[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Critical care](https://durgical.com/en/nursing/areas/critical-care/) › Nutrition in the ICU: early enteral feeding, feeding intolerance, parenteral nutrition, glucose and refeeding

# Nutrition in the ICU: early enteral feeding, feeding intolerance, parenteral nutrition, glucose and refeeding

- Safe practice

Most ICU patients are fed through the gut within 48 hours, slowly at first; the nurse watches tolerance, glucose and refeeding risk.

Updated Nov 13, 2026

## Key points

- Early enteral nutrition (within about 48 hours) at a low rate, advanced slowly, is preferred to early parenteral nutrition or delayed feeding.
- Delay feeding in uncontrolled shock, uncontrolled life-threatening hypoxaemia or acidosis, active upper GI bleeding, bowel ischaemia or obstruction, abdominal compartment syndrome.
- Prone position and neuromuscular blockers alone are not reasons to delay feeding.
- Intolerance: pain, distension, vomiting, rising abdominal pressure: do not increase the rate and report.
- Refeeding risk: check phosphate, potassium and magnesium before and during feeding; thiamine is given before feeding as ordered.

## What it is

Critically ill patients lose muscle fast, and feeding is part of treatment. Guidelines favour early enteral nutrition, started within about 48 hours, at a low rate and advanced slowly, over early parenteral nutrition or delayed feeding. Feeding is delayed in a few situations, such as uncontrolled shock, and is not stopped for reasons that are not true contraindications. Parenteral nutrition is used when the gut cannot be used. The nurse starts and advances feeding as ordered, protects against aspiration, watches tolerance, glucose and electrolytes, and recognises refeeding syndrome. Tube checks and routine enteral feeding care are on the enteral feeding page.

## What it requires

- Gastric residual volume is not a gold standard of tolerance; follow the unit's policy for when and whether to measure it.
- Diarrhoea is investigated (for example for C. difficile) and managed rather than a reason to stop feeding.
- Parenteral nutrition goes through a central vein because it is concentrated and irritates small veins; it runs on a pump.
- Refeeding syndrome usually appears within 5 days of starting or increasing nutrition after a period of little intake.

## Components

- Timing: when to start and when to delay.
- Route: enteral first; parenteral when the gut cannot be used.
- Tolerance and aspiration prevention.
- Metabolic monitoring: glucose and electrolytes.
- Refeeding risk.

## How it is applied (and why)

- Screen nutrition risk on admission and tell the team if no feeding plan exists by the second day: early feeding is the standard.
- Start at the ordered low rate and increase only as ordered: aiming for full needs early is not recommended.
- Keep the head of the bed at 30 to 45° unless contraindicated: it reduces aspiration.
- Assess tolerance at the set times (pain, distension, nausea, vomiting, stools) and hold the increase if intolerance appears.
- Do not stop feeding only because the patient is prone, paralysed or has no bowel sounds: report instead and follow the order.
- Check glucose at the ordered times: tube-feeding carbohydrate is absorbed quickly and raises it.
- Check phosphate, potassium and magnesium as ordered in patients at refeeding risk: they can fall sharply after feeding starts.
- Give parenteral nutrition through the central line on a pump, with the line care on the central catheter page, and check the ordered labs.

## In nursing practice

- Refeeding syndrome signs: arrhythmias, respiratory muscle weakness, oedema or fluid overload, confusion or seizures.
- High-risk patients: prior malnutrition, low weight, weight loss, long fasting, alcohol use disorder, low electrolytes at baseline.
- A rising abdominal pressure, new pain or distension during feeding can be a sign of serious bowel problems: stop increasing and report.
- Thiamine is given before feeding or dextrose-containing fluids in patients at risk, as ordered.

## Common mistakes

- Leaving a stable patient without nutrition for days without asking the team.
- Increasing the rate during intolerance.
- Stopping feeds for diarrhoea without looking for the cause.
- Starting full feeding in a malnourished patient without checking electrolytes.

## Test yourself

Think of the answer, then tap the question to see it.

## When is enteral nutrition usually started in the ICU?

Early, within about 48 hours, at a low rate that is increased slowly, unless a contraindication such as uncontrolled shock is present.

## Is prone positioning a reason to delay enteral feeding?

No. Prone position or neuromuscular blockers alone should not delay enteral nutrition.

## Which electrolytes are monitored for refeeding syndrome?

Phosphate, potassium and magnesium, at baseline, before and during feeding.

## Why does parenteral nutrition need a central vein?

It is concentrated and irritates small veins, so it is given into a large central vein on a pump.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/nursing/nutrition-in-the-icu-early-enteral-feeding-feeding-intolerance-parenteral-nutrit/)

## Connections

## Related 5

- [Enteral feeding: checking the tube, feeding and care](https://durgical.com/en/nursing/enteral-feeding-checking-the-tube-feeding-and-care/)
- [Nutrition screening and helping patients eat](https://durgical.com/en/nursing/nutrition-screening-and-helping-patients-eat/)
- [Dysphagia and aspiration precautions](https://durgical.com/en/nursing/dysphagia-and-aspiration-precautions/)
- [Central venous catheter care](https://durgical.com/en/nursing/central-venous-catheter-care/)
- [Insulin infusion and glucose control in the ICU, including DKA and HHS: checks, potassium and hypoglycaemia](https://durgical.com/en/nursing/insulin-infusion-and-glucose-control-in-the-icu-including-dka-and-hhs-checks-pot/)

[← All of nursing](https://durgical.com/en/nursing/)

Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Early enteral nutrition in critically ill patients: ESICM clinical practice guidelines (Reintam Blaser A et al.)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5323492/) (Intensive Care Medicine, PubMed Central, 2017); [Understanding Refeeding Syndrome in Critically Ill Patients: A Narrative Review (Borriello R et al.)](https://pmc.ncbi.nlm.nih.gov/articles/PMC12157793/) (Nutrients, PubMed Central, 2025); [Nursing Fundamentals, 14.3: Applying the Nursing Process (Nutrition)](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Fundamentals_(OpenRN)/14:_Nutrition/14.03:_Applying_the_Nursing_Process) (Open RN, Chippewa Valley Technical College (CC BY 4.0), LibreTexts, 2021).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/nursing/nutrition-in-the-icu-early-enteral-feeding-feeding-intolerance-parenteral-nutrit/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/nutrition-in-the-icu-early-enteral-feeding-feeding-intolerance-parenteral-nutrit/