Route of feeding influences the production and expression of tumor necrosis factor alpha in burned rats

Early Enteral Nutrition for Burn Injury

Significance: Nutrition has been recognized as a critical component of acute burn care and ultimate wound healing. Debate remains over the appropriate timing of enteral nutrition and the benefit of supplemental trace elements, antioxidants, and immunonutrition for critically ill burn patients. Pharmacotherapy to blunt the metabolic response to burn injury plays a critical role in effective nutritional support. Recent Advances: Further evidence is demonstrating long-term benefits from pharmacologic immunomodulation given the prolonged metabolic response to injury that may last for over a year following the initial insult. Critical Issues: The majority of evidence regarding early enteral feeding comes from mixed populations and smaller studies. However, on balance, available evidence favors early feeding. Data regarding immunonutrition does not support the routine use of these products. Limited data regarding use of antioxidants and trace elements support their use. Future Directions: Further evaluation of anti-inflammatory mediators of the immune response, such as statins, will likely play a role in the future. Further data are needed on the dosing and route of micronutrients as well as the utility of immunonutrition. Finally, little is known about nutrition in the obese burn patient making this an important area for investigation.

Total Enteral Nutrition Facilitates Wound Healing Through Preventing Intestinal Atrophy, Keeping Protein Anabolism and Suppressing Inflammation

Background

In clinical settings, early total enteral nutrition (TEN) is known to reduce the postoperative complication and infection rate as well as duration of postoperative stay compared with total parenteral nutrition (TPN) in a variety of critical conditions. We aimed to compare effects TEN and TPN on wound healing and explore its possible mechanisms using rat model.

Methods

Seven days after operation for inserting enteral tube into gastric space for TEN, Sprague-Dawley rats were made burn (15 mm) in the back. Rats were administrated with either TEN (N = 17) or TPN (N = 15) and evaluated condition of wound healing as well as serum/urine immunological and biochemical parameters at 28 days.

Results

Burned area was significantly reduced in TEN than in TPN group. Although body weight, serum levels of total protein, albumin and transferrin were the same levels between the two groups, urine nitrogen and intestinal atrophy were significant in TPN group. Conversely, weight of small bowel showed positive linear relationship with levels of parameters calculated as follows: [medication nitrogen quantity – (urine nitrogen + feces nitrogen)]/[medication nitrogen – feces nitrogen quantity]. Weights of spleen and tumor necrotizing factor-a levels in serum were higher in TPN than in TEN.

Conclusions

These results suggest that TEN may facilitate wound healing compared with TPN through preventing intestinal atrophy, keeping protein anabolism and suppressing inflammation.

High-dose oral erythromycin decreased the incidence of parenteral nutrition-associated cholestasis in preterm infants

BACKGROUND & AIMS

Feeding intolerance because of functional gastrointestinal dysmotility and parenteral nutrition-associated cholestasis (PNAC) are common problems in preterm, very-low-birth-weight (VLBW) infants. This double-blind, randomized, placebo-controlled study aimed to assess the effectiveness of "high-dose" oral erythromycin as a prokinetic agent in decreasing the incidence of PNAC. Two secondary end points, including the time to achieve full enteral feeding and the duration of parenteral nutrition, were also evaluated.

METHODS

Infants consecutively admitted to the neonatal unit were randomized to receive erythromycin (12.5 mg/kg/dose every 6 hours for 14 days) or an equivalent volume of normal saline (placebo) if they attained less than half the total daily fluid intake (<75 mL/kg/day) as milk feeds on day 14 of life.

RESULTS

Of 182 VLBW infants enrolled, 91 received erythromycin. The incidence of PNAC was significantly lower in erythromycin-treated infants (18/91) compared with placebo infants (37/91; P = .003). Treated infants achieved full enteral nutrition significantly earlier (mean, 10.1; SE, 1.7 days; P < .001), and the duration of parenteral nutrition was also significantly decreased by 10 days (P < .001). Importantly, fewer infants receiving erythromycin had 2 or more episodes of septicemia (n = 4) compared with placebo patients (n = 13, P = .03). No serious adverse effect was associated with erythromycin treatment.

CONCLUSIONS

High-dose oral erythromycin can be considered as a rescue measure for VLBW infants who fail to establish adequate enteral nutrition and in whom anatomically obstructive pathologies of the gastrointestinal tract have been excluded.

