Respiratory changes induced by the large glucose loads of total parenteral nutrition

Total parenteral nutrition (TPN) using glucose as nonprotein calories was associated with increases in O2consumption (V̇O2) and CO2production (V̇CO2). The magnitude of the changes was a function of the patient's clinical state and glucose load. Depleted patients showed a minimal increase in V̇O2, while V̇CO2increased 23%. Minute ventilation (V̇E) increased 32%. Hypermetabolic patients (major trauma, sepsis) had a 30% increase in VO2and a 57% increase in V̇CO2, while V̇Eincreased 71%. Patients with mild to moderate injuries (energy expenditure ±15% of normal) showed a 21% increase in V̇O2and a 53% increase in V̇CO2, while V̇Eincreased 121%. Large carbohydrate intakes were associated with increases in CO2production in all patients, while increases in O2consumption were seen primarily in hypermetabolic patients. These changes suggest that the high glucose loads of TPN may be a physiologic stress. (JAMA243:1444-1447, 1980)