The influence of posttraumatic parenteral calorie and nitrogen supply upon the cumulative nitrogen balance

Abstract

The aim of the study was to describe the influence of posttraumatic calorie and nitrogen (N) supply upon the cumulative N-balance by analyzing the literature of the past 18 years. Three groups of patients were formed, in which nutritional therapy was performed following trauma of differing severity: (1) patients following moderate trauma-N-losses 10-15 g/day; (2) patients following severe trauma--N-losses 15-20 g/day; and (3) polytraumatised patients--N-losses more than 20 g/day. The data gained for the calorie and N-supplies as well as for the N-balances in each group of patients served as a basis for the calculation of regression analyses of higher order; in these the cumulative N-balance was regarded as a function of the calorie and the N-supply: NBcum = f (C, N) Whilst for the group of polytraumatized patients only statements for a nutrient supply of about 20-30 kcal/kg BW/day and 0.2-0.3 g N/kg BW/day are possible, due to the limited data available, general statements about the different influence of calorie and N-supply can be made for nutritional therapy after moderate and major trauma; the calculated functions reveal that the N-supply influences the N-balance decisively, whereas the calorie supply exerts only a slight N-sparing effect. The mathematically calculated optimum of the N-supply after severe trauma is 0.2 g/kg BW/day, corresponding to an amino acid supply of 1.25 g/kg BW/day.