Efficacy of a high-carbohydrate diet in catabolic illness

Propranolol decreases cardiac work in a dose-dependent manner in severely burned children

BACKGROUND

Severe burn is followed by profound cardiac stress. Propranolol, a nonselective β(1,) β(2)-receptor antagonist, decreases cardiac stress, but little is known about the dose necessary to cause optimal effect. Thus, the aim of this study was to determine in a large, prospective, randomized, controlled trial the dose of propranolol that would decrease heart rate ≥15% of admission heart rate and improve cardiac function. Four-hundred six patients with burns >30% total body surface area were enrolled and randomized to receive standard care (controls; n = 235) or standard care plus propranolol (n = 171).

METHODS

Dose-response and drug kinetics of propranolol were performed. Heart rate and mean arterial pressure (MAP) were measured continuously. Cardiac output (CO), cardiac index, stroke volume, rate-pressure product, and cardiac work (CW) were determined at regular intervals. Statistical analysis was performed using analysis of variance with Tukey and Bonferroni corrections and the Student t test when applicable. Significance was accepted at P < .05.

RESULTS

Propranolol given initially at 1 mg/kg per day decreased heart rate by 15% compared with control patients, but was increased to 4 mg/kg per day within the first 10 days to sustain treatment benefits (P < .05). Propranolol decreased CO, rate-pressure product, and CW without deleterious effects on MAP. The effective plasma drug concentrations were achieved in 30 minutes, and the half-life was 4 hours.

CONCLUSION

The data suggest that propranolol is an efficacious modulator of the postburn cardiac response when given at a dose of 4 mg/kg per day, and decreases and sustains heart rate 15% below admission heart rate.

Association between dietary fat content and outcomes in pediatric burn patients

BACKGROUND

The aim of the study was to compare a low fat/high-carbohydrate diet and a high-fat diet on clinical outcomes by a retrospective cohort study.

METHODS

Nine hundred forty-four children with burns ≥ 40% of their total body surface area (TBSA) were divided into two groups: patients receiving Vivonex T.E.N. (low-fat/high-carbohydrate diet; n = 518) and patients receiving milk (high-fat diet; n = 426). Patient demographics, caloric intake, length of hospital stay, and incidence of sepsis, mortality, hepatic steatosis, and organomegaly at autopsy were determined.

RESULTS

Demographics and caloric intake were similar in both groups. Patients receiving Vivonex T.E.N. had shorter (intensive care unit) ICU stays (Vivonex T.E.N.: 31 ± 2 d; milk: 47 ± 2 d; P < 0.01), shorter ICU stay per % TBSA burn (Vivonex T.E.N.: 0.51 ± 0.02 d/%; milk: 0.77 ± 0.03 d/%; P < 0.01), lower incidence of sepsis (Vivonex T.E.N.: 11%; milk: 20%; P < 0.01), and lived significantly longer until death than those receiving milk (Vivonex T.E.N.: 20 ± 3 d; milk: 10 ± 2 d; P < 0.01). There was no difference in overall mortality between the two groups (Vivonex T.E.N.:15% versus milk: 13%; P < 0.9). Autopsies revealed decreased hepatic steatosis and decreased enlargement of kidney and spleen in patients receiving Vivonex T.E.N.

CONCLUSIONS

The period with a low-fat/high-carbohydrate diet was associated with lower LOS, decreased incidence of organomegaly, infection, and hepatic steatosis post-burn compared with the period when a high-fat diet was used. These associations indicate the benefit of high carbohydrate/low fat nutrition; however, the findings in these time periods can also be likely due to the multifactorial effects of advances in burn care. We believe that these results have some relevance because high fat is associated with poorer outcomes compared with low fat.

Hypocaloric peripheral parenteral nutrition with lipid emulsion in postoperative gastrointestinal cancer patients

AIM: To investigate the use of lipid emulsion substituting for glucose in postoperative hypocaloric peripheral parenteral nutrition (HPPN).

METHODS: This prospective, randomized study was conducted on 20 postoperative gastrointestinal cancer patients. They were randomized and equally divided into interventional group and control group, and both were administered isocaloric and isonitrogenous diets with for lipid emulsion substituting for partial glucose loads in the interventional group.

RESULTS: Nutritional parameters and biochemical data were compared between the two groups before and after 6-d of HPPN. Most investigated variables showed no significant changes after administration of HPPN with lipid emulsion. However, the postoperative triglyceride level was significantly lower in the interventional group than in the control group (P < 0.05). In comparison with lipid emulsion, glucose administration resulted in less decrease in postoperative prealbumin level (P < 0.05).

