APPRAISAL AND MONITORING OF POSTOPERATIVE NUTRITIONAL SUPPORT

Quantitative and qualitative nutritional requirements depend on the le vel of energetic expenses. Various formulas, especially the tables by Harris and Benedict allow the estimation of the level of energetic exp enses with an approximation of 14 %. Corrective factors permit an adju stment of the figures, according to the level of body aggression. In c omplex cases, indirect calorimetry allows a more accurate appraisal of energetic expenses. This technique provides also indications on the u tilisation of each substrate and allows therefore to determine the opt imal carbohydrate-lipid ratio for each patient. The assessment of the direct benefit of artificial nutritional support relies on anthropomet ric techniques and at present on body composition appraisal by determi nation of its impedance. The changes in muscular strength are difficul t to assess. Moreover the time course of body weight is not specific f or nutritional status. Therefore other biological indicators such as t he nitrogen balance, the concentration of plasma proteins and albumin are more often assessed; proteins with a short half-life depend on the body aggression level. The potassium balance, which is easy to obtain in clinical practice, is a relevant indicator for nitrogen balance an d protein synthesis. Clinical monitoring includes the checking of hydr atation and its impact on the circulatory, respiratory and renal funct ions. The tolerance of enteral nutrition is appraised by the quality o f gastrointestinal function; Biological monitoring includes the electr olyte balance and various variables of carbohydrate, lipidic and prote ic metabolisms. It allows to check the absence of hyperglycaemia, hype rlipidaemia and cholestasis. The daily checking of catheters is part o f the monitoring of nutritional support. It is concluded that appraisa l and monitoring of postoperative nutritional support can be achieved in a majority of patients with indicators easily available in daily pr actice.