Invited Review Nutrition in Clinical Practice Volume 36 Number 1 February 2021 88–97 © 2020 American Society for Parenteral and Enteral Nutrition DOI: 10.1002/ncp.10621 wileyonlinelibrary.com Enteral Nutrition Safety With Advanced Treatments: Extracorporeal Membrane Oxygenation, Prone Positioning, and Infusion of Neuromuscular Blockers Hasan M. Al-Dorzi, MD ; and Yaseen M. Arabi, MD This review aims at assessing the safety and efficacy of enteral nutrition in critically ill patients receiving extracorporeal membrane oxygenation, prone positioning, and infusion of neuromuscular blockers. Existing data from randomized controlled trials demonstrate the survival benefit of early enteral nutrition in critically ill patients. Observational data have demonstrated that enteral nutrition in patients receiving extracorporeal membrane oxygenation, prone positioning, and infusion of neuromuscular blockers is generally safe. However, these patients are at increased risk for gastrointestinal complications from enteral nutrition because of critical illness–induced gastrointestinal dysfunction; associated shock; the concomitant use of vasopressor agents, sedatives, and narcotics; possibly mesenteric circulatory compromise; and regurgitation associated with prone positioning. Therefore, early enteral nutrition is generally recommended in these patients in the absence of severe gastrointestinal dysfunction or shock. To reduce the complications, early nutrition should be advanced gradually (trophic feeding or permissive underfeeding), the bed should be tilted to a maximum of 30°, and concentrated nutritional formulae and the use of prokinetics may be considered to treat enteral feeding intolerance. Physicians should be vigilant about monitoring for early signs of acute mesenteric ischemia, which should lead to holding enteral feeding. Parenteral nutrition may be utilized in patients who cannot receive enteral nutrition or are unable to reach their nutrition goals by the end of the first week. (Nutr Clin Pract. 2021;36:88–97) Keywords critical illness; enteral nutrition; extracorporeal membrane oxygenation; gastrointestinal motility; neuromuscular blockade; prone position; vasoconstrictor agents Introduction Extracorporeal membrane oxygenation (ECMO), prone po- sitioning, and infusion of neuromuscular blockers are often used for the management of critically ill patients with mod- erate or severe acute respiratory distress syndrome (ARDS) or cardiac failure. Existing data from randomized controlled trials demonstrate mortality benefit of early enteral nutri- tion (EN) commenced within 24–48 hours of admission in patients who are critically ill. 1 Parenteral nutrition (PN) may be utilized in patients who cannot receive EN or are unable to reach their nutrition goals by the end of the first week. 1,2 The safety of EN has been the subject of several studies in patients receiving ECMO, prone positioning, and infusion of neuromuscular blockers because patients receiving these therapies are at increased risk for gas- trointestinal complications. 3,4 These complications most frequently manifest as EN intolerance, but more serious complications such as acute mesenteric ischemia can occur. There is no agreed-upon definition for EN intolerance, although most definitions incorporate an increase in gastric residual volume. 5 There are several underlying mechanisms for the gastrointestinal complications in these patients. Patients receiving any of these therapies are typically severely ill, and gastrointestinal dysfunction could be a man- ifestation of the multiorgan dysfunction syndrome result- ing from critical illness. 6 Other reasons include associated shock; the concomitant use of vasopressor agents, sedatives, and narcotics; possibly mesenteric circulatory alterations; and regurgitation associated with prone positioning. 7,8 The association of shock with acute mesenteric ischemia has been demonstrated in the NUTRIREA-2 trial. 7 In this trial, patients receiving invasive mechanical ventilation and high From the College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, Intensive Care Department, King Abdulaziz Medical City, Riyadh, Saudi Arabia (E-mail: aldorzih@yahoo.com). Received for publication August 4, 2020; accepted for publication November 21, 2020. This article originally appeared online on December 29, 2020. Corresponding Author: Yaseen M. Arabi, MD, College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, Intensive Care Department, King Abdulaziz Medical City, ICU2, Mail Code 1425, PO Box 22490, 00966118011111 × 18855, Riyadh 11426, Saudi Arabia. Email: arabi@ngha.med.sa