• Mengyin Hong, Linda Wykes, Dominique Shum-Tim, Evan Nitschmann, Helen Bui, Keisuke Nakazawa, Takumi Codere-Maruyama, Thomas Schricker, and Roupen Hatzakorzian.
• School of Human Nutrition, McGill University, Montreal, Canada.
• Nutrition. 2020 Jan 1; 69: 110566.

ObjectivesSurgery triggers a stress response that produces insulin resistance and hyperglycemia. During cardiac surgery, the administration of high-dose insulin along with dextrose titration maintains normoglycemia, but dramatically decreases plasma amino acids (AAs) compared with preoperative fasting levels. Hypoaminoacidemia limits protein synthesis and prevents anabolic responses after surgery. We investigated whether parenteral infusion of AAs during and immediately after cardiac surgery would prevent hypoaminoacidemia in patients who receive high-dose insulin therapy.MethodsSixteen patients undergoing coronary artery bypass grafting surgery were randomly allocated to receive AAs with % kcal equivalent to either 20% (n = 8) or 35% (n = 8) of their measured resting energy expenditure (REE). Insulin was infused at a constant rate of 5 mU/(kg × min), whereas dextrose was titrated to maintain normoglycemia during and until 5 h after surgery. Plasma AA concentrations were measured at baseline before and after surgery.ResultsCompared with the 20% AA group after surgery, AA concentrations were significantly higher in the 35% AA group for 12 of 20 AAs (P < 0.032), including all branched-chain AAs. In the 20% AA group, total essential AAs decreased by 21% and nonessential AAs decreased by 14% after surgery compared with preoperative fasting levels. In contrast, giving 35% AAs prevented this unfavorable decrease in AAs, and in fact allowed for a 23% and 12% increase in essential and nonessential AAs, respectively.ConclusionsAA supplementation at 35% REE, but not 20% REE, can effectively prevent hypoaminoacidemia caused by high-dose insulin therapy during cardiac surgery.Copyright © 2019 Elsevier Inc. All rights reserved.

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