What is the recommended analgesic approach for an older adult patient with a proximal humerus fracture, considering the need for a phrenic nerve sparing block and potential comorbidities such as Chronic Obstructive Pulmonary Disease (COPD)?

Phrenic Nerve Sparing Block for Proximal Humerus Fracture

Primary Recommendation

For older adults with proximal humerus fractures, particularly those with COPD or respiratory comorbidities, use an ultrasound-guided superior trunk block or peri-humeral block rather than traditional interscalene block to provide effective analgesia while avoiding phrenic nerve paresis.

Rationale for Phrenic Nerve Sparing Approach

The traditional interscalene block, while highly effective for shoulder analgesia, causes phrenic nerve paresis in nearly 100% of cases 1. This is particularly problematic in elderly patients with COPD or limited respiratory reserve, where even temporary hemidiaphragmatic paralysis can precipitate respiratory failure 2.

Recommended Block Techniques

First-Line: Ultrasound-Guided Peri-Humeral Block (PHB)

• The peri-humeral block targets articular and cutaneous nerves around the distal humerus while completely sparing the phrenic nerve 2
• Provides median pain scores of 2.4 (IQR 0-3.8) over 24 hours with stable hemodynamics requiring no additional intraoperative opioids 2
• Mean time to first analgesic requirement is 425 minutes (approximately 7 hours) 2
• This block has demonstrated opioid-sparing and motor-sparing features without adverse respiratory effects 2

Alternative: Superior Trunk Block

• Targets the superior trunk of the brachial plexus with lower volumes and more distal deposition than traditional interscalene approach 1
• Reduces but does not eliminate phrenic nerve involvement compared to standard interscalene technique 1

Optimal Local Anesthetic Regimen

Use 0.2% ropivacaine with adjuvants (dexamethasone 5mg + dexmedetomidine 25mcg) for single-shot blocks 3. This combination provides:

• Median block duration of 3.5 days versus 1.5 days with plain ropivacaine (p<0.0001) 3
• Mean pain scores of 2.32 versus 8.58 on postoperative day 1 (p<0.0001) 3
• Reduced opioid consumption: 108mg versus 276mg morphine milligram equivalents (p<0.0001) 3

Dosing Considerations for Elderly/COPD Patients

• Debilitated and elderly patients require reduced doses commensurate with age and physical condition 4
• For major nerve blocks, use 35-50 mL of 0.5% ropivacaine (175-250mg total) with onset in 15-30 minutes and duration of 5-8 hours 4
• Patients with hepatic disease or cardiovascular comorbidities require lower doses due to reduced drug metabolism 4

Integration with Multimodal Analgesia

Peripheral nerve blockade should always be considered as an adjunct to avoid opioid-related respiratory depression and postoperative confusion in elderly patients 5. The comprehensive pain strategy includes:

• Baseline paracetamol (acetaminophen) 1000mg every 6 hours as first-line medication 6
• Regional nerve block as primary analgesic modality 5
• NSAIDs/COX-2 inhibitors if not contraindicated 7
• Rescue opioids only as needed, with 20-25% dose reduction per decade after age 55 5

Critical Safety Monitoring

Continuous monitoring must include pulse oximetry, ECG, and non-invasive blood pressure throughout the procedure 6, 4. Specific precautions include:

• Perform incremental dosing with 3-5 mL aliquots, allowing sufficient time between doses to detect intravascular or intrathecal injection 4
• Frequent syringe aspiration before and during injection, though negative aspiration does not guarantee extravascular placement 4
• Supplemental oxygen should be provided, particularly in patients with COPD or respiratory compromise 5

Evidence for Regional Anesthesia Benefits

Regional anesthesia for proximal humerus fractures provides:

• Superior postoperative analgesia with reduced opioid consumption 8
• Shorter hospital length of stay 8
• Better functional outcomes 8
• Fewer adverse events compared to general anesthesia alone 8
• Reduced incidence of postoperative confusion in elderly patients 5

Critical Pitfalls to Avoid

Avoid Traditional Interscalene Block in COPD Patients

The standard interscalene approach causes universal phrenic nerve paresis and should be avoided in patients with significant respiratory disease 1, 2. Even "low-volume" interscalene techniques carry substantial risk of hemidiaphragmatic paralysis.

Avoid Opioids as Sole Analgesic Strategy

Opioid analgesics as the sole adjunct are not supported due to relatively greater risk of respiratory depression and postoperative confusion in elderly patients 5. A 20-25% opioid dose reduction per decade after age 55 is recommended when opioids are necessary 5.

Avoid Certain Adjuvants

• Ketamine should be used with extreme caution or avoided in elderly patients due to significant risk of postoperative confusion and delirium 9, 7
• Clonidine is not recommended as a spinal adjuvant due to hypotension, sedation, and bradycardia risks 7
• Long-acting benzodiazepines should be avoided entirely as they are strongly associated with postoperative delirium in patients over 60 years 6

Monitor for Local Anesthetic Systemic Toxicity

Early warning signs include restlessness, anxiety, incoherent speech, light-headedness, numbness and tingling of mouth and lips, metallic taste, tinnitus, dizziness, blurred vision, tremors, or drowsiness 4. Resuscitative equipment, oxygen, and lipid emulsion should be immediately available 4.

Practical Implementation Algorithm

1. Assess respiratory status: Perform baseline pulmonary function assessment in COPD patients; if FEV1 <50% predicted or significant dyspnea at rest, phrenic-sparing technique is mandatory
2. Select block technique: Use peri-humeral block as first-line for complete phrenic sparing 2; consider superior trunk block as alternative 1
3. Prepare local anesthetic: Mix 0.2% ropivacaine with dexamethasone 5mg and dexmedetomidine 25mcg for extended duration 3
4. Perform ultrasound-guided block: Use real-time visualization to ensure optimal local anesthetic deposition 2
5. Integrate multimodal analgesia: Administer scheduled paracetamol, consider NSAIDs if appropriate, minimize opioid use 5, 6
6. Monitor continuously: Pulse oximetry, blood pressure, and clinical assessment for 30 minutes post-block 6, 4