To determine to what extent glucose homeostasis, proteolysis, and essential amino acid loss is altered in infants undergoing ECMO for persistent pulmonary hypertension, stable isotope tracer infusions were used to measure endogenous glucose production, phenylalanine (PHE) rates of appearance (Ra), and PHE hydroxylation (PHE-OH) in 7 neonates on ECMO (birth weight 3.5±0.9kg, 40±2 wks gestation, 3±1 days old) and in 10 normal newborn controls (birth weight 3.3±0.5kg, 39±1 wks gestation, 2.4±1.4 days old). ECMO infants and controls were both studied during a 7 mg/kg/min glucose infusion. In addition, to determine the effect of a combined glucose (7 mg/kg/min) and amino acid (AA) infusion (1.5 g/kg/day, 16.2μmol/kg/hr PHE) on proteolysis and PHE balance in ECMO patients, the same measurements were made in 8 ECMO patients receiving the combined infusion.

RESULTS: Mean±SE, glucose results in mg/kg/min, PHE results in μmol/kg/hr, *p<0.05 control (Gluc) vs. ECMO (Gluc),**p<0.01 ECMO (Gluc) vs. ECMO (Gluc+AA)Table

Table 1
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CONCLUSIONS: 1) In spite of their critical illness, the ECMO patients suppressed endogenous glucose production, similar to controls. In contrast, endogenous PHE Ra (reflecting proteolysis) and PHE-OH (irreversible losses) were substantially greater in ECMO patients compared to controls. 2) There was no significant change in proteolysis or PHE-OH in response to an AA infusion in ECMO patients. However, PHE balance went from negative to positive in the AA period. These results suggest that glucose metabolism in infants on ECMO is remarkably normal while there is increased proteolysis. Endogenous glucose and PHE stores can be spared in critically ill neonates on ECMO by using standard amounts of glucose and AA in intravenous fluids.