OPTIMAL PROTEIN-REQUIREMENTS DURING THE FIRST 2 WEEKS AFTER THE ONSETOF CRITICAL ILLNESS

Objective: To obtain optimal protein requirements in critically ill se psis or trauma patients during the first 2 wks after admission to the intensive care unit. Design: Retrospective study. Setting: Department of critical care medicine at a teaching hospital. Patients: Immediate posttrauma patients or severely septic patients. Interventions: In viv o neutron activation analysis was used to measure changes in total bod y protein over a 10-day period which began as soon as the patients wer e hemodynamically stable. The patients (trauma, n =18; sepsis, n = 5) were divided into three groups according to the average daily protein intakes. Because the patients were overhydrated (similar to 10 L) and had variable amounts of body fat, the protein intakes were indexed to normally hydrated (corrected) fat-free mass(FFMc): Groups A, B, and C received an average of 1.1,1.5, and 1.9 g/kg FFMc/day protein, respect ively. Measurements and Main Results: Overall, the average loss of tot al body protein was 1.2 +/- 0.7 (SD) kg. Changes in total body protein were significantly (p =.011) different between the three groups. The loss of body protein was significantly more in group A compared with g roups B (p =.013) and C (p =.023). When the protein intake was increas ed from 1.1 g/kg FFMc/day to 1.5 g/kg FFMc/day, protein lass was halve d. Further increase in protein intake up to 1.9 g/kg FFMc/day resulted in no further improvement. An intake of 1.5 g/kg FFMc/day was equival ent to 1.0 g/day/kg of body weight measured at the beginning of the st udy. Conclusions: Current recommended protein requirements of 1.2 to 2 .0 g/kg of body weight/day are excessive if they are indexed to the bo dy weight measured soon after the onset of critical illness. Because i ndividual patients have varying degrees of overhydration early in the illness onset, we suggest that the intensivist should obtain informati on on preillness body weight and prescribe 1.2 g of protein/kg body we ight/day. If information is not available, 1.0 g of protein/day/kg of measured body weight will give a fair approximation to optimal protein requirements. (Crit Care Med 1998; 28:1529-1535).