Blood transfusion
Transfuse for a reason, one unit at a time in stable patients, check identity at the bedside, and stop the moment a reaction starts.
A 74-year-old woman with heart failure is 2 days after a hip fracture repair. Hb 6.8 g/dL, BP 128/74, pulse 96, comfortable at rest. You prescribe one unit of red cells. Twenty minutes in, the nurse calls: she is breathless, BP 172/98, SpO₂ 88%, crackles at both bases. No fever, no rash, no back pain.
Is this a reaction, which one, and what do you do in the next 5 minutes?
- Right blood, right patientPositive identification at the bedside against wristband, request and unit. Two people where policy requires.
- Is it needed?Usually Hb below 7 g/dL (below 8 with heart disease), unless actively bleeding.
- Consent and documentReason, risks, alternatives, number of units.
- One unit, then reassessIn stable patients: symptoms and Hb before the next unit.
- RateUsually 90–120 minutes per unit. Slower, with furosemide if needed, when overload is a risk.
- ObservationsBefore, 15 minutes after starting, and at the end.
- Any reactionStop, keep the line open with saline through a new set, recheck identity, assess A–E, call senior.
- Finish within 4 hoursFrom leaving the fridge.
- Fever with rigors, low BP or back pain in the first 15 minutes
- Breathlessness, wheeze or low SpO₂
- Dark urine or bleeding from cannula sites
- Anaphylaxis
- Bleeding needing more than 4 units (massive haemorrhage protocol)
- ABO incompatibility (wrong blood to the wrong patient)
- TACO in the elderly, heart or kidney failure
- TRALI
- Anaphylaxis
- Bacterial contamination of the unit
- Hyperkalaemia and low calcium in massive transfusion
| Stable inpatient | Transfuse if Hb below 7 g/dL, target 7–9 |
| Ischaemic heart disease | Below 8 g/dL, target 8–10 |
| Rise per unit | About 1 g/dL in a 70 kg adult |
| Child | 10–15 mL/kg red cells |
| FFP | 15 mL/kg for bleeding with abnormal clotting |
| Platelets | Below 10,000/µL without bleeding, below 50,000/µL with bleeding or before most procedures |
| Time limit | Each red cell unit finished within 4 hours of leaving storage |
| Massive haemorrhage | Activate protocol, red cells, plasma and platelets close to 1:1:1, tranexamic acid early |
Check every dose against a current drug reference and your hospital protocol.
On this page
Why care?
Blood is donated, limited and carries real risks. In Pakistan many units come from family replacement donors and screening quality varies between blood banks. Transfuse when there is a clear benefit, give the smallest effective amount, and watch the patient closely, especially in the first 15 minutes.
When to transfuse
| Situation | Usual threshold |
|---|---|
| Stable adult inpatient | Hb below 7 g/dL, target 7–9 |
| Ischaemic heart disease, acute coronary syndrome | Hb below 8 g/dL, target 8–10 |
| Active major bleeding | Clinical decision; don't wait for Hb |
| Variceal bleeding | Restrictive: target 7–8 g/dL |
| Iron deficiency, stable and well | Iron (oral or IV), not blood |
| Thalassaemia major | Regular transfusion programme per haematology |
Hb in someone who is actively bleeding can still look normal. Transfuse on the clinical picture: pulse, BP, ongoing loss.
Before you transfuse
- IndicationWrite the reason and the Hb.
- SampleLabel the cross-match sample at the bedside, never pre-labelled.
- ConsentBenefits, risks (reactions, infection, overload), alternatives (iron, waiting).
- Special requirementsIrradiated or CMV-negative for some haematology patients; check with the blood bank.
- Risk of overload?Elderly, heart or kidney failure, low weight: slower rate, one unit, consider furosemide.
- Baseline observationsTemperature, pulse, BP, RR, SpO₂.
The bedside check
Patient's full name, date of birth and hospital number on the wristband match the request and the compatibility tag on the unit. Check the unit number, ABO and Rh group, expiry date and the bag (no leaks, clots or discolouration). Do it at the bedside, not at the nursing station. Most ABO-incompatible transfusions come from identification errors.
