Predictors of total parenteral nutrition-induced lipogenesis.
OBJECTIVE
To evaluate the incidence and cause of parenteral nutrition-induced lipogenesis.


METHODS
Retrospective patient review.


METHODS
A 40-bed predominantly surgical ICU.


METHODS
One hundred forty patients receiving central venous nutrition and mechanical ventilatory support.


METHODS
Indirect calorimetry was used to determine patient's measured energy expenditure (MEE) and respiratory quotient (RQ). Additionally total caloric intake (TCAL), glucose infusion rate, basal energy expenditure (BEE), estimated stress factor, and calculated energy expenditure (CEE) were assessed in each patient.


RESULTS
Net fat synthesis was found as RQs exceeded 1 in 47 percent of patients. Statistically significant differences in oxygen consumption, CO2 production, measured energy expenditure, total and carbohydrate caloric intake, and glucose infusion rate were found between groups of patients with an RQ < or = or > 1. Seventy-three percent of patients with glucose infusion rates > 4 mg/kg-min had RQs > 1.


CONCLUSIONS
Net fat synthesis was found in a surprisingly large number of critically ill patients receiving central venous nutrition. Many of these patients received carbohydrate calories in excess of their measured energy expenditure, even though it appeared that they needed this level of caloric intake by clinical assessment. The high carbohydrate total parenteral nutrition (TPN) solutions with lipids provided only for prevention of essential fatty acid depletion resulted in an unacceptably high incidence of fat synthesis. The results suggest that caloric intake may be optimized in critically ill patients using indirect calorimetry. When calorimetry is not available, a total caloric intake of up to 140 percent of the BEE with glucose infusion rates not exceeding 4 mg/kg-min and fats providing 40 to 60 percent of calories will meet the energy requirements of most critically ill patients without forcing the RQ > 1.
Guenst
J M
JM
Vanderbilt University, Nashville, Tenn 37232-2100.
Nelson
L D
LD
D000368:Aged; D001481:Basal Metabolism / Q000502:physiology; D002153:Calorimetry, Indirect; D002245:Carbon Dioxide / Q000378:metabolism; D016638:Critical Illness; D004040:Dietary Carbohydrates / Q000378:metabolism / Q000627:therapeutic use; D004041:Dietary Fats / Q000378:metabolism / Q000627:therapeutic use; D002149:Energy Intake; D004734:Energy Metabolism / Q000502:physiology; D005227:Fatty Acids / Q000378:metabolism / Q000627:therapeutic use; D005544:Forecasting; D005947:Glucose / Q000378:metabolism / Q000627:therapeutic use; D006801:Humans; D008055:Lipids / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism / Q000627:therapeutic use; D010101:Oxygen Consumption / Q000502:physiology; D010289:Parenteral Nutrition, Total; D012119:Respiration / Q000502:physiology; D012121:Respiration, Artificial; D012189:Retrospective Studies; D013312:Stress, Physiological / Q000378:metabolism / Q000503:physiopathology
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D008055:Lipids; D002245:Carbon Dioxide; D005947:Glucose; D009584:Nitrogen