Anticoagulation in ICU - UFH

Question 1

U F H - Overview

Answer 1

• Type: Naturally occurring polysaccharide anticoagulant
  
  • Forms: Unfractionated heparin (UFH)- molecular chains with variable lenghts and molecular weights

Question 2

MOA

Answer 2

• Potentiates antithrombin III, leading to:
  
  • Inactivation of thrombin
  • Inactivation of factors IXa, Xa, XIa, XIIa, and plasmin
  • Inhibition of fibrinogen-to-fibrin conversion

Question 3

Metabolism

Answer 3

Metabolism: Mostly hepatic by depolymerisation; partially via the reticuloendothelial system
* Half-life: 1–2 hours
* Monitoring: aPTT used to guide dosing to therapeutic levels

Question 4

clinical use

Answer 4

Primary parenteral anticoagulant for:
* DVT/PE treatment and prophylaxis
* Systemic anticoagulation in ICU
* Preferred in renal impairment: Safe in CrCl < 30 mL/min (non-renal elimination)
* Routine ICU use: Subcutaneous UFH for DVT prevention

Question 5

Reversal

Answer 5

• Protamine sulfate: Rapid reversal
  
  • Now recombinant: minimal risk of anaphylaxis

Question 6

Resistance

Answer 6

• Antithrombin III deficiency:eg- in DIC
  Other causes:
  *Large clot burden
  *High factor VIII levels

Tt:
-Antithrombin 3 concentrate
-FFP
-Change to DTI

Question 7

Complication

Answer 7

Heparin-Induced Thrombocytopenia (HIT)
* Mechanism: Immune-mediated; antibodies target heparin-platelet factor 4 complex
* Effects: Paradoxical thrombosis (venous and/or arterial) during thrombocytopenia
* Onset: Typically occurs 5–10 days after heparin exposure

Question 8

• Management

Answer 8

• Immediately stop all heparin products
  
  • Start a non-heparin anticoagulant (e.g., direct thrombin inhibitor)
  • Re-exposure is contraindicated due to risk of rapid, severe recurrence