CONCLUSION: In addition to supplementing with essential fatty acid, it seems that HPPN with lipid emulsion is well-tolerated and beneficial to postoperative gastrointestinal cancer patients.

The hypermetabolic response to burn injury and interventions to modify this response

Severe burn injury is followed by a profound hypermetabolic response that persists up to 24 months after injury. It is mediated by up to 50-fold elevations in plasma catecholamines, cortisol, and inflammatory cells that lead to whole-body catabolism, elevated resting energy expenditures, and multiorgan dysfunction. All of these metabolic and physiologic derangements prevent full rehabilitation and acclimatization of burn survivors back into society. Modulation of the response by early excision and grafting of burn wounds, thermoregulation, early and continuous enteral feeding with high-protein high-carbohydrate feedings, and pharmacologic treatments have markedly decreased morbidity.

Burn size determines the inflammatory and hypermetabolic response

Background

Increased burn size leads to increased mortality of burned patients. Whether mortality is due to inflammation, hypermetabolism or other pathophysiologic contributing factors is not entirely determined. The purpose of the present study was to determine in a large prospective clinical trial whether different burn sizes are associated with differences in inflammation, body composition, protein synthesis, or organ function.

Methods

Pediatric burned patients were divided into four burn size groups: <40% total body surface area (TBSA) burn, 40–59% TBSA burn, 60–79% TBSA burn, and >80% TBSA burn. Demographic and clinical data, hypermetabolism, the inflammatory response, body composition, the muscle protein net balance, serum and urine hormones and proteins, and cardiac function and changes in liver size were determined.

Results

One hundred and eighty-nine pediatric patients of similar age and gender distribution were included in the study (<40% TBSA burn, n = 43; 40–59% TBSA burn, n = 79; 60–79% TBSA burn, n = 46; >80% TBSA burn, n = 21). Patients with larger burns had more operations, a greater incidence of infections and sepsis, and higher mortality rates compared with the other groups (P < 0.05). The percentage predicted resting energy expenditure was highest in the >80% TBSA group, followed by the 60–79% TBSA burn group (P < 0.05). Children with >80% burns lost the most body weight, lean body mass, muscle protein and bone mineral content (P < 0.05). The urine cortisol concentration was highest in the 80–99% and 60–79% TBSA burn groups, associated with significant myocardial depression and increased change in liver size (P < 0.05). The cytokine profile showed distinct differences in expression of IL-8, TNF, IL-6, IL-12p70, monocyte chemoattractant protein-1 and granulocyte–macrophage colony-stimulating factor (P < 0.05).

Conclusion

Morbidity and mortality in burned patients is burn size dependent, starts at a 60% TBSA burn and is due to an increased hypermetabolic and inflammatory reaction, along with impaired cardiac function.

The effect of oxandrolone on the endocrinologic, inflammatory, and hypermetabolic responses during the acute phase postburn

OBJECTIVE AND SUMMARY BACKGROUND DATA

Postburn long-term oxandrolone treatment improves hypermetabolism and body composition. The effects of oxandrolone on clinical outcome, body composition, endocrine system, and inflammation during the acute phase postburn in a large prospective randomized single-center trial have not been studied.

METHODS

Burned children (n = 235) with >40% total body surface area burn were randomized (block randomization 4:1) to receive standard burn care (control, n = 190) or standard burn care plus oxandrolone for at least 7 days (oxandrolone 0.1 mg/kg body weight q.12 hours p.o, n = 45). Clinical parameters, body composition, serum hormones, and cytokine expression profiles were measured throughout acute hospitalization. Statistical analysis was performed by Student t test, or ANOVA followed by Bonferroni correction with significance accepted at P < 0.05.

RESULTS

Demographics and clinical data were similar in both groups. Length of intensive care unit stay was significantly decreased in oxandrolone-treated patients (0.48 +/- 0.02 days/% burn) compared with controls (0.56 +/- 0.02 days/% burn), (P < 0.05). Control patients lost 8 +/- 1% of their lean body mass (LBM), whereas oxandrolone-treated patients had preserved LBM (+9 +/- 4%), P < 0.05. Oxandrolone significantly increased serum prealbumin, total protein, testosterone, and AST/ALT, whereas it significantly decreased alpha2-macroglobulin and complement C3, P < 0.05. Oxandrolone did not adversely affect the endocrine and inflammatory response as we found no significant differences in the hormone panels and cytokine expression profiles.

CONCLUSIONS

In this large prospective, double-blinded, randomized single-center study, oxandrolone shortened length of acute hospital stay, maintained LBM, improved body composition and hepatic protein synthesis while having no adverse effects on the endocrine axis postburn, but was associated with an increase in AST and ALT.

