[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anaesthesia and ICU](https://durgical.com/en/anaesthesia/) › [Critical care (ICU)](https://durgical.com/en/anaesthesia/areas/critical-care/) › Transfusion thresholds in the ICU

# Transfusion thresholds in the ICU

- Concept

In intensive care, red cells are given only when haemoglobin falls quite low or the patient is bleeding, because unnecessary transfusion also carries risks.

Updated Nov 13, 2026

## Key points

- For most stable ICU patients, red cells are given when haemoglobin falls below about seven grams per decilitre (restrictive strategy).
- A somewhat higher threshold, around eight grams per decilitre, is often used in acute coronary ischaemia and after cardiac or orthopaedic surgery.
- In upper gastrointestinal bleeding a restrictive strategy reduced rebleeding and death compared with a liberal one.
- Give one unit at a time to a stable patient and reassess before the next.
- Plasma is for bleeding with coagulopathy, not for correcting a high INR in a patient who is not bleeding.

## What it is

Anaemia is very common in intensive care, from blood sampling, bleeding, inflammation and reduced red cell production. Red cell transfusion raises oxygen-carrying capacity, but it brings risks: circulatory overload, transfusion-related acute lung injury, haemolytic and allergic reactions, infection, immune modulation and iron load. Large randomised trials in critically ill adults, in upper gastrointestinal bleeding, in septic shock and after cardiac surgery have shown that a restrictive strategy, transfusing only when haemoglobin falls below about seven grams per decilitre, is as safe as a liberal one and uses far less blood. Some patients are treated with a somewhat higher threshold, around eight grams per decilitre, such as those with active coronary ischaemia or after cardiac or orthopaedic surgery, and the threshold is a guide, not a rule: symptoms, ongoing bleeding and signs of poor oxygen delivery matter. In massive bleeding, transfusion follows the bleeding and a massive transfusion protocol, not a number. Platelets, plasma and cryoprecipitate are also given to targets: platelets prophylactically only at very low counts or before procedures, plasma for bleeding with a coagulopathy rather than to correct a laboratory value, and cryoprecipitate when fibrinogen is low. Blood conservation (fewer and smaller samples, treating iron deficiency, stopping unnecessary anticoagulants) reduces the need for transfusion.

## Key points

- Every transfusion is a decision balancing oxygen delivery against risk; a threshold helps but does not replace judgement.
- Transfusion-associated circulatory overload and transfusion-related acute lung injury are leading causes of transfusion-related death.
- Signs that may justify transfusion above the threshold: active bleeding, myocardial ischaemia, or clear signs of low oxygen delivery.
- Prophylactic platelets are given only at very low counts; higher counts are aimed for before procedures and in active bleeding.
- Cryoprecipitate or fibrinogen concentrate is given when fibrinogen is low in bleeding patients.

## How it works

- Oxygen delivery depends on cardiac output, haemoglobin and saturation; healthy hearts compensate for anaemia by raising output.
- Stored red cells lose 2,3-diphosphoglycerate and deformability, so their oxygen release is less effective early after transfusion.
- Hearts with fixed coronary narrowing cannot raise flow easily, which is why ischaemic patients may need a higher threshold.
- Inflammation blocks iron use and erythropoietin action, so ICU anaemia recovers slowly.

## Usual ICU transfusion triggers (a guide, not a rule)

| Product | Usual trigger | Exceptions |
| --- | --- | --- |
| Red cells | Haemoglobin below about seven grams per decilitre | Higher in coronary ischaemia, cardiac surgery; bleeding guides in haemorrhage |
| Platelets | Very low count without bleeding | Higher before procedures, in bleeding, after neurosurgery |
| Plasma | Bleeding with prolonged clotting times | Not for an abnormal INR alone without bleeding |
| Cryoprecipitate or fibrinogen | Low fibrinogen in bleeding | Massive transfusion, obstetric haemorrhage |

## In practice

- Septic shock: restrictive threshold, as liberal transfusion gave no benefit.
- Acute coronary syndrome: many clinicians use a slightly higher threshold; evidence is still debated.
- Massive haemorrhage: activate the massive transfusion protocol and give products in fixed ratios guided by bleeding and point-of-care tests.
- Jehovah's Witness patients: discuss in advance, use blood conservation and accepted alternatives, and record the decision.
- Watch during and after transfusion for fever, breathlessness, hypotension, new infiltrates and dark urine.

