Induction — Haematology

Use: How whole blood is separated into transfusable components

• Red cells
• Platelets
• Plasma

• FFP (fresh frozen plasma)
• Cryoprecipitate
• Plasma for fractionation (not UK; pools of thousands of donors)

• Albumin
• Factor VIII / IX
• Immunoglobulins
• Anti-D, etc.

Use: What blood is made of and where each part is produced

• Red cells (erythrocytes) + reticulocytes
• White cells (leucocytes): neutrophils, lymphocytes, others e.g. monocytes, eosinophils
• Platelets (thrombocytes)

• Clotting factors
• Albumin
• Immunoglobulin

• Plasma contains fibrinogen
• Serum = plasma minus fibrinogen
• Buffy coat = white blood cells + platelets

• Light chains: kappa, lambda
• Heavy chains: IgG, IgA, IgM, IgD, IgE
• Two antigen-binding sites

Use: Storage, dosing and indications for packed red cell transfusion

• 3 ml/kg raises Hb by ~1 g/dl
• ~280 ml per unit
• Expect >1 g/dl Hb rise per unit in adults (depends on size of adult and donor unit)
• Stored at 4°C
• Shelf life up to 35 days

• Active bleeding where fluids likely insufficient
• Bone marrow failure
• Suppress / exchange abnormal red cells e.g. thalassaemia and sickle cell disease
• Rarely haematinic deficiency (usually best managed with replacement)

Use: Storage, dosing and platelet-count thresholds for transfusion

• 1 pool from 4 donors (standard adult dose) OR 1 donor by apheresis (cell separator)
• Store at 22°C (room temp), constantly agitated
• Shelf life 7 days only (bacterial infection risk, now screened)
• Need blood group, NO crossmatch
• Dose 10 ml/kg or 1 pool (whichever least)

• Bleeding or pre-operative: <80
• Bleeding eye or brain: <100
• Bone marrow failure: <10
• Neonates: <30
• Also for platelet dysfunction e.g. on bypass

Use: Storage, dosing and indications for FFP

• 1 unit from 1 donor (~300 ml); small packs for children
• Stored at -30°C
• Shelf life 1 year
• Thaw ~20-30 min before use (if too hot proteins cook)
• Give ASAP — within 1h or coag factors degenerate
• Dose 12-15 ml/kg (usually 2-3 units)
• Need blood group; no crossmatch; choose same group

• Bleeding + abnormal coag results (PT, APTT) — monitor response clinically and by coag tests
• Reversal of warfarin e.g. for urgent surgery
• Other conditions occasionally
• NOT just to replace volume / fluid loss

Use: Storage, contents and indications for cryoprecipitate

• From frozen plasma thawed at 4-8°C overnight (residue remains)
• Contains fibrinogen and factor VIII
• Same as FFP — store at -30°C for 1 year
• Standard dose from 10 donors (5 in a pack)

• Massive bleeding with very low fibrinogen
• Rarely hypofibrinogenaemia

Use: Which ABO / RhD groups are compatible for red cells vs plasma — they run in opposite directions

• A → A, O
• B → B, O
• O → O only
• AB → AB, A, B, O

• A → A, AB
• B → B, AB
• O → O, A, B, AB
• AB → AB only

• Red cells: RhD-negative recipient must receive RhD-negative; RhD-positive recipient may receive either
• Plasma: either RhD may be given

Use: When to request modified or specially selected blood products

• Age of blood: young blood lasts longer, less cation leakage
• Specific phenotype (Rh & Kell): for multiply transfused e.g. sickle and thalassaemia
• Irradiated: depressed T-cell function e.g. post-BMT, DiGeorge, Hodgkin lymphoma, certain drugs e.g. fludarabine
• CMV-negative: pregnancy and IUT (other requirements differ between institutions)
• Others: washed, plasma-depleted, T-antigen-negative

Use: How urgently blood can be provided — wait as long as is safe but no longer

• Flying-squad O-negative: at certain sites within the hospital
• Group-specific: no antibody screen or crossmatch
• Full crossmatch

• Decided with the on-call haematologist (the doctor) and blood bank (the biomedical scientist)