Rates
| Product | Usual rate |
|---|---|
| Red cells (stable) | 1 unit over 90–120 minutes (up to 3 hours if overload risk); finish within 4 hours of leaving storage |
| Red cells (major bleeding) | As fast as needed, through a warmer |
| FFP | 15 mL/kg over 30–60 minutes |
| Platelets | 1 adult dose over 30 minutes |
| Cryoprecipitate | Over 30–60 minutes, for low fibrinogen |
Reactions
Acute haemolytic (ABO): stop, resuscitate, recheck identity, send bag back, call haematology
Anaphylaxis: IM adrenaline 0.5 mg, A–E
TACO: stop, sit up, oxygen, furosemide
TRALI: oxygen, ICU, report to blood bank
Bacterial contamination: cultures from patient and bag, broad antibiotics
Mild: pause, paracetamol or chlorphenamine, restart slowly if settles
| Reaction | Features | Action |
|---|---|---|
| Febrile non-haemolytic | Temperature up under 2 °C, otherwise well | Slow or pause, paracetamol, continue if settles |
| Mild allergic | Itch, urticaria only | Pause, chlorphenamine 10 mg IV, restart slowly |
| Anaphylaxis | Wheeze, angioedema, low BP | Stop, adrenaline 0.5 mg IM, A–E, don't restart |
| Acute haemolytic | Fever, rigors, low BP, loin pain, dark urine, oozing | Stop, saline, resuscitate, DAT and haemolysis screen, coagulation, return bag, haematology |
| TACO | Breathless, high BP, crackles, low SpO₂ | Stop, sit up, oxygen, furosemide 40 mg IV |
| TRALI | Breathless, low BP, low SpO₂, no overload | Stop, oxygen, ICU, report |
| Bacterial contamination | High fever, rigors, shock | Stop, cultures, broad-spectrum antibiotics |
| Delayed haemolytic (days later) | Fever, jaundice, falling Hb | DAT, antibody screen, haematology |
Any severe reaction: stop, keep the cannula open with saline through a new giving set, check identity again, send the bag and giving set to the lab with fresh samples, and report it.
Massive haemorrhage
- Call for help and activate the massive haemorrhage protocolSay the words to the blood bank.
- Stop the bleedingPressure, tourniquet, surgery, endoscopy, uterotonics.
- Tranexamic acid1 g IV over 10 minutes within 3 hours of injury or birth, then 1 g over 8 hours (trauma).
- Blood productsRed cells, FFP and platelets close to 1:1:1; O-negative (O-positive for men) while waiting for group-specific.
- Keep warm, check calciumCitrate lowers calcium. Give calcium if ionised calcium below 1.1 mmol/L.
- MonitorHb, platelets, clotting, fibrinogen, potassium, lactate repeatedly.
Transfusion in special situations
- Heart failure or elderly: one unit at a time over 2–3 hours, furosemide 20–40 mg IV between units if overloaded, reassess.
- Jehovah's Witness patients: discuss alternatives early and respect an informed refusal; involve seniors.
- Children: prescribe in mL/kg (10–15 mL/kg raises Hb by about 2–3 g/dL).
- Thalassaemia: follow the haematology plan; iron chelation is part of long-term care.
- Rh-negative women of child-bearing age: Rh-negative blood where possible; anti-D after accidental Rh-positive platelets.
Treatment doses
Common mistakes
- Pre-labelling sample tubes away from the bedside.
- Doing the identity check at the nursing station.
- Transfusing 2 units "by default" to a stable patient.
- Running blood fast in an elderly patient with heart failure.
- Restarting a unit after a reaction without knowing what the reaction was.
- Transfusing iron deficiency anaemia in a well patient instead of giving iron.
- Forgetting calcium and warming in massive transfusion.
Frequently asked questions
What Hb level needs a blood transfusion?
Usually below 7 g/dL in stable adults, or below 8 g/dL with heart disease. Actively bleeding patients are transfused on clinical signs, not the Hb.
How much does one unit raise haemoglobin?
About 1 g/dL in an average adult.
How long should a unit of blood take?
Usually 90–120 minutes in a stable patient, and it must finish within 4 hours of leaving controlled storage.
What is TACO?
Transfusion-associated circulatory overload: breathlessness, high BP, crackles and low oxygen during or soon after transfusion, mostly in elderly patients or those with heart or kidney failure. Stop, sit up, oxygen and furosemide.
What should I do if a patient reacts to a transfusion?
Stop it, keep the line open with saline through a new giving set, recheck the identity, assess A–E and call your senior. Send the bag back to the lab.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. Twenty minutes into a transfusion, an elderly patient with heart failure becomes breathless with high BP and crackles. What is it?