A comparison study between early enteral nutrition and parenteral nutrition in severe burn patients

This clinical study compares effects between enteral nutrition and parenteral nutrition in the early stage of severe burns. Nineteen cases of severe burn patients were divided randomly into total enteral nutrition group (TEN) and total parenteral nutrition group (TPN). Plasma motilin, malondialdehyde (MDA), superoxide dismutase (SOD), endotoxin, tumor necrosis factor (TNF), serum gastrin, diamine oxidase (DAO), and urine lactulose/mannitol ratio (L/M) was determined on post burn day (PBD) 1, 4, 8, 14, respectively. The results showed that serum gastrin, plasma motilin, and SOD were significantly higher in TEN than in TPN on PBD4, 8 (p<0.05-0.01). Plasma MDA was obviously lower in TEN than in TPN on PBD4, 8 (p<0.01). Plasma endotoxin was significantly lower in TEN than in TPN on PBD4, 8 (p<0.01). Plasma TNF were significantly lower in TEN than in TPN on PBD4, 8, 14 (p<0.01). The level of serum DAO and urine L/M ratio in TEN was obviously lower than in TPN on PBD4 and 8, respectively (p<0.05-0.01). A positive correlation between L/M and DAO, MDA, TNF (r=0.5822-0.7598, p<0.05-0.01), and a negative correlation between L/M and SOD (r=-0.7771, p<0.01), and a positive correlation between plasma endotoxin and TNF, MDA (r=0.9038 and 0.6705, p<0.05-0.01) were found. These results indicate that enteral nutrition was a more effective route to preserve gastrin secretion and motility of gastrointestinal tract, lower intestinal ischemia and reperfusion injury, reduce intestinal permeability, decrease plasma endotoxin and inflammatory mediators, and maintain mucosa barrier function. Whenever gastrointestinal function permits, enteral nutrition was superior to parenteral nutrition early after burn.

Parenteral versus enteral nutrition: effect on serum cytokines and the hepatic expression of mRNA of suppressor of cytokine signaling proteins, insulin-like growth factor-1 and the growth hormone receptor in rodent sepsis

INTRODUCTION

Early nutrition is recommended for patients with sepsis, but data are conflicting regarding the optimum route of delivery. Enteral nutrition (EN), compared with parenteral nutrition (PN), results in poorer achievement of nutritional goals but may be associated with fewer infections. Mechanisms underlying differential effects of the feeding route on patient outcomes are not understood, but probably involve the immune system and the anabolic response to nutrients. We studied the effect of nutrition and the route of delivery of nutrition on cytokine profiles, the growth hormone-insulin-like growth factor-1 (IGF-I) axis and a potential mechanism for immune and anabolic system interaction, the suppressors of cytokine signaling (SOCS), in rodents with and without sepsis.

METHODS

Male Sprague-Dawley rats were randomized to laparotomy (Sham) or to cecal ligation and puncture (CLP), with postoperative saline infusion (Starve), with EN or with PN for 72 hours. Serum levels of IL-6 and IL-10 were measured by immunoassay, and hepatic expressions of cytokine-inducible SH2-containing protein, SOCS-2, SOCS-3, IGF-I and the growth hormone receptor (GHR) were measured by real-time quantitative PCR.

RESULTS

IL-6 was detectable in all groups, but was only present in all animals receiving CLP-PN. IL-10 was detectable in all but one CLP-PN rat, one CLP-EN rat, approximately 50% of the CLP-Starve rats and no sham-operated rats. Cytokine-inducible SH2-containing protein mRNA was increased in the CLP-EN group compared with the Sham-EN group and the other CLP groups (P < 0.05). SOCS-2 mRNA was decreased in CLP-PN rats compared with Sham-PN rats (P = 0.07). SOCS-3 mRNA was increased with CLP compared with sham operation (P < 0.03). IGF-I mRNA (P < 0.05) and GHR mRNA (P < 0.03) were greater in the fed CLP animals and in the Sham-PN group compared with the starved rats.

CONCLUSION

In established sepsis, nutrition and the route of administration of nutrition influences the circulating cytokine patterns and expression of mRNA of SOCS proteins, GHR and IGF-I. The choice of the administration route of nutrition may influence cellular mechanisms that govern the response to hormones and mediators, which further influence the response to nutrients. These findings may be important in the design and analysis of clinical trials of nutritional interventions in sepsis in man.

Whey feeding suppresses the measurement of oxidative stress in experimental burn injury

PURPOSE

Burns cause thermal injury to local tissue and trigger systemic acute inflammatory processes, which may lead to multiple distant organ dysfunction. We investigated the protective effect of dietary whey supplementation on distant organs in a rat model.

METHODS

Forty-eight rats were divided into six groups of eight: groups 1 and 2 were the controls, fed a standard diet and a whey-supplemented diet, respectively; groups 3 and 4 were fed a standard diet and subjected to burn injury; and groups 5 and 6 were fed a whey-supplemented diet and subjected to burn injury. We measured the oxidative stress variables, as well as glutathione in the liver and kidney, and histologically examined skin samples obtained 4 h (groups 3 and 5) and 72 h (groups 4 and 6) after burn injury.