Endocrine modifications and interventions during critical illness

The ongoing hypermetabolic response in patients with prolonged critical illness leads to the loss of lean tissue mass. Since the cachexia of prolonged illness is usually associated with low concentrations of anabolic hormones, hormonal intervention has been thought to be beneficial. However, most interventions have been shown to be ineffective and their indiscriminate use even causes harm. Before considering endocrine intervention in these frail patients, a detailed understanding of the neuroendocrinology of the stress response is warranted. It is now clear that the acute phase and the later phase of critical illness behave differently from an endocrinological point of view. The acute stress reponse consists primarily of an actively-secreting pituitary in the presence of low circulating peripheral anabolic hormones, suggesting resistance of the peripheral tissues to the effects of anterior pituitary hormones. However, when the disease process becomes prolonged, there is a uniformly-reduced pulsatile secretion of anterior pituitary hormones with proportionally reduced concentrations of peripheral anabolic hormones. The origin of this suppressed pituitary secretion is located in the hypothalamus, as hypothalamic secretagogues can reactivate the anterior pituitary and restore pulsatile secretion. The reactivated pituitary secretion is accompanied by an increase in peripheral target hormones, indicating at least partial sensitivity of these tissues to anterior pituitary hormones in this chronic phase of illness. Thus, endocrine intervention with a combination of hypothalamic secretagogues that more completely reactivate the anterior pituitary could be a more physiological and effective strategy for inducing anabolism in patients with prolonged critical illness.

Practical guidelines for nutritional management of burn injury and recovery

Nutrition practice in burn injury requires a multifaceted approach aimed at providing metabolic support during a heightened inflammatory state, while accommodating surgical and medical needs of the patient. Nutritional assessment and determination of nutrient requirements is challenging, particularly given the metabolic disarray that frequently accompanies inflammation. Nutritional therapy requires careful decision making, regarding the safe use of enteral or parenteral nutrition and the aggressiveness of nutrient delivery given the severity of the patient's illness and response to treatment. With the discovery that specific nutrients can actually alter the course of disease, the role of nutrition support in critical illness has shifted from one of preventing malnutrition to one of disease modulation. Today the use of glutamine, arginine, essential fatty acids, and other nutritional factors for their effects on immunity and cell regulation is becoming more common, although the evidence is often lagging. An exciting dichotomy exits, forcing nutrition support specialists to make responsible choices while remaining open to new potential helpful therapeutic options.

Fire and smoke injuries

The successful management of burns and related injuries requires a comprehensive team approach at a designated burn center. This team should consist of burn surgeons, burn nurses, respiratory therapists, physical therapists, occupational therapists, clinical nutritionists, social workers, chaplains, and other clinical consultants. This article focuses specifically on the management of thermal burns and inhalational injuries, with an emphasis on assessment, resuscitation, and critical care management. It also discusses special considerations related to burned trauma patients.

Advances in burn critical care

BACKGROUND

Management of burn patients requires a complex interaction of surgical, medical, critical care, and rehabilitation approaches. Severe burn patients are some of the most challenging critically ill patients who may have multiple-system organ failure with life-threatening complications.

OBJECTIVE

To review and highlight some of the recent advances in burn critical care. We focused on some of the new treatment modalities in the management of respiratory complications, advances in burn resuscitation, management of the metabolic response to burns, and recent ideas in burn immunotherapy.

DATA SOURCE

A search of the MEDLINE database and manual review of published articles and abstracts from national and international meetings. DATA SYNTHESES AND CONCLUSIONS: The respiratory management of burn patients includes strategies to minimize iatrogenic injury with low tidal volume ventilation, to improve ventilation/perfusion mismatch, and to diagnosis pneumonia. Many aspects of burn resuscitation remain controversial, and the best form of fluid resuscitation has yet to be identified. Recent research in the metabolic response to thermal injury has identified many potentially beneficial treatments. Although immunomodulation therapy is promising, currently most of these treatments are not clinically viable, and further clinical and translational research is warranted.

