transfusion medicine

Transfusion approaches

Standard: Restrictive strategy (single unit $\to$ reassess). Emergency: MTP (1:1:1 balanced resuscitation).

core principles (choosing wisely/nac)

• Single Unit Strategy (haemodynamically stable patients): Transfuse 1 unit pRBC $\to$ Reassess clinical status/Hb.
• Informed Consent: Mandatory discussion of risks (reaction, infection, alloimmunization) & alternatives. Document it.
• Pre-medication: Routine diphenhydramine/acetaminophen is not recommended (masks early reaction signs).

transfusion thresholds & products

Product	Indication / Threshold	Dose
pRBC	Hb < 70 g/L (Stable/ICU)	1 unit
	Hb < 80 g/L (ACS, Ortho post-op)	1 unit
Platelets	< 10 (Prophylaxis/Marrow failure)	1 pool
	< 50 (Major bleeding / Surgery)	1 pool
	< 100 (Neurosurgery / CNS Bleed)	1 pool
Plasma (FFP)	INR > 1.5-1.8 + Active Bleeding. Not for volume expansion.	10-15 mL/kg (~3-4 units)
Fibrinogen	< 1.5 g/L (Trauma/Major Bleed) < 2.0 g/L (Obstetrics/Post-partum)	Cryoprecipitate (10u) or Fibrinogen Conc. (4g)
PCC	Warfarin reversal (INR > 1.5 + bleeding).	Dosed by INR/weight

massive transfusion protocol (MTP)

Trigger: ABC Score $\ge$ 2 (Pulse >120, SBP <90, +FAST, Penetrating) or clinical judgement. Ratio: 1:1:1 (pRBC : Plasma : Platelets). Mimics whole blood.

the lethal diamond (physiologic)

1. Hypothermia: <35°C halts enzymatic cascade. Warm the patient.
2. Acidosis: pH < 7.2 inactivates FVIIa/thrombin. Resuscitate/Buffer.
3. Hypocalcaemia: Citrate in products chelates calcium. Keep iCa > 1.15 mmol/L.
4. Coagulopathy: Dilution/Consumption.

Adjuncts:

• TXA: 1g IV bolus + 1g infusion (<3h from injury).
• Calcium: 1g Calcium Gluconate/Chloride for every 2-4 units of blood products.

viscoelastic testing (TEG / ROTEM)

Indication: Active haemorrhage (Trauma, Liver Tx, Cardiac, OB). Results in ~10-20 mins.

• For more detail, see:
  • EMCrit IBCC: Coagulation
  • Life in the Fast Lane (LITFL): Thromboelastogram (TEG)
  • Practical Haemostasis: TEG/ROTEM

Graphic Shape	Problem	TEG Param	ROTEM Param	Treatment
Long thin line	Factors (delayed initiation)	R (Prolonged)	CT (Prolonged)	Plasma (FFP) or PCC
Narrow body	Fibrinogen (slow buildup)	K / $\alpha$-Angle	CFT / $\alpha$	Cryoprecipitate
Narrow waist	Platelets (weak clot)	MA (Low)	MCF (Low)	Platelets (or DDAVP)
Teardrop	Fibrinolysis (breakdown)	LY30 (>3%)	ML / CL30	Tranexamic Acid

interpretation pearl

• Fibrinogen First: In major bleeds, fibrinogen drops first. If the clot looks narrow (low MA/MCF), fix fibrinogen before platelets.
• “Test Tube” / Flat Line: No clotting $\to$ Check heparin effect (Heparinase TEG) vs. profound factor deficiency.

product modifications

• Irradiated: Inactivates lymphocytes to prevent TA-GVHD (Fatal).
  • Who: Hodgkin’s, Stem cell transplant, Congenital immune def, Intrauterine tx, HLA-matched.
• Washed: Removes plasma proteins/IgA.
  • Who: IgA Deficiency (prevents anaphylaxis), severe recurring allergic rxn.
• CMV -ve: Largely replaced by leukoreduction, but used for seronegative neonates/pregnant women.

transfusion reactions

Protocol: Stop transfusion $\to$ IV Access $\to$ Clerical Check $\to$ Vitals $\to$ Notify Lab.

immediate (<24h)

Reaction	Signs	Management
Febrile Non-Haemolytic	$\Delta$T >1°C, rigors. Diagnosis of exclusion.	Antipyretics. Slow rate.
Allergic	Hives, itch.	Diphenhydramine. Restart if mild.
Anaphylaxis	Hypotension, wheeze. IgA deficient pt?	Epinephrine. Do not restart. Wash cells.
AHTR (Haemolytic)	Flank pain, doom, red urine, shock.	Fluids, Pressors, Diuresis. Check Coombs.
TRALI	Hypoxia, bilat infilt <6h. No fluid overload.	Resp support. Avoid Diuretics.
TACO	HTN, JVP distension, fluid overload.	Diuretics, Oxygen, Sit up.
Sepsis	Fever >39°C, shock. (Plt > RBC).	Cx bag + patient. Broad spec Abx.

delayed (>24h)

• Delayed Haemolytic: 3-14d. New alloantibody (Kidd/Duffy). $\downarrow$ Hb, $\uparrow$ Bili.
• PTP (Post-Transfusion Purpura): 7-10d. Anti-HPA Abs. Plt < 10. Rx: IVIG.
• TA-GVHD: 1-6w. Rash + Liver + Pancytopenia. >90% mortality. Prevention (Irradiation) is key.

alternatives

• Iron: IV Iron (Sucrose/Isomaltoside) for pre-op optimization.
• EPO: Renal failure, Jehovah’s Witness (if acceptable).
• Cell Salvage: Intraoperative autologous transfusion.