USE OF UREA KINETIC-MODEL TO ESTIMATE PROTEIN-REQUIREMENTS IN CRITICALLY ILL PATIENTS - A CANADIAN VERSION

Renal impairment occurs commonly in critically ill patients, often as a component of the multiple organ dysfunction syndrome. These patients are usually hypermetabolic and aggressive nutrition support can impro ve outcome. Although newer techniques of renal replacement therapy suc h as continuous arteriovenous hemodialysis (CAVHD) have facilitated th e provision of adequate nutrition to critically ill patients with olig uric renal failure, nutritional assessment has become a challenge. The traditional method of determining nitrogen balance is inappropriate b ecause of the accumulation of both fluid and end products of protein c atabolism in these patients. An alternative method of estimating nitro gen balance is the use of urea kinetic modelling. This approach is use d to determine daily nitrogen loss so that protein requirement in the critically ill and chronic renal failure patients can be estimated. Al though the theory of urea kinetics is well established, no equation is derived to estimate nitrogen loss in patients undergoing CAVHD. In ad dition, the application of published equations in a Canadian hospital setting is cumbersome because metric units are used. This article desc ribes a general urea kinetic equation that can be adapted to various c onditions including patients undergoing CAVHD. The incorporation of SI conversion permits ease of protein requirement calculations.