Anticoagulation in ICU—LMWH

Question 1

LMWH overview

Answer 1

LMWH Overview
* Structure: Short polysaccharide chains fractionated from unfractionated heparin (UFH)
* Mechanism: Activates antithrombin III (similar to UFH), mainly inhibiting factor Xa

Question 2

Advantages Over UFH

Answer 2

• Increased bioavailability and longer duration of action
  
  • Fixed dosing — does not usually require lab monitoring
  • Lower risk of HIT (Heparin-Induced Thrombocytopenia)
  • More effective in VTE treatment:
    -Greater thrombus regression
    -Lower recurrence, bleeding, and mortality

Question 3

Clinical Efficacy

Answer 3

Clinical Efficacy
* Meta-analyses: Show LMWH is more effective than UFH for VTE treatment
* ICU thromboprophylaxis trials:
- Mixed results overall
- Dalteparin vs. UFH (3754 ICU patients):
—->No difference in DVT incidence
—->Lower incidence of PE
——>lower HIT rates with dalteparin

Question 4

HIT Risk Reduction

Answer 4

HIT Risk Reduction
* Postoperative patients: LMWH associated with significantly lower HIT risk
* Risk ratio: 0.25
* HIT complicated by VTE: LMWH reduced risk by 80% compared to UFH
* Risk ratio: 0.20

Question 5

Limitations

Answer 5

Limitations
* No routine lab test to monitor anticoagulant effect
*Longer duration of action in comparision to UFH
*Incomplete reversal if required

*	Caution in:
-Patients at high risk of bleeding
-Morbidly obese patients (standard dosing may be inadequate) *Renal clearance- best to avoid in renal failure

Question 6

Reversal

Answer 6

Reversal
* No specific antidote
* Protamine sulfate: Partial reversal (60–80% effectiveness)
* Andexanet alfa:
* FDA-approved for apixaban & rivaroxaban
* Not officially approved for LMWH, but showed promise in ANNEXA-4 study