Post burn muscle wasting and the effects of treatments

Severe burns are typically followed by a hypermetabolic response that lasts for at least 9-12 months post-injury. The endocrine status is also markedly altered with an initial and then sustained increase in proinflammatory 'stress' hormones such as cortisol and other glucocorticoids, and catecholamines including epinephrine and norepinephrine by the adrenal medulla and cortex. These hormones exert catabolic effects leading to muscle wasting, the intensity of which depends upon the percentage of total body surface area (TBSA) involved, as well as the time elapsed since initial injury. Pharmacological and non-pharmacological strategies may be used to reverse the catabolic effect of thermal injury. Non-pharmacological strategies include early excision and wound closure of burn wound, aggressive treatment of sepsis, elevation of the environmental temperature to thermal neutrality (31.5+/-0.7 degrees C), high carbohydrate, high protein continuous enteral feeding and early institution of resistive exercise programs. Pharmacological modulators of the post-burn hypermetabolic response may be achieved through the administration of recombinant human growth hormone, low dose insulin infusion, use of the synthetic testosterone analogue, oxandrolone and beta blockade with propranolol. This paper aims to review the current understanding of post-burn muscle proteolysis and the effects of clinical and pharmacological strategies currently being studied to reverse it curb these debilitating sequelae of severe burns.

Glucose-lipid ratio is a determinant of nitrogen balance during total parenteral nutrition in critically ill patients: a prospective, randomized, multicenter blind trial with an intention-to-treat analysis

OBJECTIVE

Protein sparing, the major goal of nutritional support, may be affected by the glucose/lipid ratio. This study in critically ill patients compared the efficacy and tolerance of two isocaloric isonitrogenous total parenteral nutritions (TPN) having different glucose/lipid ratios.

DESIGN

Multicentric prospective randomized study.

PATIENTS

47 patients with SAPS I score higher than 8 and requiring exclusive TPN.

INTERVENTIONS

Patients received glucose/lipid ratios of 50/50 or 80/20. For 7 days all patients received 32 glucidolipidic kcal/kg and 0.27 g/kg nitrogen daily. All-in-one bags were prepared using industrial mixtures and a fat emulsion.

MEASUREMENTS AND RESULTS

We determined TPN efficacy by nitrogen balance, urinary 3-methylhistidine/creatinine ratio, transthyretin and tolerance by glycemia, and liver enzymes. After controlling for five variables with significant effects, patients receiving the 50/50 ratio during TPN had significantly higher nitrogen balance than those receiving the 80/20 ratio. The daily difference in mean nitrogen sparing effect in favor of the latter group was 1.367 g (95% CI 0.0686-2.048). Glycemia on day 4 and gamma-glutamyltranspeptidase on day 8 were higher in group receiving the the 80/20 ratio.

CONCLUSIONS

In critically ill patients TPN at a glucose/lipid ratio of 80/20 ratio induces a small nitrogen sparing effect compared to the ratio of 50/50, at the expense of poorer glycemic control. The clinical significance is unclear.

Postoperative protein sparing with epidural analgesia and hypocaloric dextrose

OBJECTIVE

We examined the hypothesis that epidural analgesia prevents the increase in amino acid oxidation after elective colorectal surgery in patients receiving hypocaloric infusion of dextrose.

SUMMARY BACKGROUND DATA

Increased oxidative protein loss after surgery may adversely affect postoperative outcome. We have previously shown that effective segmental pain relief by epidural analgesia improves postoperative substrate utilization, resulting in less protein catabolism.

METHODS

We randomly allocated 10 patients to receive general anesthesia combined with epidural analgesia using bupivacaine/fentanyl and 10 to receive general anesthesia followed by patient-controlled analgesia with intravenous morphine. All patients received a peripheral 72-hour infusion of dextrose 10% from the day before until the second day after surgery. The dextrose infusion rate was adjusted to provide 50% of the patients' resting energy expenditure. The primary end point was whole-body leucine oxidation as determined by a stable isotope tracer technique (l-[1-C]leucine).

RESULTS

In the intravenous analgesia group, leucine oxidation increased from 19 +/- 4 to 28 +/- 6 micromol kg h after surgery. Epidural analgesia prevented this increase of leucine oxidation (preoperative 21 +/- 6 micromol kg h, postoperative 21 +/- 5 micromol kg h). This difference was statistically significant (P = 0.01; analysis of variance for repeated measures).

CONCLUSION

Perioperative epidural analgesia and hypocaloric dextrose infusion suppress the postoperative increase in amino acid oxidation, thereby saving more than 100 g of lean body mass per day.

The pragmatics of feeding the pediatric patient with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) represents the ultimate pulmonary response to a wide range of injuries, from septicemia to trauma. Optimal nutrition is vital to enhancing oxygen delivery, supporting adequate cardiac contractility and respiratory musculature, eliminating fluid and electrolyte imbalances, and supporting the proinflammatory response. Research is providing a better understanding of nutrients that specifically address the complex physiologic changes in ARDS. This article highlights the pathophysiology of ARDS as it relates to nutrition, relevant nutritional assessment, and important enteral and parenteral considerations for the pediatric patient who has ARDS.

