30 Dec 07
Posted in Nutrition, Sepsis at 23:11 by Laci
Critical Care Medicine 2007;35:S553-S556
By I Tjader, A Berg, J Wernerman
There is still insufficient knowledge about in vivo glutamine metabolism and the regulation of glutamine homeostasis, particularly during metabolic stress. A shortage of glutamine is associated with a poor outcome, whereas for septic patients in the intensive care unit an increased availability of glutamine can prevent mortality and morbidity. Cellular defense mechanisms depend on normal glutamine availability to respond adequately to challenges presented. In clinical practice, treatment of plasma glutamine depletion improves outcome for the critically ill patient. An increased metabolic need for glutamine must be met with an increased consumption of glutamine. Ordinary food is not a sufficient supply of glutamine for the patient with multiple organ failure in the intensive care unit, but that is also true for several other nutrients. It is, therefore, debatable whether an exogenous supply of glutamine should be regarded as a pharmacologic treatment or whether this just represents physiology in stressed states. If a glutamine shortage requires substitution, supplementation to the normal concentration is compensation of a shortage, and the effect is physiological.
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Posted in Nutrition, Sepsis at 23:06 by Laci
By T Bongers, R D Griffiths, A McArdle
Critical Care Medicine 2007;35:S545-S552
We know that critically ill patients suffering from undernutrition with a limited nutritional reserve have a poorer outcome. Furthermore, having a low body mass index has been shown to be an independent predictor of excess mortality in multiple organ failure. Therefore, nutritional support has gained increasing interest in critical illness with the hope of preventing or attenuating the effects of malnutrition. A negative nitrogen balance is the characteristic metabolic feature in critical illness, with the major protein loss derived from skeletal muscle. In particular, glutamine concentrations are rapidly reduced in plasma and muscle.
Over the last 20 yrs or so, increasing evidence is emerging to support the use of glutamine supplementation in critical illness. Clinical trials have found a mortality and morbidity advantage with glutamine supplementation. The advantage appears to be greater the more glutamine is given and greater again when given parenterally. Various modes of action have been postulated. Glutamine seems to have an effect on the immune system, antioxidant status, glucose metabolism, and heat shock protein response. However, the benefit of exogenous glutamine on morbidity and mortality is not universally accepted. This review critically appraises the current clinical evidence regarding glutamine supplementation in critical illness.
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Posted in Nutrition, Sepsis at 23:04 by Laci
By Y C Luiking, N Deutz
Critical Care Medicine 2007;35:S557-S563
Sepsis is a severe condition in critically ill patients and is considered an arginine deficiency state. The rationale for arginine deficiency in sepsis is mainly based on the reduced arginine levels in sepsis that are associated with the specific changes in arginine metabolism related to endothelial dysfunction, severe catabolism, and worse outcome.
Exogenous arginine supplementation in sepsis shows controversial results with only limited data in humans and variable results in animal models of sepsis. Since in these studies the severity of sepsis varies but also the route, timing, and dose of arginine, it is difficult to draw a definitive conclusion for sepsis in general without considering the influence of these factors.
Enhanced nitric oxide production in sepsis is related to suggested detrimental effects on hemodynamic instability and enhanced oxidative stress. Potential mechanisms for beneficial effects of exogenous arginine in sepsis include enhanced (protein) metabolism, improved microcirculation and organ function, effects on immune function and antibacterial effects, improved gut function, and an antioxidant role of arginine. We recently performed a study indicating that arginine can be given to septic patients without major effects on hemodynamics, suggesting that more studies can be conducted on the effects of arginine supplementation in septic patients.
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Posted in Nutrition, Sepsis at 23:02 by Laci
By A Barbul, A Uliyargoli
Critical Care Medicine 2007;35:S564-S567
Given the multiple biological, metabolic, and pharmacologic effects of supplemental arginine, much effort has been devoted to defining its role in numerous clinical conditions. Herein, we review the multiple pathways of arginine metabolism with its various enzyme systems; the effect of arginine on nutrition, healing, and immune system; and its clinical use. Sepsis has been postulated to be an arginine-deficient state and/or a syndrome with elevated levels of nitric oxide. So-called immunonutritional formulations containing various nutritional components have been used most often, yet the effects often are attributed to arginine alone. Such conclusions led to guidelines recommending against the use of arginine-supplemented diets in critically ill patients. While caution in the face of a lack of evidence for benefit in sepsis is commended, well-defined studies examining arginine monotherapy in the context of full nutritional support should be carried out so as to define the possible clinical uses of arginine in critically ill and septic patients.
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