Surgeon: “Don’t worry, there won’t be much bleeding.”
Resident: “Not sure I can trust that…😡．Last time I was told not to place an extra line, but unexpected adhesions led to massive bleeding. It was tough, and the surgeon just left without saying a word. Luckily the assistant apologized…”
Anesthesiologist: “At least we were prepared 👍”
In daily practice, when people hear the word “transfusion,” they usually think of red blood cell transfusion. In the operating room or ICU, it’s something we encounter almost every day.
And yet, it always feels like the blood products don’t arrive quite as quickly as we’d like 😅
Why do we transfuse red cells (RCC)?
“Because the patient is bleeding!”
“Because the patient is anemic!”
That’s true — but why exactly do we need red cells rather than fluids alone?
🔷 The key point is hemoglobin.
Hemoglobin’s main role is to deliver oxygen.
If hemoglobin becomes too low, tissues across the body cannot get enough oxygen.
👉 The primary purpose of transfusion is therefore to restore oxygen-carrying capacity (though in cases of acute bleeding, it also helps maintain circulating volume).
About RCC products
🔷 Basic facts (Japan)
- RCC (Red Cell Concentrate)
- 1 unit: ~140 mL (derived from 200 mL donation)
- Typically supplied as 2 units per pack (~280 mL, from 400 mL donation)
- Hemoglobin content: ~26.5 g per unit → ~53 g per 2-unit pack
- Hematocrit: ~60% (normal human blood ~40%)
- Stored at 2–6 °C, up to 21 days
- Cost: ~17,000 yen for 2 units (~110 USD)
🔷 Overseas standards (for reference)
- In the US and Europe, one unit of packed red blood cells (PRBC) is typically 250–300 mL, with a hematocrit of ~55–65%.
- One unit usually raises Hb by ~1 g/dL in adults (depending on body size and volume status).
🔷 How much does Hb rise after 2 units?
For a 50 kg patient:
- Estimated blood volume ≈ 70 mL/kg → ~3500 mL (35 dL)
- One pack (2 units) contains ~53 g Hb
- Increase = 53 ÷ 35 ≈ +1.5 g/dL
👉 Clinically, Hb rises about 1–2 g/dL per 2 units, assuming no ongoing bleeding.
🔷 When to start transfusion?
There is no absolute cutoff, but commonly:
- Hb 7–8 g/dL → transfusion often considered
- Hb <6 g/dL → almost always required
- Elderly, patients with valvular disease, ischemic heart disease, or on dialysis → transfused earlier (9–10 g/dL) ⚠️ However, there is little strong evidence that “early transfusion” improves outcomes in these groups.
Internationally, the restrictive transfusion strategy (threshold ~7 g/dL, or ~8 g/dL in cardiac surgery/ICU) is widely recommended.
Electrolyte changes with RCC transfusion
Besides the general transfusion risks (allergic reactions, TRALI, infection), RCC specifically affects potassium and calcium:
- Potassium rise Stored RBCs gradually hemolyze, releasing K+. Normally not an issue, but in dialysis patients or massive transfusion → risk of dangerous hyperkalemia.
- Calcium drop Anticoagulant citrate in blood products binds calcium → transient hypocalcemia (“citrate toxicity”). Usually self-corrects as citrate is metabolized by liver/kidneys. Persistent hypocalcemia may occur in liver failure or renal failure, requiring monitoring.
📝 Summary
- Main goal: restore oxygen delivery capacity
- 2 units (1 pack) → Hb ↑ by ~1–2 g/dL
- Start transfusion at 7–8 g/dL (adjust by patient condition)
- Watch for hyperkalemia and hypocalcemia, especially in massive transfusion, renal failure, or liver failure.