Support of the metabolic response to burn injury

Severe burn causes metabolic disturbances that can last for a year after injury; persistent and profound catabolism hampers rehabilitative efforts and delays the meaningful return of individuals to society. The simplest, effective anabolic strategies for severe burn injuries are: early excision and grafting of the wound; prompt treatment of sepsis; maintenance of environmental temperature at 30-32 degrees C; continuous feeding of a high carbohydrate, high protein diet, preferably by the enteral route; and early institution of vigorous and aerobic resistive exercise programmes. To further keep erosion of lean body mass to a minimum, administration of anabolic agents, recombinant human growth hormone, insulin, oxandrolone, or anticatabolic drugs such as propranolol are alternative approaches. Exogenous continuous low-dose insulin infusion, beta blockade with propranolol, and use of the synthetic testosterone analogue oxandrolone are the most cost effective and least toxic pharmacological treatments to date.

Metabolic, endocrine, and immune effects of stress hyperglycemia in a rabbit model of prolonged critical illness

Stress hyperglycemia is frequent in critically ill patients. The aim of this study was to investigate the effect of blood glucose control with insulin on endocrine, metabolic, and immune function in an animal model of severe injury. Seventy-two hours after alloxan injection and exogenous insulin infusion combined with continuous iv parenteral nutrition, male New Zealand White rabbits received a burn injury and were allocated to a normoglycemic (n = 17) or hyperglycemic (n = 13) group. In the normoglycemic group, blood glucose levels were kept between 3.3 and 6.1 mmol/liter by insulin infusion, whereas in the hyperglycemic group blood glucose levels were maintained at 13.8-16.6 mmol/liter. Blood was drawn for biochemical analysis at regular time points. At 24 and 72 h after burn injury, immune function of monocytes was assessed in vitro. Maintenance of normoglycemia with exogenous insulin after severe trauma to a large extent prevented weight loss, lactic acidosis, and hyponatremia. Furthermore, within 3 d after injury, the intervention improved phagocytosis of monocytes investigated in fresh cells by more than a mean 150% (P = 0.006) and after 24-h incubation with or without lipopolysaccharide by more than a mean 4-fold (P = 0.001) and 2-fold (P = 0.05), respectively. Oxidative killing after 24-h incubation was also improved by 2-fold (P = 0.05), but no effect on chemotaxis was detected. Concomitantly, inflammation and stress-induced growth hormone hypersecretion were suppressed. Prevention of catabolism, acidosis, excessive inflammation, and impaired innate immune function may explain previously documented beneficial effects of intensive insulin therapy on outcome of critical illness.

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.

Effects of early excision and aggressive enteral feeding on hypermetabolism, catabolism, and sepsis after severe burn

BACKGROUND

Severe burn induces a systemic hypermetabolic response, which includes increased energy expenditure, protein catabolism, and diminished immunity. We hypothesized that early burn excision and aggressive enteral feeding diminish hypermetabolism.

METHODS

Forty-six burned children were enrolled into a cohort analytic study. Cohorts were segregated according to time from burn to transfer to our institution for excision, grafting, and nutritional support. No subject had undergone wound excision or continuous nutritional support before transfer. Resting energy expenditure, skeletal muscle protein kinetics, the degree of bacterial colonization from quantitative cultures, and the incidence of burn sepsis were measured as outcome variables.

RESULTS

Early, aggressive treatment did not decrease energy expenditure; however, it did markedly attenuate muscle protein catabolism when compared with delay in aggressive treatment. Wound colonization and sepsis were diminished in the early treatment group as well.

CONCLUSION

Early excision and concurrent aggressive feeding attenuate muscle catabolism and improve infectious outcomes after burn.

Nutritional papers in ICU patients: what lies between the lines?

The abundance of literature related to nutritional support reflects its recently recognised role in preventing metabolic complications and gut dysfunction during critical illness. However, some published studies lack relevance to critically ill patients, as a result of the selection of subjects and outcome variables, or flaws in the study design, as well as in the type, composition, timing, route of administration and amount of nutritional support given. This review will highlight these confounding factors by describing two imaginary (but typical) clinical trials and by analysing some studies published. The point at issue is that basic quality requirements, such as the formulation of a prospective hypothesis and the delineation of the effects of the reference treatment, are often lacking in many studies published. Data analysis was often found to be biased by the absence of statistical power calculation and intention-to-treat analysis. Globally, studies designed to assess the effects of nutritional support on the outcome of critically ill patients, rarely fulfil basic quality requirements and should therefore be interpreted cautiously. We suggest simple strategies or study design that will allow important questions to be answered by future clinical trials.