Energy and nitrogen balance and changes in midupper-arm circumference with multiple organ failure.

Energy intake and energy expenditure, nitrogen intake, and urinary nitrogen excretion (or urea production rates) were measured in 35 intravenously fed patients with multiple organ failure over the course of their illness to determine to what extent nutrient requirements were met despite fluid retention. Energy and nitrogen balance were related to serial measurements of midupper-arm circumference (MAC). The target feeding regimen of 176 kJ (42 kcal)/kg fat-free mass (FFM) was achieved in only three patients and the target of 0.24 g N/kg FFM in only four. Two patterns of change in MAC were noted: a steady decrease with time and no change with time. Serial muscle biopsy data indicated that all the patients were wasting away; the maintenance of MAC in the group with no change over time was due to fluid retention. Abnormal losses were not measured, but energy and nitrogen balance in the group in which arm circumference decreased had no apparent effect on the rate of wasting.