Use: Framework for classifying transfusion reactions

• Acute haemolytic transfusion reactions
• Transfusion-associated GvHD (TA-GvHD)
• Anaphylaxis

• Delayed haemolytic transfusion reactions
• Post-transfusion purpura
• Neonatal alloimmune disorders including Rh disease of the newborn

• Infective: bacterial, viral, prion
• Iron overload

Use: Framework for classifying acquired haemolytic anaemias

• Autoimmune
• Alloimmune
• Hyperhaemolysis

• Hypersplenism
• Paroxysmal nocturnal haemoglobinuria
• Secondary to renal or liver disease
• Miscellaneous: chemicals, toxins, infections

Use: Distinguishing and shared features of haemolysis

• Extravascular: RES picks up damaged RBC
• Intravascular: haemoglobinaemia, haemoglobinuria
• Intravascular usually with IgM or complement — cf PNH and ABO-incompatible transfusion
• May be both

• Anaemia
• Reticulocytosis (polychromasia on the ordinary blood film)
• Macrocytosis (young cells are big cells)
• Unconjugated hyperbilirubinaemia
• Morphological changes e.g. spherocytes, fragmented cells
• Marrow hypertrophy and hyperplasia

Use: When to transfuse red cells by Hb and clinical context

• Hb >100 g/L — RBC transfusion NOT indicated
• Hb 70–100 g/L — less clear; assess cardiopulmonary reserve
• Hb <70 g/L — strong indication for transfusion
• Critical Care — 70 g/L (may be 90 g/L if cardiac)

• Fatigue, dizziness, shortness of breath, new or worsening angina

• Only absolute indication for red cells = increase O2 delivery to vital organs in anaemic patients
• Each organ system has a different O2 demand & critical point for hypoxia
• No universal trigger — weigh cause/severity of anaemia, ability to compensate, rate & likelihood of further blood loss, risk vs benefit
• Haemoglobinopathy — normally individualised
• Transfusion-dependent (e.g. MDS) — whatever best suits quality of life

• TRICC trial (NEJM, 11 Feb 1999) — restrictive vs liberal transfusion strategy in critical care

Use: Framework to reduce unnecessary transfusion across the surgical pathway

• 1st pillar — optimise erythropoiesis
• 2nd pillar — minimise blood loss & bleeding
• 3rd pillar — harness & optimise the physiological reserve of anaemia

• Preoperative · Intraoperative · Postoperative

• Detect anaemia; identify & manage the underlying disorder
• Treat iron deficiency / anaemia of chronic disease / other haematinic deficiencies
• Note: anaemia is a contraindication for elective surgery

• Identify & manage bleeding risk; minimise iatrogenic blood loss
• Meticulous haemostasis, blood-sparing surgical techniques, pharmacological/haemostatic agents
• Vigilant monitoring & management of post-operative bleeding

• Assess/optimise physiological reserve & risk factors; restrictive transfusion thresholds
• Optimise cardiac output, ventilation & oxygenation; maximise O2 delivery, minimise O2 consumption

Use: Grades hypovolaemic shock by blood-loss volume and physiological signs (70 kg male)

• Class I — <15% TBV / 750 ml
• Class II — 15–30% TBV / 800–1500 ml
• Class III — 30–40% TBV / 1500–2000 ml
• Class IV — >40% TBV / >2000 ml

• I — unchanged / unchanged
• II — normal / raised (narrow pulse pressure)
• III — reduced / reduced
• IV — very low / very low

• I — mild tachycardia
• II — 100–120
• III — >120 (reduced volume)
• IV — >120 (very weak)

• I — normal · II — slow (>2s) · III — slow (>2s) · IV — undetectable

• I — normal · II — normal · III — tachypnoea (>20/min) · IV — tachypnoea (>20/min)

• I — >30 ml/hr · II — 20–30 · III — 10–20 · IV — 0–10 ml/hr

• I — normal / normal · II — pale / pale · III — pale / pale · IV — pale & cold / ashen

• I — alert · II — anxious/aggressive · III — anxious, aggressive or drowsy · IV — drowsy, confused or unconscious