What is the recommended pain management approach for a patient with a femur fracture, considering potential impaired renal function and gastrointestinal health?

Pain Management for Femur Fracture

Regional anesthesia with femoral nerve block or fascia iliaca compartment block should be the primary analgesic approach for femur fractures, combined with scheduled acetaminophen and cautious use of NSAIDs only if renal function is adequate. 1

First-Line: Regional Anesthesia

Femoral nerve blocks or fascia iliaca compartment blocks (FICB) are the gold standard for femur fracture pain management, providing superior analgesia with fewer systemic side effects compared to opioids alone. 1 These techniques:

• Significantly reduce morphine consumption and opioid-related complications 1
• Decrease rates of acute confusion, postoperative delirium, and chest infections 1
• Enable earlier mobilization, which is critical for preventing thromboembolic complications 1
• Continuous catheter techniques are superior to single-shot blocks for extended pain control 1

Second-Line: Multimodal Non-Opioid Analgesia

Acetaminophen (Mandatory Baseline)

• Administer acetaminophen 1000 mg IV or PO every 6 hours routinely for all patients unless contraindicated 2, 1
• This decreases supplementary analgesic requirements and forms the foundation of multimodal analgesia 2
• Continue throughout the perioperative period 2

NSAIDs (Use With Extreme Caution)

NSAIDs are contraindicated in patients with renal dysfunction and should be used with extreme caution in all femur fracture patients. 2 Given the context of potential impaired renal function:

• Avoid NSAIDs entirely if any degree of renal impairment exists 2, 1
• If renal function is normal and no GI contraindications exist, COX-2 selective inhibitors may be added 1
• Co-prescribe a proton pump inhibitor if NSAIDs are used, particularly in patients on ACE inhibitors, diuretics, or antiplatelets 2, 3
• Monitor for acute kidney injury, especially in elderly or volume-depleted patients 3

Third-Line: Opioids (Rescue Therapy Only)

Reserve opioids strictly for breakthrough pain unresponsive to regional anesthesia plus non-opioid analgesics. 1 When opioids are necessary:

Dosing Modifications for Renal Dysfunction

• Avoid oral opioids completely in patients with renal dysfunction 2
• Reduce both dose and frequency of IV opioids by half (e.g., 50% dose reduction) in renal impairment 2
• Use IV patient-controlled analgesia (PCA) rather than fixed-interval dosing 1

Specific Opioid Considerations

• Never use codeine - it is constipating, emetic, and associated with perioperative cognitive dysfunction in this population 2
• Tramadol should be used cautiously with reduced dosing in renal dysfunction 2
• Morphine and fentanyl carry risks of accumulation and respiratory depression in renal impairment 2

Neuraxial Anesthesia Options

For operative management:

• Spinal anesthesia with local anesthetic plus low-dose opioid provides excellent perioperative analgesia 1
• Continuous epidural with local anesthetic and opioids is recommended for patients with cardiopulmonary risk factors 1

Critical Pitfalls to Avoid

• Never use opioids as the sole analgesic - this increases respiratory depression and postoperative confusion risk 1
• Never administer intramuscular opioids 1
• Never use NSAIDs in any patient with renal dysfunction - this is an absolute contraindication 2, 1
• Avoid combining general and neuraxial anesthesia 1
• Do not use weak opioids for severe pain in the first 6 hours postoperatively 1

Additional Perioperative Considerations

Fluid Management

• Many femur fracture patients are hypovolemic preoperatively and require routine pre-operative fluid therapy 2
• Optimized fluid management reduces morbidity and hospital stay 2
• This is particularly important before considering NSAIDs, as volume depletion increases renal toxicity risk 3

Thromboprophylaxis

• Administer low molecular weight heparin or fondaparinux between 18:00-20:00 to minimize bleeding risk with neuraxial techniques 2
• Timing is critical if regional anesthesia is planned 2