Parenteral administration of different amounts of branch-chain amino acids in septic patients: clinical and metabolic aspects

Nutritional support in sepsis: still skeptical?

The immediate metabolic response to a septic challenge is probably adaptive, meaning that nutritional interference, mainly via the parenteral route, during this early phase of instability can do more harm than good. During the later phases, a gradual increase in enteral nutrition, at the expense of parenteral nutrition, combined with the administration of nutraceuticals such as glutamine and omega-3 fatty acids, can counteract wasting and modulate the complex inflammatory response and immunosuppression associated with sepsis. In these times of scarce resources, there is an urgent need to clearly document the efficacy of immuno/pharmaconutrients, individually and in combination, enterally or parenterally, before proposing them for routine management of septic patients in the intensive care unit.

Nutritional assessment in head injured patients through the study of rapid turnover visceral proteins

BACKGROUND & AIMS

Nutritional monitoring of rapid turnover visceral protein is important in the recognition of malnutrition in patients admitted to the Intensive Care Unit (ICU). We studied prealbumin and retinol-binding protein in patients who received three different kinds of artificial nutrition in order to evaluate the appropriateness of artificial nutrition.

METHODS

45 consecutive head injury patients received enteral (Group A), parenteral (Group B) or both enteral and parenteral nutrition (Group C) at random. We considered these parameters: prealbumin, retinol binding protein and nitrogen balance before (T1), after 3 (T2), 7 (T3) and 11 (T4) days after the beginning of study. Statistical analysis was performed with Kruskal-Wallis test and Bonferroni's t -test.

RESULTS

Plasma prealbumin and Retinol binding protein (RBP) showed an increasing of basal values during the study period in all groups (<< 0.0001) and more significantly in group A (Enteral nutrition P < 0. 001 vs Total parenteral nutrition (TPN) and Enteral P<< 0.01 vs Enteral and parenteral nutrition).

CONCLUSION

Data obtained in the present study indicate that a laboratory is essential for monitoring nutritional assessment and for checking the appropriateness of nutritional therapy. We found prealbumin to be the most sensitive measure and found it to be the test of choice for early assessment and intervention.

Adjunctive Therapies for Sepsis and Septic Shock

The inflammatory cascade that ensues after an infectious insult is protean in its manifestations, resulting in mild self-limited illness in some patients, while progressing to fulminant sepsis and multisystem organ failure in others. Research into the pathophysiology of this cascade has been intense, but advances in the treatment of sepsis have been few and far between. Although mortality rates have been impacted slightly in patients with sepsis--with improved survival in certain patient subgroups--overall survival still reaches only 55% to 60%. In this paper we will review some of the most recent advances in the therapy of the sepsis syndrome, specifically the roles of cytokine modifiers, supranormal delivery of oxygen, granulocyte colony-stimulating factor administration in leukopenic patients, and parenteral nutrition. Hopefully, these modalities represent additional steps in the path towards a meaningful improvement in survival from this catastrophic condition.

A comparison of anthropometry, biochemical variables and plasma amino acids among centenarians, elderly and young subjects

OBJECTIVE

Aging health is associated with nutritional changes which are not well understood and were therefore evaluated in this study by comparing the nutritional status of centenarians and elderly (in their 70s) relative to young subjects.

SUBJECTS

The participants were 27 young subjects (10 males, 17 females), 40 healthy elderly (20 males, 20 females) and 32 centenarians (9 males, 23 females).

METHODS

The activities of daily living (ADL), height, weight, body mass index (BMI), biochemical variables (total protein, albumin, triglycerides as well as total, HDL, LDL and VLDL cholesterol) and plasma amino acid profiles were evaluated.

RESULTS

Compared with young subjects, lower (p<0.05) height, weight, total protein, albumin and albumin/globulin (A/G) ratio and total cholesterol for centenarians and height, albumin and A/G ratio for elderly were observed in both genders. Total cholesterol of male centenarians was lower than in young and elderly subjects and total and LDL cholesterol concentrations of female elderly were higher than those of young and centenarian subjects. However, the cholesterol concentrations of all the centenarians were within the reference range. The ratios of essential amino acids to nonessential amino acids were significantly lower (p<0.05) in the centenarians than the young subjects. Clear changes in individual amino acids with aging were lower (p<0.05) branched chain amino acids and methionine and higher proline and cystine, which are similar to the amino acid profiles in liver deterioration.

