Continuous Peripheral Nerve Catheters

CPNCs - Nerve Soothe Cruise

• Definition: Catheters near peripheral nerves for continuous local anesthetic (LA) infusion, providing targeted pain relief.
• Benefits: 📌 POMS for CPNC perks!
  • Prolonged analgesia (often 2-5 days).
  • Opioid-sparing, reducing side effects.
  • Mobilization enhanced, faster recovery.
  • Satisfaction increased.
• Key Indications:
  • Major limb surgeries (total knee/shoulder).
  • Significant trauma (rib/femoral fractures).
  • Phantom limb pain management.
• Technique Highlights:
  • Ultrasound guidance for precise placement.
  • LAs: Ropivacaine (0.2%), Bupivacaine (0.125%).
  • Infusion: Basal rate + Patient-Controlled Epidural Analgesia (PCEA) boluses.

⭐ CPNCs effectively reduce chronic post-surgical pain (CPSP) risk, especially after major joint arthroplasty.

CPNCs: Insertion & Infusions - Probes & Potions

• Probes: Insertion Techniques & Equipment

  • Guidance: Ultrasound (USG) is standard (in-plane or out-of-plane views). Nerve stimulator as adjunct for confirmation (motor response at <0.5mA).
  • Catheters: Stimulating (confirm proximity before LA) vs. Non-stimulating. Multi-orifice preferred.
  • Techniques: Seldinger (guidewire) or Catheter-over-needle. Tunneling (2-5 cm from insertion) reduces dislodgement & infection.

• Potions: Infusion Strategies

  • Local Anesthetics (LAs): Dilute, long-acting agents.
    • Ropivacaine: 0.1-0.2%
    • Bupivacaine/Levobupivacaine: 0.0625-0.125%
  • Regimens:
    • Continuous Basal Infusion (CBI): 4-8 mL/hr.
    • Patient-Controlled Regional Analgesia (PCRA): Bolus 3-5 mL, lockout 20-60 min.
    • Programmed Intermittent Bolus (PIB): e.g., 5-10 mL every 1-2 hrs; may offer better spread.
  • Adjuvants: Limited role in continuous infusions; focus on LA selection & concentration.

⭐ Catheter tip to nerve distance is critical; US-guided hydrodissection with LA or saline confirms perineural spread before full bolus or infusion initiation for optimal analgesia and safety.

CPNCs: Monitoring & Mayhem - Guarding & Gotchas

• Vigilant Monitoring:
  • Assess pain (VAS/NRS), sensory/motor block levels (e.g., Bromage scale for lower limb) q4-8h.
  • Catheter site: Inspect for leakage, dislodgement, kinking, signs of infection (erythema, warmth, tenderness, pus).
  • Pump function: Confirm correct LA, rate, volume infused, battery.
  • Patient education: Report pain, numbness changes, pump alarms. Ambulation safety.
• Gotchas & Guarding (Complications):
  • Catheter Issues:
    • Migration/Dislodgement: ↓ analgesia. Secure well.
    • Leakage: Common. Adjust dressing; may need resiting.
    • Occlusion: Pump alarm. Gentle flush; avoid high pressure.
  • Block Issues:
    • Inadequate analgesia: Check system. Consider rescue bolus (e.g., 5-10ml of dilute LA) or adjuncts.
    • Unintended spread (e.g., phrenic nerve palsy with interscalene).
  • Infection: Strict asepsis. Remove catheter if suspected.
  • ⚠️ LAST: Rare with dilute infusions. Early signs: tinnitus, metallic taste, perioral numbness. Late: seizures, arrhythmias. Management: Intralipid 20% (Bolus $1.5$ ml/kg, then infusion $0.25$ ml/kg/min).
  • Nerve Injury: Persistent paresthesia/deficit. Stop infusion, investigate.
  • ⭐ > Compartment syndrome can be masked by effective analgesia. Maintain high index of suspicion for pain out of proportion, especially in trauma or tight casts.

High‑Yield Points - ⚡ Biggest Takeaways

• Continuous Peripheral Nerve Catheters (CPNCs) offer prolonged postoperative analgesia, reducing opioid consumption.
• Key sites include femoral, interscalene, sciatic, and popliteal nerves.
• Ultrasound guidance is crucial for accurate placement and minimizing complications.
• Major risks: catheter-related infection and Local Anesthetic Systemic Toxicity (LAST).
• Regular monitoring for block effectiveness, catheter dislodgement, and neurovascular status is essential.
• Particularly beneficial for major joint replacements and ambulatory pain management strategies.