RESULTS

Glutathione (GSH) levels remained the same in the liver but were slightly elevated in the kidneys after burn injury in the rats fed a standard diet. Whey supplementation caused a significant increase in hepatic GSH levels 4 h after burn injury. Moreover, there was a significant rebound effect in the liver and kidney GSH levels after 72 h and whey supplementation potentiated this effect. Hepatic and renal lipid peroxide levels were also increased 4 h after burn injury in the rats fed a standard diet. Whey supplementation significantly suppressed the burn-induced increase in hepatic and renal lipid peroxide levels. Histological examination revealed that although whey supplementation resulted in decreased subepidermal inflammation, the indicators of wound healing and collagen deposition were not improved.

CONCLUSION

Whey pretreatment suppressed hepatic and renal oxidative stress measurements after experimental burn injury.

Impact of intraoperative duodenal feeding on the oxygen balance of the splanchnic region in severely burned patients

Enteral feeding causes an increase of intestinal oxygen demand depending on the amount administered. The aim of this study presented was to evaluate, whether intraoperative duodenal feeding might put patients at risk developing splanchnic O(2)-imbalance due to an intraoperatively compromised intestinal perfusion based on stress and unrecognized hypovolemia. In 18 severely burned patients, the CO(2)-gap between the arterial and gastric CO(2), as a parameter for the intestinal O(2)-balance, was measured during the first operation. All operations were performed on day 3-5 after admission and lasted for 4-5h. Half of the patients (nine patients) were fed intraoperatively, whereas in the other nine patients feeding was suspended beginning 1h prior to surgery until 6h after surgery. CO(2)-gap measurements were carried out prior to surgery, hourly during the operation and 5h postoperatively. Measurements 3 and 4h after beginning of the operation revealed significantly higher CO(2)-gap values in the fasting group. All other measurements showed no significant difference between both groups. Therefore, intraoperative enteral nutrition, at least in the early postburn phase, is not only necessary for reducing caloric deficits, but also seems to have a protective effect on gut oxygen balance.

Parenteral nutrition associated liver disease

Liver disease is relatively common during parenteral nutrition (PN). Cholestasis predominates in infants, and ranges in severity from mild increases in plasma conjugated bilirubin to progressive liver failure that results in death of the patient. Severity of liver disease depends primarily on the magnitude of the underlying intestinal problem that indicated PN. Transient ileus resulting from a non-intestinal disorder usually results in trivial, self-limited liver injury. Removal of a large segment of the intestinal tract because of necrotizing enterocolitis or a congenital malformation predicts a more prolonged course with a guarded prognosis, particularly when initially complicated by sepsis. Pathogenesis of PN-associated liver disease is not completely understood. There is no proven treatment short of ending PN through adaptation of remnant intestine or intestinal transplantation, with or without a concurrent liver graft. Effective interventions that are less radical than transplantation are needed. Research that includes prospective trials of novel therapies in PN-associated liver disease is the key to improving outcome.

Nutrition and anabolic agents in burned patients

PURPOSE OF REVIEW

Much of the morbidity and mortality of severely burned patients is connected with hypermetabolism and catabolism with its accompanying impairment of wound healing and increased infection risks. In order to prevent the erosion of body mass, nutritional support and other strategies to prevent catabolism have become a major focus in the care of severely burned patients.

RECENT FINDINGS

Major themes discussed in recent literature are dealing with enteral versus parenteral nutrition and gastric versus duodenal feeding. The possibility of overfeeding is another important aspect of high calorie nutrition as commonly used in burned patients. Specific formulas for enteral nutrition for specific metabolic abnormalities are under evaluation as well as the role of anabolic and anticatabolic agents.

SUMMARY

From the clinical literature, total enteral nutrition starting as early as possible without any supplemental parenteral nutrition is the preferred feeding method for burned patients. Using a duodenal approach, especially in the early postburn phase, seems to be superior to gastric feeding. Administration of high calorie total enteral nutrition in any later septic phase should be critically reviewed due to possible impairment of splanchnic oxygen balance. Therefore, measurement of CO(2)-gap should be considered as a monitoring method during small bowel nutrition. The impact on the course of disease of supplements such as arginine, glutamine and vitamins as well as the impact of the use of anabolic and anticatabolic agents is not yet evident. Furthermore, the effect of insulin administration and low blood sugar regimes on wound healing and outcome in burned patients should be evaluated in future studies.