CONCLUSION

The results suggest that the centenarians had poor nutritional status, which may be due to their decreased metabolism and the possibility that only short, slender individuals with low lipids, protein and essential amino acids are those that tend to survive to be centenarians.

Enteral infusion of sodium 2-ketoisocaproate in endotoxic rats

OBJECTIVE

In view of our previous finding that the intravenous infusion of 2-ketoisocaproate (KIC) improved survival in septic rats, we endeavored to determine whether the enteral infusion of KIC improves survival in endotoxic rats, and, if so, the mechanism of this effect.

SUBJECTS

Eighty-five rats were given 15 mg/kg of Escherichia coli lipopolysaccharide (026:B6).

INTERVENTIONS

KIC, sodium pyruvate (PYR), or sodium bicarbonate (HCO3) was infused continuously intragastrically at 18.75 mmol/kg/day.

MEASUREMENTS AND MAIN RESULTS

KIC administration increased circulating concentrations of KIC and ketone bodies. Survival rates were: KIC 17/32; PYR 2/22; and HCO3 8/31. The significant improvement in survival with KIC, in contrast with HCO3 (p<.04) or PYR (p<.002), points to an effect specific to KIC rather than to ketoacids generally, and argues against an antioxidant mechanism to explain improved survival with enteral administration. To determine whether altered nitric oxide production was responsible, plasma nitrite plus nitrate concentrations were measured sequentially in rats given a lower dose of lipopolysaccharide plus continuous intragastric KIC, PYR, or HCO3. All rats exhibited pronounced increases in plasma nitrite plus nitrate concentrations, peaking at 8 hrs, but both KIC and PYR caused greater increases than HCO3. Thus, differences in nitric oxide production cannot account for the different effects of PYR and KIC on survival. However, KIC infusion for 8 hrs substantially increased ketone bodies in blood and liver, in comparison with the infusion of HCO3 or PYR.

CONCLUSION

Continuous enteral infusion of KIC improves survival in endotoxemia, probably by its conversion to ketone bodies, which serve as an alternative energy substrate.

Regulation of type I collagen mRNA in lung fibroblasts by cystine availability

The steady-state level of alpha1(I) collagen mRNA is regulated by amino acid availability in human lung fibroblasts. Depletion of amino acids decreases alpha1(I) collagen mRNA levels and repletion of amino acids induces rapid re-expression of alpha1(I) mRNA. In these studies, we examined the requirements for individual amino acids on the regulation of alpha1(I) collagen mRNA. We found that re-expression of alpha1(I) collagen mRNA was critically dependent on cystine but not on other amino acids. However, the addition of cystine alone did not result in re-expression of alpha1(I) collagen mRNA. Following amino acid depletion, the addition of cystine with selective amino acids increased alpha1(I) collagen mRNA levels. The combination of glutamine and cystine increased alpha1(I) collagen mRNA levels 6.3-fold. Methionine or a branch-chain amino acid (leucine, isoleucine or valine) also acted in combination with cystine to increase alpha1(I) collagen mRNA expression, whereas other amino acids were not effective. The prolonged absence of cystine lowered steady-state levels of alpha1(I) collagen mRNA through a mechanism involving decreases in both the rate of gene transcription as assessed by nuclear run-on experiments and mRNA stability as assessed by half-life determination in the presence of actinomycin D. The effect of cystine was not mediated via alterations in the level of glutathione, the major redox buffer in cells, as determined by the addition of buthionine sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase. These data suggest that cystine directly affects the regulation of alpha1(I) collagen mRNA.

Nutrition support in patients with multiple organ failure

The problem with any attempt to feed patients in multiple organ failure is that, because of an ongoing inflammatory process, the conventional techniques of supplying energy and protein do not maintain lean tissue mass. In addition, the conventional markers of nutritional status, both anthropometric (body mass and composition, arm circumference, etc.) and visceral protein (albumin, prealbumin) as well as immunological markers (delayed reactive skin hypersenstivity to common antigens and lymphocyte counts) are confounded by fluid retention (5-15 l) and the metabolic response to the illness. Recent research has focussed on the nature and origin of this inflammatory response, the problems of trying to feed an individual undergoing such a response, the details of the protein breakdown observed in sepsis and multiple organ failure and methods of modifying the response favourably.