What is the recommended DVT (Deep Vein Thrombosis) prophylaxis regimen for a patient who is strictly NPO (Nil Per Os) after undergoing hip surgery?

DVT Prophylaxis for Strict NPO Post-Hip Surgery Patients

For patients who are strictly NPO after hip surgery, use subcutaneous low-molecular-weight heparin (LMWH), specifically enoxaparin 30 mg every 12 hours, starting 6-8 hours postoperatively once hemostasis is established, combined with mechanical prophylaxis. 1, 2

Primary Pharmacological Agent for NPO Patients

• LMWH (enoxaparin) is the preferred agent because it requires no oral intake, no monitoring, and demonstrates superior efficacy with lower rates of DVT, PE, bleeding complications, and mortality compared to alternatives 1, 2
• The standard dose for elderly patients (>65 years) is enoxaparin 30 mg subcutaneously every 12 hours 2
• Do not initiate prophylaxis earlier than 6-8 hours after surgery, as earlier administration significantly increases major bleeding risk 3

Alternative Parenteral Agents When LMWH Cannot Be Used

• If renal failure is present (creatinine clearance <30 mL/min), switch to unfractionated heparin 5000 units subcutaneously every 8 hours, as LMWH is contraindicated in severe renal impairment 2
• Fondaparinux 2.5 mg subcutaneously once daily is an FDA-approved alternative when heparins cannot be used 2, 3
• Fondaparinux must also be started no earlier than 6-8 hours postoperatively after hemostasis is established 3

Duration of Prophylaxis

• Minimum duration is 7-10 days for all hip surgery patients 1
• Extended prophylaxis up to 32-35 days total is strongly recommended for hip fracture patients, as the SAVE-HIP3 trial demonstrated reduction in VTE/mortality from 18.6% to 3.9% with extended prophylaxis 1
• For hip replacement surgery, the usual duration is 5-9 days minimum, with extended prophylaxis consideration up to 35 days 1, 3

Mandatory Adjunctive Mechanical Prophylaxis

• Combine pharmacological prophylaxis with intermittent pneumatic compression (IPC) devices for 18 hours daily, as combined therapy reduces DVT risk by 66% compared to either modality alone 1, 2
• Mechanical prophylaxis should be initiated intraoperatively and continued postoperatively 1

Critical Contraindications Requiring Delayed Prophylaxis

Delay all pharmacological prophylaxis until stabilization occurs in patients with: 1, 2

• Active bleeding

• Coagulopathy

• Hemodynamic instability

• Traumatic brain injury

• Spinal trauma

• Use mechanical prophylaxis alone until pharmacological agents can be safely initiated in these cases 1, 2

Neuraxial Anesthesia Timing Considerations

• LMWH timing must be carefully coordinated with neuraxial anesthesia to minimize epidural/spinal hematoma risk, which can result in permanent paralysis 3
• Consider administering LMWH between 18:00-20:00 to minimize risk during daytime surgical procedures 1

Monitoring and Dose Adjustments

• For elderly patients with renal impairment, dose adjustment according to anti-Xa levels may be warranted 2
• Major bleeding with LMWH occurs in approximately 1.0-1.4% of hip fracture patients 1
• Regular assessment for signs and symptoms of DVT/PE is necessary throughout the prophylaxis period 2

Common Pitfalls to Avoid

• Never use aspirin as sole therapy for DVT prophylaxis in hip surgery patients—it is explicitly contraindicated by ACCP guidelines due to inferior efficacy 1, 2
• Do not rely on mechanical prophylaxis alone except when pharmacological agents are absolutely contraindicated 2
• Failure to adjust for renal function can lead to bleeding complications, particularly with renally-cleared LMWH 1
• Do not anticoagulate before emergency hip surgery, as this significantly increases surgical site bleeding and wound hematoma risk 4