Hemostasis and Blood Transfusion

Hemostasis Essentials - Clotting Crew Call

• Hemostasis: Physiological process halting blood loss post-injury.
• Key Stages:
  • Vascular Spasm: Initial vasoconstriction reduces blood flow.
  • Primary Hemostasis (Platelet Plug Formation):
    • Adhesion: Platelets bind exposed collagen via vWF-GpIb.
    • Activation: Shape change; release of ADP, TXA2 (potent vasoconstrictor & platelet activator).
    • Aggregation: GpIIb/IIIa binds fibrinogen, linking platelets.
  • Secondary Hemostasis (Coagulation Cascade): Enzymatic cascade forming fibrin clot.
    • 
  • Fibrinolysis: Clot dissolution by plasmin.
• Simplified Coagulation Pathways:

⭐ Vitamin K is crucial for factors II, VII, IX, X (📌 Mnemonic: 1972) & anticoagulant proteins C, S.

Bleeding & Clotting Chaos - When Systems Fail

Disorders of hemostasis: excessive bleeding or thrombosis. Key conditions:

• Thrombophilias (Hypercoagulable States):
  • Factor V Leiden: Most common inherited (APC resistance).
  • Antiphospholipid Syndrome (APS): Acquired; arterial/venous thrombosis, recurrent fetal loss.
  • Protein C/S, Antithrombin III deficiencies.

⭐ FFP replaces all clotting factors; Cryoprecipitate: rich in Fibrinogen, FVIII, vWF, FXIII.

Hemostasis Meds & Moves - Drug & Scalpel Fixes

Pharmacological:

• Anticoagulants:

  Drug	MOA	Monitor	Reversal
  UFH	Potentiates ATIII	aPTT	Protamine (1mg/100U)
  Warfarin	Vit K antag	PT/INR (2-3)	Vit K, PCC, FFP
  DOACs	Direct Th/Xa inhib	(Specific)	Idaru (Dabi), Andex (Xa inh)

• Procoagulants:
  • Tranexamic Acid (TXA): Antifibrinolytic (1g IV).
  • DDAVP: ↑vWF, FVIII.
  • Blood: FFP, Cryo, Plts.

    ⭐ FFP replaces all clotting factors; dose 10-15 mL/kg. Cryoprecipitate: Fibrinogen, FVIII, FXIII, vWF.

Surgical & Topical:

• Mechanical: Pressure, ligature, tourniquet.
• Thermal: Cautery, Argon Plasma Coagulation (APC).
• Topical: Gelfoam, Surgicel, Thrombin. 📌 Surgicel Slowly resorbed.

Anticoagulation Reversal Algorithm:

Blood Transfusion Basics - Life‑Saving Liquids

• Indications: Symptomatic anemia, Hb < 7 g/dL (or < 8 g/dL if cardiac hx), active bleeding, coagulopathy.

• Blood Products Table:

  Product	Content	Key Indication	Volume/Effect (Typical)	Storage Temp
  PRBC	RBCs	↑O₂ capacity	~300mL; 1U ↑Hb 1g/dL	2-6°C
  Platelets	Platelets	Bleeding, Plt < 10-20k	~50mL(RDP); 1U RDP ↑Plt 5-10k	20-24°C (agitate)
  FFP	All factors	Coagulopathy (INR > 1.5)	~250mL; 10-15mL/kg	≤ -18°C
  Cryoprecipitate	Fibrinogen, FVIII, vWF	Fibrinogen < 100mg/dL	~15mL/U; 10U ↑Fib 50-70mg/dL	≤ -18°C

• Massive Transfusion Protocol (MTP): >10 units PRBC/24h. Ratio 1:1:1 (PRBC:FFP:Platelets).

• Acute Transfusion Reaction Management:

⭐ ABO incompatibility (clerical error) is the leading cause of fatal transfusion reactions.

High‑Yield Points - ⚡ Biggest Takeaways

• Primary hemostasis: Platelet plug formation (adhesion, activation, aggregation).
• Secondary hemostasis: Coagulation cascade activation leads to a stable fibrin clot.
• Vitamin K dependent factors include II, VII, IX, X, Protein C & S.
• FFP replaces all clotting factors; Cryoprecipitate for fibrinogen, Factor VIII, vWF, Factor XIII.
• Massive transfusion protocol (MTP) aims for 1:1:1 ratio of PRBC:FFP:Platelets.
• Febrile non-hemolytic is the most common transfusion reaction; monitor for TRALI and TACO.