Prise en charge nutritionnelle préopératoire. [Preoperative nutritional support.]

Undernutrition is an independent factor of postoperative morbidity and mortality The aim of a preoperative nutritional support is to enhance immune muscular and cognitive functions, and to support wound healing This nutritional support (e g dietary management enteral or parenteral nutrition) should be limited to high risk situations with a beneficial effect of nutrition for the patient undernutrition major surgery and elderly Preoperative nutritional support should be scheduled for atleast 7 to 10 days before the surgery During the preoperative period the type and route of an eventual postoperative nutritional assistance should be anticipated In the case of emergency surgery nutritional assessment of the patient should be done as soon as possible before surgery or in the 48 h postoperative period Finally, in elective surgery, preoperative fasting should be limited to 2-3 hours for clear liquids and 6 hours for solids (C) 2010 Published by Elsevier Masson SA

Br J Anaesth

BACKGROUND: We investigated whether cardiac output measured with pulse wave transit time (esCCO, Nihon Kohden, Tokyo, Japan) is able to track changes in cardiac output induced by an increase in preload (volume expansion/passive leg-raising) or by changes in vasomotor tone (variation in norepinephrine dosage) in critically ill patients. METHODS: Eighty patients for whom the decision to give fluid (500 mL of saline over 15 min) (n=20), to perform passive leg-raising (n=20), and to increase (n=20) or to decrease (n=20) norepinephrine were included by the physician. Cardiac output was measured with pulse wave transit time (CO-esCCO) and transthoracic echocardiography (CO-TTE) before and after therapeutic intervention. RESULTS: Comparison between CO-TTE and CO-esCCO showed a bias of -0.7 l min(-1) and limits of agreement of -4.4 to 2.9 l min(-1), before therapeutic intervention and a bias of -0.5 l min(-1) and limits of agreement of -4.2 to 3.2 l min(-1) after therapeutic intervention. Bias was correlated with systemic vascular resistance (r(2)=0.60, P\textless0.0001). Percentage error was 61% before and 59% after therapeutic intervention. Considering the overall data (n=80), the concordance rate was 84%, polar plot analysis revealed an angular bias (sd) of -11°(35°) and radial limits of agreement of (sd 50°). With regard to passive leg-raising and volume expansion groups (n=40), the concordance rate was 83%, the angular bias (sd) was -20°(36°) and radial limits of agreement ( 50°). Considering variations in norepinephrine dosage groups (n=40), the concordance rate was 86%, the angular bias (sd) was -1.8°(33°) and radial limits of agreement (40°). CONCLUSIONS: esCCO was not able to track changes in cardiac output, induced by an increase in preload or by variations in vasomotor tone. Therefore, esCCO cannot guide haemodynamic interventions in critically ill patients

Scénarios de pénétration des réacteurs à neutrons rapides en vue de limiter la consommation d'uranium naturel cumulée

Dans un contexte de croissance modérée de la demande électrique en France (temps de doublement : cent ans), on montre que les réacteurs à neutrons rapides (RNR) peuvent constituer la relève des réacteurs à eau pressurisée (REP) à partir des années 2000, permettant ainsi de limiter à moins de 450 000 t la consommation en uranium naturel cumulée, sous réserve : — qu'ils soient initialement de bons surgénérateurs ; — que le temps de séjour hors pile soit faible (au plus égal à trois ans). Le recyclage du plutonium dans les REP permet d'éviter des fluctuations importantes du stock de plutonium. Cependant, ce recyclage réduit les quantités de plutonium disponibles. De ce fait, le démarrage des RNR est retardé et les besoins en uranium naturel sont augmentés sensiblement. A court terme, un bon convertisseur est une solution de substitution au « recyclage Pu classique », mais non aux RNR ; à long terme, en symbiose avec les RNR, il permet une bonne gestion des stocks de plutonium. La vitesse de croissance du parc RNR nécessite d'avoir un produit industriel dès l'an 2000