enteral feeding has several advantages over parenteral nutrition (PN), which include preservation of the gastrointestinal mucosa and decreasing the occurrence of sepsis related to bacterial translocation. Although feeding through the gastrointestinal tract is the preferred route for nutritional management, there are specific instances when PN as adjunctive or sole therapy is necessary to meet nutritional needs. With meticulous attention to fluid, caloric, protein, and fat requirements along with monitoring the metabolic status of the patient, it is possible to provide full nutritional support for the critically ill child within 24 to 48 hours of hospital admission.

An immune-enhancing enteral diet reduces mortality rate and episodes of bacteremia in septic intensive care unit patients

OBJECTIVE

To determine whether early enteral feeding in a septic intensive care unit (ICU) population, using a formula supplemented with arginine, mRNA, and omega-3 fatty acids from fish oil (Impact), improves clinical outcomes, when compared with a common use, high protein enteral feed without these nutrients.

DESIGN

A prospective, randomized, multicentered trial.

SETTING

ICUs of six hospitals in Spain.

PATIENTS

One hundred eighty-one septic patients (122 males, 59 females) presenting for enteral nutrition in an ICU.

INTERVENTIONS

Septic ICU patients with Acute Physiology and Chronic Health Evaluation (APACHE) II scores of > or =10 received either an enteral feed enriched with arginine, mRNA, and omega-3 fatty acids from fish oil (Impact), or a common use, high protein control feed (Precitene Hiperproteico).

MEASUREMENTS AND MAIN RESULTS

One hundred seventy-six (89 Impact patients, 87 control subjects) were eligible for intention-to-treat analysis. The mortality rate was reduced for the treatment group compared with the control group (17 of 89 vs. 28 of 87; p < .05). Bacteremias were reduced in the treatment group (7 of 89 vs. 19 of 87; p = .01) as well as the number of patients with more than one nosocomial infection (5 of 89 vs. 17 of 87; p = .01). The benefit in mortality rate for the treatment group was more pronounced for patients with APACHE II scores between 10 and 15 (1 of 26 vs. 8 of 29; p = .02).

CONCLUSIONS

Immune-enhancing enteral nutrition resulted in a significant reduction in the mortality rate and infection rate in septic patients admitted to the ICU. These reductions were greater for patients with less severe illness.

Immunonutrition in the critically ill: a systematic review of clinical outcome

OBJECTIVE

To perform a meta-analysis addressing whether enteral nutrition with immune-enhancing feeds benefits critically ill patients after trauma, sepsis, or major surgery.

DATA SOURCES

Studies were identified by MEDLINE search (1967 to January 1998) for original articles in English using the search terms "human," "enteral nutrition," "arginine," "nucleotides," "omega-3 fatty acids," "immunonutrition," "IMPACT," and "Immun-Aid." Additionally, the authors of the studies and the manufacturers of the feeds were contacted for additional information. Access to original databases was obtained for the three largest studies.

STUDY SELECTION

Fifteen randomized controlled trials comparing patients receiving standard enteral nutrition with patients receiving a commercially available immune-enhancing feed with arginine with or without glutamine, nucleotides, and omega-3 fatty acids were identified by two independent reviewers (Dr. Beale and Dr. Bryg).

DATA EXTRACTION

Descriptive and outcome data were extracted independently from the papers by the same two reviewers, one of whom (Dr. Bryg) analyzed the original databases. Three studies were excluded from analysis, leaving 12 studies containing 1,557 subjects, 1,482 of whom were analyzed. Main outcome measures were mortality, infection, ventilator days, intensive care unit stay, hospital stay, diarrhea days, calorie intake, and nitrogen intake. The meta-analysis was performed on an intent-to-treat basis.

DATA SYNTHESIS

There was no effect of immunonutrition on mortality (relative risk = 1.05, confidence interval [CI] = 0.78, 1.41; p = .76). There were significant reductions in infection rate (relative risk = 0.67, CI = 0.50, 0.89; p = .006), ventilator days (2.6 days, CI = 0.1, 5.1; p = .04), and hospital length of stay (2.9 days, CI = 1.4, 4.4; p = .0002) in the immunonutrition group.

CONCLUSIONS

The benefits of enteral immunonutrition were most pronounced in surgical patients, although they were present in all groups. The reduction in hospital length of stay and infections has resource implications.

Pharmacological nutrition after burn injury

Burn patients develop pathophysiological alterations, which include extensive nitrogen loss, malnutrition, markedly increased metabolic rate and immunologic deficiency. This predisposes burn patients to frequent infections, poor wound healing, increased length of hospitalization and increased mortality. The nutritional support requires high protein and high energy diets preferably administered enterally soon after injury. The effects of increased dietary components such as glutamine, arginine and (n-3) fatty acids and related compounds have been evaluated in burn victims. These components, when supplied in quantities two to seven times of those in normal diets of healthy persons, appear to have beneficial pharmacological effects on the pathophysiological alterations associated with burns. However, the efficacy of immune-enhancing diets remains to be convincingly shown.

Postoperative nutrition in surgery for major trauma

Research in the area of the nutritional support of trauma patients has continued to focus on a few main areas: the effect that the route, timing and type of feeding has on patient outcome, nutritional assessment and mucosal immunity. This year a nutritional conference has released a paper, summarizing the current state of research in this area, that generated some controversy.