Mécanismes de la dénutrition chez l'enfant et l'adolescent

Malnutrition in child and adolescent is observed in various situations where there is an imbalance between the food intakes and caloric and proteic needs. Child is particularly vulnerable because its reserves are weak and its high caloric and proteic needs because of its growth. Various mechanisms leading to malnutrition were brought back and correspond to distinct clinical entities. The situations of malnutrition by exclusive mechanism of intake deficiency meet primarily in third world where they can take the form of starvation, extreme adaptive situation with prolonged fast. During situations known as of aggression like severe sepsis, polytraumatism, extended burn, surgery, malnutrition can settle quickly. Mechanism brought back in situation of acute aggression is defined classically like related to hypermetabolism with hypercatabolism. Kwashiorkor, another type of caloric and proteic malnutrition concerning child in third world, cannot be regarded as a simple caloric and proteic deficiency. It currently seems that a deficiency at the same time in macronutriments and micronutriments plays a part in genesis of this pathology. The glutathion seems in particular, to play a fundamental part in the kwashiorkor's pathophysiology. The most documented hypothesis relates imbalance between production of free radicals and mechanisms of defence. Mechanisms of repair would be insufficient, and persistence of membrane deteriorations would cause anomalies observed in kwashiorkor like oedema, hepatic overload, neurological disorders and diarrhoea.     

Mécanismes de l’action antidiabétique des thiazolidinediones

The range of therapeutic modalities to treat type 2 diabetes mellitus has broadened in recent years. Thiazolidinediones (TZD) are currently available classe of anti-hyperglycemic agents with insulin-sensitizing properties. TZD improve insulin resistance. TZD act as agonists of peroxisome proliferator-activated receptor-gamma (PPARγ) primarily in adipose tissue. PPAR-gamma receptor activation by TZD improves insulin sensitivity by promoting fatty acid uptake into adipose tissue, increasing production of adiponectin and reducing levels of inflammatory mediators such as tumour necrosis factor-alpha (TNF-alpha), plasminogen activator inhibitor-1(PAI-1) and interleukin-6 (IL-6).     

Les conséquences de la malnutrition chez le patient chirurgical

In patients with severe diseases, malnutrition could be a supplementary source of post-operative complications. In these cases, the mechanisms of immunity are profoundly altered and the risk of septic complications is increased. The prognostic nutritional indices make it possible to assess the role of malnutrition in evaluating the postoperative risk. The efficacy of preoperative parenteral nutrition is uncertain and depends mainly on the underlying disease. In cancer patients, the overall results showed that preoperative parenteral nutrition could effectively reduce postoperative complications and mortality rates. Nevertheless, more specific studies on homogeneous series should be performed to determine the real effect of correcting malnutrition in surgical patients.     

Place de l’alpha-cétoglutarate d’ornithine dans le traitement de la sarcopénie

Sarcopenia is defined as the loss of muscle mass and function during ageing. Despite its important metabolic and functional consequences, the underlying mechanisms of sarcopenia are poorly understood. A blunted anabolic response to food intake together with a reduction in the peripheral availability of amino acid associated with a greater use by the splanchnic bed likely participate in this phenomenon. In this context, ornithine α-ketoglutarate (OKG), which stimulates the secretion of insulin and growth hormone and the production of amino acids with anabolic function and/or low splanchnic extraction could improve the mechanical and metabolic capacities of muscle in older individuals. If so, the ultimate goal of such treatment should be to improve muscle contractile function and limit the loss of mobility in the elderly.     

Biodisponibilité de la glutamine et réponse du métabolisme protéique à l'apport de glutamine chez l'homme

Glutamine is synthetized in most tissue and accounts for two-thirds of the free amino acid pool in skeletal muscle. Glutamine is not only an interorgan nitrogen shuttle but a precursor of urinary ammonium, and a favorite fuel of the immune system and the gut (which uses ≠ 17 g of glutamine per day). Because they were designed at a time when glutamine was considered both unstable and non-essential, « tradtionalparenteral nutrition (PN) solutions are devoid of glutamine. Although « classicPN is able to maintain normal rates of glutamine turnover in healthy subjects or unstressed patients, classic PN solutions are unable to correct the precipitous depletion of glutamine pool that accompagnies catabolic illness. Glutamine becomes a « conditionally essentialamino acid in these situations. Replenishment of glutamine pool seems to stimulate protein synthesis, and improve nitrogen balance in catabolic patients. Supplementation of PN with glutamine-containing dipeptides or α-ketoglutarate (at doses of 15–50 g/d) is as effective as glutamine itself. The enteral route represents an attractive alternative for the supply of glutamine since : 1) glutamine is efficiently absorbed ; 2) nearly 50 % of enterally infused glutamine reaches systemic blood ; 3) glutamine residues present in a bound form in peptides seem to be bioavailable ; and 4) in addition to its protein anabolic effect, glutamine affects intestinal absorption and trophicity.     

