Can Lovenox (enoxaparin) be given to a patient with subarachnoid hemorrhage?

Venous Thromboembolism Prophylaxis in Subarachnoid Hemorrhage

Lovenox (enoxaparin) should NOT be given to patients with subarachnoid hemorrhage until the aneurysm is secured. After aneurysm securing, VTE prophylaxis with Lovenox can be safely initiated 1.

Timing of VTE Prophylaxis in SAH

The management of thromboprophylaxis in subarachnoid hemorrhage requires careful consideration of competing risks:

1. Before aneurysm securing:

   • Withhold pharmacological VTE prophylaxis
   • Use mechanical prophylaxis (intermittent pneumatic compression devices)
   • Risk of rebleeding outweighs VTE risk during this period

2. After aneurysm securing:

   • Initiate pharmacological VTE prophylaxis with LMWH (Lovenox)
   • According to the 2023 AHA/ASA guidelines, "When aneurysm is secured, VTE prophylaxis should be used" 1

Dosing Considerations

When initiating Lovenox after aneurysm securing:

• Standard dosing: Enoxaparin 40mg subcutaneously once daily
• Renal adjustment: Required for patients with CrCl <30 mL/min 1
• Monitoring: Consider anti-Xa levels in high-risk patients 2

Safety Profile

The safety of Lovenox in secured SAH has been demonstrated in several studies:

• A retrospective study of 241 SAH patients with ventriculostomies found that prophylactic anticoagulation was associated with only minor hemorrhages and no major hemorrhages 3
• Recent data shows no statistically significant difference in secondary intracranial hemorrhage between patients receiving enoxaparin (3.83%) versus no VTE prophylaxis (3.94%) after aneurysm securing 2

Special Considerations

1. Patients with external ventricular drains (EVDs):

   • Prophylactic enoxaparin can be used safely in patients with EVDs
   • Ventriculostomy-associated hemorrhages are rare and typically minor 3

2. Renal impairment:

   • Use with extreme caution in patients with severe renal impairment (CrCl <30 mL/min)
   • Consider dose reduction or alternative agents 1

3. Monitoring effectiveness:

   • Higher steady-state anti-Xa levels (>0.3 units/mL) may be associated with lower VTE incidence without increasing hemorrhage risk 2

Pitfalls to Avoid

1. Premature initiation: Starting Lovenox before aneurysm securing significantly increases rebleeding risk

2. Delayed initiation: Withholding prophylaxis after securing increases VTE risk (up to 18% in untreated patients vs. 7.5% in treated patients) 3

3. Failure to adjust for renal function: Patients with renal impairment have increased bleeding risk with standard doses 1

4. Inadequate monitoring: Patients should be monitored for signs of both VTE and hemorrhagic complications

In conclusion, while Lovenox is contraindicated in patients with unsecured aneurysmal subarachnoid hemorrhage, it becomes an important component of care once the aneurysm is secured to prevent potentially fatal venous thromboembolism.