Amino acids and respiration.

Parenteral nutrition containing glucose and amino acids may stimulate respiration. To ascertain the effects of these solutions on respiration, eight normal subjects received an infusion of 5% dextrose (100 mL/h) for 7 days followed by an infusion of 3.5% amino acids (125 mL/h) for 24 hours. Minute ventilation (VE), tidal volume, mean inspiratory flow (VT/VI), oxygen consumption, and carbon dioxide production were significantly depressed after 7 days of 5% dextrose infusion. Ventilation and metabolic rate increased within 4 hours after initiation of the amino acid infusion and returned to normal 24 hours after the infusion. The effects of the amino acids on (VE) was secondary to an increase in (VT/VI), which is an indicator of neuromuscular ventilatory drive. Thus, within 4 hours amino acids will restore depressed metabolic rate, minute ventilation, and ventilatory drive after prolonged infusion of 5% dextrose.