Free fatty acid turnover and lipolysis in septic mechanically ventilated cancer-bearing humans

Loss of body fat and lean body mass are features of critical illness, and anabolism is difficult to achieve despite parenteral nutrition. Resting energy expenditure (REE), free fatty acid turnover (FFT) and glycerol turnover (glyTO) were measured in septic, mechanically ventilated cancer-bearing patients, both fasting and immediately following or during a glucose infusion providing 87% of REE. No patient was in septic shock nor required pressor support. In the fasting state, REE was greatly elevated compared with basal energy expenditure calculated using the Harris-Benedict equations. Fasting FFT (14.2 +/- 0.9 mumol/kg/min) and glyTO (4.7 +/- 0.5 mumol/kg/min) were elevated compared with normal humans. Fasting respiratory quotient (RQ) was 0.68 +/- 0.02 and did not rise significantly with glucose. Fat appears to be the preferred calorie source in septic, cancer-bearing humans even in the presence of glucose. As similar, but less pronounced, changes have been seen in septic and injured humans without cancer, it is likely that these changes are not cancer-specific.