Influence of Total Parenteral Nutrition on Fuel Utilization in Injury and Sepsis

Abstract

Total parenteral nutrition with hypertonic glucose/AA solutions given to eighteen nutritionally depleted patients resulted in a rise in the respiratory quotient (RQ) from 0.83 to 1.05 (p < .001), while oxygen consumption (JOURNAL/ansu/04.02/00000658-198001000-00008/ENTITY_OV0312/v/2017-07-25T071118Z/r/image-pngO2) increased only 3%. Excess glucose in depleted patients was converted to fat as evidenced by an RQ greater than 1.0. Administration of a similar glucose load to fourteen hypermetabolic patients (injury/infection) resulted in a rise in RQ from 0.76 to 0.90 while JOURNAL/ansu/04.02/00000658-198001000-00008/ENTITY_OV0312/v/2017-07-25T071118Z/r/image-pngO2 increased 29% (p < .001). In hypermetabolic patients, even with administration of glucose in quantities above energy expenditure, there was still ongoing utilization of fat for energy, resulting in a RQ significantly less than 1.0. Excess glucose under these circumstances is apparently converted to glycogen while fat stores are utilized to partially meet energy needs. Septic and injured man seems to preferentially utilize endogenous fat as an energy source. Administration of a large glucose load to hypermetabolic patients does not totally suppress the net fat oxidation as it does in depleted patients. Rather there is an increase in JOURNAL/ansu/04.02/00000658-198001000-00008/ENTITY_OV0312/v/2017-07-25T071118Z/r/image-pngO2, continuing oxidation of fat and apparently an increase in the conversion of glucose to glycogen.