Energy expenditure in the acute renal failure patient mechanically ventilated

Twenty mechanically ventilated patients with acute renal failure were studied on 31 occasions to determine their energy expenditure (EE) during a 2 h period before a hemodialysis. Oxygen consumption and CO₂ elimination were measured continuously with a mass spectrometer system. EE (1660±48 kcal day^-1) was close to the total caloric intake (1682±83 kcal day-1) and represented 1.19±0.03 times the predicted resting energy expenditure (PREE) with large inter-individual variations (0.7-1.7 PREE). EE/PREE was higher when sepsis was present (1.31±0.03 versus 1.14±0.02; p<0.05). Glucose oxidation rate (4.35 mg kg^-1 min^-1) exceeded glucose intake (2.6 mg kg^-1 min^-1). Respiratory quotient was 1.02±0.01. Nitrogen loss was 17.3±1.7 g day^-1 and nitrogen balance-11.9±1.9 g day^-1. In conclusion, EE values were scattered but never exceeded 1.7 times the PREE. Sepsis increased EE. With a nutritional support covering EE, nitrogen balance remained markedly negative and a preferential utilisation of glucose and lipogenesis occurred.