## Next step

- Check haemoglobin after each unit in a stable patient before deciding on the next.
- Call a senior when transfusing above the usual threshold or when bleeding needs a massive transfusion protocol.
- Reduce sampling volume and frequency, treat iron deficiency and review anticoagulants to prevent further anaemia.
- Report any suspected reaction to the blood bank and haemovigilance system, and keep the bag and line.
- Record the indication, the product, its identifiers and the response in the notes.

## Test yourself

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

## What red cell transfusion threshold is used for most stable ICU patients?

A restrictive threshold of about seven grams per decilitre, which trials showed to be as safe as a liberal strategy while using much less blood.

## Which patients often receive a slightly higher transfusion threshold?

Patients with acute coronary ischaemia and those after cardiac or orthopaedic surgery, commonly around eight grams per decilitre.

## Why should plasma not be given for a high INR in a patient who is not bleeding?

It rarely corrects mild abnormalities, exposes the patient to overload, lung injury and reactions, and does not reduce bleeding risk in that setting.

## What are two leading causes of death from transfusion?

Transfusion-associated circulatory overload and transfusion-related acute lung injury.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anaesthesia/transfusion-thresholds-in-the-icu/)

## Elsewhere in DurgiPedia

- [Blood groups, transfusion and transfusion reactions](https://durgical.com/en/physiology/blood-groups-transfusion-and-transfusion-reactions/)
- [Oxygen content, delivery and extraction](https://durgical.com/en/physiology/oxygen-content-delivery-and-extraction/)
- [Transfusion reactions](https://durgical.com/en/immunology/transfusion-reactions/)
- [Complications of transfusion](https://durgical.com/en/general-pathology/complications-of-transfusion/)
- [Blood transfusion: bedside checks, monitoring and reactions](https://durgical.com/en/nursing/blood-transfusion-bedside-checks-monitoring-and-reactions/)

## Connections

## Related 5

- [Massive haemorrhage in theatre](https://durgical.com/en/anaesthesia/massive-haemorrhage-in-theatre/)
- [Shock: a bedside approach by type](https://durgical.com/en/anaesthesia/shock-a-bedside-approach-by-type/)
- [Stress-ulcer prophylaxis: who needs it](https://durgical.com/en/anaesthesia/stress-ulcer-prophylaxis-who-needs-it/)
- [Anaesthesia for cardiac surgery, in principle](https://durgical.com/en/anaesthesia/anaesthesia-for-cardiac-surgery-in-principle/)
- [The ICU daily bundle (FAST HUGS and similar checklists)](https://durgical.com/en/anaesthesia/the-icu-daily-bundle/)

## Related conditions 6

- [Transfusion reactions](https://durgical.com/en/conditions/transfusion-reactions/)
- [Upper gastrointestinal bleeding](https://durgical.com/en/conditions/upper-gastrointestinal-bleeding/)
- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Disseminated intravascular coagulation](https://durgical.com/en/conditions/disseminated-intravascular-coagulation/)
- [Immune thrombocytopenia (ITP)](https://durgical.com/en/conditions/immune-thrombocytopenia/)
- [Anaemia of chronic disease (anaemia of inflammation)](https://durgical.com/en/conditions/anaemia-of-chronic-disease/)

## In Pharmacology 2

- [Tranexamic acid](https://durgical.com/en/pharmacology/tranexamic-acid/)
- [Anticoagulant reversal agents](https://durgical.com/en/pharmacology/classes/anticoagulant-reversal-agents/)

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

Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: [Blood Transfusion](https://www.ncbi.nlm.nih.gov/books/NBK499824/) (StatPearls (NCBI Bookshelf), 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anaesthesia/transfusion-thresholds-in-the-icu/