Supplémentation en vitamine K lors de la nutrition parentérale chez l’enfant

The supplementation of vitamin K is necessary for total parenteral nutrition (TPN) patient to avoid hemorrhagic risk. In home TPN and to simplify the children administration, the vitamin K could be added once or twice monthly in admixtures. The aim of this work was to evaluate the vitamin K stability (20 mg/L) in usual conditions of administration (binary or ternary mixtures, at room temperature and at artificial light for 24 hours) and at storage (binary mixtures protected from light, at 4 °C for 12 hours). Each step of the study was performed with quantification using HPLC method coupled with UV detection at 244 nm on five TPN bags. The results of this study show that the vitamin K was stable for 24 hours at light exposure and at room temperature in binary mixture (96.6%) also ternary (99.8%). The vitamin K was stable at 4 °C for 12 days (98.4%). This work shows that vitamin K can be added directly in TPN and could avoid painful intramuscular injection. Such nutritional admixtures could be prepared beforehand and allow administration at home. This practice is actually consensual in gastro-enterology department at Necker University Hospital. A clinical and biologic monitoring is essential.     

Stratégies de dépistage de la dénutrition chez l''enfant hospitalisé

Metabolic stress modifies homeostasis, therefore nutrient's metabolism and nutritional needs. Stress is a risk factor of malnutrition, which increases morbidity and short-term mortality, and, in the child, can threaten long-term growth. Nutritional assessment is difficult in critically ill children. Nutritional support must be undertaken early as possible, especially in malnourished children and with severe agression. Enteral nutrition must be privileged. Parenteral nutrition is indicated when enteral nutrition is impossible, badly supported or insufficient to satisfy needs. Monitoring must be rigorous because aggression increases the risk of metabolic complications.     

La nutrition artificielle en periopératoire chez le patient diabétique

The diabetic patients are at high risk of malnutrition. One recommends seeking specific deficiencies (zinc, selenium, vitamins C and E) for malnourished diabetic patients. For the perioperative cares, one recommends to cover their protein needs and their caloric needs and to accordingly optimize the antidiabetic treatment. One should probably use oral supplements or enteral nutrition products with a low glycemic index. The presence of diabetic gastroparesis can make it difficult or dissuade enteral nutrition. The incidence of gastroparesis justifies gastric residue control, the use of prokinetic, and nutrition in postpyloric site. An equivalent parenteral carbohydrate intake has a hyperglycaemic effect more important than with the oral or enteral way. It is recommended to use an infusion pump in diabetic patients to administer parenteral nutrition. Daily use of lipid emulsions is recommended in this context.     

Les complications hépatiques de la nutrition parentérale chez l'adulte

Parenteral nutrition-associated liver disease is a frequent and sometimes life-threatening event. The usual presentation consists of chronic cholestasis, which can evolve within months to years to extensive fibrosis and cirrhosis. Histologic lesions are very similar to those observed in cholestatic liver diseases such as primary biliary cirrhosis and sclerosing cholangitis, and can lead to terminal liver failure and portal hypertension. Pathogenic factors involved in these complications are still poorly understood. Patient-dependent factors include very short bowel syndrome and chronic bacterial overgrowth. Nutrition-dependent factors, easy to correct, are hypercaloric parenteral feeding and, especially in Europe, excess fat, the threshold of which is 1 g · kg⁻¹ · d⁻¹ with ω-6 fat emulsions. It is fundamental to decrease the overall frequency of these complications in patients with long-term intestinal failure in order to avoid a combined liver-intestine transplantation. Preventive measures may combine limitation of parenteral fat intake and treatment of putative patient-dependent factors. Ursodeoxycholic acid and taurine-enriched solutions might be promising treatments for such patients.     

Nutrition périopératoire chez la personne âgée. Cas particulier de la fracture de l’extrémité supérieure du col du fémur

Emergency surgery is associated with an increase in the risk of malnutrition in the elderly. Thirty to fifty percent of elderly persons admitted to in surgery are malnourished. In patients for which nutritional status is threatened by both the aging process and comorbidities, the surgical intervention represents an additional stress that will induce or worsen malnutrition. Nutritional care must no be delayed. First choice is the oral route, including protein and energy rich nutritional supplements, and must be a part of multidimensional perioperative care It is recommended to reach 30 to 40 kcal tot/kg/day and 1.2 to 1.5 g of proteins/kg/day. It is recommended to prescribe, during the stay in rehabilitation wards after surgery, oral nutritional supplements. This oral supplementation has been shown to be efficacious in malnourished elderly patients: there is weight gain, a lower risk for complications and a lower mortality rate. However, compliance may be reduced in elderly patients with low appetite, especially in case of dementia, or early medical complications. In order to prevent other falls and fractures, it is recommended to look for vitamin D deficiency and to prescribe vitamin D 800–1200 UI/day.     

L’évaluation nutritionnelle chez le sujet âgé en 2008

Malnutrition is frequent in elderly patients and results from multifactorial mechanisms, including age-related metabolic alterations, reduction of food intake and intercurrent diseases, especially inflammatory processes, that compromise nutritional status. Nutritional evaluation must be systematically and repeatedly performed and based primarily on clinical parameters such as weight, body mass index, weight loss, anthropometric measurements and dietetic history eventually combined in scores such as the mini-nutritional assessment (MNA). Fat-free mass evaluated by bioimpedance analysis has a prognostic value. Hypoalbuminemia is indicative of bad prognosis and may be combined with weight loss in the geriatric nutritional risk index (GNRI) to assess the nutritional risk. The determination of plasma transthyretin (prealbumin) is especially useful to assess acute malnutrition state and the response to nutritional support. Routine determination of the above criteria may be facilitated by the spreading of simple integrated tools and a better education of health professionals to the screening and active treatment of malnutrition in the elderly.