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 O₂ consumption (V̇O₂) and CO₂ production (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 V̇CO₂ increased 23%. Minute ventilation (V̇_E) increased 32%. Hypermetabolic patients (major trauma, sepsis) had a 30% increase in VO₂ and a 57% increase in V̇CO₂, while V̇_E increased 71%. Patients with mild to moderate injuries (energy expenditure ±15% of normal) showed a 21% increase in V̇O₂ and a 53% increase in V̇CO₂, while V̇_E increased 121%. Large carbohydrate intakes were associated with increases in CO₂ production in all patients, while increases in O₂ consumption were seen primarily in hypermetabolic patients. These changes suggest that the high glucose loads of TPN may be a physiologic stress.

(JAMA 243:1444-1447, 1980)