Table 4.

Clinical practice guidelines for the initiation of EN and PN in critically ill patients.

Clinical Practice Guideline	Initiation of EN	Initiation of PN
Canadian Clinical Practice Guideline[76]	Early EN (within 24–48 h)	- Exclusive PN (when oral intake or EN contraindicated): should be considered early in nutritionally high-risk patients - Patients who are not malnourished, are tolerating some EN, or when PN is indicated for <10 days: low dose PN should be considered - Supplemental PN: should be considered on a case-by-case basis
ASPEN/SCCM[77]	Early EN (24–48 h) - Patients at high nutrition risk or severely malnourished: EN should advance to goal as quickly as tolerated over 24–48 h (while monitoring for refeeding) - Patients at low nutrition risk, well-nourished, and/or with low disease severity: Specialized nutrition therapy over the first week in ICU not required	Exclusive PN (when oral intake or EN contraindicated): - For patients at high nutrition risk or severely malnourished, start PN as soon as possible - For patients at low nutrition risk, withhold for the first 7 days Supplemental PN: should be considered after 7–10 days if unable to meet > 60% of energy and protein requirements by EN
ESPEN[15]	Early EN (within 48 h) - Early acute phase (ICU Day 1–3): Hypocaloric nutrition (< 70% of EE) - After Day 3: If using predictive equations, continue hypocaloric nutrition (< 70% of EE) for the first week If using indirect calorimetry, normocaloric nutrition (70–100% EE) can be progressively implemented	- Exclusive PN (when oral intake or EN contraindicated): within 3–7 days - For severely malnourished patients, consider early and progressive PN - Supplemental PN: should be considered on a case-by-case basis

ASPEN: American Society for Parenteral and Enteral Nutrition; EE: Energy expenditure; EN: Enteral nutrition; ESPEN: European Society for Clinical Nutrition and Metabolism; ICU: Intensive care unit; PN: Parenteral nutrition; SCCM: Society of Critical Care Medicine.