Answer: TACO. TACO: stop, sit up, oxygen, furosemide.
- Anaphylaxis: Low BP, wheeze, swelling.
- Acute haemolytic reaction: Fever, low BP, back pain.
- TRALI: Low BP, no overload.
- Febrile reaction: Mild fever only.
2. A patient develops fever, low BP and back pain minutes after starting a transfusion. What is the first step?
Answer: Stop the transfusion. Possible ABO incompatibility: stop, keep the line open with saline, check identity, call senior.
- Slow it down: Stop completely.
- Change the unit: Stop and investigate first.
- Give furosemide: Not first.
- Give paracetamol and continue: Dangerous.
3. What is the usual Hb threshold for transfusion in a stable adult without heart disease?
Answer: Below 7 g/dL. Restrictive thresholds are safe; below 8 if heart disease, and clinically in active bleeding.
- Below 12 g/dL: Too liberal.
- Any drop: No.
- Below 5 g/dL: Too low.
- Below 10 g/dL: Too liberal.
4. A trauma patient has received 6 units of red cells in 2 hours and continues to bleed. INR is 1.9 and fibrinogen 1.0 g/L. What should be given with the red cells?
Answer: FFP + platelets (1:1:1). Massive transfusion protocols use balanced resuscitation — red cells, FFP and platelets in roughly 1:1:1 — with cryoprecipitate or fibrinogen concentrate if fibrinogen < 1.5 g/L, tranexamic acid within 3 hours of injury, permissive hypotension until haemorrhage control, and prevention of the lethal triad (hypothermia, acidosis, coagulopathy). Monitor calcium (citrate toxicity) and potassium.
- Further crystalloid boluses: More crystalloid dilutes clotting factors.
- IV vitamin K 10 mg only: Vitamin K acts too slowly in massive haemorrhage.
- Human albumin 20%: Albumin does not correct coagulopathy.
5. Ten minutes into a blood transfusion, a patient develops fever, rigors, loin pain, hypotension and dark urine. What is the first action?
Answer: Stop transfusion; check identity. This suggests an acute haemolytic transfusion reaction, usually from ABO incompatibility due to identification errors. Stop the transfusion, keep IV access with a new giving set and saline, resuscitate, recheck patient and unit identity, inform the lab and haematologist, and send the unit back with samples. Monitor for DIC and renal failure.
- Slow rate and give paracetamol: This is acute haemolysis, not a simple febrile reaction.
- Continue with chlorphenamine: Antihistamines are for mild allergic reactions.
- Give furosemide and continue: The unit may be ABO-incompatible — stop it.
6. Blood typing: the red cells agglutinate with anti-A and anti-D antisera, and the plasma contains anti-B antibodies. What is the blood group?
Answer: A Rh-positive. Agglutination with anti-A means the cells carry the A antigen; with anti-D means they are Rh-positive. Group A people naturally have anti-B in their plasma, which confirms the result.
- B Rh-positive: Cells would react with anti-B and plasma would contain anti-A.
- AB Rh-negative: Cells would react with both anti-A and anti-B and not with anti-D.
- O Rh-positive: Cells would not react with anti-A.
- A Rh-negative: Cells would not react with anti-D.
7. Which part of an antibody molecule determines its biological effects (complement activation and binding to phagocytes)?
Answer: Fc portion. The Fab region binds antigen. The Fc region (constant part of the heavy chains) decides the antibody's effector functions: binding to Fc receptors on phagocytes, NK cells and mast cells, crossing the placenta (IgG) and activating complement.
- Fab portion: Binds antigen; does not determine effector function.
- Hypervariable region: Part of Fab; determines specificity.
- Light chain: Part of Fab; contributes to antigen binding.
- J chain: Joins IgM and IgA units together.
References and dose sources
- Furosemide dosing: Drugs.com: Furosemide dosage (see also our furosemide dose page)
- Chlorphenamine (chlorpheniramine) dosing: Drugs.com: Chlorpheniramine dosage (see also our chlorphenamine (chlorpheniramine) dose page)
- Adrenaline (epinephrine) dosing: Drugs.com: Epinephrine dosage (see also our adrenaline (epinephrine) dose page)
- Tranexamic acid dosing: Drugs.com: Tranexamic acid dosage (see also our tranexamic acid dose page)
- Calcium gluconate dosing: Drugs.com: Calcium gluconate dosage (see also our calcium gluconate dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.