Uptake of dietary amino acids into arterial blood during continuous enteral feeding in critically ill patients and healthy subjects

Abstract

Background: Amino acid availability is a regulatory factor of protein anabolism and is partly dependent on enteral amino acid uptake. During continuous enteral feeding, enteral amino acid uptake may vary considerably, but this has not been documented systematically.

Methods: In this pragmatic study, we investigated patients in the intensive care unit (n = 10) and healthy adults (n = 10). The time course of essential amino acid concentrations in arterial plasma and the uptake of dietary phenylalanine were recorded during 12 hours of continuous enteral feeding, using a 13C-labeled phenylalanine tracer.

Results: Plasma essential amino acid concentrations and 13C-phenylalanine enrichment reached a tentative steady state after no more than 4.5 h from start of tracer infusion. There was a large intra- and inter-individual variability in both cohorts. No periodicity could be detected in the temporal variation.

Conclusion: During continuous enteral feeding, uptake of amino acids shows large intra- and inter-individual variation. A tentative steady state of 13C-phenylalanine uptake is eventually reached.

Trial registration: Registered at Australian New Zealand Clinical Trials Registry, trial ID ACTRN12616000593437.

Keywords: Amino acid tracers; Critical illness; Enteral nutrition; Nutritional support.

Conflict of interest statement

Conflicts of interest Felix Liebau received a speaker honorarium from Baxter. Olav Rooyackers is a consultant for Fresenius-Kabi and is occasionally paid for lectures by Fresenius-Kabi, Nestle, Nutricia and Baxter. Jan Wernerman has been paid for lectures and advisory boards by Nestle, GE Health Care, Nutricia, Baxter and Fresenius. Emilie Király and Daniel Olsson declare that they have no competing interests.

Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.